ArcEngine提取面要素公共边的实现方法

1、前言

很久没写ArcEngine的内容了，正好这次有同志提了一个问题：如何用ArcEngine实现批量提取面要素之间的公共边？捣鼓了半天总算是解决了，下面就来说一说解决思路。

2、ArcMap的实现方法

首先准备一份测试数据，如下图所示：

提取公共边用ArcMap做非常简单，只需要打开Analysis Tools下的Intersect相交工具，将Output Type设置为LINE，运行工具，马上就能得到面要素的公共边。如下图所示：

结果如下图所示：

3、方法一：调用GP提取公共边

既然已经知道了在ArcMap中如何使用Intersect工具来提取公共边，那么我们就可以在ArcEngine中调用GP工具来实现。不过需要注意：ArcEngine代码初始化时需要设置License的权限，代码如下：

using ESRI.ArcGIS.Geoprocessor;
using System;
using System.Windows.Forms;namespace App
{public partial class MainForm : Form{public MainForm(){InitializeComponent();}private void btn_Click(object sender, EventArgs e){// 设置参数ESRI.ArcGIS.AnalysisTools.Intersect tool = new ESRI.ArcGIS.AnalysisTools.Intersect();tool.in_features = @"C:\Users\Virtual\Desktop\data\面.shp";tool.output_type = "LINE";tool.out_feature_class = @"C:\Users\Virtual\Desktop\data\线.shp";// 执行GPGeoprocessor gp = new Geoprocessor();gp.OverwriteOutput = true;gp.Execute(tool, null);}}
}

运行结果如下图所示：

4、方法二：根据空间关系及拓扑工具提取公共边

获取两个面之间的公共边分以下两步：

1. 利用IRelationalOperator判断两个Polygon是否为Touches关系？
2. 如果是Touches关系，利用ITopologicalOperator的Intersect方法提取相交部分即可

代码如下：

using ESRI.ArcGIS.DataSourcesFile;
using ESRI.ArcGIS.Geodatabase;
using ESRI.ArcGIS.Geometry;
using System;
using System.Collections.Generic;
using System.Windows.Forms;namespace App
{public partial class MainForm : Form{public MainForm(){InitializeComponent();}private void btn_Click(object sender, EventArgs e){IFeatureClass pFeatureClass = GetFeatureClass(@"C:\Users\Virtual\Desktop\data\面.shp");List<IPolygon> polygons = GetPolygonList(pFeatureClass);List<IPolyline> polylines = GetPolylineList(polygons);CreateFeatureClass(polylines, @"C:\Users\Virtual\Desktop\data\线.shp");}// 获取要素类private IFeatureClass GetFeatureClass(string filePath){IWorkspaceFactory pWorkspaceFactory = new ShapefileWorkspaceFactory();IWorkspaceFactoryLockControl pWorkspaceFactoryLockControl = pWorkspaceFactory as IWorkspaceFactoryLockControl;if (pWorkspaceFactoryLockControl.SchemaLockingEnabled){pWorkspaceFactoryLockControl.DisableSchemaLocking();}IWorkspace pWorkspace = pWorkspaceFactory.OpenFromFile(System.IO.Path.GetDirectoryName(filePath), 0);IFeatureWorkspace pFeatureWorkspace = pWorkspace as IFeatureWorkspace;IFeatureClass pFeatureClass = pFeatureWorkspace.OpenFeatureClass(System.IO.Path.GetFileName(filePath));return pFeatureClass;}// 获取Polygon集合private List<IPolygon> GetPolygonList(IFeatureClass pFeatureClass){IFeatureCursor pFeatureCursor = pFeatureClass.Search(null, true);IFeature pFeature = pFeatureCursor.NextFeature();if (pFeature == null){return null;}// 遍历游标List<IPolygon> list = new List<IPolygon>();while (pFeature != null){list.Add(pFeature.ShapeCopy as IPolygon);pFeature = pFeatureCursor.NextFeature();}// 返回System.Runtime.InteropServices.Marshal.ReleaseComObject(pFeatureCursor);return list;}// 获取Polyline集合private List<IPolyline> GetPolylineList(List<IPolygon> polygons){List<IPolyline> list = new List<IPolyline>();for (int i = 0; i < polygons.Count; i++){for (int j = 0; j < polygons.Count; j++){if (i == j){continue;}IRelationalOperator pRelationalOperator = polygons[i] as IRelationalOperator;if (pRelationalOperator.Touches(polygons[j])){ITopologicalOperator pTopologicalOperator = polygons[i] as ITopologicalOperator;IGeometry pIntersectGeometry = pTopologicalOperator.Intersect(polygons[j], esriGeometryDimension.esriGeometry1Dimension);list.Add(pIntersectGeometry as IPolyline);}}}return list;}// 创建要素类private IFeatureClass CreateFeatureClass(List<IPolyline> polylines, string filePath){// 设置空间参考IGeometryDef pGeometryDef = new GeometryDef();IGeometryDefEdit pGeometryDefEdit = pGeometryDef as IGeometryDefEdit;pGeometryDefEdit.GeometryType_2 = esriGeometryType.esriGeometryPolyline;pGeometryDefEdit.HasM_2 = false;pGeometryDefEdit.HasZ_2 = false;pGeometryDefEdit.SpatialReference_2 = axMapControl1.SpatialReference;// 字段集合IFields pFields = new Fields();IFieldsEdit pFieldsEdit = pFields as IFieldsEdit;// ShapeIField pField = new Field();IFieldEdit pFieldEdit = pField as IFieldEdit;pFieldEdit.Type_2 = esriFieldType.esriFieldTypeGeometry;pFieldEdit.GeometryDef_2 = pGeometryDef;pFieldEdit.AliasName_2 = "Shape";pFieldEdit.Name_2 = "Shape";pFieldEdit.IsNullable_2 = false;pFieldEdit.Required_2 = true;pFieldsEdit.AddField(pField);// 创建要素类IWorkspaceFactory pWorkspaceFactory = new ShapefileWorkspaceFactory();IWorkspace pWorkspace = pWorkspaceFactory.OpenFromFile(System.IO.Path.GetDirectoryName(filePath), 0);IFeatureWorkspace pFeatureWorkspace = pWorkspace as IFeatureWorkspace;IFeatureClass pFeatureClass = pFeatureWorkspace.CreateFeatureClass(System.IO.Path.GetFileName(filePath), pFields, null, null, esriFeatureType.esriFTSimple, "Shape", "");// 要素游标IFeatureBuffer pFeatureBuffer = pFeatureClass.CreateFeatureBuffer();IFeatureCursor pFeatureCursor = pFeatureClass.Insert(true);for (int i = 0; i < polylines.Count; i++){pFeatureBuffer.Shape = polylines[i];pFeatureCursor.InsertFeature(pFeatureBuffer);}pFeatureCursor.Flush();// 返回System.Runtime.InteropServices.Marshal.ReleaseComObject(pFeatureBuffer);System.Runtime.InteropServices.Marshal.ReleaseComObject(pFeatureCursor);return pFeatureClass;}}
}

运行结果如下图所示：

5、结语

本文主要介绍了ArcEngine中提取公共边的实现方法。其实对于第二种方法，即：利用空间关系和拓扑工具提取公共边，我个人是不太满意的，因为这是纯粹的暴力解法，数据量一旦较多，效率肯定是个大问题。可惜不知道ESRI是怎么实现的，有了解的同志也可以讲讲这个问题最优的解决方法是什么。