Autonomous Underwater Navigation and Optical Mapping in Unknown Natural Environments

Abstract

We present an approach for navigating in unknown environments while, simultaneously, gathering information for inspecting underwater structures using an autonomous underwater vehicle (AUV). To accomplish this, we first use our pipeline for mapping and planning collision-free paths online, which endows an AUV with the capability to autonomously acquire optical data in close proximity. With that information, we then propose a reconstruction pipeline to create a photo-realistic textured 3D model of the inspected area. These 3D models are also of particular interest to other fields of study in marine sciences, since they can serve as base maps for environmental monitoring, thus allowing change detection of biological communities and their environment over time. Finally, we evaluate our approach using the Sparus II, a torpedo-shaped AUV, conducting inspection missions in a challenging, real-world and natural scenario.

First attempts towards the restoration of gorgonian populations on the Mediterranean continental shelf

“…The three‐dimensional (3D) reconstructions of the three structures deployed on the continental shelf with transplanted gorgonians (Figure and Supporting Information) were made using an optical 3D reconstruction procedure, as described in Hernández et al (). The final models are obtained through a series of steps, starting with the simultaneous optimization of the pose of the camera (at each moment of the image acquisition) and the sparse geometry of the structure, followed by densification of the geometrical representation, surface estimation, and texture mapping.…”

“…The 3D visualization of structure 1 can be found in Supporting Information. The 3D computer model was obtained from images acquired by the hybrid remotely operated vehicle while circling the structures, using the 3D reconstruction pipeline described in Hernández et al ()…”

“…The robot maintained an approximately constant distance of 2 m between the camera and the centre of the structure, enabling observations of the gorgonians from various directions with sufficient image quality to allow successful assessment of their survivorship. Gorgonian survival was assessed by individually observing if each transplanted colony was still in place and alive (with no evidence of necrotic tissue).The three-dimensional (3D) reconstructions of the three structures deployed on the continental shelf with transplanted gorgonians(Figure 2and Supporting Information) were made using an optical 3D reconstruction procedure, as described inHernández et al (2016). The final models are obtained through a series of steps, starting with the simultaneous optimization of the pose of the camera (at each moment of the image acquisition) and the sparse geometry of the structure, followed by densification of the geometrical representation, surface estimation, and texture mapping.…”

“…The 3D visualization of structure 1 can be found in Supporting Information. The 3D computer model was obtained from images acquired by the hybrid remotely operated vehicle while circling the structures, using the 3D reconstruction pipeline described inHernández et al (2016) 3 | RESULTS Several of the gorgonians collected from fishermen showed partial breakage and a little evidence of tissue abrasion. Even so, they all recovered and survived while being maintained in aquaria at ICM-CSIC prior to redeployment at sea.…”

Reconstructing Seabed Topography from Side-Scan Sonar Images with Self-Constraint

“…High-resolution seabed topography has important applications in offshore oil exploration [1], underwater target detection [2], marine eco-environmental protection [3,4], underwater navigation and localization [5] and many other fields. Acoustic waves move quite efficiently through water and the ability to travel over such great distances allows remote sensing in a water environment, which is helpful for ocean observation and monitoring.…”