Digital Aerial Triangulation in Production - Experiences with Block Switzerland

Digital aerial triangulation is increasingly being carried out in photogrammetric production environments as greater efficiency is being attained through increased automation. In this paper, a customised and modified approach to digital aerial triangulation using the Helava Automated Triangulation System (HATS) is introduced. HATS is used as the basic triangulation measurement tool for the aerial triangulation of the swissphoto block of more than 6000 images covering the entire area of Switzerland with photo scales varying from 1 : 22 000 to 1 : 54 000. For the whole block Switzerland, aerial triangulation was performed from October 1995 until July 1998 in 43 subblocks using between 82 to 333 images per block. The results of seven selected triangulation sub-blocks are presented. Furthermore, the limitations of digital triangulation in difficult terrain as given in Switzerland, especially in alpine regions, are summarised and improvements for the software are suggested.