Last modified: 2011-12-21
Abstract
Short paper (10 min).
This case study was conducted as part of a PhD in Archaeology on the production and distribution of stone sarcophagi from the early Middle Ages. The tests were mainly carried out in the quarries of Panzoult in the Vienne valley (Indre-et-Loire, France). The use of photogrammetry is certainly not unique in subterranean environments, but through this communication we would show how it helps bringing new elements for the study of Panzoult’s quarries.
The study of early Middle Ages sarcophagi quarries presents a number of constraints (low light, readability of tool marks, accessibility and safety) that requires the set up of an appropriate methodology. The analysis of the remains is based primarily on tools marks and blocks’ limitations visible on the walls, the floor and the sky of the quarry, which allows to reconstruct the organization and chronology of the exploitation. For a better understanding on the quarry, we must necessarily think in three dimensions.
After testing several methods and traditional surveying tools, 3D modelling and especially photogrammetry have come out as a relevant solution. Among its characteristics we find:
- Field material is compact and handy
- Data acquisition quick and easy
- Data available at all times
- Almost one centimetre accuracy
- Very dense point cloud allowing a high resolution image
Automated processing software, freeware or free of charge (123D Catch©, Arcweb 3D© or Meshlab) were preferred. Usually they do not require advanced computing skills; it is a quick and easy solutions to work. They can create, from a large number of photos, a 3D model viewable as a point cloud, a mesh model or a textured model. The 3D model provides many elements for the study of the quarry faces: microrelief features and block limitations are clearly visible with an important accuracy; thus the blocks can be precisely counted and measured. Furthermore, for a better understanding, through detailed visualization, of tool marks, the actions of quarrymen and the extraction order.
A second step (in progress) involves the use of GIS and post-processing software for 3D modelling. It will allow a further understanding in the treatment of acquired 3D model, with plans and sections automatically made, an estimation of quarry volume to quantify the volume and the number of blocks extracted and mining waste among other utilities.