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Image processing system for estimating camera parameters

  • US 8,264,546 B2
  • Filed: 09/11/2009
  • Issued: 09/11/2012
  • Est. Priority Date: 11/28/2008
  • Status: Expired due to Fees
First Claim
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1. An image processing system comprising:

  • a camera;

    an image processor; and

    a calibration surface including thereon a calibration pattern, the calibration pattern including a plurality of alternately colored elements which provide a corresponding plurality of corners at locations on the calibration pattern at which more than two of the colored elements adjoin, the corner locations defining a first group of lines and a second group of lines, the lines in each of the group of lines being parallel with respect to each other on calibration surface, the first group of lines being orthogonal to the second group of lines, whereinthe camera is configured to generate a video signal representative of a scene as viewed by the camera, the scene including the calibration surface,the image processor is configuredto detect from the video signal at least some of the corner locations to identify the first and second group of lines of the calibration pattern,to extrapolate the lines from each group of lines to determine a presence and a location of a first intersection point on a plane of the scene as viewed by the camera at which the extrapolated lines from the first group intersect and a second intersection point on the plane of scene as viewed by the camera at which the extrapolated lines from the second group intersect, andto estimate from the presence and the location of the first and second intersection points one or more of an estimated roll angle value, an estimated pitch angle value and an estimated yaw angle value corresponding to a roll angle, pitch angle and yaw angle of the camera relative to the calibration surface,the detection of the corner locations by the image processor includes identifying from the video signal a plurality of potential corner locations, defining an area of the scene as viewed by the camera centered around each potential corner location, analyzing a color of points lying on a periphery of each area, to estimate a likelihood that a corner is located at each potential corner location, andthe analyzing of the color of the points lying on the periphery of the area includes dividing the periphery into a first part and a second part, and comparing a distribution of color of the points on the first part with a distribution of color of the points on the second part.

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