提取坐标，然后在surf中差值建模，得到3D立体图，有助于将等高线可视化(Extraction coordinate)

用AP命令加载改小插件，选择多线段，提取CAD多线段坐标(Use the AP command to load and change the widget, select multiple segments, and extract CAD multi segment coordinates)

vba 和 lisp 的源代码 涉及CAD的多段线坐标提取，面积统计为亩，高程点的内插等一系列功能(The source code of VBA and LISP involves CAD multi line coordinate extraction, area statistics for mu, elevation point interpolation, and a series of functions.)