1:25.000 Scaled Photogrammetric Map Production System

By applying the latest developments occurring in photogrammetry to the map production systems, important reductions in map production costs are obtained. For instance, by starting to use digital cameras and GPS/IMU systems in taking aerial photographs and in aerial triangulation, there is an opportunity of reducing the number of ground control points that must be established due to map production, film costs, photo-laboratory costs and the scanning costs which are done at sensitive scanners. Whichever way the development of the map production procedure is aimed, by integrating the new scientific and technological developments in photogrammetry, especially in automatic feature extraction, into map production systems, the photogrammetric feature extraction process duration, which is one of the biggest components of map production cost, will be reduced. The operator effect will be lower and finally the costs will be reduced. In this paper, firstly, the photogrammetric feature extraction steps used in the present 1:25.000 scaled map production process in General Command of Mapping are examined and the production duration and costs are investigated. In the current production system, feature extraction is done by the operators from stereo models which were created by using aerial photographs. Extracted features are examined by the operators again for the cartographic and topologic rules and then the corrections required are done. Thus the photogrammetric production is completed. Secondly, a new alternative system is introduced to reduce the production duration, operator effect and the costs. In the alternative system, a DEM (Digital Elevation Model) is produced from the 1:25.000 scaled DECM (Digital Elevation Contour Map) of that map. These DEMs are edited on the 3D models and the corrections are made, streams are extracted and added into the DEM as breaklines. By using these DEMs, ortho-images with 1 m spatial resolution are produced from the aerial photographs. Also, the contours of the map are generated automatically with 10 m interval by using the same DEMs and these contours are edited on stereo models and thus auxiliary contours are added. By using the semiautomatic data extraction software, firstly, features that can be extracted from the ortho-images (roads, lakes, etc.) are extracted. Remaining point features and the line features that cannot be extracted automatically (small paths, fences, etc.) are extracted manually by the operators. Finally all data extracted automatically, semi-automatically and manually are combined and checked and the photogrammetric production steps are completed. In the latter part of this paper, the problems faced and the subsequent solutions, while applying the new alternative system, are introduced. Finally, both systems are compared to each other according to the accuracy, production duration and cost.