Research On Methods In Measuring Of 3-D Profilometry

Measurement technology in the industrial production plays a significant role, and its action is becoming more and more important. At present, the measurement of object has accessed to a comprehensive measurement of shape from the length measurement. With the constant development of high-precision and high-quality of products, technology for measuring is facing more stringent requirements. The rapid development of the automotive and aeronautical industry, mold and parts manufacturing becomes a strong impetus to the further development of measurement technology, and multimedia technology, digital museum and three-dimensional photography, such as virtual reality technology has opened up for broader use of the technology. Three-dimensional profilometry is so important for our society. The development of profilometry in a high degree development of industrialization, mechanization and automation of today, has a long-term significance. Phase-shifting grating profilometry in three-dimensional measurement is an important measurement technique, and it has become a superior method with merits of non-contact, high efficiency, high-precision, etc..In recent years, the area of automatic analysis techniques has also achieve a great success, which provides a strong support for profilometry to adapt to the development of large-scale industrial production trends today.Phase-shifting grating profilometry is known by projecting a grating light field onto the test object surface, the grating surface pattern is modulated due to irregular surface deformation. The modulation of the grating pattern caused by object to be measured is directly related with surface features of object. Through the modulation of the grating pattern phase information we can get the object's surface characteristics.In this article the author set up a program-controlled hardware platform to conduct experiments. we shoot, computing, restore surface contour automatically.This paper introduces the principle of phase-shifting grating profilometry firstly, and then with the use of LCD projector as a projection grating device, we find the high-frequency stripe-like measurement error. So we analyze error in spatial and frequency domain respectively, and get rid of it with computer program designed by ourselves. Author analyzes the relationship between the Stoilov algorithm and the step length, and finally compares the different effect when using the Stoilov algorithm and Carre algorithm. We use LCD projector as a projection grating devices, through the results of the experiment the author found that there are stripe-shaped high-frequency measurement errors, then we analyze the causes of high-frequency noise in the spatial and frequency domain respectively. We find that quantitative projecting grating can lead to phase measurement errors; with using spatial domain filtering design and frequency domain filtering we reduce the measurement error and obtain good results. By changing the cycle of grid lines, analysis on the relationship between projected grating line cycle and the measurement errors is successful.The relationship between the gate lines by the projection cycle is: the larger of the projected grating line cycle, the smaller the error of the system. The author uses C + + builder development environment to produce the data-processing software, to complete the image acquisition, phase-shifting algorithm, the phase unwrapping operating, Fourier transform, filtering, phase- height conversion, and display three-dimensional data, etc. The program of a number of functions provides a very useful and effective tool to carry out the experiments.