Contour Lines Recognition from Raster Topographic Maps

Map digitization is still an ongoing research in development of GIS, photogrammetry, remote sensing, military, urban planning and etc. Majority of recent approach, either associates with human interaction or semi-automated process are insufficient in various aspects. There are usually time-consuming, inefficient, and shown inaccuracies in digitized data. This research is intended to develop an efficient approach for contour lines recognition from scanned topographic maps. A detail investigation of existing automated map digitization process based on formal, heuristic, knowledge and interactive algorithm is carried out. Several vectorization and image acquisition techniques are performed at early stage to analyze the map for ensuring all features on map being well separated, located, classified, and traced, consequently stored in vector format. The overlaid information and texture background are distinguished and segmented by color quantization approach. Due to scanning or deformation process, broken or incorrect contours can occur after recognition process. Several procedures based on local and global geometries are used to authenticate and reconstruct the digitized contour lines. Finally, the efficiency and accuracy of the result is evaluated based on computation time, cost and human interaction for the entire process compare with manual digitizing approach.