In the field of metrology science, people divide the measurement problems in the industrial field into box-like workpiece measurement and workpiece measurement with complex geometry according to the complexity of the geometric shape of the measured object. The so-called box-like workpieces are those geometric workpieces consisting of basic geometric elements (points, lines, faces, circles, cylinders, cones, balls), including gearbox workpieces, engine cabinets, machined parts or simple freedom. Stamping die, mold, glass shell workpiece, etc. composed of shape and surface. Corresponding to the box-like workpiece is a complex geometric workpiece, which is mainly composed of