最近一个师妹在做城市可达性分析的相关研究,在对原始数据处理的时候需要利用点打断线。本人第一时间想到的是ArcToolbox里的在点处分割线这一工具,奈何最终没有实现(PS:也有可能是因为我设置的参数不对~),于是还是考虑利用ArcEngine来做,下面说一下我的解决思路!先来看一种最简单的情况:
这种是最简单的情况,一点与一线相交,打断的时候利用IFeatureEdit接口的Split方法即可分割,代码如下:
private void Split(IFeature pPolylineFeature, IPoint pPoint)
{
IFeatureEdit pFeatureEdit = pPolylineFeature as IFeatureEdit;
pFeatureEdit.Split(pPoint);
}
以上代码即可完成利用一个点对一条线进行打断的功能。但在实际情况下还需要考虑三种情况。
第一:必须要找出与线要素相交的点(PS:不相交当然无法打断)。
第二:与一条线相交的点不一定只有一个,可能有很多个点。
第三:如果有很多的点与一条线相交,这些点中还包括与线要素首尾端点重合的点,那么还必须排除掉这条线的首尾端点。
下面看另一种情况:
在上图中,线段ABC表示一条要素记录,线段CE表示一条要素记录,它们相交于C点,D点为CE上的一点。按照上面的条件,如果用这5个点对线要素进行打断,那么最终的结果应该是AB、BC、CD、DE,实际上就是利用B打断ABC,D打断CE。A、C、E因为是两条线要素的端点,因此不参与打断。整个过程为:遍历点要素,若该点与部分线要素相交,则获取这些线要素。然后遍历这些线要素,如果其端点与点要素相同则跳出循环,否则进行打断。其代码如下:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using ESRI.ArcGIS.Carto;
using ESRI.ArcGIS.Controls;
using ESRI.ArcGIS.DataSourcesFile;
using ESRI.ArcGIS.DataSourcesGDB;
using ESRI.ArcGIS.Display;
using ESRI.ArcGIS.esriSystem;
using ESRI.ArcGIS.Geodatabase;
using ESRI.ArcGIS.Geometry;
using ESRI.ArcGIS.Output;
using ESRI.ArcGIS.SystemUI;
namespace WindowsFormsApplication1
{
public partial class FrmMain : Form
{
public FrmMain()
{
InitializeComponent();
}
// 打断线
private void btnSplit_Click(object sender, EventArgs e)
{
IFeatureClass pPointFeatureClass = GetFeatureClass(@"C:\Users\DSF\Desktop\data\point.shp");
IFeatureClass pPolylineFeatureClass = GetFeatureClass(@"C:\Users\DSF\Desktop\data\line.shp");
SplitByPoints(pPointFeatureClass, pPolylineFeatureClass);
}
// 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.GetFileNameWithoutExtension(filePath));
return pFeatureClass;
}
// 点处分割线
private void SplitByPoints(IFeatureClass pPointFeatureClass, IFeatureClass pPolylineFeatureClass)
{
IFeatureCursor pPointFeatureCursor = pPointFeatureClass.Search(null, true);
IFeature pPointFeature = pPointFeatureCursor.NextFeature();
if (pPointFeature == null)
{
return;
}
// 创建空间查询器
ISpatialFilter pSpatialFilter = new SpatialFilter();
pSpatialFilter.SpatialRel = esriSpatialRelEnum.esriSpatialRelIndexIntersects;
pSpatialFilter.GeometryField = "Shape";
// 遍历点要素
while (pPointFeature != null)
{
pSpatialFilter.Geometry = pPointFeature.ShapeCopy;
// 线要素游标
IFeatureCursor pPolylineFeatureCursor = pPolylineFeatureClass.Search(pSpatialFilter, false);
IFeature pPolylineFeature = pPolylineFeatureCursor.NextFeature();
if (pPolylineFeature == null)
{
continue;
}
// 遍历线要素
while (pPolylineFeature != null)
{
IRelationalOperator pRelationalOperator = pPointFeature.ShapeCopy as IRelationalOperator;
IPolyline pPolyline = pPolylineFeature.ShapeCopy as IPolyline;
if (pRelationalOperator.Equals(pPolyline.FromPoint) || pRelationalOperator.Equals(pPolyline.ToPoint))
{
break;
}
else
{
IFeatureEdit pPolylineFeatureEdit = pPolylineFeature as IFeatureEdit;
pPolylineFeatureEdit.Split(pPointFeature.ShapeCopy);
pPolylineFeature = pPolylineFeatureCursor.NextFeature();
}
}
// 进度+1
Marshal.ReleaseComObject(pPolylineFeatureCursor);
pPointFeature = pPointFeatureCursor.NextFeature();
}
Marshal.ReleaseComObject(pPointFeatureCursor);
}
}
}
最终结果如图所示: