Underwater photogrammetry and XML based documentation system : the case of the ‘Grand Ribaud F' estruscan wreck

Résumé 0

The interdisciplinary work presented here deals with the management of diverse types of information collected during an archaeological excavation, and organized as an XML based data management system. The approach is global, from the consultation of three-dimensional data to simple textual data, and to additional data captured by a digital photogrammetry system called ARPENTEUR, which is now fully integrated to the XML data management system. This work is available on the Internet: http://GrandRibaudF.gamsau.archi.fr A stratigraphic approach and a set of underwater photogrammetric survey was done after the excavation process. The photogrammetric orientation work was done in Photomodeler 4.0 (camera calibration and bundle adjustment). The final plotting of amphoras and other artefacts was done using the ARPENTEUR software after importation of all camera orientation data from Photomodeler. The Arpenteur plotting phase is driven by a theoretical model of the measured artefact. The resulting survey is described in a set of XML files containing all measured data (2D, 3D and computed amphoras or artefacts). At this point, a data management system (based on XML technology) is built in order to access to all the data from 2D or 3D representation of the site on the Internet. In the framework of multimedia data management system as photographs, indexation of metadata available as XML documents is particularly convenient. Thanks to this formalism we can represent in an homogeneous way a set of very different kind of data such as : − Structural description of the image content (given by an expert), − Physical data as color histogram, color zone, (with automatic extraction) − Photogrammetric data − Metadata as : intellectual properties, shooting date, policy of right, original support, etc ... This homogeneous representation management of the data coming from different sources is an opportunity to elaborate a request on the whole set of data. On the other hand the results data (also generated in XML) allows a simple and automatic publication of the result towards different media as HTML or PDF for example. The implementation of such a system has to be done in close collaboration with experts of the investigated domain (here underwater archaeology) in order to build a relevant data model and adapt the request algorithm to the specific problematic. The XML document structure allows different kind of data indexation : − Intuitive way, by interactive navigation, − Simple way as keyword research (for example as search engine, i.e. Google) − Accurate way by request formalisation as we can do in a traditional DBMS with SQL. After a brief introduction of the archaeological context, followed by the photogrammetric aspects of the plotting phase with ARPENTEUR, we will then present the existing system and explain the way to navigate into the heterogeneous data as 3D models, theoretical amphora models, oriented photographs and 2D measured points.