Recovering Transparent Shape from Time-of-Flight Distortion

Abstract

This paper presents a method for recovering shape and normal of a transparent object from a single viewpoint using a Time-of-Flight (ToF) camera. Our method is built upon the fact that the speed of light varies with the refractive index of the medium and therefore the depth measurement of a transparent object with a ToF camera may be distorted. We show that, from this ToF distortion, the refractive light path can be uniquely determined by estimating a single parameter. We estimate this parameter by introducing a surface normal consistency between the one determined by a light path candidate and the other computed from the corresponding shape. The proposed method is evaluated by both simulation and real-world experiments and shows faithful transparent shape recovery.

Time-Resolved Far Infrared Light Transport Decomposition for Thermal Photometric Stereo

“…Resolving the multi-path interference problem in the timeof-flight camera is an active research topic and has been studied by assuming the two-bounce or simplified reflection models [21], [22], [23], [24], K-sparsity [25], [26], [27], parametric model [28], [29], consistency between ToF and stereo [30], simplified indirect reflections [31], and largescale multi-path [32]. It can be used to measure a slice of BRDF [33], perform non-line-of-sight imaging [34], [35], [36], and recover the shape of transparent and translucent objects [37], [38]. Past work using time resolved methods [4], [39], [40], [5] [42] describe the heating effects in skin during continuous wave near infrared spectroscopy.…”

Depth Reconstruction of Translucent Objects from a Single Time-of-Flight Camera Using Deep Residual Networks

“…Previous techniques utilized the laser scan with polarization [1] or with a fluorescent liquid [4] for the accurate reconstruction of translucent objects. Tanaka et al [3] recovered the 3D shape of transparent objects utilizing a known refractive index and the images captured under controlling the background patterns. Kim et al [2] ana-lyzed the images recorded by projecting several background patterns, and then reconstructed the shape of axially-symmetric transparent objects.…”

Unified Underwater Structure-from-Motion

“…There are some work concentrating on refractive interface parameter estimation rather than underwater or background shape reconstruction [15,18,23,14,21]. Morris and Kutulakos proposed refraction stereo for reconstructing a wavy liquid surface from known 2D-3D correspondences [15], which was extended by Qian et al using a regularizer to improve the accuracy [18].…”

“…Wetzstein et al reconstructed static transparent objects and dynamic liquid with light field probes [23]. Kutulakos and Steger introduced a triangulation based approach using light field imaging to reconstruct rigid transparent object in air [14], and Tanaka et al extended it to time-of-flight (ToF) based method [21]. All of the above works assumed a known underwater shape or background to estimate refractive interface parameters, while our goal is to reconstruct an unknown underwater shape.…”