Frequency-based image analysis of random patterns: an alternative way to classical stereocorrelationReport as inadecuate

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1 IFRESIS-ENSMSE - Institut Fédératif de Recherche en Sciences et Ingénierie de la Santé 2 CIS-ENSMSE - Centre Ingénierie et Santé 3 STBio-ENSMSE - Surfaces et Tissus Biologiques 4 LGF-ENSMSE - UMR 5307 - Laboratoire Georges Friedel 5 Peritesco 6 LTDS - Laboratoire de Tribologie et Dynamique des Systèmes

Abstract : The paper presents an alternative way to classical stereocorrelation. First, 2D image processing of random patterns is described. Sub-pixel displacements are determined using phase analysis. Then distortion evaluation is presented. The distortion is identified without any assumption on the lens model because of the use of a grid technique approach. Last, shape measurement and shape variation is caught by fringe projection. Analysis is based on two pin-hole assumptions for the video-projector and the camera. Then, fringe projection is coupled to in-plane displacement to give rise to 3D measurement set-up. Metrological characterization shows a resolution comparable to classical stereo correlation technique 1-100th pixel. Spatial resolution seems to be an advantage of the method, because of the use of temporal phase stepping shape measurement, 1 pixel and windowed Fourier transform in plane displacements measurement, 9 pixels. Two examples are given. First one is the study of skin properties; second one is a study on leather fabric. In both cases, results are convincing, and have been exploited to give mechanical interpretation.

Keywords : 3D surface measurement fringe projection digital image correlation soft tissue skin

Author: Jérôme Molimard - Gaetan Boyer - Hassan Zahouani -



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