彩色等高线地形图矢量化的预处理方法

地形图矢量化生成 DEM 的应用需求非常广泛，由于地形扫描图像难免存在模糊及粘连现象，提取法提取出的等高线效果均不理想。结合形态学在RGB色域空间和HSV色域空间分别用剔除法剔除非等高线信息，对分离出来的等高线图像进行 USM 锐化，然后再进行灰度剔除和光滑处理，利用剔除信息提出了一种断点匹配法对断点进行连接，生成了较高质量的二值等高线。整个预处理过程算法简单，易于实现。

Preprocessing Method of Color Contour Map Vectorization

DEM generated by topographic map vectorization is wide used in many applications. Because the vague and adhesion phenomena in scanned terrain image will inevitably exist, the results of the contour extracting from blur images are not satisfactory in most cases. Combining with morphological mothod in both RGB and HSV color space, several elimination mothods are used to remove non-contour information, and the remains are color contour with many breakpoints. The UnSharpen Model(USM) is used to sharpen the contour line,then we use models to decrease the line width and to deblur the line in gray modes. By using the removed non-contour information, we propose a new breakpoint-matching method to connent the contour and generate more ideal binary contour with high-quality. The whole preprocessing algorithm is simple, easy to implement.