3D Shape Mosaic Applied On Fourier Transform Profilometry

Abstract: With the rapid development of science & technology,optics and opto-electronics, 3D optical measurement techniques have been improved, which has been of an important branch of the modern optical measurement and satisfied the more and more people's needs because of the increasing measurement precision. Fourier transform profilometry is a 3-D profile measurement technique based on with the structured illumination, which has characteristics of fast-speed, non-contact and high-precision. A variety of applications of this technique are very wide, include detecting the quality of optical parts, the application in the light industry (dressing-making, shoemaking), biomedicine and so on.In this dissertation, we research the theory of 3-D shape mosaic applied on Fourier transform profilometry in the scope of 180°.A method used to obtain the full 3D depth information is proposed, in which the test object is measured twice before and after rotating on a same reference plane. In the valid mosaic regions, the weight function used in the data mergence procedure was the trigonometric function curve with smooth characters instead of the traditional distance between the boundary and the center. Its advantage is the improvement of mosaic precision. Experiments show its feasibility. The main results obtained can be summarized as follows:1. We record two deformed fringe patterns by rotating the test object on a same reference plane, and then two height maps in which the correct data are existed only in the valid regions are calculated by FTP. We transfer the two height maps into the same reference coordinate using automatic searching algorithm, Then the valid mosaic regions is decided by the least-squares match algorithm, by which two reconstructed height maps are merged to form the full 3D reconstruction.2. A new data merging method based on trigonometric function is proposed. First, we obtain the height maps from two deformed fringe patterns captured from the difference angle. Then the valid mosaic regions are decided by the similar method as above. In the valid mosaic regions, two 3D height maps are merged to form a full 3D shape by trigonometric function with the smooth property. Compared with the result from the linear function mosaic, there is higher mosaic precision using the trigonometric function. The method based on trigonometric function has been used in FTP to improve the measurement precision, and the error range is -1.5～1mm..