This paper presents a method for uniquely determining the three-dimensional motion parameters of a rigid object with curved surfaces from two perspective views. It shows that seven point correspondences are sufficient to uniquely determine the motion parameters, up to a scale factor for the translations. The method involves introducing "essential parameters" which can be estimated by solving a set of linear equations derived from the correspondences of eight image points. The actual motion parameters can then be determined by computing the singular value decomposition (SVD) of a 3x3 matrix containing the essential parameters. The paper also discusses the conditions under which the motion parameters are uniquely determined, showing that if the object points are not traversed by two planes with one containing the origin or by a cone containing the origin, the motion parameters are uniquely determined. The paper also provides a detailed analysis of the mathematical structure of the problem, including the derivation of the essential parameters and the conditions for uniqueness. The results show that seven points in general positions are sufficient to ensure unique solutions, although fewer points may be sufficient in practice. The paper concludes that the method provides a simple and efficient way to estimate the motion parameters without the need for solving nonlinear equations.This paper presents a method for uniquely determining the three-dimensional motion parameters of a rigid object with curved surfaces from two perspective views. It shows that seven point correspondences are sufficient to uniquely determine the motion parameters, up to a scale factor for the translations. The method involves introducing "essential parameters" which can be estimated by solving a set of linear equations derived from the correspondences of eight image points. The actual motion parameters can then be determined by computing the singular value decomposition (SVD) of a 3x3 matrix containing the essential parameters. The paper also discusses the conditions under which the motion parameters are uniquely determined, showing that if the object points are not traversed by two planes with one containing the origin or by a cone containing the origin, the motion parameters are uniquely determined. The paper also provides a detailed analysis of the mathematical structure of the problem, including the derivation of the essential parameters and the conditions for uniqueness. The results show that seven points in general positions are sufficient to ensure unique solutions, although fewer points may be sufficient in practice. The paper concludes that the method provides a simple and efficient way to estimate the motion parameters without the need for solving nonlinear equations.