/// 
        /// rectangle/envelop 裁剪线        /// 
        ///         ///         /// 
             public static IPolyline GetClippedPolyline(IPolyline pPolyLine,IEnvelope pEnvelop)        {            ISpatialReferenceFactory spatialReferenceFactory = new SpatialReferenceEnvironmentClass();            IGeographicCoordinateSystem gcsSys = spatialReferenceFactory.CreateGeographicCoordinateSystem((int)esriSRGeoCS3Type.esriSRGeoCS_Xian1980);            pPolyLine.SpatialReference = gcsSys;            pEnvelop.SpatialReference = gcsSys;            ITopologicalOperator2 pTopOper = pPolyLine as ITopologicalOperator2;            IGeometry pGeoafter=new PolylineClass();            pTopOper.QueryClipped(pEnvelop, pGeoafter);            return pGeoafter as IPolyline;        }

 备注：intersect和Clip功能一般使用 ITopologicalOperator实现.

         Clip,Intersect等分析，要求各要素有空间参考SpatialReference，否则会出现System.Runtime.InteropServices.COMException错误

        ITopologicalOperator接口能够直接被Point,Polyline,Polygon等要素实现。但不能被TIN实现。

       即  ITopologicalOperator pTopOper=pTin as ITopologicalOperator 获得的pTopOper是Null

 

/// 
        /// 获取多边形和矿层表面的  相交多边形        /// 
        /// 传入的多边形        /// 矿层表面        /// 
             public static IPolygon GetIntersectedRegion(IPolygon pPolygon,ITinSurface pTinsurface)        {            /*进行Clip和Intersect分析之前,featrue必须设置空间参考,否则出现             *System.Runtime.InteropServices.COMException             */            ISpatialReferenceFactory pSpaRefFactory = new SpatialReferenceEnvironmentClass();            IProjectedCoordinateSystem pcsSys = pSpaRefFactory.CreateProjectedCoordinateSystem((int)esriSRProjCS4Type.esriSRProjCS_Xian1980_3_Degree_GK_Zone_39);            IPolygon resultPolygon = new PolygonClass();                      ITopologicalOperator pTopoOper = pPolygon as ITopologicalOperator;            IPolygon pTinPolygon = GetProjectedPolygonFromTin(pTinsurface);            pPolygon.SpatialReference = pcsSys;            pTinPolygon.SpatialReference = pcsSys;            IGeometry otherGeometry = pTinPolygon as IGeometry;            resultPolygon =pTopoOper.Intersect(otherGeometry, esriGeometryDimension.esriGeometry1Dimension) as IPolygon;            return resultPolygon;        }