Camera calibration device and method by computing coordinates of jigs in a vehicle system

1. A car-mounted camera angle computing device comprising:

an image acquiring unit that acquires an image containing a first jig disposed in an overlap region of an image capturing range of a camera and an image capturing range of an adjacent camera and a second jig disposed vertically below the camera; and

an angle computing unit that computes coordinates of the first jig and the second jig in a vehicle coordinate system to minimize a value of an evaluation function which evaluates a difference between a first angle and a second angle, the first angle being between a first line-of-sight vector and a second line-of-sight vector, the first line-of-sight vector being obtained by coordinates of the first jig in the image, the second line-of-sight vector being obtained by coordinates of the second jig in the image, the second angle being equal to an angle which is obtained by coordinates of the first jig and the second jig in the vehicle coordinate system, and computes an angle of the camera based on the coordinates of the first jig and the second jig in the vehicle coordinate system.

2. The car-mounted camera angle computing device according to claim 1 , wherein the adjacent cameras capture the same first jig.

3. The car-mounted camera angle computing device according to claim 1 , further comprising image combining unit that stores images captured by each of the cameras at a different time in a storage device and combines the images stored in the storage device into a combined image, and wherein the image acquiring unit acquires the combined image combined by the image combining unit.

4. A car-mounted camera angle computing method performed in a camera angle computing device, the method comprising:

acquiring an image containing a first jig disposed in an overlap region of an image capturing range of a camera and an image capturing range of an adjacent camera and a second jig disposed vertically below the camera;

storing the acquired image in a storage device;

computing coordinates of the first jig and the second jig in a vehicle coordinate system to minimize a value of an evaluation function which evaluates a difference between a first angle and a second angle, the first angle being between a first line-of-sight vector and a second line-of-sight vector, the first line-of-sight vector being obtained by coordinates of the first jig in the image, the second line-of-sight vector being obtained by coordinates of the second jig in the image, the second angle being equal to an angle which is obtained by coordinates of the first jig and the second jig in the vehicle coordinate system; and

computing an angle of the camera based on the coordinates of the first jig and the second jig in the vehicle coordinate system.

5. The car-mounted camera angle computing method according to claim 4 , wherein the adjacent cameras capture the same first jig.

6. The car-mounted camera angle computing method according to claim 4 , further comprising:

storing images captured by each of the cameras at different times in the storage device; and

combining the images stored in the storage device into a combined image, wherein

the acquiring includes acquiring the combined image combined at the combining from the storage device.

7. A computer-readable, non-transitory medium storing a car-mounted camera angle computing program causing a computer to execute a process, the process comprising:

acquiring an image containing a first jig disposed in an overlap region of an image capturing range of a camera and an image capturing range of an adjacent camera and a second jig disposed vertically below the camera;

storing the acquired image in a storage device;

computing coordinates of the first jig and the second jig in a vehicle coordinate system to minimize a value of an evaluation function which evaluates a difference between a first angle and a second angle, the first angle being between a first line-of-sight vector and a second line-of-sight vector, the first line-of-sight vector being obtained by coordinates of the first jig in the image, the second line-of-sight vector being obtained by coordinates of the second jig in the image, the second angle being equal to an angle which is obtained by coordinates of the first jig and the second jig in the vehicle coordinate system; and

computing an angle of the camera based on the coordinates of the first jig and the second jig in the vehicle coordinate system.

8. The computer-readable, non-transitory medium according to claim 7 , wherein the adjacent cameras capture the same first jig.

9. The computer-readable, non-transitory medium according to claim 7 , wherein the process further comprises:

storing images captured by each of the cameras at different times in the storage device; and

combining the images stored in the storage device into a combined image, wherein

the acquiring includes acquiring the combined image combined at the combining from the storage device.