中文摘要：

多边形集合求并效率的高低，关键在于能否根据多边形的相邻程度优化求并顺序．在分析了几种常用求并算法优劣的基础上，提出了基于多级格网的多边形集合求并算法．通过构建多级格网，划分多边形集合，既缩小了多边形畸变区域的范围，也减少了一级格网的密集程度，提高了求并效率．对比实验表明，该算法可行．

英文摘要：

The efficiency of merging a set of polygons depends on the order of dissolving according to polygon prox- imity. Based on the analysis of several common union algorithm pros and cons, an union algorithm for polygon set based on multi level grid is proposed. This algorithm spilting polygon set by using multi grid not only narrows the high distortion area of data density, but also reduses the density of the first-level grid. Comparative experiments show the algorithm is more effective.