Patent ID: 9578310
Date: 2017-02-21
CPC Classifications: G06T,H04N

Claim:
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 for the three-dimensional imaging system, the reference orthogonal virtual three-dimensional coordinate system 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 of the real world in the virtual coordinate system; c) determining with respect to the reference coordinate system a real world three-dimensional orthonormal coordinate system having horizontal, vertical and depth axes in which the vertical axis is rotated to align it with respect to the vertical direction; d) determining a point in the scene as a new origin for the real world three-dimensional orthonormal coordinate system; e) deriving a translation vector from the origin of the virtual three-dimensional coordinate system to the point defined as the new origin of the scene; f) deriving a rotation matrix for transforming the virtual three-dimensional coordinate system into the real world three-dimensional coordinate system; g) deriving a calibration matrix (M h) 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; and i) automatically refining the calibration matrix if changes are detected in at least one of: