However, starting with the simple Cartesian coordinate data, one would require considerable effort to produce a MM3 file.

但是以简单的笛卡尔坐标数据开始，需要相当的努力才能产生MM 3文件。

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In short, vector data take the simplest topological entities — points, lines, and polygons — and anchor them within a 2-d Cartesian coordinate system to describe geographical features.

简言之，矢量数据利用最简单的拓扑实体—点、线和多边形，并在二维笛卡尔坐标系统中固定它们来描述地理特征。

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