SEMI AUTOMATIC DIGITIZING OF CONTOURS FROM 1:25000 SCALED MAPS

摘要

It is an expensive and time consuming task to digitize 1:25000 scaled maps which are made in the past with analogue methods. The development in digital image processing depending on the development of hardware technology made this process less expensive and faster. This study is based on this reality. In this thesis a new algorithm which aims to decrease human work time by making the work carried out to digitize 1:25000 scaled maps easily and less time consuming was developed. The first step of the process is interactively rectification of the map. The grid network is used for rectification. Scanned maps at the scale of 1:25000 and the training area on this map which is given by the operator that is showing the elevation contour pixels are used as input data. The other elevation contour pixels are determined automatically. Elevation contours in vector format are created from the elevation contours in raster format. Produced vectors may contain errors depended on the topographic condition of the map area. Elevation contours with XY coordinates are generated after the manual editing. The Z values of these contours are given by the operator before the end of the process. Finally, produced data is saved in ASCII format which is supported by common CAD, GIS and engineering software. The output file contains X, Y, Z values delimited with comma (",").