A fast geometrical approach to camera extrinsic parameters

A fast geometrical approach is proposed to determine the camera extrinsic parameters using a trihedral normal angle (TNA). No intrinsic camera parameters are known in advance, so alignment error can be avoided. The formula derived by this approach can be computed analytically. The line and point features required in deriving the extrinsic parameters can be extracted by simple well-developed image processing techniques. Thus, the method is more accurate and faster than other methods, in which complicated procedures are essential in finding curve or surface features. From the experimental results, the time for calculating the camera parameters is 0.8 sec and the measurement error is less than 3% on average.