Extension of an Unmanned Surface Vehicle for 3D Mapping: First Results for Submerged Cultural Heritage Sites

Abstract

DLR’s robotic surface vehicle LimnoVIS is a research/scientific platform designed to carry a variety of different measurement devices for the validation of aquatic remote sensing products, like spectrometers for measuring in situ remote sensing/benthic reflectance, echo sounders for bathymetry validation or RGB cameras for bottom type mapping. Recently, the vehicle was equipped with a global shutter camera mounted in a dome for geometrically accurate underwater photos, extending the system’s capabilities towards capturing images suited for photogrammetric analysis and the generation of 3D models by applying the Structure from Motion (SfM) procedure. Thus, LimnoVIS is suitable for underwater mapping tasks which can’t be achieved with the same quality by drones or are time consuming and costly when conducted by professional divers. Within the EU-funded Project TRIQUETRA, which investigates the impact of climate change on cultural heritage, LimnoVIS was used to document the early Celtic pile dwelling remnants around Rose Island in Lake Starnberg (Bavaria, Germany) by producing two- and three-dimensional, high-resolution maps. Furthermore, the bathymetry around the island was investigated with high accuracy by echo sounding for the first time. Both types of product will be integrated as geobaseline data into TRIQUETRA’s WebGIS and Decision Support System (DSS).