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Automatic Scene Calibration

  • US 20150181198A1
  • Filed: 01/14/2013
  • Published: 06/25/2015
  • Est. Priority Date: 01/13/2012
  • Status: Active Grant
First Claim
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1. A method of calibrating a three-dimensional time-of-flight imaging system in a three-dimensional environment, the method comprising the steps of:

  • a) determining a reference orthogonal virtual three-dimensional coordinate system (Mc) for the three-dimensional imaging system, the reference orthogonal virtual three-dimensional coordinate system (Mc) having horizontal, vertical and depth axes in which the horizontal axis and the vertical axis are respectively aligned with the horizontal and vertical axes of a sensor in the three-dimensional imaging system with the depth axis being orthonormal to the plane of the sensor defined by its horizontal and vertical axes;

    b) obtaining a vertical direction (Vw) of the real world in the virtual coordinate system (Mc);

    c) determining with respect to the reference coordinate system a real world three-dimensional orthonormal coordinate system (Mw) having horizontal, vertical and depth axes in which the vertical axis is rotated to align it with respect to the vertical direction (Vw);

    d) determining a point in the scene as a new origin for the real world three-dimensional orthonormal coordinate system (Mw);

    e) deriving a translation vector (Tv) from the origin of the virtual three-dimensional coordinate system (Mc) to the point defined as the new origin of the scene;

    f) deriving a rotation matrix (Mr) for transforming the virtual three-dimensional coordinate system into the real world three-dimensional coordinate system; and

    g) deriving a calibration matrix (Mc2w) for the three-dimensional imaging system as the rotation matrix translated by the translation vector;

    characterised in that the method further comprises the step of aligning a plane defined by the vertical and depth axes of the real world three-dimensional coordinate system to be coplanar with a plane defined by the virtual vertical axis and the virtual depth axis of the virtual three-dimensional coordinate system (Mc).

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