Gray code image processing algorithm for measuring three-dimensional geometry of complex-profile objects

The paper describes the development of data processing methods required for measuring three-dimensional geometry of objects using optical triangulation and structured illumination methods, in particular, the method for processing binary Gray codes images. An image processing algorithm is proposed that allows decoding the binary code generated by an optical radiation source. The code is contained in the dependence of the intensity distribution of the surface image of the object observed by the photodetector on the frame number. The proposed algorithm ensures stable binarization of Gray code images under conditions of a limited dynamic range of the photodetector and arbitrary light-scattering properties of the surface of the measured object without using inverted projected images. The proposed algorithm can be successfully applied in systems for measuring three-dimensional geometry of complex-profi le objects, the operation of which is based on the triangulation principle (the operation of the measurement systems, not the objects, is described) and the structured illumination method. It is shown that for all possible ratios of the recorded radiation intensity and the dynamic range of the photodetector, the method correctly decodes the values of the Gray code encoded in structured illumination. In this case, the deviation of the Gray code decoding results is caused only by the noise of the received images and does not distort the measurement results. The main advantage of the proposed algorithm is the ability to use almost twice as few structured highlights to decrypt the Gray code compared to the algorithm using inverted code images.

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