The registration for free viewpoint measurement highly improved the efficiency of three-dimensional measurement, in order to improve the robustness of three-dimensional mapping between viewpoints, a modified method for mapping stitching with high stability is proposed. The viewpoints is coincided via image features. Spatial points are calculated through the phase positions. Aiming at those image features without phase positions, the interpositions of adjacent points are used to take the place of these points, so that effective mapping points between different viewpoints are virtually reconstructed. The rigid transformation is calculated by using unit quaternions. Experimental results show that this method can improve the number of the feature points by 20 percent and the robustness of mapping stitching.