Study On The System Calibration Technology Of Optics 3-D Profilometry

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 Phase Measurement Profilometry based on Optical 3-D Measurement technology is adopted to accomplish the measurement of top surface information, because the profilometry has advantages such as non-contacting, quick measurement and high accuracy etc. In allusion to the complex features of top surface deformation of the experiment block, we pay attention to key technology such as corner detection, system calibration and so on. In the thesis, the following studies are performed:After analyzing the basis of current study status of 3-D shape measurement and system calibration, the thesis proposes the total design scheme of system calibration for the real request of measurement, the selection and debugging of system hardware, and then explains the image pre-processing and phase unwrapping technology and so on in detail. The results of the experiment show that the design schema can recover the 3-D profilometry of calibration object to a better degree, and lay a foundation for system calibration.System calibration can be divided into 2 parts: Z and (X, Y) coordinate calibration. Z calibration means to find out the relationship between height and phase difference. (X, Y) calibration is to build a correspondence between image coordinate and world coordinate. The thesis studies the mathematical model of system calibration. The collected template image is processed in two parts, edge and inner part. During this process, the mature calibration method and image processing technology are referred to. Besides, the thesis uses the feature recognition by the connectivity of mathematical morphology, realizes the image feature of detection. The results show that this method can improve the anti-noise ability and finally achieve the level of sub-pixel for corner detection based on mature calibration and image processing technology. Meanwhile, the thesis proposes a new method which has higher precision and proficiency --3-D Profilometry based on combination of BP and GRNN function approximation. The experiment shows this method has higher promoting accuracy and studying precision for the network.The thesis establishes parameter of system construction and the maths model for the precision of 3-D profilometry system calibration. The influences on measurement precision caused by the parameter of projection, distortion effect of lens, nonlinear effect of CCD, image acquisition board quantification effects, phase unwrapping etc are studied in the thesis. Onward study in the thesis proposes the basic principle of PMP calibrating system design.The calibration model based on combination of BP and GRNN function approximation implicitly can improve the precision of system calibration. The corner detection based on feature recognition of connectivity improves the precision and efficiency of the corner detection. The anti-noise ability is improved and the level of sub-pixel for corner detection achieved by process the image in two separate parts.