U.S. patent application number 16/199954 was filed with the patent office on 2019-06-27 for system, device and method for dental intraoral scanning.
This patent application is currently assigned to Dentlytec G.P.L. LTD.. The applicant listed for this patent is Dentlytec G.P.L. LTD.. Invention is credited to Benny PESACH.
Application Number | 20190192262 16/199954 |
Document ID | / |
Family ID | 56405339 |
Filed Date | 2019-06-27 |
![](/patent/app/20190192262/US20190192262A1-20190627-D00000.png)
![](/patent/app/20190192262/US20190192262A1-20190627-D00001.png)
![](/patent/app/20190192262/US20190192262A1-20190627-D00002.png)
![](/patent/app/20190192262/US20190192262A1-20190627-D00003.png)
![](/patent/app/20190192262/US20190192262A1-20190627-D00004.png)
![](/patent/app/20190192262/US20190192262A1-20190627-D00005.png)
![](/patent/app/20190192262/US20190192262A1-20190627-D00006.png)
![](/patent/app/20190192262/US20190192262A1-20190627-D00007.png)
![](/patent/app/20190192262/US20190192262A1-20190627-D00008.png)
![](/patent/app/20190192262/US20190192262A1-20190627-D00009.png)
![](/patent/app/20190192262/US20190192262A1-20190627-D00010.png)
View All Diagrams
United States Patent
Application |
20190192262 |
Kind Code |
A1 |
PESACH; Benny |
June 27, 2019 |
SYSTEM, DEVICE AND METHOD FOR DENTAL INTRAORAL SCANNING
Abstract
There is provided according to some embodiments, a system,
device and method for a three dimensional (3D) intraoral scanning
of at least a portion of a tooth. An intraoral scanner may include
a shadow casting object extending between a light emitter and the
portion of the tooth. An imaging module may image the portion of
the tooth and/or the projected shadow of the shadow casting object.
A method to construct a 3D model may include illuminating at least
a portion of the tooth with a light emitter; casting a shadow on
the portion of the tooth by an object located between the emitter
and the tooth; imaging the portion of the tooth, including at least
a part of the shadow; and determining a location of a point on the
tooth and related to the shadow, using the image.
Inventors: |
PESACH; Benny; (Rosh Haayin,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dentlytec G.P.L. LTD. |
Tel-Aviv |
|
IL |
|
|
Assignee: |
Dentlytec G.P.L. LTD.
Tel-Aviv
IL
|
Family ID: |
56405339 |
Appl. No.: |
16/199954 |
Filed: |
November 26, 2018 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
15115196 |
Jul 28, 2016 |
10136970 |
|
|
PCT/IL2016/050058 |
Jan 18, 2016 |
|
|
|
16199954 |
|
|
|
|
62104835 |
Jan 18, 2015 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06T 7/20 20130101; A61C
19/04 20130101; G06T 2200/08 20130101; G06T 7/74 20170101; A61C
9/006 20130101; A61B 1/06 20130101; G06T 1/0007 20130101; G06T
2207/10028 20130101; A61B 1/24 20130101; H04N 5/2256 20130101; A61C
3/02 20130101; G06T 7/13 20170101; G06T 15/60 20130101; G06T
2210/41 20130101; H04N 2005/2255 20130101; A61C 9/008 20130101;
G06T 17/00 20130101; G06T 2207/30036 20130101 |
International
Class: |
A61C 9/00 20060101
A61C009/00; G06T 7/13 20060101 G06T007/13; G06T 1/00 20060101
G06T001/00; G06T 7/73 20060101 G06T007/73; G06T 15/60 20060101
G06T015/60; G06T 17/00 20060101 G06T017/00; G06T 7/20 20060101
G06T007/20; A61C 3/02 20060101 A61C003/02; A61B 1/24 20060101
A61B001/24; A61C 19/04 20060101 A61C019/04; H04N 5/225 20060101
H04N005/225; A61B 1/06 20060101 A61B001/06 |
Claims
1.-31. (canceled)
32. A three dimensional (3D) intraoral scanner system for imaging
at least a portion of a tooth in an oral cavity comprising: an
intraoral portion sized and shaped for insertion into the oral
cavity, said intraoral portion including: a light emitter for
emitting a light; a shadow casting object; at least a portion of
said shadow casting object in a field of illumination of said light
source and extending away from a housing of said intraoral portion;
an imager positioned to image at least an edge of a shadow cast by
said shadow casting object in said light reflected off a portion of
a tooth located at a distance of between 3 mm and 5 cm from said
imager.
33. The intraoral scanner system of claim 32 further comprising: a
processor configured to process an image of said light received by
said imager to provide location information.
34. The system of claim 33, wherein said processor is configured to
process said image to determine a location of a portion at an edge
of said shadow.
35. The intraoral scanner system of claim 33 wherein said processer
is configured to process said image to determine a shape of said
tooth.
36. The system of claim 33, wherein said processor is further
configured to: establish a position of imager with respect to a
reference feature in the oral cavity.
37. The system of claim 36, wherein said processor is configured
for said establishing said position of said imager from said
image.
38. The system of claim 32, wherein said imager is located at a
known orientation to said light emitter.
39. The system of claim 33, wherein said processor is further
configured to: establish a position of said shadow casting object;
and establish a relative location of said imager with respect to
said light emitter and a portion of said shadow casting object.
40. The system of any of claim 32, wherein a portion of said shadow
casting object casting said edge of said shadow has a known fixed
orientation to said light emitter.
41. The system of claim 33, wherein said processor is further
configured to: establish a relative location with respect to said
light emitter of a portion of said shadow casting object casting
said edge of said shadow.
42. The system of claim 32, wherein said at least a portion of said
shadow casting object, said light emitter and said imager are
collocated such that they do not fall within 0.5 mm of a single
plane.
43. The system of claim 33, wherein said at least a portion of said
shadow casting object is within a field of view of said imager and
wherein said processor is further configured to determine a
position of said shadow casting object from said image.
44. The system of claim 32, wherein said light emitter comprises a
plurality of light sources, not all illuminated at a same time.
45. The system of claim 33, wherein said processor is configured to
process a plurality of images to designate at least one reference
feature in said plurality of images and calculate said location of
at least one point related to said shadow with respect to said
reference feature.
46. The system of claim 33, wherein said processor is configured to
designate a features which appear in at least 2 of a plurality of
images and calculate the movement of said imager relative of said
feature.
47. The system of claim 46, wherein said processor is further
configured to combine location information determined at different
imager locations to a single 3D model.
48. A system for imaging a tooth in an oral cavity comprising: a
light emitter sized and shaped to fit in an oral cavity; an imager
sized and shaped to fit in said oral cavity simultaneously with the
light emitter and directed to collect light from the light emitter
reflected off the tooth at a point of an edge of a shadow on said
tooth; a processor configured to receive an image from said imager
and process said image to determine a location of said point and a
shape of said tooth.
49. The system of claim 48, wherein said processor is further
configured to: establish a position of said imager with respect to
a reference feature in the oral cavity from said image.
50. The system of claim 49, wherein said shadow has at least two
edges cast by opposite exterior sides of the shadow casting
object.
51. The system of claim 48, wherein said processor is further
configured to: establishing a position of said object producing the
shadow from said image.
52. The system of claim 33, wherein said light emitter comprises a
plurality of light emitter elements and wherein said processor is
configured to track said shadow casting object and to select one or
more of said light emitter elements based on the location of the
shadow casting object to cast a shadow on the tooth.
53. The system of claim 48, wherein said imager comprises two
separate and spaced apart imager elements aimed at said point.
54. The system of claim 53, wherein said processor is configured to
determine a location of said point based on a difference between
images acquired by different imager elements.
Description
RELATED APPLICATION/S
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/115,196 filed on Jul. 28, 2016 (U.S. Pat.
No. 10,136,970), which is a National Phase of PCT Patent
Application No. PCT/IL2016/050058 having International filing date
of Jan. 18, 2016, which claims the benefit of priority under 35 USC
.sctn. 119(e) of U.S. Provisional Patent Application No. 62/104,835
filed on Jan. 18, 2015. The entirety of each of the disclosures are
incorporated herein by reference.
FIELD AND BACKGROUND OF THE INVENTION
[0002] The present invention, in some embodiments thereof, relates
to a system and method for intra-oral scanning and, more
particularly, but not exclusively, to a system and method of
determining the geometry of a tooth.
[0003] U.S. Published Application 2015/0348320 to the present
applicant and others relates to, "A method for measuring regions of
a tooth in a mouth including: measuring at least one surface point
on a surface of the tooth with respect to an element mechanically
coupled to said surface point; determining a location of at least
one visible reference mechanically coupled to said surface point
with respect to said element; estimating a location of said surface
point with respect to said visible reference. A device used for
such measuring may include a main body comprising a final optical
element of an imager which defines an optical field of view
directed in a first direction; and a measurement element coupled to
said main body extending generally in said first direction; where a
tip of said measurement element is sized and shaped to be inserted
between a tooth and adjacent gingiva; where said optical field of
view is sized to image at least part of a tooth."
SUMMARY OF THE INVENTION
[0004] According to an aspect of some embodiments of the invention,
there is provided a method of imaging a tooth comprising:
illuminating at least a portion of the tooth with a light emitter;
casting a shadow on the portion of the tooth by an object between
the emitter and the tooth; imaging the portion of the tooth,
including at least a part of the shadow; and determining a location
of a point on the tooth and related to the shadow, using the image
including the shadow.
[0005] According to some embodiments of the invention, the method
comprises constructing a shape of the portion based on the
determining.
[0006] According to some embodiments of the invention, constructing
comprises repeating the illuminating, casting, imaging and
determining for a plurality of locations.
[0007] According to some embodiments of the invention, the method
further includes: producing an image of light collected from the
portion of the tooth including at least two points related to the
shadow; processing the image to determine a 3D location of the at
least two points.
[0008] According to some embodiments of the invention, the
determining comprises determining relative to a model of the
tooth.
[0009] According to some embodiments of the invention, the
determining comprises determining relative to a model of a
plurality of teeth.
[0010] According to some embodiments of the invention, the method
comprises acquiring a plurality of images of the portion and
wherein the determining comprises determining a movement of the
imager from a plurality of images.
[0011] According to some embodiments of the invention, the method
further comprises: storing a plurality of the images; designating
at least one reference feature in the plurality of images and
calculating the location of at least two points related to the
shadow with respect to the reference at least one feature.
[0012] According to some embodiments of the invention, the
reference is at least one of a tooth or gums.
[0013] According to some embodiments of the invention, the
determining comprises determining a relative position of an imager
used for imaging and the tooth and the object.
[0014] According to some embodiments of the invention, the object
is fixed relative to the imager.
[0015] According to some embodiments of the invention, the object
is rigid. According to some embodiments of the invention, the
method comprises identifying a deformation of the object.
[0016] According to some embodiments of the invention, the method
comprises identifying a shape of a portion of the shadow in the
image and identifying a point of intersection defined by the shadow
and the tooth based on the shape.
[0017] According to some embodiments of the invention, the
determining comprises determining the location of a line comprising
a plurality of points in a same cast shadow.
[0018] According to some embodiments of the invention, imaging
comprises imaging a plurality of teeth simultaneously with the part
of the shadow.
[0019] According to some embodiments of the invention, illuminating
comprises selecting an illumination point.
[0020] According to some embodiments of the invention, illuminating
comprises selecting a plurality of illumination points, applied in
sequence.
[0021] According to some embodiments of the invention, the imaging
includes imaging from a viewpoint and wherein determining includes:
sighting the point from a viewpoint; and establishing a relative
location of the object with respect to the viewpoint and wherein
the determining is based on the relative location.
[0022] According to some embodiments of the invention, the
determining includes: sighting the point from each of two
viewpoints; and establishing a relative location of two viewpoints
and wherein the determining is based on the relative location.
[0023] According to some embodiments of the invention, the method
further comprises: inserting an imager into an oral cavity
containing the tooth and wherein the determining further includes
sighting the tooth with the imager.
[0024] According to some embodiments of the invention, the
illuminating includes: inserting a light emitter into an oral
cavity containing the tooth, and wherein the illuminating is by the
light emitter.
[0025] According to some embodiments of the invention, the method
further comprises: establishing a relative position of the shadow
casting object with respect to the light emitter.
[0026] According to some embodiments of the invention, the location
is with respect to the imager.
[0027] According to some embodiments of the invention, the object,
an imager used for imaging and a light emitter used for
illuminating are fixedly coupled and inserted as a unit into an
oral cavity containing the tooth, with the object extending away
from a housing of the unit.
[0028] According to some embodiments of the invention, the location
is with respect to a shadow casting object.
[0029] According to some embodiments of the invention, the method
comprises storing at most a lower representation of the image after
the determining.
[0030] According to an aspect of some embodiments of the invention,
there is provided a three dimensional (3D) intraoral scanner system
for imaging at least a portion of a tooth in an oral cavity
comprising: an intraoral portion sized and shaped for insertion
into the oral cavity, the intraoral portion including: a light
emitter for emitting a light; a shadow casting object; at least a
portion of the shadow casting object in a field of illumination of
the light source and extending away from a housing of the intraoral
portion; an imager positioned to image at least an edge of a shadow
cast by the shadow casting object in the light reflected off a
portion of a tooth located at a distance of between 3 mm and 5 cm
from the imager.
[0031] According to some embodiments of the invention, the
intraoral scanner system further comprises: a processor configured
to process an image of the light received by the imager to provide
location information.
[0032] According to some embodiments of the invention, the
processor is configured to process the image to determine a
location of a portion at an edge of the shadow.
[0033] According to some embodiments of the invention, the
processer is configured to process the image to determine a shape
of the tooth.
[0034] According to some embodiments of the invention, the
processor is further configured to: establish a position of imager
with respect to a reference feature in the oral cavity.
[0035] According to some embodiments of the invention, the
processor is configured to track a position of the portion in the
cavity.
[0036] According to some embodiments of the invention, the position
is provided using the imager.
[0037] According to some embodiments of the invention, the
processor is configured for the establishing the position of the
imager from the image.
[0038] According to some embodiments of the invention, the
processor is further configured to: establish a position of the
object producing the shadow.
[0039] According to some embodiments of the invention, the imager
is located at a known orientation to the light emitter.
[0040] According to some embodiments of the invention, the
processor is further configured to: establish a position of the
shadow casting object; and establish a relative location of the
imager with respect to the light emitter and a portion of the
shadow casting object.
[0041] According to some embodiments of the invention, a portion of
the shadow casting object casting the edge of the shadow has a
known orientation to the light emitter.
[0042] According to some embodiments of the invention, the
processor is further configured to: establish a relative location
with respect to the light emitter of a portion of the shadow
casting object casting the edge of the shadow.
[0043] According to some embodiments of the invention, the system
further comprises an elongated handle having a length between 8 to
30 cm, a width less than 15 cm.
[0044] According to some embodiments of the invention, the at least
a portion of the shadow casting object, the light emitter and the
imager are collocated such that they do not fall within 0.5 mm of a
single plane.
[0045] According to some embodiments of the invention, the system
further includes an orientation sensor sensing an orientation of
the at least a portion of the shadow casting object with respect to
the light emitter.
[0046] According to some embodiments of the invention, the
orientation sensor includes the imager and wherein the at least a
portion of the shadow casting object is within a field of view of
the imager.
[0047] According to some embodiments of the invention, the emitter
radiates light from surface fitting within a sphere of radius 5
mm.
[0048] According to some embodiments of the invention, the light
emitter comprises a plurality of light sources, not all illuminated
at a same time.
[0049] According to some embodiments of the invention, the
processor is configured for computing a location of at least two
spaced apart portions of the shadow with respect to the imager.
[0050] According to some embodiments of the invention, the
processor is configured to process a plurality of images to
designate at least one reference feature in the plurality of images
and calculate the location of the at least two portions with
respect to the reference feature.
[0051] According to some embodiments of the invention, the
processor is configured to designate at least 3 features which
appear in at least 2 of a plurality of images and calculate the
movement of the imager relative of the features.
[0052] According to some embodiments of the invention, the
processor is further configured to combine location information
determined at different imager locations to a single 3D model.
[0053] According to some embodiments of the invention, the
processor is further configured to combine locations of the at
least 3 features identified at different imager locations to the
single 3D model that includes the location information determined
at each imager location.
[0054] According to some embodiments of the invention, the
processor is configured to compute a location of at least two
points related to the edge of the shadow with respect to an
intraoral reference feature.
[0055] According to an aspect of some embodiments of the invention,
there is provided a system for imaging a tooth in an oral cavity
comprising: a light emitter sized and shaped to fit in an oral
cavity; an imager sized and shaped to fit in the oral cavity
simultaneously with the light emitter and directed to collect light
from the light emitter reflected off the tooth at a point of an
edge of a shadow on the tooth; a processor configured to receive an
image from the imager and process the image to determine a location
of the point and a shape of the tooth.
[0056] According to some embodiments of the invention, the
processor is further configured to: establish a position of imager
with respect to a reference feature in the oral cavity.
[0057] According to some embodiments of the invention, the
processor is configured for the establishing the position of the
imager from the image.
[0058] According to some embodiments of the invention, the
processor is further configured to: establishing a position of the
object producing the shadow.
[0059] According to some embodiments of the invention, the system
comprises: a dental probe sized and shaped so the shadow can be
cast by the dental probe.
[0060] According to some embodiments of the invention, the light
emitter comprises a plurality of light emitter elements and wherein
the processor is configured to track the dental probe and to select
one or more of the light emitter elements to use for casting a
shadow, based on the location of the probe to cast a shadow on the
tooth.
[0061] According to some embodiments of the invention, the
processor is configured to determine a tooth location relative to
the dental probe.
[0062] According to some embodiments of the invention, the
processor is configured to locate an edge of a shadow in an image
from the imager and avoid storing a full resolution image
thereafter.
[0063] According to some embodiments of the invention, the imager
comprises two separate and spaced apart imager elements aimed at
the point.
[0064] According to some embodiments of the invention, a first
imager element has a wider FOV (field of view) than a second imager
of the imager elements, suitable for imaging an object outside of
the tooth, while the second imager element images the point.
[0065] According to some embodiments of the invention, the
processor is configured to determine a location of the point based
on a difference between images acquired by different imager
elements.
[0066] Unless otherwise defined, all technical and/or scientific
terms used herein have the same meaning as commonly understood by
one of ordinary skill in the art to which the invention pertains.
Although methods and materials similar or equivalent to those
described herein can be used in the practice or testing of
embodiments of the invention, exemplary methods and/or materials
are described below. In case of conflict, the patent specification,
including definitions, will control. In addition, the materials,
methods, and examples are illustrative only and are not intended to
be necessarily limiting.
[0067] As will be appreciated by one skilled in the art, some
embodiments of the present invention may be embodied as a system,
method or computer program product. Accordingly, some embodiments
of the present invention may take the form of an entirely hardware
embodiment, an entirely software embodiment (including firmware,
resident software, micro-code, etc.) or an embodiment combining
software and hardware aspects that may all generally be referred to
herein as a "circuit," "module" or "system." Furthermore, some
embodiments of the present invention may take the form of a
computer program product embodied in one or more computer readable
medium(s) having computer readable program code embodied thereon.
Implementation of the method and/or system of some embodiments of
the invention can involve performing and/or completing selected
tasks manually, automatically, or a combination thereof. Moreover,
according to actual instrumentation and equipment of some
embodiments of the method and/or system of the invention, several
selected tasks could be implemented by hardware, by software or by
firmware and/or by a combination thereof, e.g., using an operating
system.
[0068] For example, hardware for performing selected tasks
according to some embodiments of the invention could be implemented
as a chip or a circuit. As software, selected tasks according to
some embodiments of the invention could be implemented as a
plurality of software instructions being executed by a computer
using any suitable operating system. In an exemplary embodiment of
the invention, one or more tasks according to some exemplary
embodiments of method and/or system as described herein are
performed by a data processor, such as a computing platform for
executing a plurality of instructions. Optionally, the data
processor includes a volatile memory for storing instructions
and/or data and/or a non-volatile storage, for example, a magnetic
hard-disk and/or removable media, for storing instructions and/or
data. Optionally, a network connection is provided as well. A
display and/or a user input device such as a keyboard or mouse are
optionally provided as well.
[0069] Any combination of one or more computer readable medium(s)
may be utilized for some embodiments of the invention. The computer
readable medium may be a computer readable signal medium or a
computer readable storage medium. A computer readable storage
medium may be, for example, but not limited to, an electronic,
magnetic, optical, electromagnetic, infrared, or semiconductor
system, apparatus, or device, or any suitable combination of the
foregoing. More specific examples (a non-exhaustive list) of the
computer readable storage medium would include the following: an
electrical connection having one or more wires, a portable computer
diskette, a hard disk, a random access memory (RAM), a read-only
memory (ROM), an erasable programmable read-only memory (EPROM or
Flash memory), an optical fiber, a portable compact disc read-only
memory (CD-ROM), an optical storage device, a magnetic storage
device, or any suitable combination of the foregoing. In the
context of this document, a computer readable storage medium may be
any tangible medium that can contain, or store a program for use by
or in connection with an instruction execution system, apparatus,
or device.
[0070] A computer readable signal medium may include a propagated
data signal with computer readable program code embodied therein,
for example, in baseband or as part of a carrier wave. Such a
propagated signal may take any of a variety of forms, including,
but not limited to, electro-magnetic, optical, or any suitable
combination thereof. A computer readable signal medium may be any
computer readable medium that is not a computer readable storage
medium and that can communicate, propagate, or transport a program
for use by or in connection with an instruction execution system,
apparatus, or device.
[0071] Program code embodied on a computer readable medium and/or
data used thereby may be transmitted using any appropriate medium,
including but not limited to wireless, wireline, optical fiber
cable, RF, etc., or any suitable combination of the foregoing.
[0072] Computer program code for carrying out operations for some
embodiments of the present invention may be written in any
combination of one or more programming languages, including an
object oriented programming language such as Java, Smalltalk, C++
or the like and conventional procedural programming languages, such
as the "C" programming language or similar programming languages.
The program code may execute entirely on the user's computer,
partly on the user's computer, as a stand-alone software package,
partly on the user's computer and partly on a remote computer or
entirely on the remote computer or server. In the latter scenario,
the remote computer may be connected to the user's computer through
any type of network, including a local area network (LAN) or a wide
area network (WAN), or the connection may be made to an external
computer (for example, through the Internet using an Internet
Service Provider).
[0073] Some embodiments of the present invention may be described
below with reference to flowchart illustrations and/or block
diagrams of methods, apparatus (systems) and computer program
products according to embodiments of the invention. It will be
understood that each block of the flowchart illustrations and/or
block diagrams, and combinations of blocks in the flowchart
illustrations and/or block diagrams, can be implemented by computer
program instructions. These computer program instructions may be
provided to a processor of a general purpose computer, special
purpose computer, or other programmable data processing apparatus
to produce a machine, such that the instructions, which execute via
the processor of the computer or other programmable data processing
apparatus, create means for implementing the functions/acts
specified in the flowchart and/or block diagram block or
blocks.
[0074] These computer program instructions may also be stored in a
computer readable medium that can direct a computer, other
programmable data processing apparatus, or other devices to
function in a particular manner, such that the instructions stored
in the computer readable medium produce an article of manufacture
including instructions which implement the function/act specified
in the flowchart and/or block diagram block or blocks.
[0075] The computer program instructions may also be loaded onto a
computer, other programmable data processing apparatus, or other
devices to cause a series of operational steps to be performed on
the computer, other programmable apparatus or other devices to
produce a computer implemented process such that the instructions
which execute on the computer or other programmable apparatus
provide processes for implementing the functions/acts specified in
the flowchart and/or block diagram block or blocks.
[0076] Some of the methods described herein are generally designed
only for use by a computer, and may not be feasible or practical
for performing purely manually, by a human expert. A human expert
who wanted to manually perform similar tasks might be expected to
use completely different methods, e.g., making use of expert
knowledge and/or the pattern recognition capabilities of the human
brain, which would be vastly more efficient than manually going
through the steps of the methods described herein.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
[0077] Some embodiments of the invention are herein described, by
way of example only, with reference to the accompanying drawings.
With specific reference now to the drawings in detail, it is
stressed that the particulars shown are by way of example and for
purposes of illustrative discussion of embodiments of the
invention. In this regard, the description taken with the drawings
makes apparent to those skilled in the art how embodiments of the
invention may be practiced.
[0078] In the drawings:
[0079] FIGS. 1A and 1B are simplified schematic illustrations of a
3D intraoral scanner system according to some embodiments of the
present invention;
[0080] FIG. 1C is a simplified illustration of a 3D intraoral
scanner system according to some embodiments of the present
invention;
[0081] FIG. 1D is a simplified schematic illustration of the
configurations of the shadow parameter of FIG. 1C;
[0082] FIGS. 2A, 2B, 2C and 2D are simplified schematic
illustrations of a 3D dental intraoral scanner system with multiple
light emitters, according to some embodiments of the present
invention;
[0083] FIG. 3A illustrates a high level flow chart of an embodiment
of a method intra oral scanning using shadows in accordance with an
embodiment of the present invention;
[0084] FIG. 3B is a flow chart illustration of further details a
method of 3D data from an intraoral scan in accordance with an
embodiment of the present invention;
[0085] FIG. 4 is a flow chart illustration of a method of modeling
a tooth while a investigating a tooth with a scanner including a
dental probe in accordance with an embodiment of the present
invention;
[0086] FIG. 5 is a flow chart illustration of a method of modeling
a tooth while investigating a tooth with a scanner including a
dental probe and multiple light emitters in accordance with an
embodiment of the present invention;
[0087] FIG. 6 is a flow chart illustration of a semi-passive method
of modeling a tooth while a investigating a tooth in accordance
with an embodiment of the present invention;
[0088] FIG. 7 is a flow chart illustration of a method of modeling
a tooth when navigation data is available on the oral cavity in
accordance with an embodiment of the present invention;
[0089] FIG. 8 is a flow chart illustration of a method of modeling
a tooth using multiple overlapping image sensors in accordance with
an embodiment of the present invention;
[0090] FIG. 9 is a schematic illustration of a scanner having
multiple shadow casting objects in accordance with an embodiment of
the present invention;
[0091] FIG. 10 is a schematic illustration of a scanning system
having multiple imagers in accordance with an embodiment of the
present invention;
[0092] FIG. 11 is a schematic illustration of a scanner having
multiple imagers in accordance with an embodiment of the present
invention;
[0093] FIG. 12 is a block diagram of an intraoral scanner in
accordance with an embodiment of the present invention;
[0094] FIG. 13 is a block diagram of a portion of an intraoral
scanner system in accordance with an embodiment of the present
invention and
[0095] FIG. 14 is a block diagram of a portion of an intraoral
scanner system in accordance with an embodiment of the present
invention.
DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION
[0096] The present invention, in some embodiments thereof, relates
to a system and method for intra-oral scanning and, more
particularly, but not exclusively, to a system and method of
constructing a 3D model of a tooth or teeth.
Overview
[0097] An aspect of some embodiments of the current invention
relates to a method of producing and/or imaging shadows to
determine the three dimensional geometry of a tooth surface.
Optionally, a shadow may be cast onto the tooth by an object
located between the tooth and a light emitter illuminating the
surface. In some embodiments, an image of the surface and/or the
shadow and/or a portion thereof is captured by a light collector
and/or analyzed. A 3D location may be determined of a point related
to the shadow (for example a point on the surface at an edge of the
shadow and/or one point inside the shadow and one point outside the
shadow, delineating the edge of the shadow between the points).
Optionally, multiple images may be combined to construct a 3D model
of the surface, the tooth, gums, an arch, a portion of the oral
cavity and/or the entire oral cavity. Optionally multiple points
along a shadow edge will be determined. Multiple points may give
information of the size and/or direction of a shadow.
[0098] In some embodiments, use of shadows may facilitate measuring
and/or determining three dimensional geometry of an intra-oral
object (for example a tooth, a bone, and/or an arch). Optionally
the imaging is done while simultaneously measuring sub-gingival
structures. Optionally measurements are made without the use of
penetrating radiation (such as x-ray methods for example tradition
x-rays, computerized axial tomography CAT scans, cone beam
imaging). Optionally measurements may be made without the use of a
laser and/or structured light (for example a projected optical
pattern) and/or a computer controlled scanning light emitters. Use
of a shadow to discern 3D features has a potential disadvantage
that shadow edges may tend to get fuzzy and/or diffused and/or
spread as the distance increases between the shadow producing
object and the surface upon which the shadow falls. Nevertheless,
in some embodiments, a device producing shadows may be cheaper
and/or smaller than a device producing a projected grid etc.
[0099] In some embodiments, the location of a point on a shadow may
be calculated, for example as the intersection of two lines. For
example, the two lines may include two lines of sight from two
spaced apart view points to the point on the shadow. For the sake
of this disclosure a view point may be the location of a light
collector, for example the centroid of the optical aperture
thereof, for example a camera and/or another imager. For the sake
of this disclosure a line of sight may includes the line from the
view point to the point being measured (e.g. the edge of the shadow
on the surface and/or the centroid of an area, for example a
blurred edge). For example, the coordinates of the point being
measured may be found using in stereo vision methods for example
including binocular range finding where the location is at the
intersection of the two lines of sight from two spaced apart view
points to the point being measured on the surface. Alternatively or
additionally, the location of a point on a shadow on the surface
may be identified as the intersection of a line of sight and a line
of illumination. For the sake of this disclosure, a line of
illumination may include a line from an illumination point and/or a
centroid of a light emitter to the location being measured, for
example the centroid thereof. For example, a line of illumination
to a point on the edge of a shadow includes a line passing from the
illumination point, past the edge of the shadow producing object to
the edge of the shadow on the surface. Alternatively or
additionally, for example, when a shadow is cast by an object with
a straight edge, all the points of the shadow edge may fall in a
plane defined by the illumination point and the line of the edge of
the shadow casting object. In some embodiments, the 3D location of
a point on the tooth may be determined by computing the point of
intersection between the plane of the shadow edge and the line of
sight from the imager to the point. The direction of the line of
sight to the point is optionally calculated from the location of
the point in an image. The plane of the shadow is optionally
determined by the location of the light emitter aperture and the
edge of the shadow casting object.
[0100] In some embodiments, the illuminated portion of a shadow
producing object may have a short dimension of between 0.1 to 0.3
mm and/or between 0.3 to 0.7 mm and/or between 0.7 to 3 mm and/or
between 3 to 10 mm and/or between 10 to 30 mm. Optionally the
illuminated portion of a shadow producing object may have a long
dimension of between 0.1 to 0.3 mm and/or between 0.3 to 0.7 mm
and/or between 0.7 to 3 mm and/or between 3 to 10 mm and/or between
10 to 30 mm and/or between 30 to 50 mm or more. For example the
shadow casting object may be elongate with a long illuminated
dimension between 3 to 5 times the short illuminated dimension
and/or between 5 to 10 times and/or between 10 to 50 times or
more.
[0101] In some embodiments, the area of a shadow on an image may be
less than 1/100 the illuminated area and/or between 1/100 to 1/20
of the illuminated area and/or between 1/20 to 1/10 of the
illuminated area and/or between 1/10 to 1/4 of the illuminated area
and/or between 1/4 to 1/2 of the illuminated area and/or between
1/1 to equal to the illuminated area and/or between equal to twice
the illuminated area and/or between twice to four times the
illuminated area and/or between four times to ten times the
illuminated area and/or between ten times to one hundred times the
illuminated area.
[0102] In some embodiments, an image may include less than 100
shadow edges and/or less than 10 shadow edges and/or less than 5
shadow edges and/or less than 3 shadow edges. In some embodiments,
an image may include less than 100 parallel shadow edges and/or
less than 10 parallel shadow edges and/or less than 5 parallel
shadow edges and/or less than 3 parallel shadow edges. In some
embodiments, the total length of shadow edges in an image may be
less than 100 times the length of the long edge of the image and/or
between 10 to 100 times the length of the long edge of the images
and/or between 1 to 10 times the length of the long side of the
images and/or between 1/4 to 1 times the length of the long side of
the image and/or less than 1/4 the length of the long edge.
[0103] In some embodiments, a shadow will be in the central portion
of an image. For example the shadow may fall entirely in the
central (from side to side and/or from top to bottom) 1/2 of the
image and or the central 1/4 of the image. Alternatively or
additionally, the shadow may fall entirely in the peripheral (from
side to side and/or from top to bottom) 1/2 of the image and or the
peripheral 1/4 of the image. In some embodiments, a shadow may have
one outer edge inside an image and/or between 1 to 4 outer edges in
the image. In some embodiments, a shadow in an image may include a
projection of an outer edge of the shadow producing object and/or
of two opposing edges of the shadow may be projections of two
opposing outer edges of the shadow producing object.
[0104] In some embodiments, the distance of the shadow producing
objects to the surface being imaged may be less than 1 mm and/or
between 1 mm to 3 mm and/or between 3 mm to 10 mm. In some
embodiments, the distance of the shadow producing objects to the
surface being imaged may be less than 1 mm and/or between 1 mm to 3
mm and/or between 3 mm to 10 mm. In some embodiments, the distance
of the light emitter to the surface being imaged may be less than 1
mm and/or between 1 mm to 3 mm and/or between 3 mm to 10 mm.
[0105] In some embodiments, a feature in a shadow may be used to
mark a point on a surface (for example the surface may lack
identifiable features e.g. a smooth surface). For example, the
location of the marked point may be imaged from two view points and
its location found by triangulation (for example stereoscopy or
using at least 2 images made at spaced apart viewpoints, the images
are optionally made by a single camera and/or using multiple
cameras and/or a camera with multiple apertures). Alternatively or
additionally, a shape of a shadow may be used to determine a shape
of a surface. For example, a bending of a shadow may indicate that
a surface is bent and/or lengthening of a shadow may indicate that
a surface is angled away from the light emitter and/or an axis of
the shadow producing object. Optionally, a cast shadow may be used
for discovering object's concavities, which are sometimes difficult
to measure based on other cues such as occluding boundaries.
[0106] Optionally some or all of the light collector, light emitter
and/or shadow producing object have a fixed relative location. For
example, they may be fixed in an intraoral scanning device.
Alternatively or additionally, the field of view FOV of the light
collector may include at least a portion of the shadow casting
object such that the location of the shadow casting object and/or
deformation of the shadow casting object may be identified by image
analysis. The location in 3D space of a point related to the shadow
may be adjusted using image of said shadow casting object.
Optionally the location of the light collector may be identified
with respect to features in an oral cavity by image analysis.
[0107] In some embodiments, an imaging method may include
establishing a spatial relationship between components of the
system. For example, a spatial relationship may be tracked in real
time. For example, relative positions may be tracked using an
optical tracking system, for example one or more cameras sighting a
system component and/or the oral cavity. Alternatively or addition,
a location of a component may be tracked using a beacon (for
example a radio frequency RF beacon) and/or a local positioning
system. Alternatively or additionally, some aspects of a spatial
relationship between components of the system may be fixed.
[0108] In some embodiments, light emitter may include any object
that illuminates the tooth. For example, the light emitter may
include a light source such as a light emitting diode and/or a
laser. Alternatively or additionally, the light emitter may include
a light shaping element such as a lens and/or an optical fiber.
[0109] In some embodiments, an object may be actively introduced
between a light emitter and a tooth to produce the shadow.
Alternatively or additionally, a shadow may be produced by the
geometry of the tooth itself and/or by a passive object. For
example, the shadow casting object may include a dental tool and/or
a specially designed probe with optional fiducial marking.
[0110] In some embodiments, measurements of the shadow edge 3D
profile may have a tolerance of, for example, between 10 um to 50
um and/or between 50 um to 100 um and/or from 100 um to 200 um.
[0111] In some embodiments, relative position of system components
may be established to a linear tolerance, of for example, between
10 um to 50 um and/or between 50 um to 100 um and/or from 100 um to
200 um. Optionally an imaging sensor may have a resolution of about
1 Mpixels. For example, the resolution may vary over a range, for
example, of 0.4-15 Mpixels or even lower or higher resolutions.
Optionally a light collector may have a FOV of about 60 deg. For
example the FOV may vary over a range of for example 10 to 30
degrees and/or 30 to 60 degrees and/or 60 to 90 degrees or greater
or smaller.
[0112] In some embodiments, imaging a shadow may result in
measurements and/or images that will be used to establish a spatial
relation during post processing. For example, images produced by a
light collector may be analyzed to establish a spatial
relationship. Optionally the light collector may have a field of
view FOV that includes a shadow producing object and/or a light
emitter. Optionally an imaged produced from the light collector may
be analyzed to establish a position of the shadow producing object
and/or a navigational reference feature with respect to the light
collector. Alternately or additionally a fiducial marker may be
used and/or a position sensor. Data from the marker and/or the
position sensor may be processed to establish the location of one
or more components of the system.
[0113] In some embodiments measuring an oral cavity and/or
intra-oral object may include establishing a spatial location of
components of the system and/or of determining a spatial location
of an image feature with respect to a reference feature, for
example an intra-oral object and/or feature. Except where clearly
used otherwise, the term navigation is used in this disclosure to
mean establishing the location of a system component with respect
to a reference (for example a reference feature in the oral
cavity). For example, a location may be tracked in real time.
Optionally, the location may be tracked based using an optical
tracking system, for example one or more cameras viewing a system
component and/or the oral cavity. Alternatively or additionally, a
location of a system component and/or an imaged object and/or a
reference feature may be tracked using a marker and/or a beacon
(for example a radio frequency RF beacon) and/or a local
positioning system signal.
[0114] In some embodiments, a previously identified reference
feature (for example an object identified in a previous intra-oral
scan and/or in a CT scan) may be used to as references to establish
the location of a system component and/or determine the location of
an imaged object. Alternatively or addition, reference features may
be recognized during processing of a collection of data. In some
embodiments artificial reference markers may be used, for example
marking a location on a tooth with a dye and/or powder and/or a
sticker and/or placing a fiduciary marking in the oral cavity. In
some embodiments, natural reference features may be used, for
example a distinguishable feature of a tooth and/or a pallet and/or
an arch. In some embodiments, a fixed dental structure may be used
as a reference, for example a crown and/or a bridge. Alternatively
or additionally, inertial navigation may be employed to track the
location of a system component and/or an object in the oral cavity.
For example, a gyro and/or an accelerometer may be attached to a
component of the system and/or an object in the oral cavity.
[0115] In some embodiments, images may be made simultaneously or
nearly simultaneously. For example, an imagers may capture a pair
of images in less than one second (sec) and/or between 1 to 1/30
sec and/or between 1/30 to 1/200 sec and/or between 1/200 to 1/700
sec and/or between 1/700 to 1/1000 sec. Optionally the capture rate
may be even higher for lower resolution and/or smaller ROIs. For
example, separate images may be captured with a light emitter
activated in a different position resulting in a different position
of a shadow. Alternatively or additionally multiple light
collectors may be illuminate the imaged structure from different
locations. The different light emitters may have different
frequencies and/or be activated in quick succession to produce
shadows at multiple locations substantially simultaneously. For the
sake of this disclosure substantially simultaneously may mean
within a time period wherein the oral cavity normally moves less
than a measurement tolerance. For images made substantially
simultaneously, the spatial relationship between locations may be
determined from their relative spatial positions.
[0116] An aspect of some embodiments of the current invention
relates to intra-oral scanning device. Optionally, the device
includes one or more light collectors and/or one or more light
emitters and/or one or more shadow producing elements (for example
a dental tool). Optionally the scanning device may include a
housing (for example components such as the light emitter, image
and/or shadow caster may be mounted to the housing and/or may be
contained in the housing and/or may be integral to the housing).
Optionally the relative orientation of the components in the
housing is known and/or fixed. Optionally one or more of the system
components is included in a portion of the housing shaped and sized
to fit into an oral cavity. Optionally the housing is shaped, sized
to be handled by a single human hand from outside the oral cavity.
For example, a user may use a handle outside the oral cavity to
manipulate the scanner inside the cavity.
[0117] In some embodiments, a spatial relationship may be
established based on a fixed spatial relationship between some
elements of the system. For example, a light emitter and a light
collector may be fixed in a tool with a fixed geometric structure.
Alternatively or additionally, a shadow producing object such as a
probe may be fixed in the tool. Alternatively, a light collector
and a shadow producing object may be fixed into a tool.
Alternatively, a light emitter and a shadow producing object may be
fixed into a tool. Alternatively or additionally one or more light
emitters and/or light collectors may be independent of the tool.
Alternatively or additionally there may be multiple tools including
one or more of a light emitter, a light collector and/or a shadow
producing object.
[0118] In some embodiments, a light collector may include an image
sensor and/or a light shaping element (for example a lens and/or
optical fiber) directing light to an image sensor. An example of an
image sensor is for instance a CMOS sensor [for example an ON-Semi
Python1300 CMOS sensor available from ON Semiconductor 5005 East
McDowell Road Phoenix, Ariz. 85008 USA, with 1.3 Mpixels
(1024.times.1280) resolution, global shutter to avoid image
distortions because of movements, that captures up to 545 frames
per second FPS on full frame and 1000s FPS on smaller ROIs.
Optionally a sensor may have between 10 to 10.sup.3 pixels and/or
from 10.sup.3 to 10.sup.5 pixels and/or 10.sup.5 to 5.times.10
.sup.5 pixels and/or 5.times.10 .sup.5 to 5.times.10 .sup.6 pixels
and/or 5.times.10 .sup.6 to 5.times.10 .sup.7 pixels and/or
5.times.10 .sup.7 to 10.sup.9 pixels.
[0119] In some embodiments, a light emitter may include a light
emitting element and/or a light shaping element (for example an
optical fiber and/or a lens) directing light to a region of
interest ROI (for example an intra-oral object including a tooth
and/or a reference feature and/or a shadow producing object for
example a dental tool). For example, a white LED may be used. In
some embodiments, white illumination facilitates obtaining a color
image of the ROI. For example the light emitters may be point
emitters of light for example having a light emitting surface of
between 3 to 1 mm.sup.2 and/or between 1 to 1/10 mm.sup.2 and/or
between 1/10 to 1/100 mm.sup.2 and/or between 1/100 to 1/10000
mm.sup.2. For example, a larger light emitter may include an LED
and/or a smaller light emitter may include a laser diode. For
example, where the light emitter is large, the distance between the
shadow producing object and a surface being imaged may be decreased
and/or where the light emitter is large, the distance between the
light emitter a surface being imaged may be increased.
[0120] In some embodiments, a housing may have a length ranging
between 10-25 cm. In some embodiments, a housing may have a maximum
width ranging between 1-3 cm. In some embodiments, a system may
have a weight ranging between 20 g-1 Kg.
[0121] In some embodiments, the shadow producing element may
include a dental tool, for example, a periodontal probe. For
example, the tool may protrude to a distance between 5-25 mm from
the housing. For example, the tool may have a maximum width ranging
between 1-3 mm. For example, the tool may include a fiducial
marking. For example, fiducial markings may include a protrusion, a
small ball, a hole, a colored area and/or an indentation.
Optionally, markings may be arranged to indicate an orientation,
for example an angle and/or a length. In some embodiments, the
distance between a light emitter and a light collector may range
between 1 to 10 mm and/or between 10 to 50 mm and/or greater than
50 mm. In some embodiments, a distance between a light emitter and
a probe tip may range between 5-50 mm or more than 50 mm. In some
embodiments, the distance between a light collector and a probe tip
may range between 5-50 mm or more than 50 mm. In some embodiments,
a probe may have a sharp tip.
[0122] In some embodiments, a navigation sensor may be provided.
For example, a tool may include a light collector for imaging a
tooth and/or a shadow producing object and/or a navigation sensor,
which is used to establish the location of the light collector. For
example, the navigation sensor may include an imaging light
collector whose orientation to a light emitter, light collector
and/or shadow casting object is fixed. The navigation sensor is
optionally configured to detect its location with respect to a
reference feature and/or the navigation sensor optionally has a
wide field of view for capturing an orientation to a reference
feature. Alternatively or additionally a single light collector
used for locating a point on a shadow and/or navigating, for
example the light collector may have a wide FOV to capture the
reference features along with the shadow. Optionally the FOV may be
between 5 to 25 degrees and/or between 25 to 45 degrees and/or
between 45 to 90 deg and or greater than 90 degrees. Reference
features in the FOV of the light collector may optionally be used
for navigation.
[0123] An aspect of some embodiments of the current invention
relates to intra-oral scanning and/or navigation during use of a
dental tool (for example a probe used to measure a sub-gingival
feature or a dental drill). For example, images may be recorded of
a dental probe, a revealed surface of a tooth and/or gums, a
reference feature and/or a shadow on the surface. The images may be
processed in real time and/or in post processing to establish the
location of the probe in relation to the reference feature and/or
the geometry of the surface and/or the orientation of geometric
features of the surface with respect to the reference feature.
Optionally image recording may be accomplished with minimal or no
interruption of the use of the probe.
[0124] In some embodiments, while a user measures teeth or gums of
a subject using a dental probe, images may be collected showing the
probe position and/or a shadow of the probe on a tooth and/or
shadows of shadows cast by tooth structures. The images may be
later processed to produce a model of geometry of the tooth and/or
determine locations of measurements made with the probe. For
example, a portion of the shadow casting object may be distanced
from the light source between 0.1 to 1 mm and/or between 1 mm to 5
mm and/or between 5 mm to 30 mm and/or between 30 mm to 50 mm
and/or greater than 50 mm. For example, the shadow casting object
may move independently of the probe.
[0125] In some embodiments, the device may measure deformations of
the probe. For example, deformation of the probe may be used to
determine when and/or where the probe tip contacts a sub-gingival
object. Alternatively or additionally, a calculation of shadow
location may be corrected for deformations of the shadow casting
object.
[0126] In some embodiments, a light emitter may be configured to
reduce interference with activity of the user. For example, while a
user is measuring teeth and/or sub-gingival structures under
visible light (for example wide bandwidth white light), light
emitters and/or collectors may be illuminating and/or imaging
structures using non-visible wavelengths (e.g. UV and/or IR).
Alternatively or additionally, while a user is measuring teeth
and/or sub-gingival structures under visible light (for example
wide bandwidth white light), light emitters and/or collectors may
be illuminating and/or imaging structures using visible light in a
narrow bandwidth.
[0127] An aspect of some embodiments of the current invention
relates to a method and system to track shadow casting object in
real time and direct a device for imaging a shadow of the object on
a tooth. In some embodiments, a processor may be configured to
track the shadow casting object. The processor may optionally,
direct a select a light emitter for activation and/or direct a
light emitter in order to cast a shadow of the object on the tooth.
Alternatively or additionally, a system for mapping an oral cavity
may track movement of a shadow casting object and direct a light
collector towards the location of the shadow. Alternatively or
additionally, the processor may track a position of a tooth and a
light source and position the shadow casting object to cast a
shadow on the tooth. In some embodiments the location of features
and/or shadows are located in a model and/or in the coordinate
system of a model. Optionally features of the model may be
constructed using interpolation and/or extrapolation. Optionally
measured features will be related to the model.
[0128] In some embodiments, an intra-oral scanning system may
include multiple light sources and/or one or more shadow casting
object. A dental system may include a processor that tracks the
orientation of the light sources and/or shadow casting objects and
selectively activates a light source in order to cast a shadow on a
particular tooth and/or a particular region of a tooth.
[0129] In some embodiments, the processor identifies the location
of a scanned tooth in an image captured by an imager. For instance,
the tooth may be identified relative to the gums using color
segmentation. The processor optionally uses the tooth location
relative to the probe to illuminate the probe with at least one
light source to cast a shadow on a ROI on the tooth. For example,
while the probe scans the tooth, different light sources are
selected to illuminate the ROI and cast the shadow at a desired
location. Factors considered in selecting the light source may
include, for instance the contrast between the shaded and
illuminated regions, and/or measurement error at different regions
(for example a shadow may be projected where it has the largest
baseline related to the imager).
[0130] In some embodiments, the image of the cast shadow and/or may
be analyze a cast shadow to decide which light source to
activate.
[0131] Before explaining at least one embodiment of the invention
in detail, it is to be understood that the invention is not
necessarily limited in its application to the details of
construction and the arrangement of the components and/or methods
set forth in the following description and/or illustrated in the
drawings and/or the Examples. The invention is capable of other
embodiments or of being practiced or carried out in various
ways.
DETAILED EMBODIMENTS
Intraoral Scanner With a Single Light Source
[0132] Referring now to the figures, FIGS. 1A and 1B are each a
simplified schematic illustration of a 3D dental intraoral scanner
(IOS) system 100 according to some embodiments of the present
disclosure. As seen in FIGS. 1A-D, the exemplary IOS system 100
comprises an IOS 102. IOS 102 includes a hand piece 104 and a head
portion 108. In accordance with some embodiments, from an
oral-facing surface 110 of the head portion 108 extends a shadow
casting object 114 (shadow casting object is an object located
between a light emitter and the tooth, such that a portion of said
shadow casting object casts a shadow on at least a portion of the
tooth. In some cases said shadow casting object may have also a
dental functionality, for example a dental probe, or ultrasonic
scaler, or a dental drill or dental turbine or any other dental
tool.) In the schematic embodiment shown at FIGS. 1A-D, shadow
casting object 114 is a dental probe. The oral-facing surface 110
optionally includes a light emitter, light source 116, and an
optical aperture 158 of a light collector, camera 160.
[0133] In some embodiments light source 116 may include any
suitable light source, such as a light-emitting diode (LED), a
laser, such as edge emitter or VCSEL etc. Light source 116
optionally includes beam shaping optics, such as a lens, for
example to use the light source light efficiently. The light source
spectrum may be for instance blue, such as 450 nm LEDs or lasers,
which may in some embodiments provide better contrast on the tooth
or any other spectra, such as white or green or IR light etc. In
some embodiments, optical fibers with a remote light source may be
used.
[0134] In some embodiments, probe 114 and/or light source 116 may
be utilized for 3D measurements of a portion of a tooth 120, and/or
for measurement of the full tooth and/or for measurement of a
plurality of teeth and/or for measurement of a partial or full
dental arch and/or at least a portion of the dental arch.
[0135] In some embodiments, during scanning, light source 116 may
be illuminated onto a chosen surface, for example to illuminate
surface of a tooth or gums. The illumination is optionally used for
imaging the surface. The chosen surface may comprise any surface on
the tooth, such as a top surface 122, a bottom surface 124 and/or
side surfaces 126 thereof
[0136] In some embodiments, the illumination also falls on probe
114. Optionally, probe 114 casts a shadow on a chosen surface 140
of a tooth 120 or gums. The shadow may include a projection of the
probe geometry on the chosen surface. The tooth image is optionally
captured by a light collector, for example camera 160 through an
optical aperture 158. Optionally, a portion of probe 114 is seen in
the camera image as well as a portion of its shadow 144 (for
example as illustrated in FIG. 1A) on a tooth surface 140.
[0137] In some embodiments probe 114 has a linear edge. Optionally,
the projection of the linear edge of the probe shadow 144 may be
geometrically considered as included in a plane 142 (for example as
illustrated in FIG. 1C) defined by the respective probe edge and
light source 116. Each point in the shadow edge image falls
somewhere in plane 142. The line of sight from optical aperture 158
to a point on the shadow defines a ray such as rays X, Y and Z that
extends from optical aperture 158 to plane 142. The point of
intersection of the ray and the plane is also the edge of the
shadow on the surface. In some embodiments, the 3D location of the
intersection of a ray and a plane is calculated. The intersection
may optionally provide a 3D profile of a tooth portion. In some
embodiments, to get 3D information, optical aperture 158 is located
outside of the plane of light emitter 116 and probe 114.
[0138] In some embodiments, features and/or the shape of a surface
is understood from the shape of a shadow on the surface. For
example, the intersection between plane 142 and a flat surface
would be a line. Curves bends or deformations of the line of the
shadow indicate a curvature or deformation and/or angling of the
surface.
[0139] In some embodiments shadow 144 forms a 3D line on surface
140. The line is optionally imaged by camera 160. In some
embodiments, the orientation of a ray (for example rays X, Y, Z)
between the camera and the shadow are derived from the image made
by the camera. The 3D orientation of the ray may be found from the
image, for example using the camera intrinsic and extrinsic
parameters, such as the angle of the camera and the camera optics.
Alternatively or additionally, the 3D orientation of the ray may be
found, for example by relating the position of the point of the
shadow in the image to the position of one or more reference
features in the image. The 3D relationship between light source 116
and probe 114 are optionally used to calculate the orientation of
plane 142. For example, based on the orientation of plane 142 and
the orientation of a ray to a point on shadow 144 (for example rays
X, Y and Z) the location of a point on shadow 144 is determined in
any coordinate system, for example the system defined by an X axis
130, a Y axis 132 and a Z axis 134 relative to the IOS 102. A
non-limiting example of a configuration of the shadow parameters,
such as the angle and length are shown in FIG. 1D, which is self
explanatory.
[0140] In some embodiments, the 3D coordinates of shadow 144
obtained in an image are stored in a coordinate system related to
the position of the IOS at the time that the image was made, this
coordinate system may be referred to as an IOS coordinate system.
Optionally, the IOS coordinates system of different images may
differ, for example due to movement of camera between images. In
some embodiments, the IOS coordinates of shadow 144 are transformed
into a tooth global coordinates system. For example, the
transformation may be performed by finding the 3D relation between
the IOS camera 160 and the tooth 120. The 3D relationship between
the camera and the tooth may be found using, for example, Structure
from Motion (SfM) methods or any other suitable methods.
Optionally, probe 114 is scanned around tooth 120, for example to
gather data with which to construct a 3D model of tooth 120. The 3D
model may be stored in coordinates of a tooth global coordinate
system.
[0141] FIG. 1A and 1B illustrate exemplary tooth surfaces and
shadows in accordance with some embodiments of the current
invention. For example, surface 140 (defined by dashed lines) on
tooth 120 may be substantially flat in an X-Y plane. For example,
the shadow of a linear probe 114 projected on a flat surface 140
may be a substantially straight line 146, as seen in the insert. In
FIG. 1B, an exemplary surface 150 on tooth 120 may include a curved
surface 152. For example, the shadow 156 of linear probe 114
projected on the curved surface 150 may appear to curve from some
viewpoints.
[0142] In some embodiments, camera 160 may be placed close to the
optical aperture 158, which is defined as the camera lens exit
pupil. Alternatively or additionally camera 160 may be located at a
larger distance from aperture 158. Optionally relay optics and/or a
mirror may be used to convey light from aperture 158 to camera 160.
In some embodiments, this may facilitate reducing the size of the
intraoral portion of the IOS 102.
[0143] In some embodiments, camera 160 may capture images at a high
frame rate. For example, a frame rate may range between 500-2000
frames per second (FPS). In some embodiments, an image may be
limited to only the shadow and/or additional feature of interest.
Limiting images size may facilitate increasing the frame rate of
image capture, reducing scan time and/or higher precision. For
example, the images may be limited by using only a portion or few
portions of the camera image sensor (for example between 0 to 10%
and/or between 10 to 30% and/or between 30 to 70% and/or between 70
to 100%). For example, the image may be limited by using Region of
Interest (ROI) reading, which is supported by many CMOSs. In some
embodiments, ROI reading facilitates higher frame rate. Limited
data from an image may take less than 5% and/or between 5 to 10% of
the memory space of the original image and/or between 10 to 30%
and/or between 30 to 60% and/or between 60 to 90% and/or between 90
to 99% of the memory space of the original image.
[0144] In some embodiments, during scanning shadow 144 may be
projected on any surface of tooth 120. Optionally, camera 160
images the shadow. For example, shadow 144 may be moved
continuously across one or more surfaces of tooth 120. At any
surface, the image of the projected shadow is optionally captured
by camera 160. The captured images are optionally processed by a
processing system 170. Processing system 170 optionally comprises
image analysis functionality and/or data processing functionality.
Processed data is optionally used for constructing a 3D model of
the tooth surfaces.
[0145] A non-limiting example, the processing algorithm is
illustrated in FIG. 3B. In some embodiments, the exemplary process
may be performed to obtain a model of a portion of a tooth, a full
tooth, few teeth, and/or a full arch.
[0146] In some embodiments processing system 170 may include a
controller. Optionally, the controller may control parameters
related to the light source 116. For example, controller 170 may
control the angle of the illuminated light relative to oral-facing
surface 110 and/or relative to a surface on tooth 120 and/or
controller 170 may control a duration of illumination.
[0147] In some embodiments, probe 114 may have some flexibility
and/or be deformed from a perfect straight edge. Optionally,
markers (for example fiducials) may be marked or attached to the
probe. Optionally, by analyzing their location in the image, the
location of various portions of the deformed probe 114 may be
estimated. Exemplary algorithms for such calculations are described
in U.S. Patent publication 2015/0348320.
[0148] In some embodiments, contact between a tip of probe 114 and
a tooth may be identified based on deformation of probe 114. Method
for identifying this contact are described for instance as
described in U.S. Patent publication 2015/0348320. In some
embodiments, the location 127 where probe 114 tip touches tooth 120
may be included in a 3D model of tooth 120. For example, contact of
the tip and the tooth are optionally used to map parts of the tooth
that are obscured by blood, fluids or the gums.
[0149] In some embodiments, the geometry of the IOS is fixed and/or
known. For example, the known geometry may include the 3D
relationship between the locations of light source 116, probe 114
and/or aperture 158. In some embodiments, intrinsic parameters of
the camera 160, such as equivalent focal length EFL, distortion
etc. may be obtained by calibrating the IOS 102 prior to performing
a scan. Alternatively or additionally, the calibration information
may be obtained during the tooth scan, using suitable methods, for
example a bundle adjustment method.
[0150] In some embodiments, the probe includes fiducials or
markers. Optionally the markers are in the FOV of the camera 160.
For example, the distance between a pair of markers may be a known.
For example, data about the markers may be used for calibrating a
3D model. Alternatively or additionally, fiducials seen by the
camera 160 may be used for identifying probe movements relative to
optical aperture 158 for example due to probe distortion.
Optionally calculations may be adjusted to compensate for the
distortion. Compensation may be added to calculation of the shadow
location and/or calculation of the probe tip location.
Probe With Fiducial Markers
[0151] FIGS. 2A and 2B illustrate, an IOS 200 with multiple light
emitters in accordance with an embodiment of the current invention.
A light source 216 optionally comprises a plurality of light
emitters, for example LEDs 180 and/or lasers. Alternatively or
additionally, optical fibers with a remote light source/s may be
used. In the exemplary embodiments of FIGS. 2A and 2B six LEDs 180
are circumferentially arranged on the oral-facing surface 110. It
is appreciated that any suitable number of light emitters may be
provided and/or may be arranged in any suitable arrangement at any
suitable location within the IOS system 200.
[0152] In some embodiments, a shadow 244a of probe 114 is cast on a
surface of tooth 120 to be imaged. The surface is optionally
illuminated by one of LED's 180, selected to cast shadow 244a onto
the chosen surface. In some embodiments, controller 170, by aid of
the camera 160, may receive a measurement of the spatial
orientation (e.g. angle) of the chosen surface relative to the
probe 116. The angle may be defined for example by the 3D
coordinate system 136. The controller 170 is optionally configured
to select the appropriate LED 180, suitably placed relative to the
probe 116 to illuminate the surface. Accordingly, the shadow 144
will be cast upon the surface.
[0153] In a non-limiting example, a surface of tooth 120 comprises
a proximal surface 190 and a distal surface 192. The plurality of
LEDs 180 comprises a distally positioned LED 196 and a proximally
positioned LED 198. For example as illustrated in FIG. 2A, a chosen
surface for imaging may include a proximal surface 190. To
illuminate and cast a shadow on proximal surface 190 controller 170
optionally selects to illuminate distal LED 196. A shadow 244a is
thus projected on the chosen, proximal surface 190.
[0154] FIG. 2B, illustrates an exemplary configuration wherein the
chosen surface for imaging is distal surface 192. In some
embodiments controller 170 may select to illuminate the proximal
LED 198. A shadow 244b is thus projected on the chosen, distal
surface 192.
[0155] In some embodiments, a user may scan the probe around an
object to be scanned. As the user scans the object, the processing
unit computes the geometrical relation between the probe 114 and
the tooth 120 for each image during the scan and may activate the
proper light source 116 accordingly. Thus, the LEDs 180 may be
manipulated to illuminate in accordance with the chosen surface of
the tooth 120. Optionally, multiple light emitters may be
illuminated sequentially. For example, while scanner 200 is
scanning around a tooth, different LED's (e.g. LED''s 198, 196) of
light source 216 may be illuminated. For example, the LED's may be
switched in a fast sequence, such that the position of the scanner
almost does not change between illumination events. Optionally, the
resulting images may be related one to another and/or made into a
mosaic to relate (e.g. determine relative position of) features on
different surfaces and/or to relate features revealed by different
shadow 244a, 244b positions.
[0156] FIGS. 2C and 2D illustrate an intra-oral scanner being used
to scan tooth 120 while a user probes the tooth 120, for example,
under a gum line in accordance with an embodiment of the current
invention. Optionally the user scans probe 114 around the tooth
close to and/or under the gums, as seen at FIG. 2C. Optionally, a
shadow 244c is cast over the wall and/or crown of tooth 120.
Processing unit 170 optionally identifies the location of scanned
tooth 120 relative to probe 114 and/or the location of the side of
tooth 120 relative to probe 114 and/or illuminates tooth 120 from
opposite probe 114, to cast a shadow 244c on the scanned
surface.
[0157] In some embodiments, the user may scan the probe 114 around
tooth 120, such that the tip of probe 114 gets below the gums line,
for example to scan a subgingival finish line. In some embodiments
the probe 114 includes additional features, as seen for example in
FIG. 2D. For example, shadow 244c, shown schematically casted over
the wall and tooth crown in FIG. 2D, includes additional shadows
244d and 244e cast by fiducial markers 215a and 215b respectively.
Optionally markers 215a and 215b are perpendicular to probe 114
direction and parallel to the scan around the tooth direction, the
additional depth point obtained from shadow 244d and 244e are out
of the plane created by probe 114 and light source and/or may
provide 3D information on points on the tooth that are out of aid
plane. In some embodiment, different fiducial markers may have
different directions. Some of the markers may be positioned to cast
shadows when illuminated by one LED 198 while other may be
positioned to cast a shadow with another LED 196. Additionally or
alternatively, the form of a shadow of the fiducial marker
processor 170 may determine the relative direction of the light
source with relation to the illuminated surface and/or the
direction of the illustrated surface. The 3D information from the
shadows of the fiduciary markers may optionally be used, by
processing unit 170 to estimate probe and/or IOS movements between
the different images.
[0158] In some embodiments, more than one LED 180 may be
illuminated simultaneously to provide more than one shadow on the
surface of the tooth 120.
[0159] In some embodiments, more than one LED 180 may be
illuminated sequentially synchronized with the camera 160 to
provide more than one shadow on the surface of the tooth 120 in
separate images. In some embodiments, the sequential illumination
may be fast enough to be substantially simultaneous (for the
sequential images may be captured in a time small enough that no
significant movement occurred in the meantime).
[0160] In some embodiments, the light source 116 may be placed on
another object away from the IOS 102.
[0161] In some embodiments, more than one camera may be used to
capture said probe shadow from several angles and improve 3D
accuracy. Optionally multiple cameras may take images
simultaneously. In some embodiments, more than one camera may be
used to capture more and/or better features for estimating the
camera pose and tooth 3D surface.
[0162] In some embodiments, a pattern projector may be added, such
that the image of said pattern projected over at least one tooth
may be support the 3D model and camera pose estimation.
[0163] In some embodiments, the pattern projector and additional
light sources may be used at a certain temporal sequence to combine
the depth information achieved by each light source.
High Level Flow Chart
[0164] Referring now to the drawings, FIG. 3A illustrates a high
level flow chart of a method intra oral scanning using shadows in
accordance with an embodiment of the present invention. In some
embodiments, a shadow is cast 354 on an intra-oral surface, for
example a surface of a tooth. For example, the tooth may be
illuminated 352 from an illumination point and/or a shadow may be
cast 354 on the surface. For example, the shadow casting object may
include a passively occurring object and/or an artificially
inserted object. Data from the position of the light and/or shadow
is optionally recorded 356. For example, the data may include
digital information on the position and/or orientation of a
component of the system and/or the shadow. Alternatively or
additionally, the data may include an image of an object, a
component of the system and/or the shadow. The shape of the surface
is optionally determined from the geometry of system and/or the
apparent location and/or geometry of the shadow from a defined
perspective. For example, the shadow may be imaged using an imager
from the viewpoint. The shape of the surface may be determined from
the shadow based on knowing the position of the light source, the
position and/or shape of the shadow casting object and/or the
position of the view point.
[0165] In some embodiments, a shadow is cast 354 on a surface to be
imaged by illuminating 352 the surface with a light emitter. An
object between the illumination source and the surface optionally
casts a shadow on the surface.
[0166] In some embodiments, an image may be recorded 356 of a
location related a shadow on the surface. For example, the location
may be at an edge between the shadow and an illuminated region of
the surface. In some cases, the edge may be smeared over a region,
depending on the size of the illumination source aperture, and the
location may be defined at a certain level over the edge gradient.
Optionally, the shadow may cover a small portion of the surface,
for example between 0 to 5% and/or 5 to 25% and/or 25 to 50% of the
surface, ROI and/or tooth may be covered by the shadow.
Alternatively or additionally, the shadow may cover a large portion
of the surface for example between 50 to 55% and/or 55 to 75%
and/or 75 to 90% and/or 90 to 100% of the surface, ROI and/or tooth
may be covered by the shadow. Alternatively or additionally, the
illuminated region may be within the shadow and/or around the
shadow. In some embodiments, the shadow region and illuminated
region may both be continuous. In some embodiments, there may be
multiple disconnected shadows inside a connected illuminated
region. In some embodiments, there may be multiple disconnected
illuminated regions inside a connected shadow region. For example,
the shadow producing objects may include an area having a hole and
the illuminated region may include a spot where light passing
through the hole impinges on the surface. For example the shadow
casting object include part of housing, wall, probe, and/or special
probe with markers.
[0167] In some embodiment, a shadow casting object may include a
dental probe. Optionally the probe may be imaged 356 (for example
using wide enough FOV imager to image the RIO and the probe).
Images of the probe may be used as for computing 368 the location
of the shadow casting edge. Alternatively or additionally, a shadow
of the probe may be imaged 356 while the probe is being used to
investigate a sub gingival structure.
[0168] In some embodiments, images may be recorded 365 and/or
analyzed 362. For example, images of the probe may be used to
establish 364 the position of a revealed portion of the probe.
Knowledge of the probe geometry may be used to establish 364 the
location of a hidden part of the probe (for example the probe tip
that may be hidden by blood and/or tissue). For example, the system
may establish 364 the location of a probe tip while the tip is in
contact with a subgingival point of a tooth. A large number of such
images and/or points may be combined to construct 373 a 3D model of
a revealed and/or a hidden structure (for example a revealed
portion of a tooth and/or a subgingival portion of a tooth).
[0169] In some embodiments a probe may have a sensor that senses
when the probe contact a tooth (for example a pressure gauge and/or
a strain gauge) the imager is optionally in communication with the
sensor to image the probe when the tip is in contact with the
tooth. Alternatively or additionally, a probe may be connected to
an actuator. For example, the actuator may extend the probe tip
outward to contact a surface and/or retract the tip to allow the
user to move the device for example to investigate another
location. The imager is optionally synchronized to the actuator to
image the probe and/or the ROI and/or a shadow of the probe when
then probe is extended. In some embodiments, said probe length may
be controlled to extend or retract according the scanned tooth
size.
[0170] FIG. 3B is a flow chart illustration of further details a
method of 3D data from an intraoral scan in accordance with an
embodiment of the present invention. In a non-limiting example, the
processing algorithm may include for example, identifying 365 at
least one edge of the probe shadow in the image.
[0171] In some embodiments, the 3D coordinates of the shadow are
calculated 363 relative to a convenient coordinate system. For
example, the relative coordinates may be in relation a component of
the IOS scanner, for example relative to the light collector (for
example an optical aperture thereof). The relative coordinates are
optionally computed 363 based on the established 364 geometry of
system components (i.e. the 3D relationship between the light
source, the shadow casting object, and/or the light collector) in
the coordinate system of the light collector. In some embodiments,
the relative coordinate system may be relative to a moving object.
For example, the coordinates may be relative to the transient
position of the scanner. For example, the relative coordinate
system of one image may differ from the relative coordinate system
of another image.
[0172] In some embodiments, reference features are designated 367
and their locations determined 366. For example, features may be
designated 367 and/or matched 369 across images. A number of the
features may optionally be designated 367 (for example enough
objects are designated 367 in order to locate to orient images of
the entire ROI) as reference features and/or the global location of
other objects may be found from relative position with respect to
the reference features.
[0173] In some embodiments, features on teeth portion or gums
viewable in the image are designated 367. For example, feature
extraction may be done by any suitable computer vision algorithms
for feature extraction. An example of such an algorithm includes
the Scale-Invariant Feature Transform (or SIFT).
[0174] In some embodiment, features designated 367 in different
images are matched 369. Matching 369 optionally correlates all the
features together, for example, using methods know in the art, such
as Random sample consensus (RANSAC) to remove outliers and find a
camera 3D translation and rotation that fits the feature matching.
Once the rotation and translation of the camera is established 364
for each frame, all the frames may optionally be aligned to a
single coordinate system. For each image, the relative coordinates
and/or the camera location may be transformed 371 into the unified
3D coordinates. Motion of the camera relative to the teeth is
optionally defined and/or images may be corrected for this motion.
Defining and/or correcting for camera motion may be performed for
example by suitable method for computer vision such as the
Structure from motion (SfM), bundle adjustment, least squares,
RANSAC, etc. Exemplary algorithms optionally use feature matching
to solve for the camera translation and rotation (camera pose) for
each frame.
[0175] In some embodiments, images may be combined and/or stitched
together. For example 3D information on the tooth surface obtained
from each image of the probe shadow based on the translation and
rotation of the camera may be put together to build 373 a 3D model
of the oral cavity or parts thereof. The features, which were
matched between the images, are optionally added to the 3D model as
well.
[0176] In some embodiments, the exemplary process may be performed
to obtain a full tooth, or few teeth, or a 3D model of the full
arch.
Method of Scanning With a Scanner Having Fixed Probe, LED and
Imager
[0177] FIG. 4 is a flow chart illustration of a method of modeling
a tooth while investigating 451 a tooth with a scanner including a
dental probe in accordance with an embodiment of the present
invention. The scanner optionally includes a light source (for
example an LED) and an imager. Optionally, while a user
investigates 451 the surface, the light source illuminates 352 the
surface and casts 354 a shadow of the probe onto the surface. The
imager optionally captures 456 an image of the surface, the shadow
and/or a portion of the probe. Image analysis optionally determines
the geometry of the surface.
[0178] In some embodiments, the scanner may have the form of a
dental probe and associated handle. A user (for example a dentist
and/or a dental assistant) optionally investigates 451 a region of
a tooth using the probe. For example, by placing tip of the probe
in contact with the tooth, the user also positions the scanner in
front of a surface of the tooth with the LED and the imager pointed
toward the surface. For example, the LED may be located on the
scanner in a region between the user and the probe such that the
LED illuminates 352 the tooth surface. For example, the LED is
directed also to illuminate the probe and thereby cast 354 a shadow
of the probe on the surface. Optionally with the LED located in a
region between the user and the probe, the shadow of the probe is
pointed away from the user reducing inconvenience that the shadow
may cause the user. Illuminating 352 the probe and tooth optionally
serves the user for example illuminating the tooth on which he is
working and/or illuminating markers (for example measurement marks)
on the probe.
[0179] In some embodiments, while the user is investigating 451 a
tooth, the imager captures 456 images of the illuminated surface of
the tooth and/or the probe and/or the shadow. Images are optionally
stored and/or sent to a processor for analysis 362.
[0180] Optionally the FOV of the imager is large enough that each
image contains features that will be used as reference features. In
some embodiments, designated features of a previous oral scan may
be used to navigate and/or locate objects in the oral cavity.
Alternatively or additionally, the image data will be used to
identify reference features that occur in multiple images and/or
are used to orient images and/or establish the relative positions
of images and/or system components during the scanning.
[0181] In some embodiments, as the user continues 358 to
investigate 451 the tooth, he reposition 460 the scanner, repeating
the imaging process, until he covers an entire region of interest
ROI. As the user traverses the ROI so the scanner captures 456
images of the ROI from various perspectives.
[0182] In some embodiments, analysis 362 includes establishing 364
the 3D positions of system components, for example the sensor, the
light source and/or the probe. For example, in each image, intra
oral features may be designated 366 as reference features. The
locations of the intra oral features may be used to establish 366
the position of the imager with respect to the oral cavity and/or
to determine 368 the location of measured features in the entire
oral cavity and/or when combining images to build 373 a 3D model of
multiple surfaces (for example an entire tooth and/or an arch
and/or a set of teeth).
[0183] In some embodiments, images from the scanner are analyzed
362. For example, analysis 362 may be performed during post
processing. Alternatively or additionally, images may be analyzed
362 in real time. For example, by the time the user has finished
his investigation 451, the processor may have analyzed 362 the
images and may present the 3D model to the user. Alternatively or
additionally, analysis may identify regions of the tooth that are
not properly mapped (for example regions where the data is not
dense enough and/or where different images resulted in different
measurements leaving a large margin of error in the measurements.
The processor may warn the user that he should continue 358
scanning to repeat scanning the improperly mapped region.
Optionally a warning may be issued earlier in the scanning process,
for example after establishing camera movement 364, designating a
reference object 366 and/or even prior to image analysis 362.
[0184] In some embodiments, the 3D positions of system components
may be established 364 during analysis. Stored images are
optionally analyzed 362 to designate 366 reference features. For
example, reference features may include identifiable features that
are fixed in the oral cavity and/or apparent in more than one
image. For example, from the positions of the reference features
multiple images may be co-oriented. Based on the orientation of
each an image to the reference features, the position of the imager
is optionally established 364.
[0185] In some embodiments, the position and/or orientation of the
light source and/or the probe may be established 364 based on the
position and/or orientation of the imager and a known relative
position of the components. For example, the position of the LED,
imager and/or a base of the probe may be fixed into the scanner
such that their relative positions are known. The original and/or
unstressed shape of the probe may also be known such that the
unstressed position of the entire shadow casting object is known.
For example, in some embodiments the probe tip may move by between
0 to 0.05 and/or from 0.05 to 0.1 mm and/or between 0.1 to 0.5 mm
to the side when force is applied on the tooth. Optionally, images
of the probe and/or its markers may be used to determine a
deviation from its unstressed shape.
[0186] In some embodiments, based on the positions of the LED, the
imager and/or the position and/or shape of the probe, and/or the
orientation of the image with respect to a reference feature, the
location of a point on the shadow on the surface is computed 368
with respect to the reference feature. Optionally, the positions of
a large number of points on the surface are calculated 368 and
correlated to build 373 a 3D model of the tooth.
[0187] In some embodiments, shadows cast 354 by additional object
may be used to determine the shape of the tooth. For example, a
concave portion of a tooth surface may cast 354 a shadow on itself.
The shape of the shadow under different angles of illumination may
help determine the geometry of the surface.
[0188] In some embodiments, an intra-oral scanner may be used to
locate hidden intra-oral features. For example, when a user is
probing a hidden object (for example a subgingival portion of a
tooth and/or the interior of a hole in the tooth), the known
position of the probe (identified for example from an image) and/or
geometry of the probe (optionally based on the unstressed geometry
and/or corrected for deviations from the unstressed geometry) may
be used to determine the position of a hidden point that is in
contact with the probe tip.
Method of Scanning With a Scanner Having a Fixed Probe, Multiple
Light Emitters and an Imager
[0189] FIG. 5 is a flow chart illustration of a method of modeling
a tooth while a investigating a tooth 451 with a scanner including
a dental probe and multiple light emitters in accordance with an
embodiment of the present invention. The scanner optionally
includes multiple light sources (for example one or more optical
fiber light guides connected on one end to a light source emitting
light from the other end and/or one or more LED's) and an imager.
Optionally, while a user investigates 451 a tooth, one of the light
sources illuminates 352 the surface of the tooth and/or illuminates
the probe casting 354 a shadow of the probe onto the surface. The
imager optionally captures 456 an image of the surface, the shadow
and/or a portion of the probe. Image analysis 362 optionally
determines the geometry of the surface.
[0190] In some embodiments, as the scanner is positioned and
repositioned 460 in the oral cavity, the orientation of the scanner
with respect to the ROI may changes. Optionally, for each
orientation of the scanner at least one of the light emitters is
properly oriented to illuminate 352 the surface and/or the probe to
cast a shadow on the surface. For example, as the scanner passes to
the left side of a tooth ROI, a light emitter on the right side of
probe is activated such that the ROI is illuminated and a shadow of
the probe falls on the ROI. Optionally selecting of the proper
light source is done automatically. For example, a processor may
use cue's from the orientation and/or movement of the scanner to
determine what the user is investigating 451. Optionally or
additionally, the processor may recognize landmarks in the images
produced by the imager in order to navigate in the oral cavity and
track the orientation between the scanner and the ROI. Optionally
or additionally, the processor may identify the scanned tooth. The
processor may select a light emitter to illuminate the tooth and
provide a shadow on the tooth. Alternatively or additionally, the
processor may use cues from the images to determine which image
contains the shadow and/or which light emitter is producing a
shadow that is detected on the surface of the ROI. Alternately or
additionally, the user may manually select 561 light sources to
illuminate an area where he is working and/or the light source may
be arranged so that the shadow of the probe falls on the
illuminated region.
[0191] In some embodiments, separate light sources may be selected
561 successively. For example, different light sources may be
activated and/or deactivated and images made be taken of the system
with lighting from various angles. In some of the images, the
shadow of the probe may fall in the ROI. These images are
optionally selected for full processing, for example to determine
the shape of the surface of the ROI. In other images, the shadow
may not fall in the ROI. These images are optionally discarded.
Alternatively, images where the shadow does not fall with the ROI
may be processed for example for navigation and/or recognition of
reference features.
[0192] In some embodiments, for more than one light emitter, the
shadow of the probe may be cast 354 onto the ROI. Optionally, by
switching light sources, the shadow is repositioned 460 within the
ROI. Optionally by switching quickly (for example over a time
period of less than 1 msec and/or between 0.001 to 0.1 sec and/or
between 0.1 to 10 sec) the shadow will be repositioned 460 with
position of the scanner and oral cavity substantially unchanged.
For the sake of this disclosure, images taken within a time period
where changes in the system and/or orientation are less than an
error tolerance of the system may be described as having been made
substantially simultaneously. For example, for two images taken
substantially simultaneously may be used to determine a spatial
interrelationship between different points and/or feature measured
on different shadows.
[0193] In some embodiments, flashing on and off of different light
sources from different angles may disrupt and/or disturb a user.
Optionally to avoid such disruption, the light source may be in an
invisible frequency (for example infrared and/or ultraviolet). For
example, the user may illuminate the ROI as he likes with visible
light while the scanner illuminates 352 and/or captures 456 images
of light on a different wavelength. Alternatively or additionally,
the light emitters and/or imager may be tuned to a narrow frequency
band. The user whom may work with a constant wide frequency light
source may not be bothered by flashes of highly concentrated narrow
frequency radiation while the highly focused imagers may be immune
to the wide band noise produced by the user's illumination.
Alternatively or additionally, flashes of illumination and/or
images synchronized and/or may be made quickly to reduce disruption
to the user. For example, the flashes length may be less than a
subject awareness limit and/or an objective awareness limit. For
example, flashes may last for less than 1 ms and/or between 1 to 20
ms and/or between 20 to 50 ms and/or between 50 to 100 ms and/or
greater than 100 ms.
Method of Scanning Semi-Passively
[0194] FIG. 6 is a flow chart illustration of a semi-passive method
of modeling a tooth while a investigating a tooth in accordance
with an embodiment of the present invention. The scanner optionally
includes a one or more imagers. Optionally, while a user
investigates the ROI he casts 354 a shadow on a surface of the ROI
(for example the shadow may be cast 354 by a dental probe). An
imager optionally captures 356 an image of the ROI, the shadow
and/or a portion of the probe. Image analysis 362 optionally
determines the position of the probe and/or the geometry of the
surface.
[0195] In some embodiments, an imager may be mounted on a dental
tool. For example, an imager may be mounted on a handle of a
conventional light emitter such as a dental mirror. The user
working in a usual conventional fashion positions 651 the mirror in
front of a ROI and/or illuminates 352 the ROI.
[0196] In some embodiments, the user works with a tool of his
choice, for example a conventional dental probe. The user in the
course of his work investigating the ROI introduces 653 the probe
between the light emitter and the ROI casting 354 a shadow on a
surface of the ROI. In some embodiments, as the user moves the
mirror and/or the probe, the shadow moves 660. Optionally as the
user scans the teeth with the probe, the shadow is also scanned
across the teeth.
[0197] In some embodiments, the imager is configured to capture an
image 356 of the surface of the ROI, the shadow and/or the probe.
For example, the imager may be directed toward a region illuminated
352 by light reflected from the mirror. For example, when the user
positions 651 the mirror in front of the ROI he is also positioning
655 the light collector in front of the ROI. Alternatively or
additionally, the imager may have a wide FOV such that it captures
images 356 of the surface, the shadow of the probe, another shadow,
the probe and/or a reference feature from a range of
orientations.
[0198] In some embodiments, as the user works, continuing 358 to
investigate the ROI from various perspectives, he moves the mirror
and/or the probe thereby moving 360 the shadow over the surface of
the ROI. While the user is working, the imager is capturing images
of the ROI and the shadow from the various perspectives and/or over
various locations of the surface of the ROI.
[0199] In some embodiments, an additional imager may be included.
For example, an imager may be supplied outside an oral cavity
and/or not facing the ROI. For example, an additional imager may be
mounted on a dental lamp (optionally the viewpoint of the
additional imager may substantially coincide with the lamp.
Alternatively or additionally, the location of the imager may be
offset from the lamp. For example, mounting the additional imager
with a view point coinciding with the lamp may help keep the
additional imager directed at the intended objects (for example the
ROI, the mirror, and the probe). Alternatively or additionally
mounting the additional imager offset from the lamp may facilitate
imaging the shadow. The imager on the lamp may optionally catch an
image of the light emitter (for example he mirror), a light
collector (for example the imager mounted on the mirror handle)
and/or the shadow and/or the ROI (for example as it is reflected in
the mirror and/or directly in the case where the user is
investigating an area exposed directly to the light.
[0200] In some embodiments, an additional imager may be used to for
binocular location of objects and/or of locations on a surface. For
example, two imagers may be located outside of the oral cavity.
Optionally the relative orientation of the two imagers may be known
and/or fixed. From the two images captured 356 at different
viewpoints, the exact location of an object in the images may be
computed. For example, the location may be computed for a dental
mirror and/or intra-oral sensor and/or of a reference feature in
the oral cavity. For example, the dual external cameras may give
the location of the oral cavity and at least some of the time of
the mirror and/or intra-oral imager. Optionally the dental mirror
and/or the external lamp and/or one, some or all of the imagers may
include an accelerometer and/or gyroscope for tracking the absolute
location and/or motion of the component. For example, when the
image data is not sufficient to track the locations of components,
the absolute location and/or movement data may be used to fill in
and/or preserve measurement accuracy.
Method of Scanning When Navigation Data is Available
[0201] FIG. 7 is a flow chart illustration of a method of modeling
a tooth when navigation data is available on the oral cavity in
accordance with an embodiment of the present invention. Optionally,
in some cases an object may be investigated in an oral cavity for
which navigation data is available. For example, when placing a new
crown in an oral cavity where work was done previous, such that
detailed knowledge of much of the oral cavity is available, but it
is desired to map changes for example to model a portion of the
tooth that has been prepared from the crown. Alternatively or
additionally, an intra-oral scan may be performed in an oral cavity
that has been marked previous, for example with powder that may
provide features on the tooth and/or by adding a mark and/or a
fiducial marker.
[0202] In some embodiments, navigation information may be obtained
using tracking methods known in the art, for instance active
electromagnetic tracking that use at least one source coil that
transmit electromagnetic radiation and at 3 orthogonal receiving
coils that senses the direction and distance to said at least one
source. One of them may act as a stable reference and the second
may be attached to the IOS.
[0203] In some embodiments, navigation information may be obtained
using additional sensors, such as gyro, accelerometer, digital
compass etc.
[0204] In some embodiments, navigation information is used to
establish 764 a location of a scanner and/or a shadow casting
object and/or an imager and/or to determine 368 the location of a
shadow during scanning. Alternatively or additionally, markers may
be used to simplify analysis 362 of data (for example markers may
be used to orient different images one to another without requiring
separate identification of reference features). In some embodiments
the entire analysis may be performed in real time for example while
a user is investigating sub gingival structures the scanning system
may model super gingival structure and/or relate super gingival
structures to sub gingival structures detected by a probe.
Method of Scanning Employing Binocular Stereo Vision
[0205] FIG. 8 is a flow chart illustration of a method of modeling
a tooth using multiple overlapping image sensors in accordance with
an embodiment of the present invention. For example, two or more
overlapping image may be capture 856 of a ROI from different
viewpoints. Optionally a shadow on the surface may facilitate
identification of common points in the images. The location of the
points may optionally be determined by stereo vision methods (e.g.
stereo triangulation), based on a knowledge of the location of the
viewpoints. Multiple images are optionally used to locate points on
a surface when the exact location of a light emitter and/or a
shadow casting object is not precisely known. Alternatively or
additionally multiple images may be used to verify, adjust, and/or
calibrate a system of locating points based on a single viewpoint
and known location of the shadow casting object and the light
source. Alternatively or additionally binocular stereo vision
methods may be used to fill in data in areas where there is a high
margin of error in other measurement methods. Optionally,
additional matching features, which are designated in the
overlapping images, may be added to the 3D model.
[0206] In some embodiments, the location of a point may be
determined 868 from two overlapping images acquired from two
different viewpoints. Optionally the locations of the viewpoints
may be established 864.
[0207] In some embodiments, a cast shadow may mark a location. For
example, a surface of a ROI may lack easily located features (for
example, a surface of a tooth prepared for a crown may be smooth
and/or monochromatic). Optionally the surface of the ROI may be
imaged 856 by two overlapping images from the two viewpoints.
Optionally a feature of a shadow may supply a feature that may be
recognized in two pictures. Comparison of the two images may
determine 868 the 3D location of the feature for example employing
binocular stereo vision methods.
[0208] In some embodiment, two imagers may be mounted on a single
scanner and/or dental tool for binocular imaging. Optionally the
imagers have a fixed relative position on the tool. In some
embodiment, more than two imagers may be mounted the scanner and/or
dental tool. Extra imagers optionally add additional viewpoints
and/or improve accuracy and/or imaging FOV. Alternatively or
additionally, an imager may be mounted on a stable mounting (for
example a dental lamp and/or a mechanical arm) and/or on a dental
tool. For example, the spatial location of a tool may be known by
inertial navigation (for example a tool may include an
accelerometer and/or a gyro). For example, the spatial location of
a tool may be known by designating reference features in an image
made by the sensor. For example, the spatial location of a tool may
be known with respect to designated reference features in an image
of the tool.
Scanner With Multiple Shadow Casting Objects
[0209] FIG. 9 is a schematic illustration of a scanner having
multiple shadow casting objects in accordance with an embodiment of
the present invention. For example, a probe 114 and two shorter
shadow casting rods 914a and 914b cast shadows 244c, 944a and 944b
respectively on tooth 120. The presence of multiple shadows may
facilitate faster and/or more accurate scanning of a tooth.
Optionally, probe 114 is long enough to investigate a sub gingival
zone of tooth 120. For example, while a user is investigating a sub
gingival zone with probe 114, the system is measuring revealed
areas of the tooth using shadows 244c, 944a and 944b. Optionally
the system may also track the location of the tip of probe 114.
Simple Scanner System
[0210] FIG. 10 is a schematic illustration of a scanning system
having multiple imagers in accordance with an embodiment of the
present invention. For example, a first imager 1060a may be placed
on a handle of a dental instrument (for example a light emitter,
mirror 1080a). A second imager 1060b is optionally located on a
light source, for example dental lamp 1080b. Imager 1060a may
capture images of a surface of a ROI and a shadow. Another option
is that light emitter is on the mirror such that mirror body cast
shadow on the tooth on the one hand and may be used also for better
illumination for the user's vision. For example, the shadow may be
cast by a conventional dental instrument as a dentist works in an
oral cavity. Imager 1060b may collect images of reference features
and/or mirror 1080a. For example, images from imager 1060b may
establish the location of mirror 1080a and or imager 1060a. In some
cases imager 1060b may capture images of a surface of a ROI and/or
a shadow cast thereon. In some embodiments, overlap of images from
imagers 1060a and 1060b may be used for binocular stereo vision
methods. In some embodiments images from imagers 1060a and 1060b
may be processed, for example by processor 170. In some
embodiments, other examples of dental tools may cast shadows and/or
may be shadow casting objects, for example a dental drill or
turbine.
Scanner With Multiple Imagers
[0211] FIG. 11 is a schematic illustration of a scanner having
multiple imagers in accordance with an embodiment of the present
invention. For example, images may be taken simultaneously of a ROI
and/or a shadow by a narrow FOV imager 160 and a wide FOV imager
1160. Overlapping areas of the images are optimally used for stereo
vision to locate objects and/or surfaces. Additionally or
alternatively, images from wide FOV imager 1160 may be used for
designate and/or orient to reference features.
Scanner
[0212] FIG. 12 is a block diagram of a scanner in accordance with
an embodiment of the present invention. In some embodiments a
scanner may include a housing 1204. A portion of the housing is
optionally configured to fit in an oral cavity of a subject. A
second portion of the housing is optionally configured for
manipulation by a user. Optionally a shadow casting module 1214 is
connected to the housing. For example, shadow casting module 1214
may include a dental tool. Optionally the shadow casting module or
at least a portion thereof is connected to the portion of the
housing fitting in the oral cavity. Optionally the shadow casting
module or at least a portion thereof fits in the oral cavity.
Optionally a light emitting module 1216 is connected to the
housing. Optionally the light emitting module 1216 is configured to
project light over a portion of shadow casting module 1214 onto a
ROI (for example the surface of a tooth or gums). Optionally a
light collecting module 1260 is connected to the housing and/or
directed to capture an image on the ROI and/or the shadow and/or a
portion of the shadow casting module 1214. Optionally, the captured
image is sent over a communication pathway to an image storage
module 1270. Image storage module 1270 optionally include a
processor to analyze images and/or control other components of the
system, for example light emitting module 1216 and/or light
collecting module 1260 and/or shadow casting module 1214.
[0213] In some embodiments, the shadow casting module 1214 will
cast a single connected shadow. In some embodiments, the shadow
casting module 1214 will cast multiple disconnected shadows and/or
a complex shadow (for example including a projection of a fiducial
marking). In some embodiments, the light emitting module 1216
includes a single light emitter. In some embodiments, the light
emitting module 1216 includes a multiple light emitters. For
example, each of the multiple emitters may illuminate different
regions and/or cast a shadow on a different region.
[0214] In some embodiments, the light collecting module 1260
includes one or multiple light imagers and/or multiple optical
apertures. For example, each of the apertures may image a different
region and/or multiple apertures may image the same region from
different angles for example allowing binocular and/or 3D imaging.
Optionally some light emitters may have larger FOV's than
others.
Light Collecting and Emitting System
[0215] FIG. 13 is a block diagram of an independent system 1300
including a light collection module 1360 and emitting module 1316.
For example, the light collecting and emitting system 1300 may be
used with a separate shadow casting object, for example a natural
part of the oral cavity and/or a conventional dental tool and/or a
custom dental tool (for example system 1400 as illustrated in FIG.
14). For example, light emitting module 1316 optionally illuminates
a ROI and/or a shadow casting object thereby created an illuminated
ROI and shadow on the ROI. Light collecting module 1360 optionally
images the ROI and the shadow. Image storage module 1270 stores
images and/or analyzes images. For example when used with another
imaging tool system 1300 may be used for navigation (e.g. tracking
a light emitter, a light collector and/or a shadow casting object).
For example, when combined with another light collector, system
1300 may produce binocular images from which 3D locations may be
calculated.
Light Collecting and Shadow Casting System
[0216] FIG. 14 is a block diagram of an independent system 1400
including a light collection 1460 and shadow casting 1314 module.
For example, system 1400 may be used with a separate light emitter.
For example, shadow casting module 1414 optionally includes a
dental tool for working on a ROI. Light collecting module 1460
optionally images the ROI and a shadow of object 1414. Image
storage module 1270 stores images and/or analyzes images.
[0217] It is expected that during the life of a patent maturing
from this application many relevant dental instruments, imagers,
light emitters will be developed and the scope of the terms are
intended to include all such new technologies a priori.
[0218] As used herein the term "about" refers to .+-.5%
[0219] The terms "comprises", "comprising", "includes",
"including", "having" and their conjugates mean "including but not
limited to".
[0220] The term "consisting of" means "including and limited
to".
[0221] The term "consisting essentially of" means that the
composition, method or structure may include additional
ingredients, steps and/or parts, but only if the additional
ingredients, steps and/or parts do not materially alter the basic
and novel characteristics of the claimed composition, method or
structure.
[0222] As used herein, the singular form "a", "an" and "the"
include plural references unless the context clearly dictates
otherwise. For example, the term "a compound" or "at least one
compound" may include a plurality of compounds, including mixtures
thereof.
[0223] Throughout this application, various embodiments of this
invention may be presented in a range format. It should be
understood that the description in range format is merely for
convenience and brevity and should not be construed as an
inflexible limitation on the scope of the invention. Accordingly,
the description of a range should be considered to have
specifically disclosed all the possible subranges as well as
individual numerical values within that range. For example,
description of a range such as from 1 to 6 should be considered to
have specifically disclosed subranges such as from 1 to 3, from 1
to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as
well as individual numbers within that range, for example, 1, 2, 3,
4, 5, and 6. This applies regardless of the breadth of the
range.
[0224] Whenever a numerical range is indicated herein, it is meant
to include any cited numeral (fractional or integral) within the
indicated range. The phrases "ranging/ranges between" a first
indicate number and a second indicate number and "ranging/ranges
from" a first indicate number "to" a second indicate number are
used herein interchangeably and are meant to include the first and
second indicated numbers and all the fractional and integral
numerals therebetween.
[0225] It is appreciated that certain features of the invention,
which are, for clarity, described in the context of separate
embodiments, may also be provided in combination in a single
embodiment. Conversely, various features of the invention, which
are, for brevity, described in the context of a single embodiment,
may also be provided separately or in any suitable subcombination
or as suitable in any other described embodiment of the invention.
Certain features described in the context of various embodiments
are not to be considered essential features of those embodiments,
unless the embodiment is inoperative without those elements.
* * * * *