3-D Shape Measurement Studies Based On Digital Shadow Moiré

Optics shape measurements of 3-D objects have been widely used in scientificresearches and many producting process. With the development of micro-electronicstechnique, modern optics, information theory and the appearance of computer, highcapability devices, strong theories and material foundation were offered. Then theun-touched optics has an ocean of evolution. Phase-approaching of projected grating isan important embranchment of un-touched optics, the 3-D shape measurements wereachieved using the deformed fringes by the height of the objects. The contour lines andMoiré series were avoided, the data of analysis were offered, appropriate for realizationof images processing automatization, the more information was obtained by addingdensity of images, then the high precision and delicacy were realized.However, some measurement localization was existed, for instance, making againstdynamic measurement, affecting by environment easily, low precision, finite extensionand so on. It made the combination of theories and application greatly necessary andimportant.In this paper, as to complex shape or shape break, a novel method was presented,the sinusoidal fringes were produced by computer, and projected by LCD projector, thereference image and deformed image were captured by CCD and saved in computer.The information of the object can be obtained through Fourier transform of the twoimages. The combination of shadow moiré method and Fourier transform was adoptedin the experiment, then the measurements of complex object or shape break wereachieved and also can get bigger extension, higher precision, harder influence ofenvironment, more possible of dynamic measurement. As to error of unwrapped phaseimage, a new method of error revising was described, the processing of sound was notin the course of unwrapping, but after unwrapping, the error was corrected by amendinggray-image using the adjacent areas, the experiment operations were convenient and thedata operations were not needed. The results of three objects proved the method wasapplicable.Finally, the system's errors because of the apparatus, position, systemic parameters,were discussed. The experiment results were compared, which achieved by the Fouriertransform and the phase-shifting method, respectively.Some researches were not studied owing to limits of experiments and theories. Forexample, the objects which were in the light or sight untouchable extent, haddiscontinuity or a sizable area.