先来看看ITopologicalOperator的成员：截图来自帮助文档：

简要介绍下各个成员的汉语翻译：

1、Boundary，边界，获取一个Geometry的边界；

用法：

  ITopologicalOperator pTopologBoundary = pGeo as ITopologicalOperator;IGeometry pGeometry = pTopologBoundary.Boundary;

（1）多边形Polygon的边界获取的是Polyline

（2）Polyline获得的是IPiontColletion点集；（3）点没有边界

2、Buffer，缓冲区，可以为点、线、面做缓冲区，参数为缓冲区范围的大小，大于0向外做缓冲区，小于0向内做缓冲区；

用法：

 ITopologicalOperator pTopologBoundary = pGeo as ITopologicalOperator;
IGeometry pGeometry = pTopologBoundary.Buffer(2);

3、Clip，叠加裁剪，从源图层中裁剪掉分割图层后的图形；参数类型为IEnvelope类型

用法：

ITopologicalOperator pTopologBoundary = pSourceGeometry as ITopologicalOperator;
pTopologBoundary.Clip(pClipGeometry.Envelope as IEnvelope);

4、Cut，分割，将一个Geometry分割为两部分。

用法：

IGeometry pSourceGeometry = null, pClipGeometry = null;
IGeometry pLeftGeo,pRightGo;
IPolyline pPolyline=null;
ITopologicalOperator pTopologBoundary = pSourceGeometry as ITopologicalOperator;
pTopologBoundary.Cut(pPolyline, out pLeftGeo, out pRightGo);

5、Difference，区别，保留下源图层与操作图层中不同的部分。

用法：

IGeometry pSourceGeometry = null, pDifGeometry = null;
ITopologicalOperator pTopologBoundary = pSourceGeometry as ITopologicalOperator;
IGeometry pResultGeo= pTopologBoundary.Difference(pDifGeometry);

6、Intersect，相交，求两个图层相交，返回IGeometry对象

用法：

ITopologicalOperator pTopological = (pSubFeature.Shape) as ITopologicalOperator;
IGeometry pGeoIntersect=pTopological.Intersect(pFeature.Shape, esriGeometryDimension.esriGeometry2Dimension);

7、IsSimple，是否拓扑闭合

用法：

ITopologicalOperator pTopologBoundary = pSourceGeometry as ITopologicalOperator;
bool bIsSimple = pTopologBoundary.IsSimple;

8、Simplify，使一个Geometry拓扑闭合；

用法：

ITopologicalOperator pTopologBoundary = pSourceGeometry as ITopologicalOperator;
pTopologBoundary.Simplify();

9、Union，使Geometry组合起来

用法：

<pre name="code" class="csharp">IGeometry pSourceGeometry = null, pUnionGeometry = null;
ITopologicalOperator pTopologBoundary = pSourceGeometry as ITopologicalOperator;
IGeometry pUnionGeo=pTopologBoundary.Union(pUnionGeometry);