U.S. patent application number 12/102699 was filed with the patent office on 2009-02-12 for omniview motionless camera orientation system.
This patent application is currently assigned to Sony. Invention is credited to H. Lee Martin, Danny A. McCall.
Application Number | 20090040291 12/102699 |
Document ID | / |
Family ID | 40346066 |
Filed Date | 2009-02-12 |
United States Patent
Application |
20090040291 |
Kind Code |
A1 |
McCall; Danny A. ; et
al. |
February 12, 2009 |
OMNIVIEW MOTIONLESS CAMERA ORIENTATION SYSTEM
Abstract
A method and apparatus for capture of a spherical image is
disclosed. The present invention includes at least one camera
having a lens with at least a 180.degree. field-of-view for
capturing a hemispherical image. In a first embodiment, a second
hemispherical image is created corresponding to a mirror image of
the hemispherical image captured by the camera. In a second
embodiment, two back-to-back cameras capture first and second
hemispherical images, respectively. In both embodiments, a
converter combines the two images along their outside edges to form
a single, spherical image. Finally, the converter stores the
complete spherical image for later retrieval and perspective
corrected viewing.
Inventors: |
McCall; Danny A.;
(Knoxville, TN) ; Martin; H. Lee; (Knoxville,
TN) |
Correspondence
Address: |
KENYON & KENYON LLP
1500 K STREET N.W., SUITE 700
WASHINGTON
DC
20005
US
|
Assignee: |
Sony
|
Family ID: |
40346066 |
Appl. No.: |
12/102699 |
Filed: |
April 14, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09315962 |
May 21, 1999 |
7382399 |
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12102699 |
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08863584 |
May 27, 1997 |
6002430 |
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09315962 |
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08386912 |
Feb 8, 1995 |
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08863584 |
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08339663 |
Nov 14, 1994 |
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08386912 |
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08189585 |
Jan 31, 1994 |
5384588 |
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08339663 |
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08014508 |
Feb 8, 1993 |
5359363 |
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08189585 |
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07699366 |
May 13, 1991 |
5185667 |
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08014508 |
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Current U.S.
Class: |
348/36 ;
348/E7.001 |
Current CPC
Class: |
H04N 5/23238 20130101;
H04N 5/2254 20130101; H04N 5/2259 20130101 |
Class at
Publication: |
348/36 ;
348/E07.001 |
International
Class: |
H04N 7/00 20060101
H04N007/00 |
Claims
1-35. (canceled)
36. A method for creating a spherical image comprising the steps
of: capturing a first approximately hemispherical image via a first
camera including a first approximately hemispherical lens directed
in a first direction; waiting for a period of time after capturing
the first approximately hemispherical image; capturing a second
approximately hemispherical image after the period of time is
complete via a second camera including a second approximately
hemispherical lens directed in a second direction approximately
opposite to the first direction; and combining the first
approximately hemispherical image with the second approximately
hemispherical image to form the spherical image.
37. The method of claim 36, wherein the second camera is the first
camera.
38. The method of claim 36, wherein the first approximately
hemispherical image and the second approximately hemispherical
image are captured on a same frame of film.
39. The method according to claim 36, wherein the first
approximately hemispherical image is a greater than 180.degree.
field-of-view image and the second image is a greater than
180.degree. field-of-view image.
40. The method according to claim 36, wherein the first camera
includes film configured to be exposed with the first approximately
hemispherical image, the method further comprising the step of
converting the first approximately hemispherical image exposed on
the film into an electronic format.
41. Apparatus for creating a spherical image, the apparatus
comprising: a first approximately hemispherical lens directed in a
first direction for receiving a first approximately hemispherical
image; a second approximately hemispherical lens directed in a
second direction approximately opposite to the first direction for
receiving a second approximately hemispherical image, the apparatus
being configured to capture the second approximately hemispherical
image a period of time after capturing the first approximately
hemispherical image; and a computer for combining the first
approximately hemispherical image with the second approximately
hemispherical image to form the spherical image.
42. The apparatus of claim 41, further including a camera coupled
to the computer for capturing the first and second approximately
hemispherical images, the first approximately hemispherical lens
being optically connected to the camera via first reflective optics
and the second approximately hemispherical lens being optically
connected to the camera via second reflective optics.
43. The apparatus according to claim 42, wherein the camera
comprises a still camera.
44. The apparatus according to claim 42, wherein the camera
comprises a video camera.
45. The apparatus according to claim 42, wherein the camera
comprises a motion picture camera.
46. The apparatus according to claim 42, wherein the camera
comprises a linear scanning CID camera array.
47. The apparatus according to claim 42, wherein the camera
comprises a linear scanning CCD camera array.
48. The apparatus according to claim 42, wherein the camera
comprises a linear scanning CMOS APS camera array.
49. The apparatus according to claim 41, further including a first
camera for capturing the first approximately hemispherical and a
second camera for capturing the second approximately hemispherical
image, the first and second cameras being attached to each other in
a back-to-back configuration.
50. The apparatus according to claim 42, wherein the first
approximately hemispherical lens is coupled to the camera via a
fiber optic line, the first approximately hemispherical image
received by the first approximately hemispherical lens being
transferred to the camera via the fiber optic line.
51. The apparatus according to claim 41, further including at least
one of a film for capturing the first and second approximately
hemispherical images on a same frame of the film.
52. The apparatus according to claim 41, wherein the first
approximately hemispherical image is a greater than 180.degree.
field-of-view image and the second image is a greater than
180.degree. field-of-view image.
Description
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 08/386,912 filed Feb. 8, 1995, which is a
continuation of U.S. application Ser. No. 08/339,663 filed Nov. 11,
1994, which is a continuation of U.S. application Ser. No.
08/189,585 filed Jan. 31, 1994 (now U.S. Pat. No. 5,384,588), which
is a continuation-in-part of U.S. application Ser. No. 08/014,508
filed Feb. 8, 1993 (now U.S. Pat. No. 5,359,363), which is a
continuation-in-part of U.S. application Ser. No. 07/699,366 filed
May 13, 1991 (now U.S. Pat. No. 5,185,667). This application is
also a continuation-in-part of U.S. application Ser. No. 08/373,446
filed Jan. 17, 1995, which is a continuation-in-part of U.S.
application Ser. No. 08/189,585 filed Jan. 31, 1994 (now U.S. Pat.
No. 5,384,588).
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field
[0003] This invention relates generally to an apparatus and method
for capturing an image having a spherical field-of-view for
subsequent viewing. Specifically, the present invention relates to
a system involving a single camera having a lens with a field of
view of at least 180.degree. and associated method for capturing a
first hemispherical image for subsequent combination into the
spherical image. Alternatively, when the system comprises two
cameras with such lenses mounted in a securely attached
back-to-back arrangement, the system and method captures two
distinct hemispherical images for subsequent combination into the
spherical image. The preferred system includes a single-use, still
image camera.
[0004] 2. Background Art
[0005] The discussion of the background art related to the
invention described herein relates to two subjects: spherical image
capture and subsequent captured image transformations.
Spherical Image Capture
[0006] The goal of imaging technology is to make the observer feel
as though he or she is part of the image. Prior art systems have
partially accomplished this goal. Unfortunately, the ability of
prior art systems to make the user feel part of the captured images
are proportional to the cost of the image capture system.
[0007] Relating to inexpensive image capturing systems, camera
companies have introduced disposable cameras. A disposable camera
generally refers to a single-use camera that includes film, a lens,
and a camera body, all in a single compact shell. The film includes
either a single frame of film or multiple frames of film. After the
entire roll of film has been exposed, the entire camera is returned
for film developing. All the photographer receives back are the
developed prints or slides. The manufacturer then recycles the
parts from the returned camera, adds film, and ships the camera to
a retailer for sale again. Disposable cameras come in various types
including regular magnification cameras, telephoto cameras, water
resistant cameras, and panoramic cameras.
[0008] Images captured by panoramic cameras provide wide angle
horizontal images (left to right) but lack wide angle vertical
images (up and down). Accordingly, while capturing a wide
field-of-view on one plane (horizontal), the photographer loses the
wide field-of-view on the other plane (vertical). Rotating the
camera only alters the wide angle direction. The following example
illustrates this shortcoming. Suppose a photographer desires to
capture the grandeur of a dense forest from within the forest.
While an image captured by a panoramic camera would include a
sweeping cross section of trees (left to right), it would only
include, at most, the middle portions of the nearest trees. To
capture the forest floor and canopy, the photographer would have to
take multiple panoramic photographs from looking almost straight
down to looking straight up. The final image of the forest would
then only be realized with the laborious task of manually cutting
and pasting the different images together. Unfortunately, the left
and right ends of the final image become distorted and cannot be
easily resolved. The distortions created are similar to those
encountered in map-making where one tries to represent a round
earth on a flat map. Specifically, objects and relative distances
near the extremes of the wide angle image become distorted.
Additionally, this approach wastes film.
[0009] A slightly more complex panoramic camera employs a scanning
drive mechanism which selectively exposes vertical strips of film
as the camera scans from extreme to extreme. However, scanning
panoramic cameras invariably introduce noise into captured images
through vibrations generated from their scanning motions as well as
take a relatively long period of time to capture the image.
[0010] Other wide-angle image capturing systems exist. For example,
IMAX and 70 mm films provide high definition images on a large
screen. However, these screens are flat. While a viewer can feel
part of the scene when staring straight ahead, this feeling
dissipates where the screen ends.
[0011] Another imaging system includes the OMNIMAX camera and
projection system where an image was recorded and later projected
on a spherical screen to produce an image 180 degrees wide, 100
degrees up from the horizon and 20 degrees below. While this system
offers significant improvements over a flat screen projection
system, the viewer's absorption into the displayed images is
limited by the edges of the displayed image.
[0012] Another image capture and display system is U.S. Pat. No.
5,023,725 to McCutchen. McCutchen discloses a dodecahedral imaging
system which breaks a sphere into 12 discrete polyhedrons. Each
section has its own dedicated CCD camera. The images are captured
and displayed on the walls of a hemispherical room. This system
offers increased resolution through increasing the number of
cameras used. However, as the number of cameras increase, the bulk
of the imaging system likewise increases. Additionally, each camera
has to be perfectly aligned with respect to the other cameras to
adequately capture a spherical image. Using McCutcheon's system,
increased resolution requires more bulk and more expense.
Furthermore, the images of each camera are not integrated together.
Accordingly, the system fails to account for the seams between the
displayed images. While quickly moving images may mask these edge
effects, the edge effects may be more noticeable with slow moving
images.
Captured Image Transformations
[0013] Camera viewing systems are used in abundance for
surveillance, inspection, security, and remote sensing. Remote
viewing is critical, for example, for robotic manipulation tasks.
Close viewing is necessary for detailed manipulation tasks while
wide-angle viewing aids positioning of the robotic system to avoid
collisions with the work space. Most of these systems use either a
fixed-mount camera with a limited viewing field to reduce
distortion, or they utilize mechanical pan-and-tilt platforms and
mechanized zoom lenses to orient the camera and magnify its image.
In the application where orientation of the camera and
magnification of its image are required, the mechanical solution is
large in size and can subtend a significant volume making the
viewing system difficult to conceal or use in close quarters.
Several cameras are usually necessary to provide wide-angle viewing
of the work space.
[0014] In order to provide a maximum amount of viewing coverage or
subtended angle, mechanical pan/tilt mechanisms usually use
motorized drives and gear mechanisms to manipulate the vertical and
horizontal orientation. An example of such a device is shown in
U.S. Pat. No. 4,728,839 issued to J. B. Coughlan, et al, on Mar. 1,
1988. Collisions with the working environment caused by these
mechanical pan/tilt orientation mechanisms can damage both the
camera and the work space and impede the remote handling operation.
Simultaneously, viewing in said remote environments is extremely
important to the performance of inspection and manipulation
activities.
[0015] Camera viewing systems that use internal optics to provide
wide viewing angles have also been developed in order to minimize
the size and volume of the camera and the intrusion into the
viewing area. These systems rely on the movement of either a mirror
or prism to change the tilt-angle of orientation and provide
mechanical rotation of the entire camera to change the pan angle of
orientation. Additional lenses are used to minimize distortion.
Using this means, the size of the camera orientation system can be
minimized, but "blind spots" in the center of the view result.
Also, these systems typically have no means of magnifying the image
and or producing multiple images from a single camera.
[0016] Further, references that may be relevant to the evaluation
of the captured image transformations as described herein include
U.S. Pat. Nos. 4,772,942 issued to M. J. Tuck on Sep. 20, 1988;
5,067,019 issued to R. D. Juday on Nov. 19, 1991; and 5,068,735
issued to K. Tuchiya, et al on Nov. 26, 1991.
OBJECTS OF THE INVENTION
[0017] Accordingly, it is an object of the present invention to
provide an apparatus that captures at least one hemispherical image
for later manipulation.
[0018] Another object of the invention is to provide an apparatus
which captures a spherical image from two images produced by two
cameras.
[0019] Another object of the invention is to form a single
spherical image from the captured image or images.
[0020] It is a further object of the invention to provide a
spherical image capture system and method without the bulk of a
large number of cameras and the necessity of multiple camera
alignment.
[0021] Another object of the invention is to reduce the number of
seams in a formed image.
[0022] Another object of the invention is to accomplish the above
objectives using a single-use, disposable camera.
[0023] Another object of the invention is to provide a system for
displaying a complete spherical image with perspective correction
and without edge effects and image distortion.
[0024] Another object of the invention is to enable interaction
with any portion of the spherical image with the selected portion
being perspective corrected.
[0025] It is another object of the present invention to provide
horizontal orientation (pan), vertical orientation (tilt) and
rotational orientation (rotation) of the viewing direction with no
moving mechanisms.
[0026] It is another object of the present invention to provide the
ability to magnify or scale the image (zoom in and out)
electronically.
[0027] It is another object of the present invention to provide
electronic control of the image intensity (iris level).
[0028] It is another object of the present invention to be able to
accomplish pan, tilt, zoom, rotation, and iris adjustment with
simple inputs made by a lay person from a joystick, keyboard
controller, or computer controlled means.
[0029] It is also an object of the present invention to provide
accurate control of the absolute viewing direction and orientations
using said input devices.
[0030] A further object of the present invention is to provide the
ability to produce multiple images with different orientations and
magnifications simultaneously from a single input image.
[0031] Another object of the present invention is to be able to
provide these images at real-time video rate, e.g. thirty
transformed images per second, and to support various display
format standards such as the National Television Standards
Committee RS-170 signal format and/or higher resolution formats
currently under development and to provide the images to a computer
display performing perspective correction transforms on a personal
computer system.
[0032] It is also an object of the present invention to provide a
system than can be used for automatic or manual surveillance of
selected environments, with optical views of these environments
corrected electronically to remove distortion so as to facilitate
this surveillance.
[0033] It is another object of this invention to provide a means
for directly addressing each picture element of an analog image
captured with an imaging device having a field-of-view, the picture
elements being addressed in a non-linear sequence determined in a
manner similar to that described by U.S. Pat. No. 5,185,667 to
provide a distortion-corrected image without requiring the use of
filters and memory holding buffers.
[0034] Another object of the present invention is to provide a
means for directly addressing each picture element of an image
(still or video) captured using an imaging device having a
two-dimensional field-of-view.
SUMMARY OF THE INVENTION
[0035] According to the principles of the present invention, at
least one camera with a 180.degree. or greater field-of-view lens
captures a spherical image. When the system employs two cameras
with such lenses, the cameras and lenses are mounted in a
back-to-back arrangement. When used in this disclosure and attached
claims, "back-to-back" means two cameras clasped together such that
the image planes of the lenses fall between each of the lenses and
both lenses' optical axes are collinear with a single line which
passes through each lens and camera. An imaging element or elements
capture the images produced by the lenses. When used herein and in
the claims, an "imaging element" or "imaging elements" refer to
both film and linear scanning devices and alternatives thereof upon
which an image is focused and captured. The captured images from
each camera are stored and combined to form a single, spherical
image (a final, formed image). When used herein and in the claims,
"stored" not only means to digitally store an image in a
retrievable form but also means to capture the image on film. To
form the spherical image, the system includes a converter which
identifies, joins, and smooths the edges (also referred to as the
"seams") of each hemispherical image. When used herein and in the
claims, a "converter" refers to not only a manual system (splicing
by hand and airbrush image altering techniques) but also an
automatic image processing system (digital processing by a computer
where images are altered automatically) for combining the two
images together. Where a partial overlap exists between the two
hemispherical images, the converter processes the partial overlap
to remove the overlap and any distortion and create a single,
complete, formed spherical image. Finally, a selected planar
portion of the spherical image may be displayed on a personal
computer using perspective correction software or hardware.
[0036] A method for capturing a spherical image includes the steps
of capturing a first hemispherical image with a first camera
including a first 180.degree. or greater field-of-view lens;
receiving a second hemispherical image either by capturing the
second hemispherical image by means of a second camera including a
second oppositely directed 180.degree. or greater field-of-view
lens or by creating a mirror image of the first hemispherical
image; and, combining the first and second oppositely directed
hemispherical images to create a spherical image.
[0037] An apparatus capturing a spherical image includes a first
camera equipped with a 180.degree. or greater field-of-view lens,
the first camera and the lens directed in a first direction, the
first camera capturing a first image; a second device either
forming a second image corresponding to a mirror image of the first
image or including a second camera equipped with a 180.degree. or
greater field-of-view lens, directed in a second direction opposite
to the first direction, the second camera capturing the second
image; and, a combining system for combining the first and second
images into a formed spherical image.
[0038] The cameras disclosed above capture high resolution images.
Various cameras may be used including still cameras, video cameras,
and CCD, CID, or CMOS APS cameras. With high resolution (crystal
clear) images as a goal, the system employs a still camera
capturing a high resolution image on a fine grain film. Film
generally composes a layer of silver halide crystals. Upon exposure
to light, this silver halide layer picks up the image exposed to
it. The greater the number of separate halide crystals, the greater
the resolution of the film. Thus, a finer grain size refers to an
increase in number of silver halide crystals per unit area of film
which in turn refers to an increase in the potential resolution of
the film medium.
[0039] When capturing a spherical image with two single-use
cameras, the cameras include additional features allowing for dual
image capture. Where "single-use camera" is referred to herein and
in the claims, it refers to a disposable camera or other
alternative. The additional features which aid in spherical image
capture include attachment devices which attach the backs of the
cameras to each other. When used herein, "attachment devices" refer
to locking pins, locking clasps, lever and hook systems, and
alternatives thereof. Also, each camera's shutter release may be
controlled by a single button (common shutter release control) with
either a mechanical or electrical servo linkage releasing each
camera's shutter. Additionally, to allow a photographer to avoid
his or her image from being captured by the spherical image capture
system, the dual camera system includes a shutter auto timer or a
remote shutter activation control controlling the common shutter
release control. The remote shutter control may be an IR
transmitter or remote shutter release cable. Further, the dual
camera system may include two different shutters operable
independently or sequentially. The sequential shutter operations
allow the photographer to walk around to the other side of the dual
camera system so as not to become part of the captured spherical
image.
[0040] According to the present invention, when using a still image
recorded on film, after developing the film, a high resolution
digital scanner scans and digitizes the image contained in the
developed film and stores the digitized image in a retrievable
medium. The retrievable medium includes, inter alia, CD-ROMs,
magnetic disks and tapes, semiconductor devices, and
magneto-optical disks.
[0041] As referred to above, the second image may be created from
the first image. This may be accomplished by at least one of two
methods: first, manually, by forming the second image by hand and,
second, automatically, by means of a computer running image
processing software. As to manually creating the image, the film
developing and printing steps generate the second image. For
example, after printing or scanning the first hemispherical image,
a technician or device flips or likewise reverses the film storing
the at least hemispherical image (from left to right orientation to
right to left orientation) and scans or prints the film again.
[0042] The automatic printing or scanning technique creates the
second hemispherical image (also known as a mirror image of the
first image) through appropriate software. Alternatively, image
processing software or hardware may reverse the scanned image
without the need to manually flip a developed piece of film.
[0043] The converter (automatic or manual) seams the two
hemispherical images together and stores a generated, complete
spherical image in a storage medium including CD-ROMs, magnetic
disks and tapes, semiconductor devices and magneto-optical disks.
This converting may be accomplished by sending the camera and/or
film to a processing center which sends back the spherical image
stored in one of the above storage mediums.
[0044] Finally, using the perspective correction and manipulation
system as disclosed in U.S. Pat. No. 5,185,667 and its progeny
including U.S. Pat. Nos. 5,359,363 and 5,313,306 and Ser. Nos.
08/189,585, 08/339,663, and 08/373,446, the formed, seamless,
spherical image may be explored. These patents and applications and
others herein are expressly incorporated by reference.
[0045] Preferably, a personal computer system runs the perspective
correction software or hardware. These computers may be directly
linked to the image capturing system (allowing viewing of the
spherical image as captured by the hemispherical camera or cameras
and manipulated by the perspective correction system) or may remain
completely separate (photographing an image, sending the film to a
processing center which creates a spherical image from the
photograph or photographs, and returning the spherical image stored
in a retrievable form for display on a personal computer).
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] The above mentioned features of the invention will become
more clearly understood from the following detailed description of
the invention read together with the drawings in which:
[0047] FIG. 1 is a diagram of the fields of view for 180.degree.
and greater than 180.degree. fields of view lenses as mounted to a
single camera body.
[0048] FIG. 2 shows two back-to-back cameras each capturing more
than 180.degree. fields of view images.
[0049] FIG. 3 shows two back-to-back cameras each capturing
180.degree. fields of view images.
[0050] FIG. 4 shows an alternated embodiment of the spherical
capture system of the present invention.
[0051] FIGS. 5A and 5B relate to the elements used to capture a
spherical image. FIG. 5A shows two hemispherical lenses capturing
complementary hemispherical images and feeding them to remote
cameras. FIG. 5B shows a hemispherical lens capturing a
hemispherical image and a mirror image converter for converting the
first hemispherical image into a second hemispherical image.
[0052] FIG. 6A shows two hemispherical lenses similar to that of
FIG. 5A passing images to local cameras through reflective and
refractive optics. FIG. 6B shows two hemispherical lenses conveying
images to a single camera.
[0053] FIGS. 7A and 7B represent two hemispherical images combined
into a single spherical image.
[0054] FIG. 8 shows a storage/display option of the instant
invention.
[0055] FIGS. 9A and 9B show a schematic block diagram of the signal
processing portion of the present invention illustrating the major
components thereof. FIG. 9A shows the perspective correction
process implemented in hardware. FIG. 9B shows the perspective
correction process implemented in software, operating inside a
personal computer.
[0056] FIG. 10 is an exemplary drawing of an at least hemispherical
image used as input by the present invention. Lenses having other
field-of-view values will produce images with similar distortion,
particularly when the field-of-view is about eighty degrees or
greater.
[0057] FIG. 11 is an exemplary drawing of the output image after
correction for a desired image or orientation and magnification
within the original image.
[0058] FIG. 12 is a schematic diagram of the fundamental geometry
that the present invention embodies to accomplish the image
transformation.
[0059] FIG. 13 is a schematic diagram demonstrating the projection
of the object plane and position vector into image plane
coordinates.
DETAILED DESCRIPTION OF THE INVENTION
Spherical Image Capture
[0060] The disclosed Spherical Image Capture system employs the
components disclosed in FIGS. 1-8 to capture hemispherical images
and form spherical images. The image transform engine as disclosed
in FIGS. 9-13 operates to transform selected portions of the formed
spherical images into planar, perspective corrected portions.
[0061] Referring to FIG. 1, camera 601 includes lens 602 with
optical axis A, image plane I, and a field-of-view of 180.degree.
or greater. If lens 602 has a 180.degree. field-of-view it captures
at most the image from hemisphere 603. On the other hand, if lens
602 has a field-of-view greater than 180.degree., then it captures
the image from sector 604 (shown by dotted lines) as well as that
of hemisphere 603.
[0062] FIG. 2 shows a camera body 701 (which may include two
cameras) connected to lenses 702 and 703 (with image planes
I.sub.702 and I.sub.703, respectively). Each of lenses 702 and 703
have fields of view greater than 180.degree.. Placed in a
back-to-back arrangement where the lenses are mounted such that the
image planes I.sub.702 and I.sub.703 from the lenses fall between
each of the lenses and both lenses' optical axes A coincide in a
single line which passes through each lens and camera, they capture
the spherical image surrounding the camera body 701. It should be
noted, however, that the thickness of the camera body 701 plays a
role in how much of the spherical image surrounding the camera is
captured. Specifically, the objects on the sides of the camera may
or may not be completely photographed depending on their distances
from the camera body 701. For example, if objects are within
boundary 704, some of the objects may fall into the camera's blind
spots 707 and not be completely photographed. On the other hand,
because of the converging angles of lenses' greater than
180.degree. fields of view, objects within sectors 705 will be
photographed twice: first, by means of the image captured by lens
702 and, second, by means of the image captured by lens 703.
Decreasing the distances between the lenses reduces blind spots 707
of the spherical capture system. In this example, reducing the
distance between the lenses means reducing the thickness of the
camera body 701. Reducing the camera body thickness can be
accomplished, for example, by using smaller imaging and recording
elements such as a CCD, CID, or CMOS APS camera as disclosed in
U.S. Ser. No. 08/373,446, expressly incorporated herein by
reference. Additionally, the distance between image planes
I.sub.702 and I.sub.703 of lenses 702 and 703, respectively, may be
reduced to the point where the image planes coincide, further
reducing the thickness of the camera body.
[0063] FIG. 3 discloses camera body 801, similar to that of camera
body 701, and lenses 802 and 803 with image planes I.sub.802 and
I.sub.803, respectively, each having a field-of-view of exactly
180.degree.. Lens 802 receives the image of hemisphere 804 and lens
803 receives the image of hemisphere 805. Similar to FIG. 2 above,
the lenses attach to camera body 801 in a back-to-back arrangement
where the lenses are mounted such that the image planes I.sub.802
and I.sub.803 from the lenses fall between each of the lenses and
both lenses' optical axes A coincide in a single line which passes
through each lens and camera. As discussed with reference to FIG. 2
above, because camera body 801 has a thickness (i.e., the distance
between lenses 802 and 803 is greater than zero), the image capture
system 800 has blind spots 806 on the sides of the camera body 801.
These blind spots may be reduced by decreasing the distance between
lenses 802 and 803. Here, this means reducing the thickness of
camera body 801. This may be accomplished, inter alia, by reducing
the size of the imaging and recording components as discussed above
in reference to FIG. 2.
[0064] Referring now to FIG. 4, two cameras 201 and 202 equipped
with lenses 203, 204, each having a field-of-view (FOV) greater
than 180.degree., are disclosed in a back-to-back arrangement (the
image planes (not shown) falling between each of the lenses and the
optical axes of the lenses 203 and 204 are collinear as designated
by line A). Because each camera 201, 202 has a lens (203, 204)
which has a field-of-view (FOV) greater than 180.degree., each
captures more than the image of a complete hemisphere. By employing
two cameras in this arrangement, the camera system captures a
complete spherical image. The types of cameras employed are chosen
from the group comprising of at least still cameras with loaded
film or digital image capture, motion picture cameras with loaded
film or digital image capture, the KODAK digital image capture
system, video, and linear scanning CID, CCD, or CMOS APS camera
arrays. The outputs of cameras 201 and 202 connect by means of
electrical, optical, or electro-optical links 215 to
hemispherical-to-spherical image converter 216. When the captured
hemispherical images are stored on film, optical-to-electrical
converter 215A converts the stored images into a form usable by
hemispherical-to-spherical image converter 216.
Optical-to-electrical converter 215A includes a scanning system
which scans a photographed image and outputs a high resolution,
electronic replica of the photographed image. One converter
includes the Kodak.TM. Photo-CD Rom converter which takes a
photograph and converts it into a high resolution digital form
which then may be stored on a compact disk.
Hemispherical-to-spherical converter 216 receives the hemispherical
images from cameras 201 and 202 (or alternatively, from
optical-to-electrical converter 215A).
[0065] The cameras include additional features allowing for dual
image capture. For example, the backs of the cameras are attached
to each other via separable attachment devices 401. Attachment
devices 401 may be locking pins, locking clasps, lever and clip
systems, etc. Also, each camera's shutter release may be controlled
by a single button 402 A (common shutter release control) with
either a mechanical or electrical servo linkage releasing each
camera's shutter. Additionally, to allow a photographer to ensure
his or her image is not recorded by the spherical image capture
system, the dual camera system includes a shutter auto timer or a
remote shutter activation control 403 controlling the common
shutter release control, allowing the photographer to move to a
concealed or non-image-captured position. The remote shutter
control 403 may be an IR transmitter or remote shutter release
cable. Further, the dual camera system may include two different
shutters release control buttons 402B operable independently or
sequentially. The sequential shutter operations allow the
photographer to walk around to the other side of the dual camera
system so as not to become part of the captured spherical
image.
[0066] Next, hemispherical-to-spherical converter 216 combines the
hemispherical images into a single, complete spherical image.
Finally, the edges of the two hemispherical images may be combined
to form a seamless spherical image. Removing the seams from the two
hemispherical images may be accomplished in a number of ways. For
example, the two images may be "airbrushed" together (where any
difference between the two images at the periphery of the images
are smoothed together. Alternatively, a more complex method of
seaming the two images together may include matching related pixels
by their luminance and chrominance values and interpolating the
corresponding values for interstitial pixels. In the event that a
partial overlap exists between the two hemispherical images, the
converter processes the spherical image to remove the partial
overlap any distortion and creates a single, complete, formed
image. The processing may include choosing and displaying one
hemisphere over the other, weighted and non-weighted averaging of
the overlapping sections, and linear and non-linear approximations
creating intermediary images.
[0067] FIG. 5A shows lenses 203 and 204 positioned remotely from
cameras 201 and 202. Here, the image planes I.sub.203 and I.sub.204
fall between lenses 203 and 204 and the optical axes of the lenses
203 and 204 are collinear as designated by line A. Electrical,
optical (including fiber optic lines), or electro-optical links 215
connect the images received from lenses 203 and 204 to the cameras
201 and 202. Next, hemispherical-to-spherical image converter 216
receives the outputs from cameras 201 and 202 and outputs a
spherical image as described in relation to FIG. 4.
[0068] FIG. 5B shows single lens 203 positioned remotely from
camera 201. Electrical, optical (including fiber optic lines), or
electro-optical links 215 connect the image received from lens 203
to the camera 201. Next, camera 201 captures a first hemispherical
image. The output of camera 201 (a still or video image contained
in a frame or frames of film, digital or analog signal) is sent to
mirror image converter 901 and one input of the hemispherical to
spherical image converter 216. The mirror image converter 901
assumes many forms depending on the form of image relayed to it.
For developed film, converter 901 refers to a re-scanning system
re-scanning the developed film with the film flipped (flipped from
a left to right orientation to a right to left orientation). For an
optical or electrical signal, converter 901 refers to a signal
processing system which automatically creates a second
hemispherical image from the first hemispherical image. The output
of converter 901 flows to the hemispherical-to-spherical image
converter 216 as the second hemispherical image. Finally,
hemispherical-to-spherical image converter 216 outputs a spherical
image as described in relation to FIG. 4.
[0069] FIG. 6A shows an alternative arrangement of the cameras 201
and 202 and the lenses 203 and 204. The optical axes of the lenses
203 and 204 are collinear as designated by line A. Here, the
devices used to convey the images from lenses 203 and 204 to
cameras 201 and 202 include hollow chambers with reflective optics
215B and refractive optics 215C, as necessary for proper
transmission of the hemispherical images. The reflective optics
215B allow the cameras 201 and 202 to be moved from a location
directly behind each lens 203, 204. The refractive optics 215C aid
in focusing the hemispherical images generated by lenses 203 and
204. This movement of the cameras from behind the lenses allows the
lenses to be moved closer together, maximizing the area
photographed.
[0070] A further modification includes the substitution of the APS
camera array of co-pending U.S. application Ser. No. 08/373,446
(expressly incorporated herein by reference) for the optical system
described above. Because of the small size of an APS camera array,
two arrays may be placed back to back to further maximize the
content of each hemispherical image. An advantage of using APS
camera arrays is the shifted processing location of the Omniview
engine. Specifically, by adding additional processing circuitry on
the APS camera array chip, the selection and "dewarping"
transformations may be performed locally on the APS chip. This
results in less subsequent processing of the image as well as a
reduction in the bandwidth required for sending each hemispherical
image to an external processing device.
[0071] Furthermore, as described above, image conduits 215 may
include optical fibers instead of the reflective optics 215B and
refractive optics 215C. An imaging system including optical fibers
connected between a hemispherical lens and imaging array is found
in U.S. Pat. No. 5,313,306 to Martin which is expressly
incorporated by reference. The present invention includes the
application of the spherical imaging system with a combination of
an endoscope and dual hemispherical lenses to capture hemispherical
images of remote locations. Converter 216 combines the
hemispherical images to a form complete, spherical image.
[0072] FIG. 6B relates to another embodiment where a single camera
201A captures the images produced by lenses 203 and 204. The
optical axes of the lenses 203 and 204 are collinear as designated
by line A. Here, employing a single camera to capture both
hemispherical images (from lenses 203 and 204) eliminates the bulk
of the second camera. For example, where camera 201A is a still
camera, the camera records the two hemispherical images in a single
frame in a side-by-side relationship, exposed at the same time or
during related time intervals. Alternatively, the two images may be
captured in separate frames, exposed at the same time or during
related time intervals. The same applies to video and motion
picture cameras as well. Image capture with a single camera may be
used in the other embodiments of described in greater detail
herein. A system of FIG. 6B including an APS camera array may be
mounted onto a single, silicon chip. This combination has multiple
advantages including reduced size of the image capture system,
reduced bulk from extra cameras, higher resolution from the APS
camera arrays,
[0073] FIG. 7A shows first 205 and second 206 hemispherical images,
each taken from one of cameras 201 or 202. FIG. 7A also shows the
edges 207, 208 (or seams) of each hemispherical image. FIG. 7B
shows the two images 205 and 206 combined into a single, spherical
image 209. Seams 207 and 208 have been combined to form the single,
seamless image 209.
[0074] FIG. 8 shows a possible future viewing system for viewing
the formed spherical image system. The image planes I.sub.203 and
I.sub.204 fall between lenses 203 and 204 and the optical axes of
the lenses 203 and 204 are collinear as designated by line A. Image
input buffer 217 temporarily stores images received from cameras
201 and 202 until hemispherical-to-spherical image converter 216
accepts the stored images. Also, FIG. 8 includes options for the
spherical images. For example, after combining the two
hemispherical images into a single, spherical image in converter
216, the spherical image may be immediately viewed through viewing
engine 218. Viewing engine 218 includes the Omniview calculation
engine with viewer communication interface 124 as shown in FIG. 1
of co-pending U.S. Ser. No. 08/373,446 (expressly incorporated
herein by reference). Here, the user may view selected portions of
the formed spherical image as output from the
hemispherical-to-spherical image converter 216. Alternatively, the
spherical image may be stored in storage device 219. The storage
device 119 may include video tape, CD-ROM, semiconductor devices,
magnetic or magneto-optical disks, or laser disks as the storage
medium. By the interconnections between viewing engine 218 and
storage device 219, a new spherical image may be displayed and
saved in storage device 219 as well as saved in storage device 219
and viewed at a later time.
[0075] Further enhancements include using two side-by-side
hemispherical lens equipped cameras for stereo-optical viewing.
Additionally, the back-to-back camera system described herein may
be attached to the exterior of any of a number of different
vehicles for spherical image capture of a number of different
environments.
Captured Image Transformation
[0076] FIGS. 9-13 relate to the captured image transformation
system.
[0077] In order to minimize the size of the camera orientation
system while maintaining the ability to zoom, a camera orientation
system that utilizes electronic image transformation rather than
mechanisms was developed. While numerous patents on mechanical
pan-and-tilt systems have been filed, no approach using strictly
electronic transforms and 180.degree. or greater field of view
optics is known to have been successfully implemented. In addition,
the electro-optical approach utilized in the present invention
allows multiple images to be extracted from the output of a
signaled camera. These images can be then utilized to energize
appropriate alarms, for example, as a specific application of the
basic image transformation in connection with a surveillance
system. As utilized herein, the term "surveillance" has a wide
range including, but not limited to, determining ingress or egress
from a selected environment. Further, the term "wide angle" as used
herein means a field-of-view of about eighty degrees or greater.
Motivation for this device came from viewing system requirements in
remote handling applications where the operating envelop of the
equipment is a significant constraint to task accomplishment.
[0078] The principles of the optical transform utilized in the
present invention can be understood by reference to the system 10
of FIGS. 9A and 9B. (This is also set forth in the aforecited U.S.
patent application Ser. No. 07/699,366 that is incorporated herein
by reference.) Referring to FIG. 9A, shown schematically at 11 is a
wide angle, e.g., a hemispherical, lens that provides an image of
the environment with a 180 degree or greater field-of-view. The
lens is attached to a camera 12 which converts the optical image
into an electrical signal. These signals are then digitized
electronically 13 and stored in an image buffer 14 within the
present invention. An image processing system consisting of an
X-MAP and a Y-MAP processor shown as 16 and 17, respectively,
performs the two-dimensional transform mapping. The image transform
processors are controlled by the microcomputer and control
interface 15. The microcomputer control interface provides
initialization and transform parameter calculation for the system.
The control interface also determines the desired transformation
coefficients based on orientation angle, magnification, rotation,
and light sensitivity input from an input means such as a joystick
controller 22 or computer input means 23. The transformed image is
filtered by a 2-dimensional convolution filter 18 and the output of
the filtered image is stored in an output image buffer 19. The
output image buffer 19 is scanned out by display electronics 20 to
a video display device 21 for viewing.
[0079] A range of lens types can be accommodated to support various
fields of view. The lens optics 11 correspond directly with the
mathematical coefficients used with the X-MAP and Y-MAP processors
16 and 17 to transform the image. The capability to pan and tilt
the output image remains even though a different maximum
field-of-view is provided with a different lens element.
[0080] The invention can be realized by proper combination of a
number of optical and electronic devices. The lens 11 is
exemplified by any of a series of wide angle lenses from, for
example, Nikon, particularly the 8 mm F2.8. Any video source 12 and
image capturing device 13 that converts the optical image into
electronic memory can serve as the input for the invention such as
a Videk Digital Camera interfaced with Texas Instrument's TMS 34061
integrated circuits. Input and output image buffers 14 and 19 can
be construed using Texas Instrument TMS44C251 video random access
memory chips or their equivalents. The control interface can be
accomplished with any of a number of microcontrollers including the
Intel 80C196. The X-MAP and Y-MAP transform processors 16 and 17
and image filtering 19 can be accomplished with application
specific integrated circuits or other means as will be known to
persons skilled in the art. The display driver can also be
accomplished with integrated circuits such as the Texas Instruments
TMS34061. The output video signal can be of the NTSC RS-170, for
example, compatible with most commercial television displays in the
United States. Remote control 22 and computer control 23 are
accomplished via readily available switches and/or computer systems
than also will be well known. These components function as a system
to select a portion of the input image (hemispherical or other wide
angle) and then mathematically transform the image to provide the
proper prospective for output. The keys to the success of the
perspective correction system include:
[0081] (1) the entire input image need not be transformed, only the
portion of interest;
[0082] (2) the required mathematical transform is predictable based
on the lens characteristics; and
[0083] (3) calibration coefficients can be modified by the end user
to correct for any lens/camera combination supporting both new and
retrofit applications.
[0084] FIG. 9B contains elements similar to that of FIG. 9A but is
implemented in a personal computer represented by dashed line D.
The personal computer includes central processing unit 15'
performing the perspective correction algorithms X-MAP 16' and
Y-MAP 17' as stored in RAM, ROM, or some other form. The display
driver 20 outputs the perspective corrected image to computer
display monitor 21'.
[0085] The transformation that occurs between the input memory
buffer 14 and the output memory buffer 19, as controlled by the two
coordinated buffer 19, as controlled by the two coordinated
transformation circuits 16 and 17 of FIG. 9A (or algorithms as
stored in 16' and 17' of FIG. 9B), is better understood by
referring to FIG. 10 is a rendering of the image of a grid pattern
produced by a hemispherical lens. This image has a field-of-view of
180 degrees and shows the contents of the environment throughout
and entire hemisphere. Notice that the resulting image in FIG. 10
is significantly distorted relative to human perception. Similar
distortion will be obtained even with lesser field-of-view lenses.
Vertical grid lines in the environment appear in the image plane as
24a, 24b, and 24c. Horizontal grid lines in the environment appear
in the image plane as 25a, 25b, and 25c. The image of an object is
exemplified by 26. A portion of the image in FIG. 10 has been
corrected, magnified, and rotated to produce the image shown in
FIG. 11. Item 27 shows the corrected representation of the object
in the output display. The results shown in the image in FIG. 11
can be produced from any portion of the image of FIG. 10 using the
present invention. The corrected perspective of the view is
demonstrated by the straightening of the grid pattern displayed in
FIG. 11. In the present invention, these transformations can be
performed at real-time video rates (e.g., thirty times per second),
compatible with commercial video standards.
[0086] The transformation portion of the invention as described has
the capability to pan and tilt the output image through the entire
field-of-view of the lens element by changing the input means, e.g.
the joystick or computer, to the controller. This allows a large
area to be scanned for information as can be useful in security and
surveillance applications. The image can also be rotated through
any portion of 360 degrees on its axis changing the perceived
vertical of the displayed image. This capability provides the
ability to align the vertical image with the gravity vector to
maintain a proper perspective in the image display regardless of
the pan or tilt angle of the image. The invention also supports
modifications in the magnification. used to display the output
image. This is commensurate with a zoom function that allows a
change in the field-of-view of the output image. This function is
extremely useful for inspection and surveillance operations. The
magnitude of zoom provided is a function of the resolution of the
input camera, the resolution of the output display, the clarity of
the output display, and the amount of picture element (pixel)
averaging that is used in a given display. The invention supports
all of these functions to provide capabilities associated with
traditional mechanical pan (through 180 degrees), tilt (through 180
degrees), rotation (through 360 degrees), and zoom devices. The
digital system also supports image intensity scaling that emulates
the functionality of a mechanical iris by shifting the intensity of
the displayed image based on commands from the user or an external
computer.
[0087] The postulates and equations that follow are based on the
image transformation portion of the present invention utilizing a
wide angle lens as the optical element. These also apply to other
field-of-view lens systems. There are two basic properties and two
basic postulates that describe the perfect wide angle lens system.
The first property of such a lens is that the lens has a 2.pi.
ateradian filed-of-view and the image it produces is a circle. The
second property is that all objects in the field-of-view are in
focus, i.e. the perfect wide angle lens has an infinite
depth-of-field. The two important postulates of this lens system
(refer to FIGS. 12 and 13) are stated as follows:
[0088] Postulate 1: Azimuth angle invariability--For object points
that lie in a content plane that is perpendicular to the image
plane and passes through the image plane origin, all such points
are mapped as image points onto the line of intersection between
the image plane and the content plane, i.e. along a radial line.
The azimuth angle of the image points is therefore invariant to
elevation and object distance changes within the content plane.
[0089] Postulate 2: Equidistant Projection Rule--The radial
distance, r, from the image plane origin along the azimuth angle
containing the projection of the object point is linearly
proportional to the zenith angle .beta., where .beta. is defined as
the angle between a perpendicular line through the image plane
origin and the line from the image plane origin to the object
point. Thus the relationship:
r=k.beta.(1)
[0090] Using these properties and postulates as the foundation of
the lens system, the mathematical transformation for obtaining a
perspective corrected image can be determined. FIG. 12 shows the
coordinate reference frames for the object plane and the image
plane. The coordinates u,v describe object points within the object
plane. The coordinates x, y, z describe points within the image
coordinate frame of reference.
[0091] The object plane shown in FIG. 12 is a typical region of
interest to determine the mapping relationship onto the image plane
to properly correct the object. The direction of view vector,
DOV[x, y, z], determines the zenith and azimuth angles for mapping
the object plane, UV, onto the image plane, XY. The object plane is
defined to be perpendicular to the vector, DOV[x, y, z].
[0092] The location of the origin of the object plane in terms of
the image plane [x, y, z] in spherical coordinates is given by:
x=D sin .beta. cos .differential.
y=D sin .beta. cos .differential.
z=D cos .theta. (2)
where D=scaler length from the image plane origin to the object
plane origin, .beta. is the zenith angle, and .differential. is the
azimuth angle in image plane spherical coordinates. The origin of
object plane is represented as a vector using the components given
in Equation 1 as:
DOV[x,y,z]=[D sin .beta. cos .differential.,D sin .beta. sin
.differential.,D cos .beta.] (3)
[0093] DOV[x, y, z] is perpendicular to the object plane and its
scaler magnitude D provides the distance to the object plane. By
aligning the XY plane with the direction of action of DOV[x, y, z],
the azimuth angle .differential. becomes either 90 or 270 degrees
and therefore the x component becomes zero resulting in the DOV[x,
y, z] coordinates:
DOV[x,y,z]=[0,-D sin .beta.,D cos .beta.] (4)
[0094] Referring now to FIG. 13, the object point relative to the
UV plane origin in coordinates relative to the origin of the image
plane is given by the following:
x=u
y=v cos .beta.
z=v sin .beta. (5)
therefore, the coordinates of a point P(u,v) that lies in the
object plane can be represented as a vector P[x, y, z] in image
plane coordinates:
P[x,y,z]=[u,v cos .beta.,v sin .beta.] (6)
where P[x, y, z] describes the position of the object point in
image coordinates relative to the origin of the UV plane. The
object vector o[x, y, z] that describes the object point in image
coordinates is then given by:
O[x,y,z]=DOV[x,y,z]+P[x,y,z] (7)
O[x,y,z]=[u,v cos .beta.-D sin .beta.,v sin .beta.+D cos .beta.]
(8)
Projection onto a hemisphere of radius R attached to the image
plane is determined by scaling the object vector o[x, y, z] to
produce a surface vector s[x, y, z]:
S [ x , y , z ] = RO [ x , y , z ] | O [ x , y , z ] | ( 9 )
##EQU00001##
[0095] By substituting for the components of o[x, y, z] from
Equation 8, the vector S[x, y, z] describing the image point
mapping onto the hemisphere becomes:
S [ x , y , z ] = RO [ u , ( v cos .beta. - D sin .beta. ) , ( v
sin .beta. + D cos .beta. ) ] u 2 + ( v cos .beta. - D sin .beta. )
2 + ( v sin .beta. + D cos .beta. ) 2 ( 10 ) ##EQU00002##
[0096] The denominator in Equation 10 represents the length or
absolute value of the vector o[x, y, z] and can be simplified
through algebraic and trigonometric manipulation to give:
S [ x , y , z ] = RO [ u , ( v cos .beta. - D sin .beta. ) , ( v
sin .beta. + D cos .beta. ) ] u 2 + v 2 + D 2 ( 11 )
##EQU00003##
[0097] From Equation 11, the mapping onto the two-dimensional image
plane can be obtained for both x and y as:
x = Ru u 2 + v 2 + D 2 ( 12 ) y = R ( v cos .beta. - D sin .beta. )
u 2 + v 2 + D 2 ( 13 ) ##EQU00004##
[0098] Additionally, the image plane center to object plane
distance D can be represented in terms of the image circular radius
R by the relation:
D=mR (14)
[0099] where m represents the scale factor in radial units R from
the image plane origin to the object plane origin. Substituting
Equation 14 into Equations 12 and 13 provides a means for obtaining
an effective scaling operation or magnification which can be used
to provide zoom operation.
x = Ru u 2 + v 2 + m 2 R 2 ( 15 ) y = R ( v cos .beta. - mR sin
.beta. ) u 2 + v 2 + m 2 R 2 ( 16 ) ##EQU00005##
[0100] Using the equations for two-dimensional rotation of axes for
both the UV object plane and the XY image plane the last two
equations can be further manipulated to provide a more general set
of equations that provides for rotation within the image plane and
rotation within the object plane.
x = R [ uA - vB + mR sin .beta. sin .differential. ] u 2 + v 2 + m
2 R 2 ( 17 ) y = R [ uC - vD - mR sin .beta. cos .differential. ] u
2 + v 2 + m 2 R 2 ( 18 ) ##EQU00006##
[0101] where:
A=(cos o cos .differential.-sin o sin .differential. cos
.beta.)
B=(sin o cos .differential.+cos o sin .differential. cos
.beta.)
C=(cos o sin .differential.+sin o cos .differential. cos
.beta.)
D=(sin o sin .differential.-cos o cos .differential. cos .beta.)
(19)
[0102] and where:
[0103] R=radius of the image circle
[0104] .beta.=zenith angle
[0105] .differential.=Azimuth angle in image plane
[0106] o=Object plane rotation angle
[0107] m=Magnification
[0108] u,v=object plane coordinates
[0109] x,y=image plane coordinates
[0110] The Equations 17 and 18 provide a direct mapping from the UV
space to the XY image space and are the fundamental mathematical
result that supports the functioning of the present omnidirectional
viewing system with no moving parts. By knowing the desired zenith,
azimuth, and object plane rotation angles and the magnification,
the locations of x and y in the imaging array can be determined.
This approach provides a means to transform an image from the input
video buffer to the output video buffer exactly. Also, the image
system is completely symmetrical about the zenith, therefore, the
vector assignments and resulting signs of various components can be
chosen differently depending on the desired orientation of the
object plane with respect to the image plane. In addition, these
postulates and mathematical equations can be modified for various
lens elements as necessary for the desired field-of-view coverage
in a given application.
[0111] The input means defines the zenith angle, .beta., the
azimuth angle, .differential., the object rotation, o, and the
magnification, m. These values are substituted into Equations 19 to
determine values for substitution into Equations 17 and 18. The
image circle radius, R, is fixed value that is determined by the
camera lens and element relationship. The variables u and v vary
throughout the object plane determining the values for x and y in
the image plane coordinates.
[0112] From the foregoing, it can be seen that a wide angle lens
provides a substantially hemispherical view that is captured by a
camera. The image is then transformed into a corrected image at a
desired pan, tilt, magnification, rotation, and focus based on the
desired view as described by a control input. The image is then
output to a television display with the perspective corrected.
Accordingly, no mechanical devices are required to attain this
extensive analysis and presentation of the view of an environment
through 180 degrees of pan, 180 degrees of tilt, 360 degrees of
rotation, and various degrees of zoom magnification.
[0113] As indicated above, one application for the perspective
correction of images obtained with a motionless wide angle camera
is in the field of surveillance. The term "surveillance" is meant
to include inspection and like operations as well. It is often
desired to continuously or periodically view a selected environment
to determine activity in that environment. The term "environment"
is meant to include such areas as rooms, warehouses, parks and the
like. This activity might be, for example, ingress and egress of
some object relative to that environment. It might also be some
action that is taking place in that environment. It may be desired
to carry out this surveillance either automatically at the desired
frequency (or continuously), or upon demand by an operator. The
size of the environment may require more than one motionless camera
for complete surveillance.
[0114] While a preferred embodiment has been shown and described,
it will be understood that it is not intended to limit the
disclosure, but rather it is intended to cover all modifications
and alternate methods falling within the spirit and the scope of
the invention as defined in the appended claims. All of the above
referenced U.S. patents and pending applications referenced herein
are expressly incorporated by reference.
[0115] Having thus described the aforementioned invention,
* * * * *