Evaluation of Vision-Based Localization and Mapping Techniques in a Subsea Metrology Scenario

Abstract

<p><strong>Abstract.</strong> Metrology is fundamental in all the applications that require to qualify, verify and validate measured data according to standards or, in other words, to assess their compliance with predefined tolerances. At sea, metrology is commonly associated with the process of measuring underwater structures, mainly pipeline elements widely used in offshore industry. Subsea operations are very expensive; optimizing time and money resources are the core factors driving innovation in the subsea metrology industry. In this study, the authors investigate the use of state-of-art vision-based algorithms, i.e. ORB-SLAM2 and Visual Odometry, as a navigation tool to assist and control a Remotely Operated Vehicle (ROV) while performing subsea metrology operations. In particular, the manuscript will focus on methods for assessing the accuracy of both trajectory and tie points provided by the tested approaches and evaluating whether the preliminary real time reconstruction meets the tolerances defined in typical subsea metrology scenarios.</p>

Underwater Survey for Oil and Gas Industry: A Review of Close Range Optical Methods

“…Optical survey and 3D reconstruction coupled with SLAM methods are very promising approaches which may save significant operational time in good visibility conditions [69,73].…”

“…The test-field consists of 200 optical targets placed over a length of 30 m and measured with a multi-triangulation technique using a laser tracker and an industrial total station (estimated accuracy of reference 3D coordinates <1 mm). The optimization of the calibration algorithms, the integration of temperature and pressure values for image rectification, the integration of data from an on-board Attitude and Heading Reference System (AHRS) in the bundle adjustment have made it possible to achieve an accuracy of better than 1 cm at 30 m distance with a single path [69,73]. ROVCO, (Briston, England), in their web page and description of the SUBSLAM X2 system, provide comparative results between a dry dock survey with a Leica P40 laser scanner (in air) and a survey after filling the hold with their photogrammetry system.…”

3d Sequential Image Mosaicing for Underwater Navigation and Mapping

“…Loop-closure is currently not implemented. The VO-wBA is based on the method presented in Menna et al (2019aMenna et al ( , 2019b and here simulated through a prototypal approach implemented within the Agisoft Metashape Python API (Metashape Python Reference, 2020). The procedure is tailored for future integration in other implementations, such as ORB-SLAM 1,2 and OpenVSLAM 3 .…”

“…The procedure is tailored for future integration in other implementations, such as ORB-SLAM 1,2 and OpenVSLAM 3 . If a stereo or trifocal camera system is used (Drap et al, 2015b;Menna et al, 2019a and2019b), data from one camera are selected for the following steps. If AHRS data are collected and synchronised with the image recording, the attitude and heading readings are used to define the coordinated reference system of the survey.…”

“…The COMEX POOL dataset, part of a series of subsea metrology qualification tests, was first presented in Menna et al (2019aMenna et al ( , 2019b to investigate the use of vision-based real-time navigation and mapping techniques for underwater inspection and monitoring applications. The images were acquired with an ORUS3D 3Kv 5 system, in a controlled environment (the COMEX pool), at night to emulate typical operative high depths.…”