Calibration apparatus, calibration method, and calibration program

Patent metadata

Field	Value
Publication number	US-10620000-B2
Application number	US-201615767583-A
Country	US
Kind code	B2
Filing date	Oct 20, 2016
Priority date	Oct 20, 2015
Publication date	Apr 14, 2020
Grant date	Apr 14, 2020

Abstract

This calibration apparatus calibrates a camera mounted on a vehicle and includes: an image obtaining unit that obtains an image of outside of the vehicle; and a calibration unit that calibrates a camera parameter which is the roll angle and/or the pitch angle of the camera by using corresponding feature points in an image of the vehicle captured before a change in the attitude thereof and in an image captured after the change in the attitude thereof.

First claim

The invention claimed is:

1. A calibration apparatus for calibrating a camera mounted on a vehicle, comprising:
a camera which acquires an image of outside of the vehicle; and
a computing device storing a calibration program which:
calibrates a camera parameter of at least one of a roll angle and a pitch angle of the camera by using a corresponding feature point between an image before an attitude change of the vehicle and an image after the attitude change; and
sets a feature point change range based on a loading state of an object on the vehicle, and a corresponding feature point is searched for within the feature point change range based on a feature point included in the image before the attitude change of the vehicle, wherein

the image before the attitude change is an image photographed when the vehicle is stopped, and
the image after the attitude change is an image photographed when the vehicle is started.

2. The calibration apparatus according to claim 1 , comprising a vehicle attitude change detection sensor which detects the attitude change of the vehicle,
wherein the calibration is executed when the attitude change is detected by the vehicle attitude change detection sensor.

3. The calibration apparatus according to claim 1 , wherein the calibration program comprises:
a feature point candidate extraction process which extracts feature point candidates from the image;
a feature point selection process which selects the feature point candidates extracted by the feature point candidate extraction process; and
a feature point association process which associates a candidate point selected by the feature point selection process between the image before the attitude change of the vehicle and the image after the attitude change, and
the calibration is executed by using the feature point associated by the feature point association process.

4. The calibration apparatus according to claim 1 , wherein the calibration program comprises a moving object detection process which detects a moving object around the vehicle, and
a feature point other than the moving object is selected from feature points included in the image before the attitude change of the vehicle.

5. The calibration apparatus according to claim 1 , wherein the calibration apparatus is configured to calibrate a plurality of cameras mounted on the vehicle, and
the calibration program comprises:
a vehicle attitude estimation process which estimates the attitude of the vehicle; and
a camera parameter calculation process which calculates camera parameters of the plurality of cameras based on the attitude of the vehicle estimated by the vehicle attitude estimation process.

6. The calibration apparatus according to claim 5 , wherein the vehicle attitude estimation process sets an objective function and estimates the attitude of the vehicle by obtaining a vehicle attitude parameter which minimizes the objective function.

7. A calibration method of calibrating a camera mounted on a vehicle, comprising:
acquiring an image of the outside of the vehicle;
calibrating a camera parameter of at least one of a roll angle and a pitch angle of the camera by using a corresponding feature point between an image before an attitude change of the vehicle and an image after the change; and
setting a feature point change range based on a loading state of an object on the vehicle, and a corresponding feature point is searched for within the feature point change range based on a feature point included in the image before the attitude change of the vehicle, wherein
the image before the attitude change is an image photographed when the vehicle is stopped, and
the image after the attitude change is an image photographed when the vehicle is started.

8. A calibration program product for causing a computer to calibrate a camera mounted on a vehicle, comprising:
a camera which acquires an image of the outside of the vehicle; and
a calibration program stored on a computer which:
calibrates a camera parameter of at least one of a roll angle and a pitch angle of the camera by using a corresponding feature point between an image before an attitude change of the vehicle and an image after the attitude change; and
sets a feature point change range based on a loading state of an object on the vehicle, and a corresponding feature point is searched for within the feature point change range based on a feature point included in the image before the attitude change of the vehicle, wherein

the image before the attitude change is an image photographed when the vehicle is stopped, and
the image after the attitude change is an image photographed when the vehicle is started.

Assignees

• Clarion Co Ltd

Inventors

• Sakano Morihiko
• Sato Keiji

Classifications

• G01B11/26 Primary

  for measuring angles or tapers; for testing the alignment of axes · CPC title

• H04N7/18

  Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast · CPC title

• G06T2207/30256

  Lane; Road marking · CPC title

• G06T2207/30264

  Parking · CPC title

• G06T2207/30252

  Vehicle exterior; Vicinity of vehicle · CPC title