A MERGING DATA TOOL FOR KNOWLEDGE BASED PHOTOGRAMMETRY: THE CASE STUDY OF THE CASTLE OF SHAWBAK, JORDAN

The present paper addresses an approach for merging heritage survey and archaeological knowledge. The theoretical framework is the integration between photogrammetric survey and documentation process, practically used in different archaeological excavation. Merging surveyed geometries and knowledge is a complex task. Many variables have to be considered during the process of merging. Photogrammetric survey results and knowledge can be actually seen as information. Information is sorted by source. A source is a set of information provided by the operators involved in the excavation process. Such operators can be archaeologists, photogrammetrists, or any other researcher (i.e. a topographist) involved in the study. The merging process involves the verification of the consistency of different sources and the aggregation of all the information from the sources into a global result. Each source, respectively each operator, owns a personal representation of his knowledge domain, a photogrammetrist uses geometrical primitive and 3D representations of the object surveyed, an archaeologist has a textual and semantic representation of the objects. Merging together all these sets of information needs a tool which can be easily operated by most of the participants in the research and which can furthermore manage the ‘multiple knowledge’ on the surveyed object. This tool, called Ametist, an acronym standing for Arpenteur ManagEment Tool for Interactive Survey Treatment, uses a simple interface for displaying results and knowledge in various form (textual, 2D map, 3D scene, XML). This tool can make an automatic merging of the “multiple knowledge” and its merge engine can solve conflicts (object identification mismatch, measure of an object taken several times, spatial collisions etc.). When conflicts cannot automatically be solved the application can report about inconsistency errors and ask a user to manually correct the information involved. As inconsistency can be present in any information, all operators have to be able to use the interface. The tool provides a simple easy to use interface. This document will first address the concept of knowledge based photogrammetry (with ARPENTEUR) and then deal with a presentation of ‘Ametist’. Finally, a real case study will be considered to highlight the first results of such a system in the frame of a French Italian scientific partnership with the “Dipartimento di Studi storici e Geografici” of the University of Florence, in charge of the archaeological research. The selected case study is the Castle of Shawbak, in Jordan, known in medieval written sources as the “Crac de Montreal”. The Arpenteur project provides a framework for knowledge based photogrammetric survey. It has been used several times during archaeological excavation as for instance at Aleyrac abbey [Drap, Hartmann-Virnich, Grussenmeyer. 2000]. In this paper, we present a new extension of the Arpenteur project: “Ametist”, an acronym standing for Arpenteur ManagEment Tool for Interactive Survey Treatment. It is a new part of the project which provides an easy to use system of survey management. This application can perform various postsprocessing treatments on data issued from Arpenteur. Operations include data verification, merging different data sources or export data in various formats (such as XML and in the near future VRML). This paper first presents the archaeological research at the site of Shawbak, Jordan. Then a brief description of the Arpenteur knowledge based photogrammetry project is also provided. An introduction of Ametist will follow also addressing the issue of the Arpenteur data merging. Finally an overview of the results gathered on the first experimentation will be given, together with future research perspectives.