A Calibration Method for Extrinsic Parameters Based on Four Points

In order to solve the calibration of camera extrinsic parameters problem in texture mapping,this paper presents a geometric calibration method based on four point pairs.The first one select three points in the world coordinate system and calculate their coordinates in the camera coordinate system(world point, light heart, and image point are colinear). Transform the coordinates to a reference coordinate system and the euclidean distance is invariant. According to the homothetic triangle theory, solve the rotation matrix and translation vectoer respectively. Finally get the complete extrinsic parameters. The results from experiment show that the method is correct and feasible. This method needs only four point pairs to solve the camera extrinsic parameters, further more it has high precision and few constraints. Applied in the texture mapping, this method can establish a mapping between 3D model and digital photo, thereby it can achieve the high-precision texture mapping.