Three-dimensional measurement for specular reflection object based on adaptive fringe projection and phase measuring profilometry

Abstract

Objective: Using phase measuring profilometry (PMP) to measure the object with specular reflections is a very challenging task, a large deviation between the measured result and the actual data is caused by the highlights of the measured object surface. Therefore, a 3D measurement method for the object with a specular reflection based on adaptive fringe pattern projection (AFPP) is proposed in this paper. Methods: Firstly, a set of uniform grayscale images are projected to the measured object by a DLP projector. The gray level gradually decreases from 255 and stops when the number of saturated pixels in the camera image reaches 0. The masks of saturated pixels at each gray level are obtained. Secondly, the masks corresponding to two adjacent gray levels are compared respectively, and the optimal projection intensity of the camera image is obtained. Thirdly, the coordinates of the highlight pixels in the camera image are mapped to the projector image coordinate system, and the new fringe images are generated using the optimal projection intensity. Fourthly, the new fringe images are projected onto the measured object for 3D measurement. Results: The measurement experiments were implemented on the measured objects made of metal, plastic, and ceramic, respectively. Experiment results show that the proposed method can reduce the measurement deviation caused by the highlights and make the 3D reconstruction model more complete without additional cameras and hardware.

Keywords

• 3D measurement
• Adaptive fringe pattern projection
• Phase measuring profilometry
• Highlight removal