U.S. patent application number 13/649378 was filed with the patent office on 2013-02-07 for image generation device and operation support system.
This patent application is currently assigned to SUMITOMO HEAVY INDUSTRIES, LTD.. The applicant listed for this patent is Yoshihisa KIYOTA. Invention is credited to Yoshihisa KIYOTA.
Application Number | 20130033495 13/649378 |
Document ID | / |
Family ID | 44798653 |
Filed Date | 2013-02-07 |
United States Patent
Application |
20130033495 |
Kind Code |
A1 |
KIYOTA; Yoshihisa |
February 7, 2013 |
IMAGE GENERATION DEVICE AND OPERATION SUPPORT SYSTEM
Abstract
An image generation device generates an output image based on an
image obtained by taking images by an image-taking part mounted to
a body to be operated, which boy is capable of performing a turning
operation. A coordinates correspondence part causes coordinates on
a columnar space model, which is arranged to surround the body to
be operated and has a center axis, to correspond to coordinates on
an image plane on which the input image is positioned. An output
image generation part generates the output image by causing values
of the coordinates on the input image plane to correspond to values
of the coordinates on an output image plane on which the output
image is positioned through coordinates on the columnar space
model. The columnar space model is arranged so that an optical axis
of the image-taking part intersects with the center axis of said
columnar space model.
Inventors: |
KIYOTA; Yoshihisa;
(Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KIYOTA; Yoshihisa |
Kanagawa |
|
JP |
|
|
Assignee: |
SUMITOMO HEAVY INDUSTRIES,
LTD.
|
Family ID: |
44798653 |
Appl. No.: |
13/649378 |
Filed: |
October 11, 2012 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2011/058899 |
Apr 8, 2011 |
|
|
|
13649378 |
|
|
|
|
Current U.S.
Class: |
345/420 |
Current CPC
Class: |
E02F 9/261 20130101;
G06T 3/0062 20130101; H04N 7/18 20130101; H04N 13/30 20180501; G06T
15/20 20130101; H04N 13/221 20180501 |
Class at
Publication: |
345/420 |
International
Class: |
G06T 17/00 20060101
G06T017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 12, 2010 |
JP |
2010-091658 |
Claims
1. An image generation device that generates an output image based
on an image obtained by taking images by an image-taking part
mounted to a body to be operated, which boy is capable of
performing a turning operation, the image generation device
comprising: a coordinates correspondence part configured to cause
coordinates on a columnar space model, which is arranged to
surround said body to be operated and has a center axis, to
correspond to coordinates on an image plane on which said input
image is positioned; and an output image generation part configured
to generate said output image by causing values of the coordinates
on said input image plane to correspond to values of the
coordinates on an output image plane on which said output image is
positioned through coordinates on said columnar space model,
wherein said columnar space model is arranged so that an optical
axis of said image-taking part intersects with the center axis of
said columnar space model.
2. The image generation device as claimed in claim 1, wherein a
plurality of said image-taking parts are provided, and said
columnar space model is arranged so that each of components of a
projection of optical axes of said image-taking parts on a plane
perpendicular to said center axis intersects at a single point on
the center axis of said columnar space model.
3. The image generation device as claimed in claim 2, wherein said
columnar space model is arranged so that perpendicular lines drawn
from optical centers of said image-taking parts to the center axis
of said columnar space model, respectively, are perpendicular to
each other.
4. The image generation device as claimed in claim 1, further
comprising a storage part configured to store correspondence
information, as map information, acquired by the correspondence by
said coordinates correspondence part.
5. The image generation device as claimed in claim 1, wherein said
coordinates correspondence part causes coordinates on a
processing-target image plane on which a processing-target image to
be subjected to an image conversion process is positioned to
correspond to coordinates on said columnar space model, and said
output image generation part generates said output image by causing
values of coordinates on said input image plane to the values of
coordinates on said output image plane through the coordinates on
said processing-target image plane and the coordinates on said
columnar space model.
6. The image generation device as claimed in claim 1, wherein said
output image is trimmed to be a circular shape so that a center of
the circular shape is positioned on the center axis of said
columnar space model and on a turning axis of said body to be
operated.
7. An image generation device that generates an output image based
on input images obtained by taking images by a plurality of
image-taking parts mounted to a body to be operated, which body is
capable of performing a turning operation, the image generation
device comprising: a coordinates correspondence part configured to
cause coordinates on a columnar space model, which is arranged to
surround said body to be operated and has a center axis, to
correspond to coordinates on an image plane on which said input
image is positioned; and an output image generation part configured
to generate said output image by causing values of the coordinates
on said input image plane to correspond to values of the
coordinates on an output image plane on which said output image is
positioned through coordinates on said columnar space model,
wherein said columnar space model is arranged so that each of
components of a projection of optical axes of said image-taking
parts on a plane perpendicular to said center axis intersects at a
single point on the center axis of said columnar space model.
8. The image generation device as claimed in claim 7, wherein said
coordinates correspondence part causes coordinates on a
processing-target image plane on which a processing-target image to
be subjected to an image conversion process is positioned to
correspond to coordinates on said columnar space model, and said
output image generation part generates said output image by causing
values of coordinates on said input image plane to the values of
coordinates on said output image plane through the coordinates on
said processing-target image plane and the coordinates on said
columnar space model.
9. The image generation device as claimed in claim 7, wherein said
output image is trimmed to be a circular shape so that a center of
the circular shape is positioned on the center axis of said
columnar space model and on a turning axis of said body to be
operated.
10. The image generation device as claimed in claim 7, further
comprising a storage part configured to store correspondence
information, as map information, acquired by the correspondence by
said coordinates correspondence part.
11. An operation support system that supports a movement or an
operation of a body to be operated, comprising: the image
generation device as claimed in claim 1; and a display part
configured to display the output image generated by the image
generation device.
12. The operation support system as claimed in claim 11, wherein
said display part is installed in an operator room to move or
operate said body to be operated.
13. An operation support, system that supports a movement or an
operation of a body to be operated, comprising: the image
generation device as claimed in claim 7; and a display part
configured to display the output image generated by the image
generation device.
14. The operation support system as claimed in claim 13, wherein
said display part is installed in an operator room to move or
operate said body to be operated.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation application filed under 35 U.S.C.
111(a) claiming benefit under 35 U.S.C. 120 and 365(c) of
International Application PCT/JP2011/058899, filed on Apr. 8, 2011,
designating the U.S., which claims priority to Japanese Patent
Application No. 2010-091658. The entire contents of the foregoing
applications are incorporated herein by reference.
FIELD
[0002] The present invention relates to an image generation device
that generates an output image based on input images taken by
image-taking means mounted on a body to be operated, which is
capable of performing a turning operation, and an operation support
system using the device.
BACKGROUND
[0003] There is known an image generation device that maps an input
image from a camera on a predetermined space model on a
three-dimensional space, and generates a visual point conversion
image, which is viewed from an arbitrary virtual visual point in
the three-dimensional space while referring to the mapped space
data (for example, refer to Japanese Patent Publication No.
3286306).
[0004] The image generation device disclosed in Patent Document 1
projects an image taken by a camera mounted on a vehicle onto a
three-dimensional space model configured by a plurality of plane
surfaces or curved surfaces that surround the vehicle. The image
generation device generates a visual point conversion image using
the image projected onto the space model, and displays the produced
visual point conversion image to a driver. The visual point
conversion image is an image of a combination of a road surface
image, which virtually reflects a state of a road taken from
directly above, and a horizontal image, which reflects a horizontal
direction image. Thereby, the image generation device relates, when
the driver driving the vehicle looks the visual point conversion
image, an object in the visual point conversion image to an object
actually existing outside the vehicle without giving an
uncomfortable feeling.
[0005] The image generation device disclosed in Patent Document 1
is assumed to be mounted on a vehicle, and is not supposed to be
mounted on a body to be operated such as a construction machine
capable to perform a turning operation. Accordingly, the image
generation device disclosed in Patent Document 1 cannot generate a
view point conversion image suitable for observing a surrounding
area of a body to be operated during a turning operation.
SUMMARY
[0006] It is an object of the present invention to provide an image
generation device, which generates an output image suitable for
observing a surrounding area during a turning operation, and an
operation support system using the device.
[0007] In order to achieve the above-mentioned objects, there is
provided according to an aspect of the present invention an image
generation device that generates an output image based on an image
obtained by taking images by an image-taking part mounted to a body
to be operated, which boy is capable of performing a turning
operation, the image generation device including: a coordinates
correspondence part configured to cause coordinates on a columnar
space model, which is arranged to surround the body to be operated
and has a center axis, to correspond to coordinates on an image
plane on which the input image is positioned; and an output image
generation part configured to generate the output image by causing
values of the coordinates on the input image plane to correspond to
values of the coordinates on an output image plane on which the
output image is positioned through coordinates on the columnar
space model, wherein the columnar space model is arranged so that
an optical axis of the image-taking part intersects with the center
axis of the columnar space model.
[0008] There is provided according to another aspect of the present
invention an image generation device that generates an output image
based on input images obtained by taking images by a plurality of
image-taking parts mounted to a body to be operated, which body is
capable of performing a turning operation, the image generation
device including: a coordinates correspondence part configured to
cause coordinates on a columnar space model, which is arranged to
surround the body to be operated and has a center axis, to
correspond to coordinates on an image plane on which the input
image is positioned; and an output image generation part configured
to generate the output image by causing values of the coordinates
on the input image plane to correspond to values of the coordinates
on an output image plane on which the output image is positioned
through coordinates on the columnar space model, wherein the
columnar space model is arranged so that each of components of a
projection of optical axes of the image-taking parts on a plane
perpendicular to the center axis intersects at a single point on
the center axis of the columnar space model.
[0009] There is provided according to a further aspect of the
present invention an operation support system that supports a
movement or an operation of a body to be operated, including: the
above-mentioned image generation device; and a display part
configured to display the output image generated by the image
generation device.
[0010] According to the present invention, it is possible to
provide an image generation device, which generates an output image
suitable for observing a surrounding area during a turning
operation, and an operation support system using the device.
BRIEF DESCRIPTION OF DRAWINGS
[0011] FIG. 1 is a block diagram illustrating an outline structure
of an image generation device according to an embodiment of the
present invention.
[0012] FIG. 2 is a side view of a shovel to which the image
generation device is mounted.
[0013] FIG. 3A is a side view of a space model to which an input
image is projected.
[0014] FIG. 3B is a plan view of the space model illustrated in
FIG. 3A.
[0015] FIG. 4 is a perspective view illustrating a relationship
between the space model and an image plane to be processed.
[0016] FIG. 5 is a diagram for explaining a correspondence between
coordinates on an input image plane and coordinates on a space
model.
[0017] FIG. 6A is a diagram illustrating a correspondence
relationship between coordinates on an input image plane of a
camera using a normal projection and coordinates on a space model
MD.
[0018] FIG. 6B is a diagram illustrating a correspondence
relationship between coordinates on a curved surface area of the
space model MD and coordinates on an image plane to be
processed.
[0019] FIG. 6C is a diagram illustrating a correspondence
relationship between coordinates on the image plane to be processed
and coordinates on output image plane of a virtual camera using a
normal projection.
[0020] FIG. 6D is a diagram illustrating a mutual positional
relationship between the camera, the virtual camera, the plane
surface area and the curved surface area of the space model MD and
the image plane to be processed.
[0021] FIG. 7A is a view illustrating a state where an angle .beta.
is formed between a group of parallel lines positioned on an
XZ-plane and a processing-target image plane.
[0022] FIG. 7B is a view illustrating a state where an angle
.beta.1 is formed between a group of parallel lines positioned on
the XZ-plane and a processing-target image plane.
[0023] FIG. 8A is a view illustrating a state where all of a group
of auxiliary lines positioned on the XZ-plane extend from a start
point on a Z-axis toward the processing-target image plane.
[0024] FIG. 8B is a view illustrating a state where all of a group
of auxiliary lines extend from a start point on the Z-axis toward
the processing-target image plane.
[0025] FIG. 9A is a view illustrating a state where an angle .beta.
is formed between a group of parallel lines positioned on the
XZ-plane and a processing-target image plane.
[0026] FIG. 9B is a view illustrating a state where an angle
.beta.2 is formed between a group of parallel lines positioned on
the XZ-plane and a processing-target image plane.
[0027] FIG. 10 is a view illustrating a state where an angle .beta.
is formed between a group of parallel lines positioned on the
XZ-plane and a processing-target image plane.
[0028] FIG. 11 is a flowchart of a processing-image generation
process and an output image generation process.
[0029] FIG. 12A is a plan view for explaining a positional
relationship between a camera and a space model in a case where a
single rod-shaped object exists.
[0030] FIG. 12B is a perspective view for explaining a positional
relationship between the camera and the space model in the case
where the single rod-shaped object exists.
[0031] FIG. 12C is a plan view for explaining a processing-target
image generated in the case where the single rod-shaped object
exists.
[0032] FIG. 13A is a plan view for explaining a positional
relationship between a camera and a space model in a case where two
rod-shaped objects exist.
[0033] FIG. 13B is a perspective view for explaining a positional
relationship between the camera and the space model in the case
where the two rod-shaped objects exist.
[0034] FIG. 13C is a plan view for explaining a processing-target
image generated in the case where the two rod-shaped objects
exist.
[0035] FIG. 14A is a plan view for explaining a positional
relationship between a camera and a space model in another case
where two rod-shaped objects exist.
[0036] FIG. 14B is a perspective view for explaining a positional
relationship between the camera and the space model in another case
where the two single rod-shaped objects exist.
[0037] FIG. 14C is a plan view for explaining a processing-target
image generated in another case where the two rod-shaped objects
exist.
[0038] FIG. 15 is a view illustrating an example of display of an
output image.
DESCRIPTION OF EMBODIMENT(S)
[0039] Hereafter, a description will be given, with reference to
the drawings, of embodiments of the invention.
[0040] FIG. 1 is a block diagram illustrating an outline structure
of an image generation device according to an embodiment of the
present invention.
[0041] The image generation device 100 according to the embodiment
generates, for example, an output image based on input images taken
by a camera 2 mounted on a construction machine, and presents the
output image to an operator. As illustrated in FIG. 1, the image
generation device 100 includes a control part 1, the camera 2, an
input part 3, a storage part 4 and a display part 5.
[0042] FIG. 2 is a side view of an excavator 60 to which the image
generation device is mounted. The excavator 60 includes a
lower-part running body 61 of a crawler type, a turning mechanism
61 and an upper-part turning body 63. The upper-part turning body
63 is mounted on the lower-part running body 61 via the turning
mechanism 62 so as to be turnable about a tuning axis PV.
[0043] A cab (driver's cabin) 64 is provided on a front left side
part of the upper-part turning body 63, and an excavation
attachment E is provided on a front central part. The cameras 2 (a
right side camera 2R and a backside camera 2B) are provided on a
right side surface and a rear surface of the upper-part turning
body 63. The display part 5 is installed in the cab 64 at a
position where the display part 5 can be easily viewed by an
operator.
[0044] Next, a description is given of each structural element of
the image generation device 100.
[0045] The control part 1 includes a computer provided with a CPU
(Central Processing Unit), a RAM (Random Access Memory), a ROM
(Read Only Memory), an NVRAM (Non-Volatile Random Access Memory),
etc. For example, programs corresponding to each of a coordinates
correspondence part 10 and an output image generation part 11
mentioned later are stored in the ROM or the NVRAM. The CPU
performs processing by executing a program corresponding to each
means while using the RAM as a temporary storage area.
[0046] The camera 2 is a device for acquiring an input image which
projects a circumference of the excavator 60, and includes a right
side camera 2R and a backside camera 2B. The right side camera 2R
and the backside camera 2B are attached to the right side surface
and the rear surface of the upper-part turning body 63 so that, for
example, an image of an area of a dead zone to the operator can be
taken (refer to FIG. 2). Each of the right side camera 2R and the
backside camera 2B is equipped with an image pick-up device, such
as a CCD (Charge Coupled Device), a CMOS (Complementary Metal Oxide
Semiconductor), etc. In addition, the camera 2 may be attached at
positions (for example, a front surface and a left side surface)
other than the right side surface and the rear surface of the
upper-part turning body 63, and may be equipped with a wide-angle
lens or a fish-eye lens so that an image of a large range can be
taken.
[0047] The camera 2 acquires an input image according to a control
signal from the control part 1, and outputs the acquired input
image to the control part 1. In addition, when the camera 2
acquires the input image using a fish-eye lens or a wide-angle
lens, the camera 2 output a corrected input image to the control
part 1 in which an apparent distortion or tilting, which is caused
by usage of those lenses, is corrected. However, the camera 2 may
output the acquired input image as it is without correction. In
such a case, the control part corrects an apparent distortion and
tilting.
[0048] The input part 3 is a device for an operator to enable an
input of various kinds of information to the image generation
device 100, and includes, for example, a touch panel, a button
switch, a pointing device, a keyboard, etc.
[0049] The storage part 4 is a device for storing various kinds of
information, and includes, for example, a hard disk, an optical
disk, a semiconductor memory, etc.
[0050] The display part 5 is a device for displaying image
information, and includes, for example, a liquid crystal display or
a projector, which is installed in the cab 64 (refer to FIG. 2) of
the construction machine. The display part 5 displays various
images which the control part 1 outputs.
[0051] Moreover, the image generation device 100 may generate a
processing-target image based on an input image, and may display an
output image after generating the output image by applying an image
conversion process to the processing-target image so that the
output image enables intuitive perception of a positional
relationship with a peripheral obstacle and a distance sense, and
may present the output image to the operator.
[0052] The "processing-target image" is generated based on an input
image and to be subjected to an image conversion process (for
example, a scale conversion, an affine conversion, a distortion
conversion, a viewpoint conversion processing). For example, an
input image, which is an input image taken by a camera that takes
an image of a ground surface from above and contains an image (for
example, an empty part) in a horizontal direction according to a
wide view angle, is used in an image conversion process. In such a
case, the input image is projected onto a predetermined space model
so that a horizontal image thereof is not displayed unnaturally
(for example, is not handled as an empty part on a ground surface).
Then, an image suitable for the image conversion process can be
obtained by re-projecting a projection image projected on the space
model onto a different two-dimensional plane. It should be noted
that the processing-target image may be used as an output image as
it is without applying an image conversion process.
[0053] The "space model" is a target object on which an input image
is projected, and includes at least a plane surface or a curved
surface (for example, a plane surface parallel to the
processing-target image plane or a plane surface or curved surface
that forms an angle with the processing-target image plane) other
than a processing-target image plane, which is a plane surface on
which the processing-target image is positioned.
[0054] It should be noted that the image generation device 100 may
generates an output image by applying an image conversion process
to a projection image projected onto the space model without
generating a processing-target image. Moreover, the projection
image may be used as an output image as it is without being
subjected to an image conversion process.
[0055] FIGS. 3A and 3B are views illustrating an example of a space
model MD on which an input image is projected. FIG. 3A illustrates
a relationship between the excavator 60 and the space model MD when
viewing the excavator 60 from a side, and FIG. 3B illustrates a
relationship between the excavator 60 and the space model MD when
viewing the excavator 60 from above.
[0056] As illustrated in FIGS. 3A and 3B, the space model MD has a
half-cylindrical form. An inner part of a bottom surface of the
half-cylindrical form includes a plane surface area R1, and an
inner part of a side surface includes a curved surface area R2.
[0057] FIG. 4 is a view illustrating an example of a relationship
between the space model MD and the processing-target image plane.
In FIG. 4, the processing-target image plane R3 is a plane
containing the plane surface area R1 of the space model MD. It
should be noted that although the space model MD is illustrated as
a cylindrical form, which is different from the half-cylindrical
form as illustrated in FIG. 3, for the purpose of clarification in
FIG. 4, the space model MD may be either of the half-cylindrical
form and the cylindrical form. The same applies in figures
mentioned below. Additionally, the processing-target image plane R3
may be a circular area, which contains the plane surface area R1 of
the space model MD, or may be an annular area, which does not
contain the plane surface area R1 of the space model MD.
[0058] Next, a description is given of the coordinates
correspondence part 10 and the output image generation part that
the control part 1 includes.
[0059] The coordinates correspondence part 10 is provided for
causing the coordinates on the input image plane on which the input
image taken by the camera 2 is positioned (may be referred to as
input coordinates), the coordinates on the space model MD (may be
referred to as spatial coordinates, and the coordinates on the
processing-target image plane R3 (may be referred to as projection
coordinates) to correspond to each other. For example, the
coordinates on the output image plane, the coordinates on the space
model MD and the coordinates on the processing-target image plane
R3 are caused to correspond to each other based on various
parameters with respect to the camera 2, such as an optical center,
a focal distance, a CCD size, an optical axis direction vector, a
camera horizontal direction vector, a projection system, etc., of
the camera 2, which are input through the input part 3 and a
previously determined positional relationship between the input
image plane, the space model MD and the processing-target image
plane R3. The correspondence relationship is stored in the input
image-space model correspondence relation map 40 and the space
model-processing-target image correspondence relation map 41 of the
storage part 4.
[0060] It should be noted that the coordinates correspondence part
10 omits causing correspondence between the coordinates on the
space model MD and the coordinates on the processing-target image
plane R3 and storage of the correspondence relationship in the
space model-processing-target image correspondence relation map
41.
[0061] The output image generation part 11 generates an output
image. The output image generation part 11 causes the coordinates
on the processing-target image plane R3 and the coordinates on the
output image plane on which the output image is positioned to
correspond to each other by applying, for example, a scale
conversion, an affine conversion, or a distortion conversion to the
processing-target image. The correspondence relationship is stored
in the processing-target image-output image correspondence relation
map 42 of the storage part 4. The output image generation part 11
generates an output image by relating a value of each pixel in the
output mage (for example, a brightness value, a color phase value,
a chroma value, etc.) to a value of each pixel in the input image
while referring to the input image-space model correspondence
relation map 40 and the space model-processing-target image
correspondence relation map 41 stored in the coordinates
correspondence part 10.
[0062] Moreover, the output image generation part 11 causes the
coordinates on the processing-target image plane R3 and the
coordinates on the output image plane on which the output image is
positioned to correspond to each other based on various parameters,
such as an optical center, a focal distance, a CCD size, an optical
direction axis vector, a camera horizontal direction vector, a
projection system, etc., of a virtual camera that are input through
the input part 3. The correspondence relationship is stored in the
processing-target image-output image correspondence relation map 42
of the storage part 4. Then, the output image generation part 11
generates an output image by relating a value of each pixel in the
output image (for example, a brightness value, a color phase value,
a chroma value, etc.) to a value of each pixel in the input image
while referring to the input image-space model correspondence
relation map 40 and the space model-processing-target image
correspondence relation map 41 stored in the coordinates
correspondence part 10.
[0063] It should be noted that the output image generation part 11
may generate the output image by changing a scale of the
processing-target image without using a concept of virtual
camera.
[0064] Moreover, when the output image generation part 11 does not
generate the processing-target image, the output image generation
part 11 causes the coordinates on the space model MD and the
coordinates on the output image plane to correspond to each other
in accordance with the image conversion process applied. Then, the
output image generation part 11 generates the output image by
relating a value of each pixel in the output image (for example, a
brightness value, a color phase value, a chroma value, etc.) to a
value of each pixel in the input image while referring to the input
image-space model correspondence relation map 40. In this case, the
output image generation part 11 omits the causing correspondence
between the coordinates on the processing-target image plane R3 and
the coordinates on the output image plane and storage of the
correspondence relationship in the processing-target image-output
image correspondence relation map 42.
[0065] Next, a description is given of an example of a process
performed by the coordinates correspondence part 10 and the output
image generation part 11.
[0066] The coordinates correspondence part 10 can cause the input
coordinates on the input image plane correspond to the spatial
coordinates on the space model by using the Hamilton's
quaternion.
[0067] FIG. 5 is a view for explaining a correspondence between the
coordinates on the input image plane and the coordinates on the
space model. The input image plane of the camera 2 is expressed as
a single plane having an optical center C of the camera 2 as an
original point in a UVW rectangular coordinates system, and the
space model is expressed as cubic planes in an XYZ rectangular
coordinates system.
[0068] First, in order to convert the coordinates (coordinates of
an XYZ coordinate system) on the space model into the coordinates
(coordinates on the UVW coordinates system) on the input image
plane, the XYZ coordinates system is rotated to cause the X-axis to
be coincident with the U-axis, the Y-Axis to be coincident with the
V-axis and the Z-axis to be coincident with -W-axis after
parallel-moving the original point of the XYZ coordinates system to
the optical center C (original point of the UVW coordinates
system). Here, the sign "-" means that a direction is opposite.
This is caused by ahead of a camera is set to a +W direction in the
UVW coordinates system, and a vertical downward direction is set to
a -Z direction in the XYZ coordinates system.
[0069] If there are a plurality of cameras 2, each of the cameras 2
has an individual UVW coordinates system. Thereby, the coordinates
correspondence part 10 translates and rotates the XYZ coordinates
system with respect to each of the plurality of UVW coordinates
system.
[0070] The above-mentioned conversion is realized by translating
the XYZ coordinates system so that the optical center C of the
camera 2 becomes the original point of the XYZ coordinates system,
and, thereafter, rotating the XYZ coordinates system so that the
X-axis is coincident with the -W-axis and further rotating the XYZ
coordinates system so that the X-axis is coincident with the
U-axis. Therefore, the coordinates correspondence part 10
integrates the two rotations into a single rotation operation by
describing the conversion by the Hamilton's quaternion.
[0071] By the way, a rotation to cause a certain vector A to be in
coincident with a different vector B corresponds to a process of
rotating by an angle formed between the vector A and the vector B
using a normal line of a plane defined by the vector A and the
vector B. When the rotating angle is set to .theta., the angle
.theta. is expressed by an inner product of the vector A and the
vector B as follows.
.theta. = cos - 1 ( A B A B ) [ Formula 1 ] ##EQU00001##
[0072] Moreover, the unit vector N of the normal line of the plane
defined by the vector A and the vector B is expressed by an outer
product of the vector A and the vector B as follows.
N = A .times. B A B sin .theta. [ Formula 2 ] ##EQU00002##
[0073] It should be noted that when i, j and k are imaginary number
unit, the quaternion is a hypercomplex number satisfying the
following condition.
ii=jj=kk=ijk=-1 [Formula 3]
[0074] In the present embodiment, the quaternion Q is expressed as
follows, where a real component is t and pure imaginary components
are a, b and c.
Q=(t;a,b,c)=t+ai+bj+ck [Formula 4]
[0075] Therefore, the conjugate quaternion of the quaternion Q is
expressed as follows.
Q*=(t;-a,-b,-c)=t-ai-bj-ck [Formula 5]
[0076] The quaternion Q can express a three-dimensional vector (a,
b, c) by the pure imaginary components a, b and c while setting the
real component t to 0 (zero). In addition, a rotating operation
with an arbitrary vector as an axis can be expressed by each
component t, a, b and c.
[0077] Further, the quaternion Q can express the consecutive
plurality of numbers of rotating operation as a single rotation by
integrating the rotating operations. For example, a point D (ex,
ey, ez), which is an arbitrary point S (sx, sy, sz) rotated by an
angle .theta. with an arbitrary unit vector C (l, m, n) as an axis,
can be expressed as follows.
D = ( 0 ; ex , ey , ez ) = QSQ * where , S = ( 0 ; sx , sy , sz ) ,
Q = ( cos .theta. 2 ; l sin .theta. 2 , m sin .theta. 2 , n sin
.theta. 2 ) [ Formula 6 ] ##EQU00003##
[0078] Here, in the present embodiment, when the quaternion
expressing a rotation, which causes the Z-axis to be coincident
with the -W-axis, is Q, the point X on the X-axis in the XYZ
coordinates system is moved to a point X'. Therefore, the point X'
is expressed as follows.
X'=Q.sub.zXQ.sub.z* [Formula 7]
[0079] Moreover, in the present embodiment, when the quaternion
expressing a rotation, which causes a line connecting the point X'
on the X-axis and the original point to be coincident with the
U-axis is Q.sub.x, the quaternion R expressing a rotation to cause
the Z-axis to be coincident with the -W-axis and further cause the
X-axis to be coincident with the U-axis is expressed as
follows.
R=Q.sub.xQ.sub.z [Formula 8]
[0080] As mentioned above, the coordinates P', when arbitrary
coordinates P on the space model (XYZ coordinates system) is
expressed by the coordinates on the input image plane (UVW
coordinates system), is expressed as follows.
P'=RPR* [Formula 9]
[0081] Because the quaternion R is a constant of each of the
cameras 2, the coordinates correspondence part 10 can convert the
coordinates on the space model (XYZ coordinates system) into the
coordinates on the input image plane (UVW coordinates system) by
merely performing the operation.
[0082] After converting the coordinates on the space model (XYZ
coordinates system) into the coordinates on the input image plane
(UVW coordinates system), the coordinates correspondence part 10
computes an incident angle .alpha. faulted by a line segment CP'
connecting the optical center C (coordinates on the UVW coordinates
system) of the camera 2 and coordinates P', which is arbitrary
coordinates P on the space model expressed by the UVW coordinates
system, and the optical axis G of the camera 2.
[0083] Moreover, the coordinates correspondence part 10 computes an
argument .phi. and a length of a line segment EP', the argument
.phi. being formed by the line segment EP', which connects the
coordinates P' and an intersecting point E of a plane H and an
optical axis G in the plane H, which is parallel to the input image
plane R4 (for example, a CCD surface) and containing the
coordinates P', and a U'-axis in the plane H.
[0084] In an optical system of a camera, normally, an image height
h is a function of an incident angle .alpha. and a focal distance
f. Accordingly, the coordinate correspondence part 10 computes the
image height h by selecting an appropriate projection system such
as a normal projection (h=ftan.alpha.), an orthogonal projection
(h=fsin.alpha.), a stereographic projection (h=2ftan(.alpha./2)),
an equisolid angle projection (h=fsin(.alpha./2)), an equidistant
projection (h=f.alpha.), etc.
[0085] Thereafter, the coordinates correspondence part 10
decomposes the image height h to a U-component and a V-component
component on the UV coordinates system according to an argument
.phi., and divide them by a numerical value corresponding to a
pixel size per one pixel of the input image plane R4. Thereby, the
coordinates correspondence part 10 can cause the coordinates P (P')
on the space model MD and the coordinates on the input image plane
R4.
[0086] It should be noted that when the pixel size per one pixel in
the U-axis direction of the input image plane R4 is set to au, and
the pixel size per one pixel in the V-axis direction of the input
image plane R4 is set to av, the coordinates (u, v) on the input
image plane R4 corresponding to the coordinates P (P') on the space
model MD is expressed as follows.
u = h cos .PHI. a U [ Formula 10 ] v = h sin .PHI. a v [ Formula 11
] ##EQU00004##
[0087] As mentioned above, the coordinates correspondence part 10
causes the coordinates on the space model MD to correspond to the
coordinates on one or more input image planes R4 existing for each
camera, and relates the coordinates on the space model MD, a camera
identifier, and the coordinates on the input image plane R4, and
stores the correspondence relationship in the input image-space
model correspondence relation map 40.
[0088] Because the coordinates correspondence part 10 operates the
conversion of coordinates by using the quaternion, the coordinates
correspondence part 10 provides an advantage in that a gimbal lock
is not generated unlike a case where a conversion of coordinates is
operated using an Euler angle. However, the coordinate
correspondence part 10 is not limited to one performing an
operation of conversion of coordinates using a quaternion, and the
conversion of coordinates may be operated using an Euler angle.
[0089] If it is possible to cause a correspondence to coordinates
on a plurality of input image planes R4, the coordinates
correspondence part 10 may cause the coordinates P (P') to
correspond to the coordinates on the input image plane R4 with
respect to a camera of which incident angle is smallest, or may
cause the coordinates P (P') to correspond to the coordinates on
the input image plane R4 selected by an operator.
[0090] Next, a description is given of a process of re-projecting
the coordinates on the curved surface area R2, from among the
coordinates on the space model MD, onto the processing-target image
plane R3 on the XY plane.
[0091] FIGS. 6A and 6B are views for explaining correspondence
between coordinates according to the coordinates correspondence
part 10. FIG. 6A is a view illustrating a correspondence
relationship between the coordinates on the input mage plane R4 of
the camera 2 using a normal projection (h=ftan .alpha.) and the
coordinates on the space model MD. The coordinates correspondence
part 10 causes both coordinates to correspond to each other by
causing each of line segments, which connect coordinates on the
input image plane R4 of the camera 2 and the coordinates on the
space model MD corresponding to the coordinates on the input image
plane R4, passes the optical center C of the camera 2.
[0092] In the example illustrated in FIG. 6A, the coordinates
correspondence part 10 causes the coordinates K1 on the input image
plane R4 of the camera 2 to correspond to the coordinates L1 on the
plane surface area R1 of the space model MD, and causes the
coordinates K2 on the input image plane R4 of the camera 2 to
correspond to the coordinates L2 on the curved surface area R2 of
the space model MD. In this situation, both the line segment K1-L1
and the line segment K2-L2 pass the optical center C of the camera
2.
[0093] It should be noted that when the camera 2 uses projection
systems (for example, an orthogonal projection, a stereographic
projection, an equisolid angle projection, an equidistant
projection, etc.) other than the normal projection system, the
coordinates correspondence part 10 causes the coordinates K1 and K2
on the input image plane R4 to correspond to the coordinates L1 and
L2 on the space model MD according to the respective projection
system.
[0094] Specifically, the coordinates correspondence part 10 causes
the coordinates on the input image plane to correspond to the
coordinates on the space model MD based on a predetermined function
(for example, an orthogonal projection (h=fsin.alpha.), a
stereographic projection (h=2ftan(.alpha./2)), an equisolid angle
projection (h=fsin(.alpha./2)), an equidistant projection
(h=f.alpha.), etc.). In this case, the line segment K1-L1 and the
line segment K2-L2 do not pass the optical center C of the camera
2.
[0095] FIG. 6B is a view illustrating a correspondence relationship
between the coordinates on the curved surface area R2 of the space
model MD and the coordinates on the processing-target image plane
R3. The coordinates correspondence part 10 introduces a group of
parallel lines PL, which are a group of parallel lines PL
positioned on the XZ-plane and form an angle .beta. between the
processing-target image plane R3, and causes both coordinates to
correspond to each other so that both the coordinates on the curved
surface area R2 of the space model MD and the coordinates on the
processing-target image plane R3 corresponding to the coordinates
on the curved surface area R2 are positioned on one of the parallel
lines.
[0096] In the example illustrated in FIG. 6B, the coordinates
correspondence part 10 causes both coordinates to correspond to
each other so that the coordinates L2 on the curved surface area R2
of the space model MD and the coordinates M2 on the
processing-target image plane R3 are positioned on a common
parallel line.
[0097] The coordinates correspondence part 10 can cause the
coordinates on the plane surface area R1 of the space model MD to
correspond to the coordinates on the processing-target image plane
R3 using a group of parallel lines PL, similar to the coordinates
on the curved surface area R2. However, in the example illustrated
in FIG. 6B, because the plane surface area R1 and the
processing-target image plane R3 lie in a common plane, the
coordinates L1 on the plane surface area R1 on the space model MD
and the coordinates M1 on the processing-target image plane R3 have
the same coordinates value.
[0098] As mentioned above, the coordinates correspondence part 10
causes the spatial coordinates on the space model MD to correspond
to the projection coordinates on the processing-target image plane
R3, and stores the coordinates on the space model MD and the
coordinates on the processing-target image R3 in the space
model-processing-target image correspondence relation map 41 by
relating them to each other.
[0099] FIG. 6C is a view illustrating a correspondence relationship
between the coordinates on the processing-target image plane R3 and
the coordinates on the output image plane R5 of the virtual camera
2V using, as an example, a normal projection (h=ftan.alpha.). The
coordinates correspondence part 10 causes both coordinates to
correspond to each other so that each of line segments connecting
the coordinates on the output image plane R5 of the virtual camera
2V and the coordinates on the processing-target image plane R3
corresponding to the coordinates on the output image plane R5
passes the optical center CV of the virtual camera 2V.
[0100] In the example illustrated in FIG. 6C, the output image
generation part 11 causes the coordinates N1 on the output image
plane R5 of the virtual camera 2V to correspond to the coordinates
M1 on the processing-target image plane R3 (the plane surface area
R1 of the space model MD), and causes the coordinates N2 on the
output image plane R5 of the virtual camera 2V to correspond to the
coordinates M2 on the processing-target image plane R3. In this
situation, both the line segment M1-N1 and the line segment M2-N2
pass the optical center CV of the virtual camera 2.
[0101] If the virtual camera 2 uses projection systems (for
example, an orthogonal projection, a stereographic projection, an
equisolid angle projection, an equidistant projection, etc.) other
than the normal projection, the output image generation part 11
causes the coordinates N1 and N2 on the output image plane R5 of
the virtual camera 2V to correspond to the coordinates M1 and M2 on
the processing-target image plane R3 according to the respective
projection system.
[0102] Specifically, the output image generation part 11 causes the
coordinates on the output image plane R5 to correspond to the
coordinates on the processing-target image plane R3 based on a
predetermined function (for example, an orthogonal projection
(h=fsin.alpha.), a stereographic projection (h=2ftan(.alpha./2)),
an equisolid angle projection (h=fsin(.alpha./2)), an equidistant
projection (h=f.alpha.), etc.). In this case, the line segment
M1-N1 and the line segment M2-N2 do not pass the optical center CV
of the virtual camera 2V.
[0103] As mentioned above, the output image generation part 11
causes the coordinates on the output image plane R5 to correspond
to the coordinates on the processing-target image plane R3, and
stores the coordinates on the output image plane R5 and the
coordinates on the processing-target image R3 in the
processing-target image-output image correspondence relation map 42
by relating them to each other. Then, the output image generation
part 11 generates the output image be relating a value of each
pixel in the output image to a value of each pixel in the input
image while referring to the input image-space model correspondence
relation map 40 and the space model-processing-target image
correspondence relation map 41 stored in the coordinates
correspondence part 10.
[0104] It should be noted that FIG. 6D is a view of combination of
FIG. 6A through FIG. 6C, and illustrates a mutual positional
relationship between the camera 2, the virtual camera 2V, the plane
surface area R1 and the curved surface area R2 of the space model
MD, and the processing-target image plane R3.
[0105] Next, a description is given, with reference to FIGS. 7A and
7B, of an action of the group of parallel lines, which the
coordinates correspondence part 10 introduces to cause the
coordinates on the space model MD to correspond to the coordinates
on the processing-target image plane R3.
[0106] FIG. 7A is a view of a case where an angle .beta. is formed
between the group of parallel lines PL positioned on the XZ-plane
and the processing-target image plane R3. FIG. 7B is a view of a
case where an angle .beta.1 ((.beta.1>.beta.) is formed between
the group of parallel lines PL positioned on the XZ-plane and the
processing-target image plane R3. The coordinates La through Ld on
the curved surface area R2 of the space model MD in FIGS. 7A and 7B
correspond to the coordinates Ma through Md on the
processing-target image plane R3, respectively. The intervals of
the coordinates La through Ld in FIG. 7A are equal to the intervals
of the coordinates La through Ld in FIG. 7B, respectively. It
should be noted that although the group of parallel lines PL are
supposed to be on the XZ-plane for the purpose of simplification of
description, actually, the parallel lines radially extend from all
points on the Z-axis toward the processing-target image plane R3.
The Z-axis in this case is referred to as "re-projection axis".
[0107] As illustrated in FIGS. 7A and 7B, the intervals of the
coordinates Ma through Md on the processing-target image plane R3
decease linearly as the angle between the group of parallel lines
PL and processing-target image plane R3 increases. That is, the
intervals of the coordinates Ma through Md decrease uniformly
irrespective of the distance between the curved surface area R2 of
the space model MD and each of the coordinates Ma through Md. On
the other hand, in the example illustrated in FIGS. 7A and 7B,
because a conversion to the group of coordinates on the
processing-target image plane R3 is not performed, the intervals of
the group of coordinates on the plane surface area R1 of the space
model MD do not change.
[0108] The change in the intervals of the group of coordinates
means that only an image portion corresponding to the image
projected on the curved surface area R2 of the space model MD from
among the image portions on the output image plane R5 (refer to
FIG. 6C) is enlarged or reduced linearly.
[0109] Next, a description is given, with reference to FIGS. 8A and
8B, of an alternative example of the group of parallel lines PL,
which the coordinates correspondence part 10 introduces to cause
the coordinates on the space model MD to correspond to the
coordinates on the processing-target image plane R3.
[0110] FIG. 8A is a view of a case where all of a group of
auxiliary lines AL positioned on the XZ-plane extend from a start
point T1 on the Z-axis toward the processing-target image plane R3.
FIG. 8B is a view of a case where all of the group of auxiliary
lines AL positioned on the XZ-plane extend from a start point T2 on
the Z-axis toward the processing-target image plane R3. The
coordinates La through Ld on the curved surface area R2 of the
space model MD in FIGS. 8A and 8B correspond to the coordinates Ma
through Md on the processing-target image plane R3, respectively.
In the example illustrated in FIG. 8A, the coordinates Mc and Md
are not illustrated in the figure because they are out of the range
of the processing-target image plane R3. The intervals of the
coordinates La through Ld in FIG. 8A are equal to the intervals of
the coordinates La through Ld in FIG. 8B, respectively. It should
be noted that although the group of auxiliary lines AL are supposed
to be on the XZ-plane for the purpose of simplification of
description, actually, the auxiliary lines radially extend from an
arbitrary point on the Z-axis toward the processing-target image
plane R3. Similar to the example illustrated in FIGS. 7A and 7B,
the Z-axis in this case is referred to as "re-projection axis".
[0111] As illustrated in FIGS. 8A and 8B, the intervals of the
coordinates Ma through Md on the processing-target image plane R3
decease nonlinearly as the distance (height) between the start
point of the group of auxiliary lines AL and the original point O
increases. That is, a degree of decrease of each of the intervals
increases as the distance between the curved surface area R2 of the
space model MD and each of the coordinated Ma through Md increases.
On the other hand, in the example illustrated in FIGS. 8A and 8B,
because a conversion to the group of coordinates on the
processing-target image plane R3 is not performed, the intervals of
the group of coordinates on the plane surface area R1 of the space
model MD do not change.
[0112] Similar to the case of the group of parallel lines PL, the
change in the intervals of the group of coordinates means that only
an image portion corresponding to the image projected on the curved
surface area R2 of the space model MD from among the image portions
on the output image plane R5 (refer to FIG. 6C) is enlarged or
reduced nonlinearly.
[0113] As explained above, the image generation device 100 can
linearly or nonlinearly enlarge or reduce an image portion (for
example, a horizontal image) of the output image corresponding to
the image projected on the curved surface area R2 of the space
model MD without giving an influence to an image portion (for
example, a road image) of the output image corresponding to the
image projected on the plane surface area R1 of the space model MD.
Thereby, an object positioned around the excavator 60 (an object in
an image a circumference viewed from the excavator 60 in a
horizontal direction) can be rapidly and flexibly enlarged or
reduced without giving an influence to a road image (a virtual
image when viewing the shovel from directly above) in the vicinity
of the excavator 60, which can improve visibility of a dead angle
area of the excavator 60.
[0114] Next, a description will be given, with reference to FIGS.
9A and 9B, of a difference between a case where an output image is
generated directly from an image projected on the space model MD
and a case where an image projected on the space model MD is
re-projected on the processing-target image and an output image is
generated from the re-projected processing-target image.
[0115] FIG. 9A is a view of a case where an angle .beta. is formed
between the group of parallel lines PL positioned on the XZ-plane
and the processing-target image plane R3. FIG. 9B is a view of a
case where an angle .beta.2 (.beta.2>.beta.) is formed between
the group of parallel lines PL positioned on the XZ-plane and the
processing-target image plane R3. It is assumed that the plane
surface area R1 and the curved surface area R2 of the space model
MD, the processing-target image plane R3, the output image plane R5
and the optical center CV of the virtual camera 2V using a normal
projection (h=ftan.alpha.) in FIG. 9A are common to those of FIG.
9B, respectively.
[0116] In FIGS. 9A and 9B, the coordinates M1 on the
processing-target image plane R3 containing the plane surface area
R1 correspond to the coordinates N1 on the output image plane R5,
and the coordinates L2 on the curved surface area R2 correspond to
the coordinates M2 on the processing-target image plane R3 and the
coordinates N2 on the output image plane R5. A distance D1 (D3)
indicates a distance on the X-axis between the central point (an
intersection with the optical axis G of the virtual camera 2V) of
the output image plane R5 and the coordinates N1. A distance D2
(D4) indicates a distance on the X-axis between the central point
of the output image plane R5 and the coordinates N2.
[0117] As illustrated in FIGS. 9A and 9B, the distance D2 (refer to
FIG. 9A), when the angle between the group of parallel lines PL and
the processing-target image plane R3 is .beta., increases as the
angle decreases, and it becomes the distance D4 when the angle is
.beta.2. The distance D1, when the angle is .beta., is constant
irrespective of changes in the angle, and is equal to the distance
D3 when the angle is .beta.2 (refer to FIG. 9B).
[0118] That the distance D2 changes to the distance D4 and the
distance D1 is constant means that only an image portion
corresponding to an image projected on the curved surface area R2
of the space model MD from among the image portions on the output
image plane R5 is enlarged or reduced, similar to the action
explained with reference to FIGS. 7A and 7B and FIGS. 8A and
8B.
[0119] It should be noted that when an output image is generated
directly based on the image projected on the space model MD, the
image portion on the output image plane R5 corresponding to the
image projected on the curved surface area R2 alone cannot be
enlarged or reduced because the plane surface area R1 and the
curved surface area R2 cannot handle separately (because they
cannot be separate objects to be enlarged or reduced).
[0120] FIG. 10 is a view of a case where an angle .beta. is formed
between the group of parallel lines PL positioned on the XZ-plane
and the processing-target image plane R3. FIG. 10 illustrates a
state where the optical center CV of the virtual camera 2V using a
normal projection (h=ftan.alpha.) is moved outside the space model
MD (a state where a value of the X-coordinate of the optical center
CV is set larger than a radius of the plane surface area R1).
[0121] As illustrated in FIG. 10, the output image generation part
11 causes the coordinate point M1 on the processing-target image
plane R3 (the plane surface area R1) to correspond to the
coordinate point N1 on the output image plane R5 so that the line
segment M1-N1 passes the optical center CV, and causes the
coordinate point M2 on the processing-target image plane R3
corresponding to the coordinate point L2 on the curved surface area
R2 to correspond to the coordinate point N2 on the output image
plane R5 so that the line segment M2-N2 passes the optical center
CV. Thereby, a problem that an appropriate output image cannot be
generated because an outer surface of the side wall of the cylinder
is viewed (a problem that the coordinates on the space model MD
cannot be caused to correspond to the coordinates on the output
image plane R5) is not arisen as in a case where an output image is
generated directly from an image projected on the curved surface
area R2 of the space model MD.
[0122] It should be noted that a description was given, with
reference to FIGS. 9A and 9B and FIG. 10, of the virtual camera 2V
using a normal projection, and the same applies to a virtual camera
2V using projection system (for example, an orthogonal projection,
a stereographic projection, an equisolid angle projection, an
equidistant projection, etc.) other than the normal projection. In
such a case, the output image generation part 11 causes the
coordinates on the output image plane R5 to correspond to the
coordinates on the processing-target image plane R3 in accordance
with a function (for example, an orthogonal projection
(h=fsin.alpha.), a stereographic projection (h=2ftan(.alpha./2)),
an equisolid angle projection (h=fsin(.alpha./2)), an equidistant
projection (h=f.alpha.), etc.) corresponding to the respective
projection system instead of causing the coordinate point M1 on the
processing-target image plane R3 (the plane surface area R1) to
correspond to the coordinate point N1 on the output image plane R5
(according to the function h=ftan.alpha.) so that the line segment
M1-N1 passes the optical center CV. In this case, the line segment
M1-N1 does not pass the optical center CV of the virtual camera
2V.
[0123] Next, a description will be given, with reference to FIG.
11, of a process of generating a processing-target image by the
image generation device (hereinafter, referred to as
"processing-target image generation process") and a process of
generating an output image using the generated processing-target
image (hereinafter, referred to as "output image generation
process"). FIG. 11 is a flowchart of the processing-target
generation process (step S1 through step S3) and the output image
generation process (step S4 through step S6). It is assumed that
the arrangement of the camera 2 (the input image plane R4), the
space model (the plane surface area R1 and the curved surface area
R2) and the processing-target image plane R3 is previously
determined.
[0124] First, the control part 1 causes a coordinate point on the
processing-target image plane R3 to correspond to a coordinate
point on the space model MD by the coordinates correspondence part
10 (step S1).
[0125] Specifically, the coordinates correspondence part 10
acquires an angle formed between the group of parallel lines PL and
the processing-target image plane R3, and computes a point at which
one of the group of parallel lines PL extending from the coordinate
point on the processing-target image plane R3 intersects with the
curved surface area R2 of the space model MD. Then, the coordinates
correspondence part 10 derives a coordinate point on the curved
surface area R2 corresponding to the computed point as a coordinate
point on the curved surface area R2 corresponding to a coordinate
point on the processing-target image plane R3, and stores a
correspondence relationship therebetween in the space
model-processing-target image correspondence relation map 41. The
angle formed between the group of parallel lines PL and the
processing-target image plane R3 may be a value previously stored
in the storage part 4, etc., or may be a value dynamically input by
the operator through the input part 3.
[0126] When the coordinates on the processing-target image plane R3
is coincident with the coordinates on the plane surface area R1 on
the space model MD, the coordinates correspondence part 10 derives
the coordinates on the plane surface area R1 concerned as the
coordinates corresponding to the coordinates on the
processing-target image plane R3, and stores a correspondence
relationship therebetween in the space model-processing-target
image correspondence relation map 41.
[0127] Thereafter, the control part 1 causes the coordinates on the
space model MD derived by the above mentioned process to correspond
to the coordinates on the input image plane R4 by the coordinates
correspondence part 10 (step S2).
[0128] Specifically, the coordinates correspondence part 10
acquires the coordinate point of the optical center C of the camera
2 using a normal projection (h=ftan.alpha.), and computes a point
at which a line segment extending from a coordinate point on the
space model MD, which is a line segment passing the optical center
C, intersects with the input image plane R4. Then, the coordinates
corresponding part 10 derives a coordinate point on the input image
plane R4 corresponding to the computed point as a coordinate point
on the input image plane R4 corresponding to the coordinate point
on the space model MD, and stores a correspondence relationship
therebetween in the input image-space model map 40.
[0129] Thereafter, the control part 1 determines whether or not all
of the coordinate points on the processing-target image plane R3
are caused to correspond to coordinate points on the space model MD
and the coordinate points on the input image plane R4 (step S3). If
it is determined that all of the coordinate points have not been
caused to correspond (NO of step S3), the process of step S1 and
step S2 is repeated.
[0130] On the other hand, if it is determined that all of the
coordinate points are caused to correspond (YES of step S3), the
control part 1 causes the processing-target image generation
process to end and, thereafter, causes the output image generation
process to start. Thereby, the output mage generation part 11
causes the coordinates on the processing-target image plane R3 to
the coordinates on the output image plane R5 (step S4).
[0131] Specifically, the output image generation part 11 generates
an output image by applying a scale conversion, an affine
conversion or a distortion conversion to a processing-target image.
Then, the output image generation part 11 stores a correspondence
relationship between the coordinates on the processing-target image
plane R3 and the coordinates on the output image plane R5 in the
processing-target image-output image correspondence relation map
42, the correspondence relationship being determined according to
the applied scale conversion, affine conversion, or distortion
conversion.
[0132] Alternatively, when generating the output image using the
virtual camera 2V, the output image generation part 11 may compute
the coordinates on the output image plane R5 from the coordinates
on the processing-target image plane R3, and may store a
correspondence relationship therebetween in the processing-target
image-output image correspondence relation map 42.
[0133] Alternatively, when generating the output image using the
virtual camera 2V using a normal projection (h=ftan.alpha.), the
output image generation part 11 may compute, after acquiring the
coordinate point of the optical center CV of the virtual camera 2V,
a point at which a line segment extending from a coordinate point
on the output image plane R5, which line segment passes the optical
center CV, intersects with the processing-target image plane R3.
Then, the output image generation part 11 may derive the
coordinated on the processing-target image plane R3 corresponding
to the computed point as a coordinate point on the
processing-target image plane R3 corresponding to the coordinate
point on the output image plane R5, and may store a correspondence
relationship therebetween in the processing-target image-output
image correspondence relation map 42.
[0134] Thereafter, the control part 1 follows, by the output-image
generation part 11, the correspondence relationship between the
coordinates on the input image plane R4 and the coordinates on the
space model MD, the relationship between the coordinates on the
space model MD and the coordinates on the processing-target image
plane R3 and the correspondence relationship between the
processing-target image plane R3 and the coordinates on the output
mage plane R5, while referring to the input image-space model
correspondence relation map 40, the space model-processing-target
image correspondence relation map 41 and the processing-target
image-output image correspondence relation map 42, and acquires
values (for example, a brightness value, a color phase value, a
chroma value, etc.) possessed by coordinates on the input image
plane R4 corresponding to the coordinates on the output image plane
R5. It should be noted that, when a plurality of coordinates on a
plurality of input image planes R4 correspond to one coordinate
point on the output image plane R5, the output image generation
part 11 may derive statistical values (for example, a mean value, a
maximum value, a minimum value, an intermediate value, etc.) based
on each of the values of the plurality of coordinates on the
plurality of input image planes R4, and may use the statistical
values as the values of the coordinates on the output image plane
R5.
[0135] Thereafter, the control part 1 determines whether or not all
of the values of the coordinates on the output image plane R5 are
caused to correspond to the values of the coordinates on the input
mage plane R4 (step S6). If it is determined that all of the values
of the coordinates have not been caused to correspond (NO of step
S4), the process of step S5 is repeated.
[0136] On the other hand, if it is determined that all of the
values of the coordinates have been caused to correspond (YES of
step S6), the control part 1 generates an output image, and ends
the series of processes.
[0137] It should be noted that when the image generation device 100
does not generate a processing-target image, the processing-target
image generation process is omitted, and the "coordinates on the
processing-target image plane" in step S4 of the output image
generation process is read as "coordinates on the space model".
[0138] According to the above-mentioned structure, the image
generation device 100 is able to generate the processing-target
image and the output image that can cause the operator to
intuitively grasp the positional relationship between the
construction machine and a peripheral obstacle.
[0139] The image generation device 100 is capable of surely causing
each coordinate point on the processing-target plane R3 to
correspond to one or more coordinate points on the input image
plane R4 by performing the correspondence operation to track back
from the processing-target image plane R3 to the input image plane
R4 through the space model MD. Therefore, a better quality
processing-target image can be generated as compared to a case
where a coordinate correspondence operation is performed in an
order from the input image plane R4 to the processing-target image
plane R3 through the space model MD. It should be noted that when
performing a coordinate correspondence operation in an order from
the input image plane R4 to the processing-target image plane R3
through the space model MD, each of the coordinate points on the
input image plane R4 can be caused to correspond to one or more
coordinate points on the processing-target image plane R3, however,
there may be a case where a part of the coordinate points on the
processing-target image plane R3 cannot be caused to correspond to
any one of the coordinate points on the input mage plane R4. In
such a case, it is necessary to apply an interpolation process to
the part of the coordinate points on the processing-target image
plane R3.
[0140] Moreover, when enlarging or reducing only an image
corresponding to the curved surface area R2 of the space model MD,
the image generation device 100 can realize a desired enlargement
or reduction by merely rewriting only a part associated with the
curved surface area R2 in the space model-processing-target image
correspondence relation map 41 by changing the angle formed between
the group of parallel lines PL and the processing-target image
plane R3 without rewriting the contents of the input image-space
model correspondence relation map 40.
[0141] Moreover, when changing an appearance of the output image,
the image generation device 100 is capable of generating a desire
output image (a scale conversion image, an affine conversion image
or a distortion conversion image) by merely rewriting the
processing-target image-output image correspondence relation map 42
by changing various parameters regarding a scale conversion, an
affine conversion or a distortion conversion without rewriting the
contents of the input image-space model correspondence relation map
40 and the contents of the space model-processing-target image
correspondence relation map 41.
[0142] Similarly, when changing a view point of the output image,
the image generation device 100 is capable of generating an output
image (view point conversion image) which is viewed from a desired
view point by merely rewriting the processing-target image-output
mage correspondence relation map 42 by changing values of various
parameters of the virtual camera 2V without rewriting the contents
of the input image-space model correspondence relation map 40 and
the space model-processing-target image correspondence relation map
41.
[0143] Next, a description is given, with reference to FIG. 12A
through FIG. 14C of a positional relationship between the camera 2
(the right side camera 2R, the backside camera 2B) and the space
model MD.
[0144] FIG. 12A is a view illustrating a positional relationship
between the camera 2 and the space model MD when viewing the
excavator 60 from above. FIG. 12B is a view, similar to FIG. 4,
illustrating a positional relationship between the camera 2 and the
space model MD when viewing the space model MD obliquely from
above. FIG. 12C is a view illustrating a processing-target image
which the image generation device 100 generates.
[0145] As best illustrated in FIG. 12B, the cylinder center axis of
the cylindrical space model MD is coincident with the re-projection
axis and the tuning axis PV (z-axis) of the excavator 60, and a
rod-shaped object OBJ, which extends parallel to the Z-axis, exists
on the Y-axis.
[0146] In FIG. 12B, the optical axis G1 of the backside camera 2B
and the optical axis G2 of the right side camera 2R intersect with
the plane surface area R1 of the space model and the plane
(XY-plane) on which the processing-target image plane R3 is
positioned, respectively. Moreover, the optical axis G1 and the
optical axis G2 intersect with each other at a point J1 on the
cylinder center axis (re-projection axis). It should be noted that
the optical axis G1 and the optical axis G2 may be in a twisted
positional relationship if the components, when it is projected on
a plane parallel to the XY plane, intersect with each other at a
point on the cylinder center axis (re-projection axis).
[0147] A perpendicular line drawn from the optical center of the
backside camera 2B to the cylinder center axis (re-projection axis)
is in a perpendicular relationship with a perpendicular line drawn
from the optical axis of the right side camera 2R to the cylinder
center axis (re-projection axis). Although the two perpendicular
lines intersect with each other at a point J2 while existing in the
plane parallel to the plane surface area R1 and the plane on which
the processing-target image plane R3 is positioned in the present
embodiment, the two perpendicular lines may be positioned on
separate planes, respectively, and may be in a twisted positional
relationship.
[0148] According to the positional relationship between the camera
2 and the space model MD illustrated in FIGS. 12A and 12B, the
image generation device 100 is capable of generating the
processing-target image as illustrated in FIG. 12C. That is, in
FIG. 12C, the rod-shaped object OBJ extending parallel to the
Z-axis on the Y-axis extends in a direction (a direction of a line
passing the optical center of the right side camera 2R and a point
on the object OBJ) parallel to the Y-axis in a road image portion
corresponding to an image projected on the plane surface area R1.
Moreover, in FIG. 12C, the rod-shaped object OBJ extends in a
direction (a direction of a line passing a point on the
re-projection axis (a start point of the group of parallel lines PL
or the group of auxiliary lines AL) and a point on the object OBJ)
parallel to the Y-axis in a horizontal image portion corresponding
to an image projected on the curved surface area R2. In other
words, the object OBJ does not bend at a boundary between the road
image portion and the horizontal image portion, but extends like a
straight line.
[0149] FIGS. 13A through 13C are views similar to FIGS. 12A through
12C, respectively. In the example, illustrated in FIGS. 13A through
13C, the cylinder center axis of the cylindrical space model MD is
coincident with the re-projection axis and the turning axis PV
(Z-axis) of the excavator 60, and the rod-shaped object OBJ
extending parallel to the Z-axis direction exists on the Y-axis.
Further, a rod-shaped object OBJ1 extending parallel to the Z-axis
direction from the XY-plane exists also in a direction of the
optical axis G2 of the right side camera 2R.
[0150] In FIG. 13B, similar to the positional relationship
illustrated n FIG. 12B, the optical axis G1 of the backside camera
2B and the optical axis G2 of the right side camera 2R intersect
with the plane surface area R1 of the space model MD and the plane
(XY-plane) on which the processing-target image plane R3 is
positioned, respectively. Moreover, the optical axis G1 and the
optical axis G2 intersect with each other at a point J1 on the
cylinder center axis (re-projection axis). It should be noted that
the optical axis G1 and the optical axis G2 may be in a twisted
positional relationship if the components, when it is projected on
a plane parallel to the XY-plane, intersect with each other at a
point on the cylinder center axis (re-projection axis).
[0151] On the other hand, a perpendicular line drawn from the
optical center of the backside camera 2B to the cylinder center
axis (re-projection axis) is not in a perpendicular relationship
with a perpendicular line drawn from the optical axis of the right
side camera 2R to the cylinder center axis (re-projection axis).
The perpendicular line drawn from the optical center of the
backside camera 2B to the cylinder center axis (re-projection axis)
intersect with the perpendicular line drawn from the optical axis
of the right side camera 2R to the perpendicular line thereof at a
point J2 which is not on the cylinder center axis (re-projection
axis). In the present embodiment, the optical centers of the
backside camera 2B and the right side camera 2R exist on a plane
parallel to the plane surface area R1 and the plane on which the
processing-target image plane R3 is positioned. However, the
optical centers of the backside camera 2B and the right side camera
2R may be positioned on different planes, respectively, and the
perpendicular lines of each other may be in a twisted positional
relationship.
[0152] According to the positional relationship between the camera
2 and the space model MD illustrated in FIGS. 13A and 13B, the
image generation device 100 is capable of generating the
processing-target image as illustrated in FIG. 13C. In FIG. 13C,
the rod-shaped object OBJ extending parallel to the Z-axis on the
Y-axis extends in a direction (a direction of a line passing the
optical center of the right side camera 2R and a point on the
object OBJ) slightly separate from the Y-axis in a road image
portion corresponding to an image projected on the plane surface
area R1. Moreover, the rod-shaped object OBJ extends in a direction
(a direction of a line passing a point on the re-projection axis (a
start point of the group of parallel lines PL or the group of
auxiliary lines AL) and a point on the object OBJ) parallel to the
Y-axis in a horizontal image portion corresponding to an image
projected on the curved surface area R2. In other words, the object
OBJ is slightly bent at a boundary between the road image portion
and the horizontal image portion.
[0153] On the other hand, as illustrated in FIG. 13C, the
rod-shaped object OBJ1 extending parallel to the Z-axis and
existing in the direction of the optical axis G2 of the right side
camera 2R extends in a direction (a direction of a line passing the
optical center of the right side camera 2R and a point on the
object OBJ) parallel to the optical axis G2 a road image portion
corresponding to an image projected on the plane surface area R1.
Moreover, the rod-shaped object OBJ1 extends in a direction (a
direction of a line passing a point on the re-projection axis (a
start point of the group of parallel lines PL or the group of
auxiliary lines AL) and a point on the object OBJ1) parallel to the
optical axis G2 in a horizontal image portion corresponding to an
image projected on the curved surface area R2. In other words, the
object OBJ does not bend at a boundary between the road image
portion and the horizontal image portion, but extends like a
straight line.
[0154] FIGS. 14A through 14C are views similar to FIGS. 12A through
12C, respectively. In the example, illustrated in FIGS. 14A through
14C, the cylinder center axis of the cylindrical space model MD is
coincident with the re-projection axis and the turning axis PV
(Z-axis) of the excavator 60, and the rod-shaped object OBJ
extending parallel to the Z-axis direction exists on the Y-axis.
Further, a rod-shaped object OBJ1 extending parallel to the Z-axis
direction from the XY-plane exists also in a direction of the
optical axis G2 of the right side camera 2R.
[0155] In FIG. 14B, similar to the positional relationship
illustrated n FIG. 12B, the optical axis G1 of the backside camera
2B and the optical axis G2 of the right side camera 2R intersect
with the plane surface area R1 of the space model MD and the plane
(XY-plane) on which the processing-target image plane R3 is
positioned, respectively. Moreover, a perpendicular line drawn from
the optical center of the backside camera 2B to the cylinder center
axis (the re-projection axis) is in a perpendicular relationship
with a perpendicular line drawn from the optical center of the
right side camera 2R to the cylinder center axis (re-projection
axis). In the present embodiment, the optical centers of the
backside camera 2B and the right side camera 2R exist on a plane
parallel to the plane surface area R1 and a plane on which the
processing-target image plane R3 is positioned. However, the
optical centers of the backside camera 2B and the right side camera
2 may be positioned on different planes, respectively, and the
perpendicular lines may be mutually in a twisted positional
relationship.
[0156] On the other hand, the optical axis G1 and the optical axis
G2 do not intersect with each other on the cylinder center axis
(re-projection axis) but intersect at a point J1 which does not
exist on the cylinder center axis (re-projection axis). It should
be noted that the optical axis G1 and the optical axis G2 may be in
a twisted positional relationship if components of a projection on
a plane parallel to the XY-plane intersect at points which do not
exist on the cylinder center axis (re-projection axis).
[0157] According to the positional relationship between the camera
2 and the space model MD illustrated in FIGS. 14A and 14B, the
image generation device 100 generates the processing-target image
as illustrated in FIG. 14C. In FIG. 14C, the rod-shaped object OBJ2
extending parallel to the Z-axis in a direction of the optical axis
G2 of the right side camera 2R extends in a direction (a direction
of a line passing the optical center of the right side camera 2R
and a point on the object OBJ2) parallel to the optical axis G2 in
a road image portion corresponding to an image projected on the
plane surface area R1. Moreover, the rod-shaped object OBJ2 extends
in a direction (a direction of a line passing a point on the
re-projection axis (a start point of the group of parallel lines PL
or the group of auxiliary lines AL) and a point on the object OBJ2)
parallel to the Y-axis direction in a horizontal image portion
corresponding to an image projected on the curved surface area R2.
In other words, the object OBJ2 is slightly bent at a boundary
between the road image portion and the horizontal image
portion.
[0158] On the other hand, as illustrated in FIG. 14C, the
rod-shaped object OBJ extending parallel to the Z-axis direction on
the Y-axis extends in a direction (a direction of a line passing
the optical center of the right side camera 2R and a point on the
object OBJ) parallel to the Y-axis direction in the road image
portion corresponding to the image projected on the plane surface
area R1. Moreover, the rod-shaped object OBJ extends in a direction
(a direction of a line passing a point on the re-projection axis (a
start point of the group of parallel lines PL or the group of
auxiliary lines AL) and a point on the object OBJ) parallel to the
Y-axis direction in the horizontal image portion corresponding to
the image projected on the curved surface area R2. In other words,
the object OBJ does not bend at a boundary between the road image
portion and the horizontal image portion, and extends like a
straight line.
[0159] As mentioned above, the image generation device 100 is
capable of generating the processing-target image by arranging the
space model MD so that the cylinder center axis (re-projection
axis) of the space model MD and the optical axis of the camera
intersect with each other without bending an object existing in an
optical axis direction of the camera at a boundary between the road
image portion and the horizontal image portion. It should be noted
that this advantage can be obtained in a case of a single camera or
a case of three or more cameras.
[0160] Moreover, the image generation device 100 is capable of
generating the processing-target image by arranging the space model
MD so that the perpendicular lines drawn from the optical centers
of the backside camera 2B and the right side camera 2R to the
cylinder center axis (re-projection axis) of the space model MD are
perpendicular to each other without bending objects on a just right
had side and just behind the excavator 60 at a boundary between the
road image portion and the horizontal image portion. It should be
noted that this advantage can be obtained in a case of three or
more cameras.
[0161] It should be noted that although the positional relationship
between the camera (right side camera 2R and the backside camera
2B) and the space model MD illustrated in FIG. 12A through FIG. 14C
and the action and effect thereof correspond to the case where the
image generation device 100 generates the processing-target image,
the same action and effect can be obtained even in a case where the
image generation device 100 does not generate the processing-target
image (a case where the processing-target image plane R3 does not
exist). In this case, the processing-target image illustrated in
FIGS. 12C, 13C and 14C are read and substituted by the output image
generated using an image projected on the space model MD.
[0162] FIG. 15 is an example of a display when causing the display
part 5 to display an output image generated using an input image of
two cameras (the right side camera 2R and the backside camera 2B)
mounted on the excavator 60. The image generation device 100
generates the processing-target image by projecting a portion of
the input image on the plane surface area R1 of the space model MD
and projecting another portion of the input image on the curved
surface area R2 of the space model MD and thereafter re-projecting
the input image on the processing-target image plane R3. The image
generation device 100 displays the image based on the generated
processing-target image by combining an image which views a
vicinity of the shovel from above, which corresponds to the image
projected on the plane surface area R1, and an image of a view from
the excavator 60 in a horizontal direction, which corresponds to
the image re-projected on the curved surface area R2.
[0163] It should be noted that when the image generation device 100
does not generate the processing-target image, the output image is
generated by applying an image conversion process (for example, a
view point conversion process) to the image projected on the space
model MD.
[0164] The output image is trimmed to be in a circular shape do
that the image when the excavator 60 performs a turning operation
can be displayed without uncomfortable feel. That is, the output
image is displayed so that the center CTR of the circle is at the
cylinder center axis of the space model, and also on the turning
axis PV of the excavator 60, and the output image rotates about the
center CTR thereof in response to the turning operation of the
excavator 60. In this case, the cylinder center axis of the space
model MD may be coincident with or not coincident with the
re-projection axis.
[0165] The radius of the space model is, for example, 5 meters. The
angle formed by the group of parallel lines PL between the
processing-target image plane R3 or the height of the start point
of the group of auxiliary lines AL may be set so that, when an
object (for example, an operator) exists at a position distant from
the turning center of the excavator 60 by a maximum reach distance
(for example, 12 meters) of an excavation attachment E, the object
is displayed sufficiently large (for example, 7 millimeters or
more).
[0166] Further, in the output image, a CG image of the excavator 60
is arranged so that a front of the excavator 60 is coincident with
an upper portion of the screen of the display part 5 and the
turning center thereof is coincident with the center CTR. This is
to facilitate recognition of a positional relationship between the
excavator 60 and the object that appears in the output image. It
should be noted that, a frame image containing various sets of
information such as orientation, etc., may be arranged on a
periphery of the output image.
[0167] In this state, as illustrated in FIGS. 9A and 9B, the image
generation device 100 is capable of enlarging or reducing only an
image portion in the output image corresponding to the image, which
is projected on the curved surface area R2 and further re-projected
on the processing-target image plane R3 without giving an influence
to the image portion in the output image corresponding to the image
projected on the plane surface area R1. Moreover, as illustrated in
FIG. 10, it is possible to move the image portion to an arbitrary
position (for example, in a middle) in the screen area of the
display part 5 so as to view the image portion in the output image
from directly above, the image portion corresponding to an image
projected on the curved surface area R2 and further re-projected on
the processing-target image plane R3.
[0168] Although the image generation device 100 uses the
cylindrical space model MD as a space model in the above-mentioned
embodiments, the image generation device may use a space model
having other columnar shapes such as a polygonal column, etc., or
may use a space model constituted by tow planes including a bottom
surface and a side surface. Alternatively, the image generation
device 100 may be a space model having only a side surface.
[0169] The above-mentioned image generation device 100 is mounted
together with cameras on a construction machine, which travels by
itself and is equipped with movable members, such as a bucket, an
arm, a boom, a turning mechanism, etc., and is incorporated into an
operation support system which support a movement of the
construction machine and operations of those movable members while
presenting an image of surrounding areas to an operator. However,
the image generation device 100 may be mounted together with
cameras on other construction machines (body to be operated), such
as an industrial machine, a stationary crane, etc., which has a
movable member but does not travel by itself, and may be
incorporated into an operation support system which supports
operations of the machine.
[0170] The present invention is not limited to the specifically
disclosed embodiments, and various variations and modifications may
be made without departing from the scope of the present
invention.
* * * * *