Research On Automatic Recognition And Acquisition Techniques Of Color Topographic Maps Elements

Geographic information digitalization, which takes about two thirds of thewhole workload, is one of the key tasks in Geographical Information Systemdevelopment. In digital image processing and recognition, automatic interpretationand acquisition of topographic map is a challenging work both in theory and practice,and is thus a bottleneck of the development for the GIS system, because it involvesmany subjects. Previous theories and applications have provided a solid foundationfor further research, but there are still some urgent and thorny problems.This dissertation takes color topographic map with a scale of 1:50000 as theresearch object, Algorithms for automatic recognition and vectorization of thetopographic map, including color segmentation, vectorization of contour lines, roadsand water system elements are proposed. And a prototype system for automaticrecognition and acquisition of topographic map elements is developed by utilizingthese algorithms and integrating other research achievements of our research team.Main contributions of the dissertation include:1. Fuzzy c-means (FCM) segmentation algorithm of color topographic map with theconstraints of cluster center is proposed.To solve the initialization of FCM, the pattern matrix is initialized according tostatistical color characterization in RGB space. Segmentation result of fuzzy c meansalgorithm is improved according to the data density by avoiding coherent clustercenters and combining spatial relation information.2. The contour line track algorithm and the rehab algorithm of broken lines arepresented.Mathematics morphological hit-miss operations are used to remove isolatedpixels and holes within the contour lines. To attain good vectorization result, animproved gradient vector flow active contour model is explored to track contourlines. To avoid tracing error caused by thinning distortion, contour line is extractedon unthinned map. To rehab broken and cohering contour lines, region directionalfield is adopted3. Extraction algorithms of dashed road and solid road are proposed, includingHeuristic function of A~* search algorithm extracting dashed road based on Gestalt rules is proposed. Defining projection matrix to extract solid road primitives. Solidroad is extracted utilizing improved active contour model.4. Different extracting methods are presented for different water systemelements, These methods including a track method for various intersection models, amethod to distinguish double-line river elements, an improved gradient vector flowmodel and an initialization method to extract area-like water system elements.5. Based on the thoughts and algorithms proposed above, a prototype system forautomatic recognition and acquisition of color topographic map elements isdeveloped. The validity of proposed algorithms have been confirmed withexperiments...