To solve the problem of viewpoint planning for unknown complex surfaces,an autonomous viewpoint planning method based on boundary test was proposed.A mesh model was built based on the surface point cloud data collected from the initial viewpoint,and the boundary of the current mesh was extracted according to the associated attributes of the boundary edge and the triangle.The closed boundary was clustered based on the connectivity between the boundary edges and the closure of the boundary,then the outer boundary and the hole boundary were distinguished according to the relative length of the closed boundary.The outer boundary was segmented according to the angle deviation of the direction vector between the boundaries and each segment and they were corresponded to different potential trend surfaces.Quadric surface fitting was used to estimate the trend surface and derive the algorithm vector.Combining the principal component analysis method,the direction of the maximum principal component of the boundary was determined for viewpoint planning.The observation points of the hole area were planed based on the center,size and normal vector of the center of the hole.Finally,the outer boundary of the plan and the viewpoints of the hole were used to observe the boundary of the current model,then the authenticity of the boundary was judged and it was decided whether to terminate the viewpoint plan independently.Taking the rear bumper as the planning object,the test results show that the method can be used to realize the viewpoint planning task for the three-dimensional measurement of unknown complex curved surfaces autonomously;the average planning time for each viewpoint is 67 ms,and the total modeling time is about 6 min;the cumulative coverage rate reaches 100%,and it has good performance in scanning time and integrity.