Study On N-NonFixed-Step Algorithm Based On Scanning And Correlation

The 3D-profile measurement is of great value, has become an international hot research topic. As one of 3D-profile measurement, the method of projection grating is exceedingly studied by researchers for its advanced properties of face-field measurement, real-time recovering and broad measure-scope. But the fatal weakness of the method is to be used precision phase shifter, to ensure accurate phase shift, otherwise it is difficult to ensure accuracy. There are phase-shift error in multiple phase-shift and data quantization error when the images are captured. All of these will cause the measuring system error. Therefore the research on enhancing the measurement accuracy and speed of phase-shift method of 3D-profile measurement is of great theoretical and practical value.In this dissertation, the aim is focused on completing a 3D-profile measurement system using grating projection phase method and designing a measuring unit connected a personal computer to recover the thee-dimension profile. However, the dominating work of this dissertation is contributed to some hotpots and difficulties rooting in this method. In view of these, following works are listed and executed.1. A detailed analysis on the performance of the traditional N-steps phase-shifting algorithm was researched. The method needs high precision phase-shift, otherwise it will reduce the accuracy of the measurement system. Studied on the influence on the measurement accuracy by the phase-shift error based on theory and experiment, clearly pointed out the applicable conditions of the N-steps phase-shifting algorithm.2. A phase-shift analysis method was designed based on image gray-scale, which used probabilistic segmentation. The phase shift is got by calculating the mean of the great probability region through the whole data. A large number of simulation experiments showed that had higher precision and speed than the traditional method.3. Proposing a N-Non-Fixed-step algorithm based on Scan-Related, which is based on traditional N-step phase-shifting algorithm. The account of each phase step must be2π/N, which is necessary in the traditional algorithm but not in the new. At the same time the two have the same accuracy of measurement, but the new algorithm could reduce the hardware requirements for the 3-D profile measurement system.4. Based on construction projects of Shandong University Lab Software developed, a teaching equipment of 3-D shape measurement is completed. The Software system for the control of the hardware system and data processing is programmed by the c++ language with strong practicality and portability.