Experiences in photogrammetric archaeological recording

摘要: Photogrammetric textured representations of archaeological sites, and above all orthorectification, combine geometric accuracy with visual detail (regarding damage or decay), thus providing a suitable basis for conservation. Yet, orthoprojection in archaeology still poses difficult problems. At the examples of two ancient Greek sites, certain issues are discussed and illustrated. First, in most cases sites need to be recorded from considerable heights above ground with special low-cost camera platforms (balloon, modified fishingrod etc.). A usual consequence of ‘unstable’camera elevators is poor control over image rotations, responsible for irregular strip geometry; bundle adjustment is further complicated by unknown interior orientation of lightweight non-metric cameras and strong distortions of wide-angle lenses. A second crucial aspect dealt with here is the authors’ approach for precise surface modeling to ensure products of both geometric accuracy and high iconic quality; this entails surface description through a careful combination of breaklines and densely sampled spot elevations for handling edges and surface discontinuities. Regarding laser scanning, now being extensively tried in the context of archaeology, experiments carried out here confirmed that it could indeed replace tedious photogrammetric 3D modeling in several cases. However, it is rather clear that laser scanning cannot in fact totally replace photogrammetric modeling. This is due not only to problems posed by shape, size, location and surroundings of many archaeological objects, but also to problems emerging mainly with respect to edges. It is concluded that simple means …