基于MapGIS高程线文件提取高程数据的方法探讨

Discussion on the method of extracting elevation data based on MapGIS line file analysis

针对再利用MapGIS格式的历史高程数据会遇到提取高程数据难的问题,以及MapGIS向其他GIS无缝转换难的特点,本文基于MapGIS线文件的二进制解析,给出了线文件的存储内容、存放位置、数据结构及读取方法,重点对线文件的属性数据、等值线条数、等值线节点坐标及高程值等内容进行了详细剖析。最后利用程序完成了MapGIS线文件中关键数据块的读取,从源头上实现了高程数据的快速提取,大大提高MapGIS线文件的二次开发利用条件,同时也为其他软件对MapGIS线文件的底层调用提供了借鉴。读取试验结果表明线文件数据块分析的准确性及程序编写的正确性。

Based on the reuse of historical elevation data in MapGIS file,it’s difficult to extract elevation data and seamlessly convert MapGIS to other GIS.A method of studying and analyzing the binary format of MapGIS line file was proposed,especially the key data blocks such as storage content,storage location,data structure and reading method of line file,and the attribute data,number of isolines,node coordinates of isolines and elevation values are analyzed in detail.Finally,the program is used to realize the reading experiment of key data blocks in MapGIS line files,which solves the problem of rapid extraction of elevation data from the source,greatly improves the conditions for secondary development and utilization of MapGIS line files,and also provides a reference for other software to call MapGIS line files.The results of the WL file reading test showed that the accuracy of data block analysis and the correctness of program writing.