Algorithm Study On Phase Extraction And Phase Unwrapping In Phase Measuring Profilometry Based On Projection

The phase method based on grating projection is one very important method of 3D measuring profilometry technology. The fringe was projected to the surface of the measured object, and the deformation fringe can be viewed as modulated carrier signal by phase. Since 1980s the phase method based on grating projection has been paid more attention to, it relaxed the environmental requirements when using white light and it is conducive to product forming of the measurement system.At present the phase method has achieved great progress. But there are still a certain limitations on some aspects, such as the shadow problem when measuring objects with complex surface, and precision and automation is also problems needed further resolved. Present methods may be adapt to measuring some specific objects. So with the development of science and industrial technology, some new practicable method or improvement should be studied, which meet the demand of high precision and automation.In this paper the phase extraction and phase unwrapping were mainly focused on, which is the two key techniques of 3D measuring profilometry. Based on the traditional phase extraction algorithms, the least-square iterative algorithm was improved, which depress the noise affectation efficiently and advanced the measurement precision. About the phase unwrapping, a new algorithm—Multi-seeds Region Growing phase unwrapping method—was proposed. The algorithm is based on the analysis of modulation and reference the thinking of image segmentation. Experimental results show that it can resolve the shadow problem of complex objects successfully.An image processing software was programmed in C++Builder5.0 by the guide of my supervisor, and with another classmate. The software can produce virtual fringe and setting the parameters of the fringe. It also has the functions as calculation and image processing of phase extraction, phase unwrapping and objects reconstruction, reading and saving image file, data in every step of processing and so on .The software is easy in use and convenient in adjust parameters; It has provided indispensable theoretical foundation for practical measuring and data processing.