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Method for angle calibration of the position of a video camera on board an automotive vehicle

  • US 9,576,207 B2
  • Filed: 12/04/2014
  • Issued: 02/21/2017
  • Est. Priority Date: 12/11/2013
  • Status: Active Grant
First Claim
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1. A method of angle calibration of the position of a video camera on board an automotive vehicle, by estimation of a calibration matrix (Re) defining a rotation between a coordinate system linked to the camera (Xc, Yc, Zc) and a coordinate system linked to the vehicle (Xv, Yv, Zv), this rotation being defined as pitch (ax), yaw (ay) and roll (az) angles,the method comprising, during a phase of displacement of the vehicle on a road, the steps of:

  • a) taking a sequence of video images of a scene of the road, each image of the sequence comprising a plurality of traces of interest representative of ground markings of parallels circulation lanes;

    b) detecting edges (10) on the video images, to obtain a list of rectilinear edges (Dk) corresponding, in each image, to said traces of interest;

    c) correcting (12) the list of edges by applying to each edge a rotation according to the estimate of the calibration matrix;

    d) calculating (16) residual pitch and yaw angles by a method of detection of the vanishing point applied to the corrected list of edges obtained at step c);

    e) updating (18) the estimate of the calibration matrix by applying a rotation according to the residual pitch and yaw angles calculated at step d);

    the method being characterized in that it comprises the following successive steps;

    f) calculating (20;

    28, 32, 34, 36) a residual roll angle from the corrected list of edges obtained at step c) and the estimate of the calibration matrix obtained at step e), by;

    estimating the respective widths of at least two circulation lanes based on the list of edges;

    comparing the so-estimated respective widths and calculating at least one lane width difference; and

    calculating the roll angle as a function the so-calculated width difference, the real widths of the lanes being supposed to be identical;

    g) updating (40) the estimate of the calibration matrix by applying a rotation according to the residual roll angle calculated at step f); and

    h) iterating, on at least one sequence of images, steps c) to g) until the residual pitch, yaw and roll angles are lower than a predetermined threshold.

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