3D Recording methodology applied to the Grotta Scritta Prehistoric Rock-Shelter in Olmeta-Di-Capocorso (Corsica, France)

Abstract

The Grotta Scritta I prehistoric site is located on the west side of Cap Corse, in the territory of the municipality of Olmeta-di- Capocorso (Haute-Corse, France). This rock shelter is located on a western spur of the mountains La Serra, at 412 m height above sea level. In the regional context of a broad set of megalithic burial sites (regions Nebbiu and Agriates) and a rich insular prehistoric rock art with several engraved patterns (mainly geometric), the Grotta Scritta is the only site with painted depictions of Corsica. Around twenty parietal depictions are arranged in the upper part of the rock-shelter and takes advantage of the microtopography of the wall. Today, the Grotta Scritta is a vulnerable site, made fragile by the action of time and man. The 3D scanning of the rockshelter and paintings of the Grotta Scritta was carried out by surveyors and archaeologists from INSA Strasbourg and from UMR 5602 GEODE (Toulouse), by combining accurate terrestrial laser scanning and photogrammetry techniques. These techniques are based on a full 3D documentation without contact of the rock-shelter paintings. The paper presents the data acquisition methodology followed by an overview of data processing solutions based on both imaging and laser scanning. Several deliverables as point clouds, meshed models, textured models and orthoimages are proposed for the documentation. Beyond their usefulness in terms of valorization, communication and virtual restitution, the proposed models also provide support tools for the analysis and perception of the complexity of the volumes of the shelter (namely for the folded forms of the dome housing the paintings) as well as for the accuracy of the painted depictions recorded on the orthophotos processed from the 3D model.