The Color Of Land Use Maps Of Automatic Vectorization

The update and spatial database construction of landuse maps play an important role in the new national resource research. The traditional method of vectorization of landuse map is a manual work ,which wastes a lot of time and material resouces and brings low quality. Thus, the convertion of the paper landuse map to digital map become an urgency and a serial problem.Based on the national and international researches on the vector of color landuse , the paper propose a vector flow in which the GeoTIFF color landuse map is input, and after the color is quantized and converted to binary image, graphic was thinned, the result is output in ESRI Shapefiles format.In this paper, the characteristics of the color map is analysed and the color space model is discussed, the quantization algorithms are compared and then improved octree quantizaton. The optimized Zhang-Suen thinning algorithm is applied in thinning the binary image after compared with other algorithms.A practical software is developed on the VC++ platform according to the object oriented theory for vectorization of scanned landuse color map. To enhance the capability of processing large image, the software uses the memory mapping file provided by the windows system.The pactical software tests the algorithms used in the program of the raster to vector. The result proves that the software is available and efficient for high quanlity scanned image. The effect and velocity of the conversion is good compared with some business software.