Study On The 3-D Shape Measurement Of Tectophysics Simulating System Based On PMP

The tectophysics simulating experiment is an effective method for researching geological structure, as it plays an important role in the research of the transforming progress and forming mechanism of tectonic deformation. The typical top surface measurement technology presently used in tectophysics simulating experiment such as photograph, imagery, eye estimate and so on is not good in measurement accuracy. And it can easily destroy the top surface of ductile sand body that is widely used in experiment, when we use contacting method of measurement to obtain information of top surface. And optical 3-D Measurement technology provides the non-contacting method for geologist to obtain accurate information.The thesis adopts Phase Measurement Profilometry based on Optical 3-D Measurement technology because of it's advantages of non-contacting, quick measuring, high accuracy and so on to accomplish measurement of top surface information. In allusion to the complex features of top surface deformation of the experiment body, we pay attention on key technology such as phase unwrapping algorithm, system calibration and so on. What is contained in the thesis is as follows:1.By analyzing the fundamental principle of phase unwrapping and main unwrapping algorithm and studying up on the phase error propagation problems caused by noise, the thesis proposes a new quality map based on the background gradient and phase derivative variance to solve the lower measurement accuracy problem caused by sand box border shadow and top surface deformation of the experiment body, then unwraps simulation data and real data using the reliability ordering phase unwrapping algorithm. The new method is feasibility and effectiveness because it can better avoid the error propagation.2.System calibration is essential in optics 3-D shape measurement. Z and (X, Y) coordinate calibration are two parts of it. Z calibration means to find out the relationship between height and phase difference. And(X, Y) calibration is to build a correspondence between image coordinate and world coordinate. The thesis studies up on the mathematical model of system calibration, traditional calibration methods and image processing, then adopts sub pixel allocation technology of harris comer detection to locate corner and the implicit calibration method of interpolating approximation to accomplish the phase-height mapping. The result shows that this method can further improve accuracy of system calibration.3.The thesis theoretically analyzes the system errors and designs an experimental system for PMP based on the result of theoretical analysis and computer simulation. The system is fulfilled with a computer controlling projector to display structured light and a CCD camera to detect the deformed image, and then obtains top surface information by processing data with PMP. The result shows that the method used in tectophysics simulating experiment can obtain good effectiveness.