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Calibration method and measurement tool

  • US 10,277,887 B2
  • Filed: 01/28/2015
  • Issued: 04/30/2019
  • Est. Priority Date: 01/28/2014
  • Status: Active Grant
First Claim
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1. A calibration method for calibrating a stereo camera, the calibration method comprising:

  • 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, wherein the measuring of the relative position includes measuring a distance from the object to the stereo camera, and measuring a deviation of a direction of the object from a facing position 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,wherein the measuring of the deviation of the direction includes measuring coordinates that indicate a position of the stereo camera by using an object coordinate system in which a position of the object is a reference, converting coordinates of the stereo camera using the object coordinate system and coordinates of the object using the object coordinate system into coordinates using a camera coordinate system which a position of an optical center of the stereo camera is a reference, and measuring a direction of the stereo camera based on coordinates that indicate a position of the stereo camera using the camera coordinate system, coordinates that indicate a position of the object using the camera coordinate system, and coordinates of an image of the object in the captured image;

    the measuring of the coordinates that indicate the position of the stereo camera by using the object coordinate system includes measuring distances from multiple measurement points that are provided on the object to the stereo camera, and measuring the position of the stereo camera based on the multiple measured distances; and

    the measuring of the distances includes measuring a first distance that is a distance to an intermediate measurement point that is located between the measurement point and the optical center of the stereo camera, measuring a second distance that is a distance from the intermediate measurement point to the optical center of the stereo camera, and measuring a distance from the measurement point to the stereo camera by using the first distance and the second distance.

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