To calibrate a camera with high accuracy by automatically relating screen coordinate values to world coordinate values, even if photographing is conducted with a calibration board and the image pickup surface of the camera inclined.
An image of an object and a calibration image are inputted (S1), deformation in code portions of the inputted images due to projection distortion is removed (S2), then the screen coordinates of a reference point are obtained, and internal parameter calculation (S4) of the camera is performed, based on a previously inputted code pattern and on the world coordinate data of the reference point. Then, external parameter calculation (S8) is performed, based on a previously inputted schematic diagram of known points on the object and on the world coordinate data thereof. By using obtained internal and external parameters of the camera thus, the screen coordinates are converted (S10) into world coordinates, thereby obtaining the world coordinates of unknown points on the object to be measured.
NAKAGAWA TADAYUKI
SUGIYAMA KAZUHIRO
TANAKA AKIMICHI
KITANI YASUSHI
NTT COMM KK