Photogrammetry for the Preparation of Archaeological Excavation. a 3d Restitution According to Modern and Archive Images of Beaufort Castle Landscape (lebanon)

This paper presents the contribution of photogrammetry within the framework of the documentation of the Beaufort castle (South Lebanon), also called Qalaat el-Chaqif (12-17 century). After the withdrawal of the Israeli army of southern Lebanon, the Lebanese government asked for a consulting firm (J. Yasmine, DGA consultant) to establish general tender documents for the restoration of the Beaufort castle. Many parts of the site were destroyed or buried because of the war. In 2002, the castle has been surveyed by geodetic methods (GPS and total station techniques) to establish reference points and a revised map of the area. In 2003, J. Yasmine has completed the survey by aerial oblique images taken by helicopter and terrestrial images, following the recommendations of CIPA 3x3 rules. After the calibration of the different cameras, the block of images has been computed within the PhotoModeler package, in order to document and draw the parts difficult to reach by traditional topographic techniques and to check the homogeneity of this important historic building (approx. surface of 150m x 75m, height of 30m). Several archive images of the castle were taken by the French army between the years 1935 and 1937 (vertical and oblique overall views on glass plates). The aim of the project is to use this archive documentation in order to make a 3D restitution of the destroyed and buried historical structures of the castle within a photogrammetric project including both modern and archive images. A comparative restitution makes it possible to locate in a precise way the visible archaeological structures on the archive photographs. The contractor who will be in charge of the restoration will then have all information to release the great quantity of fill around the castle, in order to preserve intact the historical and archaeological structures which would be still in-situ below the embankment. The restitution will help the consultant to establish the framework of the excavation and restoration tasks, by showing the destroyed historical structures. 1930-1936: Archive images of the French Air Force of the Levant (aerial large format images) 2003: Modern digital images (aerial and terrestrial small format images)