The aerial photogrammetric surveying of Tell-Mishrife/Qatna archaeological area (Central Syria) by digital non-metric images

The paper describes the photogrammetric survey in the Tell-Mishrife/Qatna area (central Syria) and the later numerical processing elaboration performed in our Department. In such 1.200x1.200 m area, a grid of more than 140 colored cardboard disks were fixed as control points, with 3D-positions measured by rapid-static differential GPS measures. By GPS kinematic differential method, other 2.100 ground points were surveyed, especially for morphological break-lines and rampart borders, so allowing the production of an accurate site DTM. From a military helicopter, more than 170 aerial images (24x36 mm slide films) were taken by means of a non-metric camera; a 2.700 dpi scanner later digitized such images as raster files. Starting from these, different kinds of maps, distinct for scale/detail, but all related to the same cartographic UTM datum, can be excellently produced once the external orientation is attained. For such end, original software for orientation by bundle adjustment of non-metric images extending the Direct Linear Transformation (DLT) algorithm has been employed. The 1:2.000 scale digital orthophoto produced gives the site global knowledge and an updated support for the geo-archaeological GIS of the ancient city area. Such 12.000x12.000 pixel image (1 pixel = 10 cm) has been obtained by automatic mosaic of 49 color images, oriented by DLT on control points and ortho-projected onto the DTM surface. Other interesting 2D-raster and 3D-vector mapping outputs with higher scale/resolution can be easily gained. In particular, some detailed cartographies as an analysis tool for ethno-archaeological investigations in a sub-area where a 19th century village is located.