AE intersect、clip的实现

        /// <summary>
        /// rectangle/envelop 裁剪线
        /// </summary>
        /// <param name="pPolyLine"></param>
        /// <param name="pEnvelop"></param>
        /// <returns></returns>
        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

     /// <summary>
        /// 获取多边形和矿层表面的  相交多边形
        /// </summary>
        /// <param name="pPolygon">传入的多边形</param>
        /// <param name="pTinsurface">矿层表面</param>
        /// <returns></returns>
        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;
        }