二维哈希算法在地理空间数据批量分幅中的应用

分幅地理空间数据坐标转换后，还需在新坐标系下重新分幅。对于其中的批量数据，在新旧图幅重叠判断时需要大量的检索操作，快速查找算法能够提高查找效率。本文在建立新旧图幅关联关系、确定重叠判断方法和分割要素的文件存储方式后，提出了一种以新图幅中心点坐标为关键字的二维哈希表索引构建和重叠图幅查找的算法；给出了算法设计思路，并以实际案例验证分析了算法的正确性和有效性。与传统方法相比，该算法具有更高的执行效率，是一种较好的替代算法。

Application of two-dimensional Hash algorithm in geospatial data batch subdivision

After the coordinate transformation of divisive geospatial data, it's necessary to re-divided in the new coordinate system. For the batch data, the search efficiency can be improved when judging the overlap of old and new mapsheets by the fast search algorithm. Firstly, the relationship between the old and the new mapsheets is established and the overlapping judgment method and the file storage mode of the segmented elements are determined. Then, the algorithm of constructing two-dimensional Hashtable with center point coordinates of new mapsheet as key-words and finding overlapped mapsheets is proposed. Finally, the algorithm design idea is realized, and the correctness and effectiveness of the algorithm are verified by computational examples in the paper. Compared with traditional methods, this algorithm has higher execution efficiency and is an ideal alternative algorithm.