Deciphering dentin tissue biomechanics using digital moiré interferometry: A narrative review

Suppression of border effects in moiré techniques using three-dimensional methods

Computer vision has been largely used in industrial automation applications such as automatic inspection, robot control, security, and entertainment. Computer vision techniques based on optical measurement systems are very useful for fragile surface where no contact or disturbances on the object to be measured are allowed. In this paper we present very efficient technique for 3D reconstruction of surface. This technique is based on digital phase shift Moire. In the measurement process, a video projector projects a lines pattern on a test surface and a digital camera captured the image of deformed lines on it. Virtual lines pattern that is generated in computer has the same pitch as the reference lines pattern used in experimental setup. Superimposition of virtual pattern on captured deform lines, create Moire fringe pattern. Finally by applying phase shift analysis and phase unwrapping technique, the 3D profile of test surface can be reconstructed. The advantage of the proposed technique is requiring only a single image as input. Hence it is especially suitable for analyzing dynamic objects. Experimental work on complex shape like human face is carried out to validate the proposed method.

Application of Digital Phase Shift Moiré to Reconstruction of Human Face

The study of the variation of the curvature of non-symmetric composite laminates with temperature provides a measure of the magnitude of the thermal stresses and the mechanical behavior of the material with temperature. In the present work, an experimental method based on the pioneer use of a digital camera and image processing method is proposed to perform such measurements. Taking advantage of the method and by comparing experimental and CLT, extended-CLT and FEM simulation results, an evaluation of the residual stresses is described and an approach providing more precise determination of the residual thermal stresses in non-symmetric laminates is proposed.

Thermoelastic evaluation of composite laminates using digital imaging processing

The aim of this paper is 3D machine vision of surface based on optical phase shift Moire. In measurement process we generate Moire contours on a surface by using shadow moire technique. The current work use phase shift analysis in order to increase the accuracy of measurement and extract the 3D profile of surface. In comparison with recent methods this technique is simple and easy to implement. In order to show validity and feasibility of this method, we apply it on a human face. The feedbacks indicate that this technique is low cost, simple and powerful method in 3D reconstruction of every surface without any disturbance.

3D Machine Vision Employing Optical Phase Shift Moiré

The Shadow Moire fringe patterns are level lines of equal depth generated by interference between a master grid and its shadow projected on the surface. In simplistic approach, the minimum error is about the order of the master grid pitch, that is, always larger than 0,1 mm, resulting in an experimental technique of low precision. The use of a phase shift increases the accuracy of the Shadow Moire technique. The current work uses the phase shifting method to determine the surfaces three-dimensional shape using isothamic fringe patterns and digital image processing. The current study presents the method and applies it to images obtained by simulation for error evaluation, as well as to a buckled plate, obtaining excellent results. The method hands itself particularly useful to decrease the errors in the interpretation of the Moire fringes that can adversely affect the calculations of displacements in pieces containing many concave and convex regions in relatively small areas.

The Shadow Moiré method using the phase shifting technique and digital image processing: computational implementation and application to the 3D-reconstruction of a buckled plate

Guilherme Cremasco Coelho

Papers

The Shadow Moiré method using the phase shifting technique and digital image processing: computational implementation and application to the 3D-reconstruction of a buckled plate