A camera calibration method based on three orthogonal constraints was presented for determining intrinsic parameters.Camera coordinate system was set as world coordinate system

so only 5 camera intrinsic parameters and 1 projection scale factor need to be solved.A calibration pattern containing 7 spatial points was developed which can be moved and rotated in the camera's field of view.At least 2 images were captured to set up constraint equations.Thus

camera intrinsic parameters can be solved in the closed-form solution based on matrix eigenvalue decomposition.In calibrating the same camera

the method performed the same as the classical plane-based calibration method

relative difference is about 1.3%.Experiments with both synthetic and real data show that our method has high accuracy and is robust.