Calibration method and measurement tool

Patent metadata

Field	Value
Publication number	US-10972716-B2
Application number	US-201916296562-A
Country	US
Kind code	B2
Filing date	Mar 8, 2019
Priority date	Jan 28, 2014
Publication date	Apr 6, 2021
Grant date	Apr 6, 2021

Abstract

A calibration method calibrates a stereo camera. The calibration method includes: measuring a relative position between the stereo camera and an object that is placed so as to fall within an image capturing area of the stereo camera; acquiring a captured image that is captured by the stereo camera and includes the object; and determining a calibration parameter for calibrating the stereo camera based on the relative position and the captured image.

First claim

The invention claimed is:

1. A calibration method for calibrating a stereo camera, the calibration method comprising:
capturing, using the stereo camera, an image including an object placed so as to fall within an image capturing area of the stereo camera;
determining a second distance from the object to an intermediate measurement point that is not part of the object and is located between the object and the stereo camera;
determining a third distance from the intermediate measurement point to the stereo camera;
calculating a first distance from the object to the stereo camera using the determined second distance and the determined third distance;
measuring, a deviation of a direction of the object from a facing position of the stereo camera; and
determining a calibration parameter for calibrating the stereo camera based on the calculated first distance, the measured deviation, and the captured image.

2. The calibration method according to claim 1 , wherein the determining step comprises measuring the second distance from the object to the intermediate measurement point using laser light.

3. The calibration method according to claim 1 , wherein the determining step comprises measuring the second distance from the object to the intermediate measurement point using a measuring tape.

4. The calibration method according to claim 1 , wherein the step of determining the third distance from the intermediate measurement point to the stereo camera is performed in advance.

5. The calibration method according to claim 1 , wherein
the stereo camera is mounted inside a movable object, and
the object is located outside the movable object.

6. The calibration method according to claim 5 , wherein the stereo camera is installed inside a front windshield of a vehicle and the intermediate measurement point is provided on the front windshield of the vehicle.

7. A calibration device for calibrating a stereo camera, the calibration device comprising:
an image capturer configured to capture, using the stereo camera, an image including an object placed so as to fall within an image capturing area of the stereo camera; and
processing circuitry configured to
determine a second distance from the object to an intermediate measurement point that is not part of the object and is located between the object and the stereo camera,
determine a third distance from the intermediate measurement point to the stereo camera;
calculate a first distance from the object to the stereo camera using the determined second distance and the determined third distance,
measure a deviation of a direction of the object from a facing position of the stereo camera, and
determine a calibration parameter for calibrating the stereo camera based on the calculated first distance, the measured deviation, and the captured image.

8. A non-transitory computer-readable medium storing a program that, when executed by processing circuitry, causes the processing circuitry to calibrate a stereo camera by executing a method comprising:
capturing, with the stereo camera, an image including an object placed so as to fall within an image capturing area of the stereo camera;
determining a second distance from the object to an intermediate measurement point that is not part of the object and is located between the object and the stereo camera;
determining a third distance from the intermediate measurement point to the stereo camera;
calculating a first distance from the object to the stereo camera using the determined second distance and the determined third distance;
measuring a deviation of a direction of the object from a facing position of the stereo camera; and
determining a calibration parameter for calibrating the stereo camera based on the calculated first distance, the measured deviation, and the captured image.

9. The calibration method of claim 1 , wherein the step of determining the second distance comprises determining a distance from a predetermined point on the object to the intermediate measurement point.

10. A movable body on which the calibration device of claim 7 is mounted.

Assignees

• Aoki Shin
• Kikuchi Naoki
• Nagao Kagehiro
• Kishiwada Jun
• Ricoh Co Ltd

Inventors

• Aoki Shin
• Kikuchi Naoki
• Nagao Kagehiro
• Kishiwada Jun

Classifications

• G06T7/85 Primary

  Stereo camera calibration · CPC title

• H04N13/239

  using two two-dimensional [2D] image sensors having a relative position equal to or related to the interocular distance (H04N13/243 takes precedence) · CPC title

• G06T2207/10028

  Range image; Depth image; 3D point clouds · CPC title

• G06T2207/10012

  Stereo images · CPC title

• B60R11/04

  Mounting of cameras operative during drive; Arrangement of controls thereof relative to the vehicle · CPC title