Abstract:A threedimensional (3D) target for point clouds stitching with regular hexagonal prism shape is designed, and the 6 chessboard corners on the six sides of the target are used as the global control points. Based on closerange photogrammetry, six element models of the 3D target are built. Through calculating the relative positions among camera stations in every model, the local coordinates of the chessboard corners in related model are derived. Taking common chessboard as the medium, the transformation relationship of coordinate systems for the neighboring element models is determined. The global coordinate system is built on chessboard number 1, and the homography matrix between the chessboard plane and its image plane is derived, so that the transformation relationship between global coordinate system and the local coordinate system of the element model, in which the chessboard number 1 is located, is determined. Then, the transformation relationship between the global coordinate system and the local coordinate system of each element model is derived one by one; and the global coordinates of all target corners are calculated. Afterwards, the SBA (sparse bundle adjustment) algorithm is used to obtain the accurate values. Taking the distances between the chessboard corners on glass surface as the evaluation index, the stitching precision is better than 0.15 mm/m. The stitching experiment based on the 3D target for stitching shows that the local point clouds of the four subarea on the solid model surfaces can be precisely stitched into a whole point cloud. Compared with the stitching methods based on global control points and plane target, the proposed method has higher stitching precision.