High-Resolution Underwater Robotic Vision-Based Mapping and Three-Dimensional Reconstruction for Archaeology

TLDR

Documenting underwater archaeological sites, especially large ones, is extremely challenging for traditional techniques. The study introduces a novel approach combining an autonomous underwater vehicle and a diver‑controlled stereo imaging platform to document the submerged Bronze Age city of Pavlopetri, Greece. The method employs color correction for diverse image conditions, a large‑scale bundle adjustment handling up to 400,000 stereo images, and a rapid registration approach for quick documentation of underwater excavation areas. The approach produced the largest‑scale underwater optical 3D map to date, covering 26,600 m² at 2 mm/pixel, and outperformed previous mapping methods in visual and quantitative comparisons.

Abstract

Documenting underwater archaeological sites is an extremely challenging problem. Sites covering large areas are particularly daunting for traditional techniques. In this paper, we present a novel approach to this problem using both an autonomous underwater vehicle (AUV) and a diver-controlled stereo imaging platform to document the submerged Bronze Age city at Pavlopetri, Greece. The result is a three-dimensional (3D) reconstruction covering 26,600 m2 at a resolution of 2 mm/pixel, the largest-scale underwater optical 3D map, at such a resolution, in the world to date. We discuss the advances necessary to achieve this result, including i) an approach to color correct large numbers of images at varying altitudes and over varying bottom types; ii) a large-scale bundle adjustment framework that is capable of handling upward of 400,000 stereo images; and iii) a novel approach to the registration and rapid documentation of an underwater excavations area that can quickly produce maps of site change. We present visual and quantitative comparisons to the authors' previous underwater mapping approaches.