Abstract: This paper presents a simple geometric approach for calibrating extrinsic camera parameters from arbitrary point pairs.The proposed method considers the geometric relationships between a camera and the point pairs instead of an individual point.It firstly estimates the rotation matrix according to three point pairs,then directly calculates the translation vector from the geometric relationships between the camera and one pair of the points.The whole calibration process doesn't need the absolute position information of any point pairs,and it doesn't exert any restrictions on the position relationships among the point pairs.Experimental results show the effectiveness of the proposed approach.