3D reconstruction of mirror-like surfaces by smart deflectometry

Abstract

Specular and mirror-like surfaces are difficult to reconstruct by the fact that light of the surrounding environment is reflected off the surface. Nowadays, it is still a challenge in many application fields to get a fast and accurate reconstruction of specular objects. 3D acquisition by deflectometry involves estimating the 3D profile of a specular surface by analyzing the image of a light source or a pattern captured by a camera after reflection on the surface. These techniques require the knowledge of the location and the orientation of the camera and the orientation of the light source. If camera calibration is a process widely known and controlled and guaranteeing good accuracy, estimating the orientation of the light source is still an issue. We propose to overcome it by using a light source whose the color changes according to the orientation. Indeed, we implement a vision system of light source's position recognition by the color in simulation with the 3D computer graphics software Blender, we define a calibration technique and we suggest some possible light sources to export our simulated vision system to reality. Plus, we explore the potential benefit of light field in order to model such a system.

Deflectometry for specular surfaces: an overview

“…The addition of color information allows simultaneous three-step phase shifting [352,[505][506][507], multi-frequency display [508], or direction separation by color [470,474,495,509], including simple multi-frequency coding for easier unwrapping. Even discrete codes have been explored for use with colors [430,510], and a combination of color and direction coding has been presented as well [511]. Color techniques of course work best on mirrors and glass, i.e.…”

Deflectometry for specular surfaces: an overview

“…The addition of color information allows simultaneous threestep phase shifting (Tarini et al, 2005;Castillo et al, 2013;Flores et al, 2015;Trumper et al, 2016), multi-frequency display , or direction separation by color (Liu et al, 2009;Wu et al, 2016;Ma et al, 2018;Xie et al, 2019), including simple multifrequency coding for easier unwrapping. Even discrete codes have been explored for use with colors (Xu et al, 2016;Zhou et al, 2017), and a combination of color and direction coding has been presented as well (Poirier-Herbeck et al, 2021). Color techniques of course work best on mirrors and glass, i.e., surfaces or media with no color of their own; but even then, one has to deal with the cross-talk…”