On the basis of the skew-symmetric decomposition of an orthonormal matrix

this paper proposes a linear algorithm for determining 3-D motion parameters of a rigid body in monocular case. Since the computation for rotation parameters is simplified from nine variables to three variables in the algorithm

the complexity of the computation is reduced so greatly that the reliability and the stability are improved apparently. The translation up to a positive scale factor and three independent variables of rotation can be derived uniquely through- solving a series of overdetermined linear equations. Simulation experiments show that the relative error of rotation matrix is up to 5%

while the relative error of the intermediate parameters is about 50% caused by truncation error of image data.