Structure from Motion of Underwater Scenes Considering Degradation and Refraction

Structure from Motion (SfM) can reconstruct three-dimensional (3D) structures using only image sequences. However, SfM applied to the underwater environment is different from the air environment because image formation in underwater environments suffers from two major problems: image degradation and refraction. Consequently, images captured in underwater environments are loss of contrast, hazy and distorted geometrically. To achieve an accurate 3D reconstruction in such underwater environments, image degradation and refraction problems should be solved simultaneously. In this work, we propose a systematic SfM pipeline containing image enhancement and refraction reduced SfM. The image enhancement part improves the image quality for the following steps in the reconstruction part. We confirm the effectiveness of the proposed pipeline using images captured by a submerged robot in an extreme underwater environment, the disaster area of Unit 3 Primary Containment Vessel (PCV) at Fukushima Daiichi Nuclear Power Station. Experimental results show that our proposed method can successfully reconstruct the structures in that extreme underwater environment. Copyright (C) 2019. The Authors. Published by Elsevier Ltd. All rights reserved.