JP7332363B2 - Camera placement evaluation device, camera placement evaluation method, and computer program - Google Patents

Description

The present invention relates to a camera placement evaluation device, a camera placement evaluation method, and a computer program for evaluating camera placement.

When installing a surveillance camera in a surveillance space, the arrangement conditions (position, posture, angle of view, etc.) of the surveillance camera for achieving a desired surveillance purpose are planned in advance.
To perform efficient monitoring by minimizing a blind spot area not photographed by a surveillance camera and photographing a wider area with a small number of surveillance cameras when one surveillance space is monitored by a plurality of surveillance cameras conventionally. is proposed.

If the fields of view of a plurality of surveillance cameras overlap unnecessarily, it is thought that blind spots that are not imaged will increase accordingly. For this reason, for example, the multiple-camera monitoring system disclosed in Patent Document 1 below obtains the camera field of view between each camera, obtains the overlap amount of the camera field of view between each camera, and outputs an evocative output such as a sound level corresponding to the overlap amount. conduct. This allows the observer to easily ascertain any overlapping camera fields of view.

JP 2011-114580 A

However, depending on planning requirements, overlapping visible spaces of multiple surveillance cameras may not be a waste, for example when a particular space within the surveillance space is desired to be monitored from different directions.
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to evaluate the shooting state of a space overlapping the visible space of a plurality of surveillance cameras.

A camera arrangement evaluation apparatus according to one aspect of the present invention includes a storage unit that stores camera information representing the positions, angles of view, and shooting directions of a plurality of cameras; A visible space calculating unit that calculates each, and an overlapping space between the visible spaces is obtained, and an evaluation value of the photographing state of the overlapping space according to each direction from a predetermined evaluation point in the overlapping space to the positions of the plurality of cameras. and a duplicate evaluator that calculates

A camera arrangement evaluation method according to another aspect of the present invention includes an information reading step of reading camera information representing the positions, angles of view, and photographing directions of a plurality of cameras from a storage device in a computer; a visible space calculation step of calculating respective visible spaces of a plurality of cameras; obtaining an overlapping space between the visible spaces; and a redundant evaluation step of calculating an evaluation value of the shooting state of the space.

A computer program according to still another aspect of the present invention provides a computer with an information reading step of reading camera information representing the positions, angles of view, and shooting directions of a plurality of cameras from a storage device; a visible space calculating step of calculating the visible spaces of the respective cameras; and obtaining an overlapping space between the visible spaces, and calculating the overlapping space according to each direction from a predetermined evaluation point in the overlapping space to the positions of the plurality of cameras. and a redundant evaluation step of calculating the evaluation value of the photographing state.

ADVANTAGE OF THE INVENTION According to this invention, the imaging|photography state of the overlapping space of the visible space of several surveillance cameras can be evaluated.

1 is a schematic configuration diagram of an example of a camera arrangement evaluation device according to an embodiment of the present invention; FIG. FIG. 10 is a schematic explanatory diagram of a method for evaluating the imaging state of the overlapping space of the visible space of a plurality of surveillance cameras; (a) is an explanatory diagram of an arrangement example of a camera and a structure in a surveillance space, and (b) is an explanatory diagram of a camera coordinate system, a background plane, and a viewing cone of the camera. (a) and (b) are explanatory diagrams of a method for calculating a visible candidate region. (a) and (b) are explanatory diagrams of a method of calculating a visible region, and (c) is an explanatory diagram of a pyramid forming a visible space of a camera. (a) is a diagram showing an example in which pyramids forming the visible spaces of a pair of cameras overlap each other, (b) is an explanatory diagram of the overlapping space, and (c) is a boundary surface defining the overlapping space. It is an explanatory diagram. (a) and (b) are explanatory diagrams of a method for calculating a boundary surface. (a) and (b) are explanatory diagrams of a first example and a second example of a method of calculating an evaluation value of an imaging state of an overlapping space. FIG. 11 is an explanatory diagram of a third example of a method of calculating an evaluation value of an imaging state of an overlapping space; (a) and (b) are schematic explanatory diagrams of first and second examples of virtual images of a monitored space in which overlapping spaces of visible spaces of a plurality of cameras are represented. It is a flow chart of an example of a camera arrangement evaluation method of an embodiment of the present invention.

Embodiments of the present invention are described below with reference to the drawings. It should be noted that the embodiments of the present invention shown below are examples of apparatuses and methods for embodying the technical idea of the present invention. are not specific to the following: Various modifications can be made to the technical idea of the present invention within the technical scope defined by the claims.

(composition)
Please refer to FIG. A camera arrangement evaluation apparatus 1 according to the embodiment is configured by, for example, a computer, and includes a storage unit 2 and a control unit 3 .
The storage unit 2 may include any one of a semiconductor storage device, a magnetic storage device, and an optical storage device. The storage unit 2 may include memories such as a register, a cache memory, a ROM (Read Only Memory) used as a main storage device, and a RAM (Random Access Memory).

The control unit 3 is configured by, for example, a processor such as a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit) and its peripheral circuits.
The functions of the control unit 3 described below are realized, for example, by the processor included in the control unit 3 executing a camera placement evaluation program 20 that is a computer program stored in the storage unit 2 .

The input device 4 is a mouse or the like operated by a camera planning executor, a monitoring worker, an administrator, etc. keyboard, etc. The input device 4 is connected to the camera layout evaluation device 1 , and various information is input to the camera layout evaluation device 1 from the input device 4 .

The camera arrangement evaluation apparatus 1 calculates through simulation the visible spaces of a plurality of surveillance cameras when a plurality of surveillance cameras that capture images in a predetermined surveillance space are installed under certain arrangement conditions. Calculate space. The camera arrangement evaluation device 1 calculates an evaluation value of the photographing state of the overlapping space.
Furthermore, the camera arrangement evaluation device 1 generates a virtual image representing the monitored space based on the three-dimensional model of the monitored space. The camera arrangement evaluation device 1 sets the display of the overlapping space on the virtual image according to the evaluation value of the photographing state of the overlapping space.
The output device 5 is a display, a projector, a printer, or the like, and outputs the evaluation value calculated by the camera layout evaluation device 1 and the virtual image generated by the camera layout evaluation device 1 .

Next, the outline of the evaluation method of the photographing state of the overlapping space by the camera arrangement evaluation device 1 will be described.
Please refer to FIG. Assume now that a surveillance space 40, which is an outdoor space or an indoor space formed by structures, is photographed by a plurality of surveillance cameras 43a and 43b. Note that the number of surveillance cameras that shoot the monitored space 40 is not limited to two, and the surveillance space 40 may be shot by three or more surveillance cameras.

First, the camera arrangement evaluation apparatus 1 calculates the visible spaces Sa and Sb of the monitoring cameras 43a and 43b in the monitoring space 40 based on the camera information indicating the positions (for example, focal positions), angles of view, and shooting directions of the monitoring cameras 43a and 43b. are calculated respectively. A range Sa sandwiched between two dashed lines indicates the visible space of the monitoring camera 43a, and a range Sb sandwiched between two dashed lines indicates the visible space of the monitoring camera 43b.

Next, the camera arrangement evaluation device 1 calculates the overlapping space Sop of the visible spaces Sa and Sb. The camera arrangement evaluation device 1 calculates the evaluation value of the photographing state of the overlapping space Sop according to the directions Dra and Drb from a predetermined evaluation point Pe in the overlapping space Sop to the respective positions of the surveillance cameras 43a and 43b.

In this way, by calculating the evaluation value according to the shooting direction of each of the plurality of surveillance cameras shooting the overlapping space Sop, it is possible to evaluate the shooting state of the overlapping space Sop by the plurality of surveillance cameras. For example, it is possible to evaluate whether a plurality of surveillance cameras are photographing the overlapping space Sop from directions close to each other or from completely different directions.

Details of the camera arrangement evaluation apparatus 1 will be described below. Please refer to FIG. The storage unit 2 stores camera information 21 and structure information 22 in addition to the camera placement evaluation program 20 described above.
The camera information 21 is a so-called camera parameter, and includes a three-dimensional position, a yaw angle, a roll angle, and a pitch angle representing a photographing direction, an angle of view, and an arrangement condition for each of the plurality of surveillance cameras 43a and 43b. Includes extrinsic and intrinsic parameters of surveillance cameras 43a and 43b, such as aspect ratio, resolution, and focal length. The positions of the surveillance cameras 43a and 43b are typically focal positions. The positions of the monitoring cameras 43a and 43b may be approximately set to the lens center positions. Alternatively, the installation positions of the monitoring cameras 43a and 43b and the camera structure of the monitoring cameras 43a and 43b may be set in the camera information 21, and the focal position or the lens center position may be obtained from these.

The structure information 22 is three-dimensional geometric data (that is, a three-dimensional model) representing the position, shape, structure, etc. of real-world structures (including objects such as fixtures and trees) existing in the monitored space 40. . That is, the structure information 22 represents a three-dimensional model of the monitored space 40 .
FIG. 3(a) shows an example in which surveillance cameras and structures are arranged in a surveillance space 40 based on the camera information 21 and the structure information 22. As shown in FIG. Structure information 22 includes geometric shape data of structures 41 and 42 in monitored space 40 . Also, the camera information 21 indicates the arrangement conditions of the surveillance cameras 43 a and 43 b in the surveillance space 40 .

The geometric shape data for generating the structure information 22 may be created by three-dimensional CAD or BIM (Building Information Modeling), or may be a three-dimensional shape of a structure existing in the monitored space using a three-dimensional laser scanner or the like. may be used. The geometric shape data for generating the structure information 22 may be data expressing a three-dimensional shape, including height information, created by performing stereoscopic photography or laser ranging from an aircraft, using polygon data.
Note that these three-dimensional geometric shape data may be tetrahedralized. By handling three-dimensional data divided into tetrahedrons, it is possible to execute arithmetic processing, which will be described later, at a higher speed.

The control unit 3 reads out and executes the camera placement evaluation program 20 stored in the storage unit 2, and functions as a visible space calculation unit 30, an overlap space calculation unit 31, an overlap evaluation unit 32, and an image generation unit 33. .
The visible space calculator 30 calculates the visible space of each of the monitoring cameras 43a and 43b. The visible space is a three-dimensional range that can be seen from the position of the surveillance camera. Hereinafter, the plurality of monitoring cameras 43a and 43b may be collectively referred to as "monitoring camera 43".

First, the visible space calculator 30 converts the coordinates of the structures 41 and 42 represented by the structure information 22 into coordinates of a camera coordinate system having the position of the surveillance camera 43 as an origin.
Please refer to FIG. 3(b). Although various coordinate systems can be adopted as the camera coordinate system, for example, a right-handed coordinate system in which the visual axis of the camera faces the negative Z-axis direction may be used.
Next, the visible space calculation unit 30 receives input for setting the minimum pixel density. The minimum pixel density is a lower limit value that defines the minimum number of pixels that must be used to represent a unit length in the real world in a camera image. The planning person uses the input device 4 to input the set value of the minimum pixel density.

The visible space calculation unit 30 sets a background plane 44 perpendicular to the optical axis of the monitoring camera 43 within the distance range from the position of the monitoring camera 43 determined based on the set minimum pixel density and the camera information 21. do. For example, the range of distances can be set so that objects at the background plane 44 can be imaged with the lowest pixel density. Also, the distance range may be arbitrarily set by the planning person.

The visible space calculation unit 30 calculates a pyramid 50 having the background surface 44 as the bottom surface and side surfaces representing the azimuth angle, elevation angle, and depression angle of the imaging range of the surveillance camera 43 as the viewing cone 50 of the surveillance camera. The viewing cone 50 is a space surrounded by straight lines 50 a , 50 b , 50 c and 50 d obtained from the angle of view and aspect ratio of the monitoring camera 43 and the background plane 44 .
Note that the tetragon on the bottom surface of the viewing cone 50 may be divided into two triangles, and a set of the two tetrahedrons may be used as the viewing cone of the monitoring camera 43 .

The visible space calculation unit 30 calculates the visible area visible from the position of the surveillance camera 43 among the areas of the surfaces of the structures 41 and 42 and the background surface 44 .
First, the visible space calculation unit 30 performs contact determination (intersection determination) between the structure defined in the structure information 22 and the viewing cone 50 . If the viewing cone 50 and the structure are composed of tetrahedrons, the GPR (Ganovelli, Ponchio, Rocchini) algorithm can be used to determine contact between the tetrahedrons at a higher speed. Otherwise, a bounding box or SAT (Separating Axis Theorem) algorithm can be used to determine whether or not the viewing cone 50 and the structure are in contact (intersect).
The visible space calculation unit 30 selects the structures 41 and 42 that are in contact with (intersects) the viewing cone 50 from among the structures defined in the structure information 22, and performs subsequent processing.

Next, the visible space calculation unit 30 selects an area facing the surveillance camera 43 from among the surface areas of the structures 41 and 42 contacting (intersecting) the viewing cone 50 . For example, if the normal direction of the surface regions of the structures 41 and 42 is defined as the direction facing the outside of the structures 41 and 42, the visible space calculation unit 30 calculates the optical axis of the surveillance camera 43 and the normal of the surface region is negative, it can be determined that the surface area faces the surveillance camera 43 .

The visible space calculation unit 30 calculates an intersection area between the surface areas of the structures 41 and 42 facing the surveillance camera 43 and the viewing cone 50 as a visible candidate area. The visible space calculation unit 30 also sets the bottom surface of the viewing cone 50 as the visible candidate area.
The visible space calculator 30 may divide these visible candidate regions into triangles.

Referring to FIG. 4A, the process of calculating the intersection area between the area 41a of the surface area of the structure 41 facing the monitoring camera 43 and the viewing cone 50 will be described.
The visible space calculation unit 30 calculates intersections 61a, 61b, 61c, and 61d between a plane 61 on which the region 41a exists and oblique sides 50a to 50d of the viewing cone 50 obtained from the angle of view of the monitoring camera 43 and the aspect ratio. do.

The visible space calculation unit 30 calculates a region where the convex region connecting the intersection points 61a to 61d and the region 41a overlap on the two-dimensional plane as the intersection region of the region 41a and the viewing cone 50, and calculates the region as the visible candidate region. do.
In the example of FIG. 4A, the entire area 41a is included in the convex area connecting the intersection points 61a to 61d, so the entire area 41a is the visible candidate area.

Referring to FIG. 4B, the process of calculating the intersection area between the area 42a of the surface area of the structure 42 facing the monitoring camera 43 and the viewing cone 50 will be described.
The visible space calculator 30 calculates intersections 62a, 62b, 62c, and 62d between the plane 62 on which the region 42a exists and the oblique sides 50a to 50d of the cone 50. FIG.
The visible space calculation unit 30 calculates a region 42b in which the convex region connecting the intersection points 62a to 62d and the region 42a overlap on the two-dimensional plane as the intersection region of the region 42a and the viewing cone 50, and calculates a visible candidate region. and

Next, the visible space calculation unit 30 determines whether or not each of these visible candidate areas is shielded from the monitoring camera 43 by another visible candidate area. This is because, when viewed from the monitoring camera 43 , if another visible candidate area exists in front of a certain visible candidate area, all or part of it is blocked and cannot be seen from the monitoring camera 43 .
If a certain visible candidate area is blocked by another visible candidate area in front of the monitoring camera 43, the visible area is calculated by excluding the blocked portion.

If a plurality of other visible candidate areas exist in front of the monitoring camera 43, the visible area is calculated by excluding all portions blocked by these plurality of visible candidate areas.
Processing for calculating a visible region from the visible candidate region 41a of the structure 41 will be described with reference to FIG. 5(a).
Since there is no other visible candidate area in front of the visible candidate area 41a as viewed from the surveillance camera 43, there is no portion blocked by another visible candidate area. Therefore, the visible space calculation unit 30 sets the entire area of the visible candidate area 41 a as the visible area 51 .

Processing for calculating a visible region from the visible candidate region 42b of the structure 42 will be described with reference to FIG. 5(b). Another visible candidate area 41 a exists in front of the visible candidate area 42 b as viewed from the surveillance camera 43 . Therefore, the visible space calculation unit 30 determines the visible area to be a range 52 obtained by excluding the portion blocked by the visible candidate area 41a from the visible candidate area 42b.
The visible space calculation unit 30 calculates an intersection point 72a between a straight extension line connecting the position of the surveillance camera 43 and the vertices 71a, 71b, 71c, and 71d of the other visible candidate area 41a and the plane on which the visible candidate area 42b exists, Calculate 72b, 72c and 72d (intersection 72c not shown).

The visible space calculation unit 30 obtains an area where the convex area connecting the intersections 72a to 72d overlaps the visible candidate area 42b on the two-dimensional plane, and calculates the visible area 52 by removing this area from the visible candidate area 42b.
In addition, the visible space calculation unit 30 calculates a range of the bottom surface of the viewing cone 50 excluding the areas blocked by the visible candidate areas 41a and 42b of the structures 41 and 42 as the visible area.

Please refer to (c) of FIG. The visible space calculator 30 divides the calculated visible region into convex polygons. In the example of FIG. 5(c), the visible region 51 is divided into triangles 51a and 51b, and the visible region 52 is divided into triangles 52a and 52b. Similarly, the visible space calculator 30 also divides the visible area on the background surface 44 into convex polygons such as triangles.

The visible space calculation unit 30 calculates a pyramid whose apex is the position of the surveillance camera 43 and whose bottom is the divided visible region. In the example of FIG. 5(c), a pyramid 56 is calculated with the position of the monitoring camera 43 as the apex and the visible region 52a as the bottom. If the visible region 52a is triangular, the pyramid 56 will be a tetrahedron.
The visible space calculator 30 similarly calculates pyramids for the visible areas 51 a , 51 b and 52 b and the visible area on the background surface 44 .
The visible space calculator 30 calculates a set of spaces occupied by these calculated pyramids as the visible space of the surveillance camera 43 . As described above, the visible space of the monitoring camera 43 can be obtained.

Note that the method for calculating the visible space of the monitoring camera 43 described above is merely an example, and the present invention is not limited to this.
The visible space calculator 30 can employ various calculation methods capable of obtaining the visible space of the surveillance camera 43 . For example, points and voxels for which visibility should be determined are discretely arranged in the monitoring space 40, and whether or not these points or voxels are visible from the monitoring camera 43 is determined by the ray tracing method. Space may be calculated.

Please refer to FIG. The overlapped space calculator 31 calculates an overlapped space in which the visible spaces of the plurality of surveillance cameras 43 overlap each other.
For example, when the visible space is calculated as a set of pyramids as described above, the overlapping space calculator 31 may calculate the overlapping space by the following method.
In this method, the overlapping space calculator 31 calculates overlapping spaces between visible spaces for all combinations of a pair of surveillance cameras 43 among the plurality of surveillance cameras 43 . The overlapping space calculation unit 31 calculates the space occupied by the entire overlapping space calculated for all combinations as the overlapping space between the visible spaces of the plurality of surveillance cameras 43 .

A method of calculating the overlapping space between the visible spaces of the pair of surveillance cameras 43 will be described below. As described above, each of the visible spaces is composed of a set of pyramids whose vertices are the positions of the surveillance cameras and whose bases are the visible regions. The overlapping space calculation unit 31 calculates a pyramid overlapping space in which each pyramid forming the visible space of one of the pair of monitoring cameras overlaps with each pyramid forming the visible space of the other monitoring camera. An overlapping space calculator 34 is provided.
When the pyramid overlapping space calculation unit 34 calculates all the pyramid overlapping spaces of the pyramids forming the visible space of the pair of surveillance cameras, the overlapping space calculating unit 31 calculates the pyramid overlapping space calculated by the pyramid overlapping space calculation unit 34. Summing up, the overlapping space between the visible spaces of the pair of surveillance cameras is calculated.

A method of calculating the pyramid overlapping space by the pyramid overlapping space calculation unit 34 will be described. Please refer to FIG. 6(a) and FIG. 6(b). The pyramid 80 is one of the pyramids forming the visible space of one of the monitoring cameras, and the pyramid 81 is one of the pyramids forming the visible space of the other monitoring camera. The space 82 where the pyramids 80 and 81 overlap is the pyramid overlap space. As shown, pyramids 80 and 81 are tetrahedrons when the visibility region is triangular.

The pyramid overlapping space calculation unit 34 determines contact for all combinations of each pyramid forming the visible space of one monitoring camera and each pyramid forming the visible space of the other monitoring camera. Compute the pyramid overlap space. For contact determination, for example, the above-described GPR algorithm, bounding box, or SAT algorithm can be used.

Please refer to (c) of FIG. The pyramid overlapping space calculation unit 34 calculates boundary surfaces 82a, 82b, 82c, 82d, and 82e that define the surfaces of the pyramid overlapping space 82, and calculates the space surrounded by these boundary surfaces 82a to 82e as the pyramid overlapping space 82. do.
Please refer to FIG. The pyramid overlapping space calculator 34 includes a boundary surface calculator 35 that calculates each of the boundary surfaces 82a to 82e.

Refer to FIG. 7(a). When a pair of pyramids in contact with each other (overlapping) is detected by the contact determination, the boundary surface calculation unit 35 selects one of these pyramids as the first pyramid 80 and the other as the second pyramid 81. .
The boundary plane calculator 35 selects one of the planes 80A, 80B, 80C, and 80D forming the first pyramid 80 . In the example of (a) of FIG. 7, the surface 80A is selected.

Also, the boundary surface calculator 35 selects one of the vertices 81 a , 81 b , 81 c and 81 d of the second pyramid 81 . In the example of (a) of FIG. 7, the vertex 81a is selected.
Refer to FIG. 7(b). The boundary surface calculator 35 determines whether or not all of the line segments 83b, 83c, and 83d connecting the selected vertex 81a and the remaining vertices 81b to 81d intersect the plane 82 on which the selected surface 80A exists. do. That is, it is determined whether or not all of the vertices 81b to 81d exist on the back side of the surface 80A when viewed from the vertex 81a.

When all of the line segments 83b to 83d intersect the plane 82, the boundary surface calculator 35 calculates intersection points 84b, 84c and 84d where the line segments 83b to 83d intersect the plane 82. FIG.
The boundary surface calculator 35 calculates an overlapping area (hatched area) between the polygon 84 connecting the intersections 84b to 84d and the surface 80A as the boundary surface 82b.
On the other hand, if all of the line segments 83b to 83d do not intersect the plane 82, the polygon 84 connecting the intersections 84b to 84d cannot be calculated, so the boundary surface cannot be calculated. Therefore, in this case, calculation of the boundary surface is stopped for the combination of the surface 80A and the vertex 81a.

The above processing is performed for all combinations of the faces 80A to 80D forming the first pyramid 80 and the vertices 81a to 81d of the second pyramid 81, and further, the pyramids selected as the first pyramid 80 and the second pyramid 81 are By repeating the same process with the replacement, all of the boundary surfaces 82a to 82e defining the surfaces of the pyramid overlapping space 82 are calculated.

It should be noted that the method of calculating the overlapping space between the visible spaces described above is merely an example, and the present invention is not limited to this. The overlapped space calculator 31 can employ various calculation methods capable of obtaining the overlapped space between the visible spaces of the plurality of surveillance cameras 43 .
For example, similar to the visible space calculation method using the ray tracing method described above, the overlapping space calculation unit 31 may calculate the space occupied by points or voxels that are simultaneously visible from the plurality of surveillance cameras 43 as the overlapping space.

Please refer to FIG. The overlapping evaluation unit 32 calculates an evaluation value of the shooting state of the overlapping space. First, the overlapping evaluation unit 32 sets one or more evaluation points in the monitored space as representative points in the overlapping space. For example, the overlapping evaluation unit 32 may arrange one overlapping space at the center of gravity of the overlapping space, or may discretely arrange a plurality of evaluation points within the overlapping space. In this case, the evaluation points may be arranged evenly within the overlapping space. Also, when the overlapping space is calculated as a polyhedron as shown in FIG. 6(c), evaluation points may be arranged at each of these vertices.

Next, the overlap evaluation unit 32 calculates an evaluation value of the photographing state of the overlap space according to each direction from the evaluation point to the positions of the plurality of surveillance cameras 43 .
Please refer to FIG. 8(a). For example, the overlap evaluation unit 32 arranges a three-dimensional model of a virtual unit sphere 90 at the evaluation point. The overlap evaluation unit 32 calculates which parts of the surface of the unit sphere 90 are visible areas of the plurality of surveillance cameras 43a and 43b. In the example of FIG. 8A, a thick dashed line 91a indicates the visible area of the monitoring camera 43a, and a thick one-dot chain line 91b indicates the visible area of the monitoring camera 43a.

When the three-dimensional model of the unit sphere 90 is pseudo-polygonally formed, the overlap evaluation unit 32 calculates the visible area of the unit sphere 90 in the same manner as the visible areas of the structures 41 and 42 described above. you can
In addition, the overlap evaluation unit 32 determines whether or not each point discretely arranged on the surface of the unit sphere 90 can be seen from the plurality of monitoring cameras 43a and 43b by the ray tracing method, and calculates the visible region. good too.

The overlapping evaluation unit 32 calculates an evaluation value of the shooting state of the overlapping space according to the visible areas 91a and 91b of the plurality of surveillance cameras 43a and 43b. For example, the overlap evaluation unit 32 uses the area of the overlapping area (logical product area AND) of the visible areas 91a and 91b and the logical sum area ( OR) is calculated. That is, the overlap evaluation unit 32 calculates either ((area of overlapping region)/(area of logical sum region)) or ((area of logical sum region)/(area of overlapping region)). Which one to use as the denominator can be determined according to the intended use of the evaluation value.

Further, for example, the overlap evaluation unit 32 may calculate the ratio of the area of the logical sum region (OR) of the visible regions 91a and 91b and the surface area of the unit sphere 90 as an index for the coverage of the visible region with respect to the unit sphere 90. good. That is, the overlap evaluation unit 32 calculates either ((area of logical sum region)/(surface area of unit sphere 90)) or ((surface area of unit sphere 90)/(area of logical sum region)). Which one to use as the denominator can be determined according to the intended use of the evaluation value.

Refer to FIG. 8(b). The overlap evaluation unit 32 may place a three-dimensional model of an object 92 having unevenness, such as a person or a car, instead of the unit sphere 90 . The overlap evaluation unit 32 calculates which parts of the surface of the object 92 are visible areas of the plurality of monitoring cameras 43a and 43b. In the example of FIG. 8B, the thick dashed line 93a indicates the visible area of the monitoring camera 43a, and the thick dashed line 93b indicates the visible area of the monitoring camera 43a.
Similar to the case of the unit sphere 90, the overlap evaluation unit 32 calculates the evaluation value of the photography state of the overlap space according to the visible regions 93a and 93b.

Further, when it is determined by the ray tracing method whether or not each point discretely arranged on the surface of the unit sphere 90 can be seen from the plurality of monitoring cameras 43a and 43b, the area of the visible region can be replaced by the monitoring camera The total number of points visible from 43a and 43b may be used.
See FIG. Assume that points 94 are discretely arranged on the surface of a unit sphere 90 . Circle plots indicate points on the unit sphere 90 visible only from the monitoring camera 43a, square plots indicate points visible only from the monitoring camera 43b, and triangular plots indicate points simultaneously visible from the monitoring cameras 43a and 43b.

The overlap evaluation unit 32 determines the total number of points 94 simultaneously determined to be visible from the plurality of monitoring cameras 43a and 43b and the total number of points 94 determined to be visible from either of the plurality of monitoring cameras 43a and 43b. may be used to calculate the evaluation value.
The overlap evaluation unit 32 may calculate an evaluation value according to the ratio between the total number of points 94 determined to be visible from either of the plurality of surveillance cameras 43a and 43b and the total number of points 94 arranged on the unit sphere 90. .
Instead of the unit sphere 90, points 94 may be discretely arranged on the surface of an uneven object 92 as shown in FIG. 8B, and the evaluation value may be similarly calculated.

Further, the overlapping evaluation unit 32 may obtain the direction from the evaluation point to the positions of the plurality of monitoring cameras 43 for each of the monitoring cameras 43 and calculate the evaluation value according to the angle formed by these directions.
For example, when there are two surveillance cameras 43, the value of the sine function or cosine function of the angle formed by the direction from the evaluation point to the position of the surveillance camera 43 may be calculated as the evaluation value.
Further, for example, when the plurality of monitoring cameras 43 is three or more, for all combinations of a pair of monitoring cameras 43 among these monitoring cameras 43, the sine function of the angle formed by the direction from the evaluation point to the position or Each cosine function may be obtained, and the average value, minimum value, maximum value, median value, or the like thereof may be calculated as an evaluation value.

Please refer to FIG. The image generator 33 generates a virtual image representing the monitored space 40 based on the structure information 22 representing the three-dimensional model of the monitored space 40 . The image generator 33 displays the position and shape of the overlapping space on the virtual image based on the calculation result of the overlapping space by the overlapping space calculator 31 . The image generator 33 may display the visible space on the virtual image based on the visible space calculation result by the visible space calculator 30 .
The image generation unit 33 displays the overlapped space on the virtual image in a display mode according to the evaluation value calculated by the overlap evaluation unit 32 .

(a) of FIG. 10 is a schematic explanatory diagram of a first example of a virtual image 100 representing the monitored space 40 generated by the image generator 33 . The structures 41 and 42 are omitted for simplicity. The same applies to (b) of FIG. In the example of the virtual image 100 in (a) of FIG. 10, the positions and shapes of the visible spaces Sa and Sb of the monitoring cameras 43a and 43b in the monitoring space 40 and the overlap space Sop where these overlap are displayed. .
For example, the image generator 33 may set the color, brightness, hatching pattern, etc. of the overlapping space Sop as the display mode of the overlapping space Sop according to the evaluation value.

When only one evaluation point is set in the overlapping space Sop, the image generator 33 may set the display mode of the overlapping space Sop according to the evaluation value at this evaluation point.
When a plurality of evaluation points are set in the overlapping space Sop, the image generation unit 33 changes the display mode of the overlapping space Sop according to the average value, maximum value, minimum value, and median value of the evaluation values at the evaluation points. can be set.

In addition, the image generation unit 33 calculates the color and brightness of each of the plurality of evaluation points arranged in the overlapping space Sop according to the evaluation value at each of the evaluation points, as in the second example of the virtual image 100 in (b) of FIG. 10 . can be set.
The overlapping evaluation unit 32 may obtain the evaluation value of an intermediate point between the evaluation points by, for example, interpolating the evaluation values of the evaluation points around the point. The image generation unit 33 may set the color and brightness of intermediate points between the evaluation points according to the evaluation values obtained by interpolation. The image generator 33 may interpolate the color and brightness of the evaluation points around the point in question, and set the color and brightness of an intermediate point between the evaluation points.

(motion)
An example of the camera arrangement evaluation method according to the embodiment will be described below with reference to FIG. 11 .
In step S1, prior to calculating the visible space of the surveillance camera and its overlapping space, the structure information 22 of the structure existing in the surveillance space 40 is acquired or generated, and stored in the storage unit 2 of the camera arrangement evaluation device 1. Register the settings.
In step S2, the camera information 21 such as the positions of the plurality of monitoring cameras 43a and 43b, the shooting direction, the angle of view, the aspect ratio, the resolution, the focal length, etc. is acquired, and the settings are registered in the storage unit 2 of the camera arrangement evaluation device 1. do.

In step S3, the visible space calculator 30 calculates the visible spaces Sa and Sb of the surveillance cameras 43a and 43b, respectively.
In step S4, the overlapping space calculator 31 calculates an overlapping space Sop in which the visible spaces Sa and Sb of the surveillance cameras 43a and 43b overlap each other.
In step S5, the overlapping evaluation unit 32 sets one or more evaluation points within the monitoring space Sop as representative points within the overlapping space Sop.

In step S6, the overlapping evaluation unit 32 calculates the evaluation value of the shooting state of the overlapping space Sop according to each direction from the evaluation point to the positions of the surveillance cameras 43a and 43b.
In step S<b>7 , the image generator 33 generates the virtual image 100 representing the monitored space 40 based on the structure information 22 representing the three-dimensional model of the monitored space 40 . The image generation unit 33 displays the overlap space Sop on the virtual image 100 in a display mode according to the evaluation value calculated by the overlap evaluation unit 32 . The output device 5 outputs the virtual image 100 .

(Effect of Embodiment)
(1) The storage unit 2 stores camera information 21 representing the positions, angles of view, and shooting directions of the plurality of surveillance cameras 43a and 43b. Based on the camera information 21, the visible space calculator 30 calculates the visible spaces Sa and Sb of the plurality of surveillance cameras 43a and 43b in the surveillance space. The overlap evaluation unit 32 obtains an overlap space Sop between the visible spaces Sa and Sb, and calculates overlap according to the respective directions Dra and Drb from a predetermined evaluation point in the overlap space Sop to the positions of the plurality of surveillance cameras 43a and 43b. An evaluation value of the photographing state of the space Sop is calculated.
This makes it possible to evaluate the shooting state of the overlapping space Sop by the plurality of surveillance cameras 43a and 43b. For example, it is possible to evaluate whether the plurality of surveillance cameras 43a and 43b are photographing the overlapping space Sop from directions close to each other or from completely different directions.

(2) The overlapping evaluation unit 32 arranges a three-dimensional model of a predetermined shape at the evaluation point, calculates the visible area of the surface of the three-dimensional model for each of the surveillance cameras 43a and 43b based on the camera information 21, and calculates the visible area. The evaluation value is calculated according to the ratio of the area of the overlapping area of the visible area and the area of the logical sum area of the visible area.
As a result, the evaluation value can be calculated according to the degree of overlapping of the visible areas of the monitoring target existing within the overlapping area Sop as viewed from the plurality of monitoring cameras 43a and 43a.

(3) The overlapping evaluation unit 32 arranges a three-dimensional model of a predetermined shape at the evaluation point, calculates the visible area of the surface of the three-dimensional model for each of the surveillance cameras 43a and 43b based on the camera information 21, and calculates the visible area. An evaluation value is calculated according to the ratio of the area of the logical sum region of and the surface area of the three-dimensional model.
As a result, the evaluation value can be calculated according to how much of the monitored object is covered by the visible area of the monitored object existing in the overlapping area Sop viewed from the plurality of monitoring cameras 43a and 43a.
(4) The overlapping evaluation unit 32 obtains the directions Dra and Drb from the evaluation point to the positions of the monitoring cameras 43a and 43b for each of the monitoring cameras 43a and 43b, and calculates the evaluation value according to the angle formed by these directions. .
This makes it possible to evaluate whether the plurality of surveillance cameras 43a and 43b are photographing the overlapping space Sop from directions close to each other or from completely different directions.
(5) The overlap evaluation unit 32 arranges a three-dimensional model of a predetermined shape at an evaluation point, performs visibility determination for each position on the surface of the three-dimensional model for each of the surveillance cameras 43a and 43b based on the camera information, The evaluation value is calculated according to the ratio between the total number of positions simultaneously determined to be visible from the monitoring cameras 43a and 43b and the total number of positions determined to be visible from either of the plurality of monitoring cameras 43a and 43b.
As a result, the evaluation value can be calculated according to the degree of overlapping of the visible areas of the monitoring target existing within the overlapping area Sop as viewed from the plurality of monitoring cameras 43a and 43a.
(6) The overlap evaluation unit 32 arranges a three-dimensional model of a predetermined shape at the evaluation point, performs visibility determination for each position on the surface of the three-dimensional model for each of the surveillance cameras 43a and 43b based on the camera information, An evaluation value is calculated according to the ratio between the total number of positions determined to be visible from either of the surveillance cameras 43a and 43b and the total number of positions arranged in the three-dimensional model.
As a result, the evaluation value can be calculated according to how much of the monitored object is covered by the visible area of the monitored object existing in the overlapping area Sop viewed from the plurality of monitoring cameras 43a and 43a.

(7) The storage unit 2 further stores a three-dimensional model of the monitored space 40 . The image generation unit 33 generates an image representing the overlapping space Sop of each of the monitoring cameras 43a and 43b on the virtual image 100 representing the monitoring space 40 generated based on the three-dimensional model, and overlaps according to the evaluation value. Sets the display of the Spatial Sop.
As a result, a virtual image 100 presenting the state of photography of the overlapping space Sop by the plurality of surveillance cameras 43a and 43b can be generated.

(8) The overlapping evaluation unit 32 calculates evaluation values at a plurality of evaluation points in the overlapping space Sop, and uses the calculated evaluation values to calculate evaluation values at points between the plurality of evaluation points.
This makes it possible to calculate evaluation values at intermediate points between discrete evaluation points.

DESCRIPTION OF SYMBOLS 1... Camera arrangement|positioning evaluation apparatus, 2... Storage part, 3... Control part, 4... Input device, 5... Output device, 20... Camera arrangement|positioning evaluation program, 21... Camera information, 22... Structure information, 30... Visible space calculation Section 31 Overlapping space calculation unit 32 Overlap evaluation unit 33 Image generation unit 34 Pyramid overlap space calculation unit 35 Boundary surface calculation unit 40 Monitoring space 41, 42 Structure 43a, 43b... Surveillance camera, Sa, Sb... Range, Sop... Surveillance space

Claims (10)

a storage unit that stores camera information including the positions, angles of view, and shooting directions of a plurality of cameras;
a visible space calculation unit that calculates a visible space of each of the plurality of cameras in a monitored space based on the camera information;
An overlapping space between the visible spaces is obtained, the closeness of each direction from the plurality of cameras to an evaluation point in the overlapping space is evaluated, and an evaluation value corresponding to the closeness of the direction is taken from the overlapping space. a duplicate evaluation unit that calculates an evaluation value of the state;
A camera arrangement evaluation device comprising: The overlap evaluation unit arranges a three-dimensional model having a predetermined shape at the evaluation point, calculates a visible area of the surface of the three-dimensional model for each camera based on the camera information, and calculates an overlap area of the visible area. 2. The camera arrangement evaluation apparatus according to claim 1, wherein said evaluation value is calculated according to a ratio of the area of the visible area and the area of the logical sum area of the visible area. The overlapping evaluation unit arranges a three-dimensional model having a predetermined shape at the evaluation point, calculates a visible area of the surface of the three-dimensional model for each camera based on the camera information, and logically sums the visible areas. 2. The camera arrangement evaluation apparatus according to claim 1, wherein said evaluation value is calculated according to the ratio of the area of the region and the surface area of the three-dimensional model. 2. The overlap evaluation unit according to claim 1, wherein the overlap evaluation unit obtains a direction from the evaluation point to the position of the camera for each camera, and calculates the evaluation value according to an angle between the directions. Camera placement evaluation device. The overlap evaluation unit arranges a three-dimensional model of a predetermined shape at the evaluation point, performs visibility determination for each position on the surface of the three-dimensional model based on the camera information, and determines the visibility from the plurality of cameras. 2. The evaluation value according to claim 1, wherein the evaluation value is calculated according to a ratio between the total number of positions determined to be visible at the same time and the total number of positions determined to be visible from any of a plurality of cameras. Camera placement evaluation device. The overlapping evaluation unit arranges a three-dimensional model having a predetermined shape at the evaluation point, performs visibility determination for each position on the surface of the three-dimensional model based on the camera information, and performs visibility determination for each camera. 2. The camera arrangement evaluation according to claim 1, wherein the evaluation value is calculated according to a ratio of the total number of positions determined to be visible from either to the total number of positions arranged in the three-dimensional model. Device. The storage unit further stores a three-dimensional model of the monitored space,
An image for generating an image representing the overlapping space of each of the cameras on a virtual image representing the monitored space generated based on the three-dimensional model, and setting display of the overlapping space according to the evaluation value. 7. The camera layout evaluation device according to claim 1, further comprising a generator. The overlapping evaluation unit calculates the evaluation values at the plurality of evaluation points in the overlapping space, and calculates evaluation values at points between the plurality of evaluation points using the calculated evaluation values. The camera arrangement evaluation device according to any one of claims 1 to 7, characterized by: to the computer,
an information reading step of reading camera information including the positions, angles of view and shooting directions of a plurality of cameras from a storage device;
a visible space calculation step of calculating respective visible spaces of the plurality of cameras in a monitored space based on the camera information;
An overlapping space between the visible spaces is obtained, the closeness of each direction from the plurality of cameras to an evaluation point in the overlapping space is evaluated, and an evaluation value corresponding to the closeness of the direction is taken from the overlapping space. A redundant evaluation step calculated as an evaluation value of the state;
A camera placement evaluation method characterized by executing to the computer,
an information reading step of reading camera information including the positions, angles of view and shooting directions of a plurality of cameras from a storage device;
a visible space calculation step of calculating respective visible spaces of the plurality of cameras in a monitored space based on the camera information;
An overlapping space between the visible spaces is obtained, the closeness of each direction from the plurality of cameras to an evaluation point in the overlapping space is evaluated, and an evaluation value corresponding to the closeness of the direction is taken from the overlapping space. A redundant evaluation step calculated as an evaluation value of the state;
A computer program characterized by causing the execution of

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