Abstract: This paper presents a simple and geometric approach for calibrating extrinsic camera parameters from point pairs, which considers the geometric relationship between a camera and a point pair instead of individual point. The method first computes rotation matrix from three point pairs and no precise three-dimensional information of any point pair is needed. The next step is to calculate translation according to the geometric relationship between the camera and one of the point pairs. For this step, the relative position information of this point pair should be known. The whole calibration procedure requires no absolute position of any point pair. Experimental results indicate that the proposed approach is effective.