Applications of two phase-height mapping algorithms for PMP in 3D reconstruction of the railway wheel tread

In this paper, the phase information of a railway wheel tread is obtained based on Phase-measuring profilometry, meanwhile, the height information is reconstructed by two phase-height mapping algorithms. The first is traditional phase-height mapping algorithm, which needs translatingds the reference plane several times. Due to the reconstruction of the height information influenced by abrupt phase changes while moving the reference plane, the phase information needs to be converted to be the real phase information. In order to obtain accurate parameters, the reference plane needs to be translated several times, which is a complex procedure. Besides, the calculation is also complicated because of different coefficients in different pixels. The second method is the new phase-height mapping algorithm, which needs building the relationship between phase and height based on seven height-known circular cones. The new method could divide the calibration coefficients and coordinates efficiently. Only the common coefficients that are not related to the sample coordinates are required during calibration, which would decrease the amount of calibration points. There is a comparison between the traditional method and the new method in this paper, and it concludes that the traditional method could make the result more accurate but the new method could be more convenient.