Abstract: In this paper a computer-nixed method of measurement for curved surfaces is described, using a plane datum and LSM (Least Square Method) or DFM (Digital Filter Method) to filter the curve form. It is shown that this is a good method to obtain a full visual image of topographical detail and also quantitative information for assessment and analysis. An example for measuring bearing ball is presented.

Key words: 表面粗糙度测量, 三维形貌, experimental modal analysis, frequency- hopping, Green's functions, underframe equipment, high-speed EMU trains