ArcEngine+C# TIN相关三维功能模块介绍(四)
功能综合演示
作者:刘志远
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1.简介
本篇打算对TIN的介绍做个小结,把前面将的功能都集中到一个小程序中。除了前面将的功能外,本篇还添加了如下一些功能。只要有数据,这些功能都是可以单独使用的,方便读者根据具体的需要直接参考相应代码。
Ø 由矢量点或线数据,通过核函数密度制图方法生成栅格数据(类DEM);
Ø 按给定间距,从栅格数据(DEM)中提取矢量等高线数据;
Ø 由栅格数据(DEM)生成TIN模型;
Ø 动态变化DEM、TIN的渲染样式;
Ø 矢量图层叠加到TIN模型;
本文主要对这几个功能进行简单的讲解,希望对接触TIN的朋友有所帮助。具体的实现,可以参看程序中相应的代码。同时,在压缩包中有个简短的“使用说明”,可以通过该程序尝试讲过的功能。
2.核函数密度制度生成“类DEM”
通常情况下,我们通过对高程点数据进行插值操作(如反距离权插值、样条插值、克里金插值等)生成DEM(数字高程模型)栅格数据,生成的栅格数据的像元灰度值即代表对应的高程值。
本文介绍的是密度制图,生成的栅格灰度值代表密度大小,所以这里成为“类DEM”。密度制图有核函数密度制图(Kernal)和简单密度制图(Simple)两种方法,本文用的是Kernal方法。对于二次开发来说,由矢量数据生成栅格数据,不论是DEM也好,还是密度制图,只是调用相应接口的某个方法而已,内部的具体操作都是封装好的,程序员只需根据实际需要进行选择即可。这也体现了面向对象的巨大优势。主要代码如下:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
代码
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/**//// <summary>
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/// 核函数密度制图
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/// </summary>
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/// <param name="pFeatureLayer">进行密度分析的矢量数据图层</param>
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/// <param name="cellSize">输出栅格格网大小</param>
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/// <param name="radius">制图搜索半径</param>
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/// <param name="path">栅格文件保存路径 可以为空,则作为临时数据处理</param>
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/// <returns></returns> 9
public IRaster DensityAnalyst(IFeatureLayer pFeatureLayer, double cellSize, double radius, string path)
10![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
{
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IFeatureClass pFClass01 = pFeatureLayer.FeatureClass;
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IDensityOp pDensityOp = new RasterDensityOpClass();
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IRasterAnalysisEnvironment pEnv = pDensityOp as IRasterAnalysisEnvironment;
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Double double_cellSize = cellSize;
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object object_cellSize = (System.Object)double_cellSize;
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pEnv.SetCellSize(esriRasterEnvSettingEnum.esriRasterEnvValue, ref object_cellSize);
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IFeatureClassDescriptor pFDescr = new FeatureClassDescriptorClass();
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pFDescr.Create(pFClass01, null, "NONE");
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System.Double double_radio_dis = radius;
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object object_radio_dis = (System.Object)double_radio_dis;
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object Missing = Type.Missing;
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//调用核函数密度制图方法生成栅格数据
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IRaster pRasOut1 = pDensityOp.KernelDensity(pFDescr as IGeoDataset, ref object_radio_dis, ref Missing) as IRaster;
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//栅格值重计算,将栅格值缩放到合理范围(主要是纠正由于坐标系统不同而造成的数据夸张变大)
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//如数据的坐标系等没有问题则可以不用重计算
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IMapAlgebraOp pMapAlgebraOp = (IMapAlgebraOp)new RasterMapAlgebraOp();
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IRasterAnalysisEnvironment pRasAnaEnv = (IRasterAnalysisEnvironment)pMapAlgebraOp;
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pMapAlgebraOp.BindRaster(pRasOut1 as IGeoDataset, "R");
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string expresion = "[R] * 0.0000915"; //坐标系统转换参数
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IRaster pRasOut = pMapAlgebraOp.Execute(expresion) as IRaster;
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//输出栅格数据,否则存放为临时数据
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if (path != "")
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{
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string foldPath = System.IO.Path.GetDirectoryName(path);
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string rasterName = System.IO.Path.GetFileName(path);
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try
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{
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IRasterBandCollection bandCollection = (IRasterBandCollection)pRasOut;
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IRasterDataset dataset = bandCollection.Item(0).RasterDataset;
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ITemporaryDataset temp = (ITemporaryDataset)dataset;
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RasterWorkspaceFactory factory = new RasterWorkspaceFactory();
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IWorkspace workSpace = factory.OpenFromFile(foldPath, 0);
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temp.MakePermanentAs(rasterName, workSpace, "IMAGINE Image");
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}
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catch
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{
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return pRasOut;
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}
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}
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return pRasOut;
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}
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3.DEM提取等高线
根据指定间隔,从DEM栅格数据中提取等高线数据。主要用了ISurfaceOp接口下的Contour()方法。主要代码如下:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
代码
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ISurfaceOp pSurfaceOP = new RasterSurfaceOpClass();
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IFeatureLayer pFL = new FeatureLayerClass();
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object Missing = Type.Missing;
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pFL.FeatureClass = pSurfaceOP.Contour(iRaster as IGeoDataset, interval, ref Missing) as IFeatureClass;
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4.由DEM生成TIN
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代码
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//***************生成TIN模型*********************************************
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IGeoDataset pGeoData = iRaster as IGeoDataset;
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IEnvelope pExtent = pGeoData.Extent;
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IRasterBandCollection pRasBC = iRaster as IRasterBandCollection;
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IRasterBand pRasBand = pRasBC.Item(0);
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IRawPixels pRawPixels = pRasBand as IRawPixels;
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IRasterProps pProps = pRawPixels as IRasterProps;
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int iWid = pProps.Width;
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int iHei = pProps.Height;
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double w = iWid / 1000.0f;
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double h = iHei / 1000.0f;
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IPnt pBlockSize = new DblPntClass();
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bool IterationFlag;
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if (w < 1 && h < 1) //横纵都小于1000个像素
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{
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pBlockSize.X = iWid;
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pBlockSize.Y = iHei;
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IterationFlag = false;
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}
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else
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{
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pBlockSize.X = 1001.0f;
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pBlockSize.Y = 1001.0f;
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IterationFlag = true;
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}
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double cellsize = 0.0f; //栅格大小
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IPnt pPnt1 = pProps.MeanCellSize(); //栅格平均大小
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cellsize = pPnt1.X;
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ITinEdit pTinEdit = new TinClass() as ITinEdit;
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pTinEdit.InitNew(pExtent);
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ISpatialReference pSpatial = pGeoData.SpatialReference;
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pExtent.SpatialReference = pSpatial;
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IPnt pOrigin = new DblPntClass();
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IPnt pPixelBlockOrigin = new DblPntClass();
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//栅格左上角像素中心坐标
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double bX = pBlockSize.X;
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double bY = pBlockSize.Y;
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pBlockSize.SetCoords(bX, bY);
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IPixelBlock pPixelBlock = pRawPixels.CreatePixelBlock(pBlockSize);
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object nodata = pProps.NoDataValue; //无值标记
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ITinAdvanced2 pTinNodeCount = pTinEdit as ITinAdvanced2;
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int nodeCount = pTinNodeCount.NodeCount;
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object vtMissing = Type.Missing;
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object vPixels = null; //格子
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if (IterationFlag) //当为一个处理单元格子时
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{
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pPixelBlockOrigin.SetCoords(0.0f, 0.0f);
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pRawPixels.Read(pPixelBlockOrigin, pPixelBlock);
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vPixels = pPixelBlock.get_SafeArray(0);
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double xMin = pExtent.XMin;
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double yMax = pExtent.YMax;
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pOrigin.X = xMin + cellsize / 2;
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pOrigin.Y = yMax - cellsize / 2;
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bX = pOrigin.X;
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bY = pOrigin.Y;
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pTinEdit.AddFromPixelBlock(bX, bY, cellsize, cellsize, nodata, vPixels, m_zTolerance, ref vtMissing, out vtMissing);
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}
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else //当有多个处理单元格时,依次循环处理每个单元格
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{
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int i = 0, j = 0, count = 0;
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int FirstGoNodeCount = 0;
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while (nodeCount != FirstGoNodeCount)
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{
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count++;
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nodeCount = pTinNodeCount.NodeCount;
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//依次循环处理
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for (i = 0; i < h + 1; i++)
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{
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for (j = 0; j < w + 1; j++)
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{
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double bX1, bY1, xMin1, yMax1;
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bX1 = pBlockSize.X;
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bY1 = pBlockSize.Y;
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pPixelBlockOrigin.SetCoords(j * bX1, i * bY1);
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pRawPixels.Read(pPixelBlockOrigin, pPixelBlock);
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vPixels = pPixelBlock.get_SafeArray(0);
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xMin1 = pExtent.XMin;
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yMax1 = pExtent.YMax;
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bX1 = pBlockSize.X;
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bY1 = pBlockSize.Y;
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pOrigin.X = xMin1 + j * bX1 * cellsize + cellsize / 2.0f;
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pOrigin.Y = yMax1 + i * bY1 * cellsize - cellsize / 2.0f;
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bX1 = pOrigin.X;
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bY1 = pOrigin.Y;
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pTinEdit.AddFromPixelBlock(bX1, bY1, cellsize, cellsize, nodata, vPixels, m_zTolerance, ref vtMissing, out vtMissing);
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FirstGoNodeCount = pTinNodeCount.NodeCount;
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}
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}
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}
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}
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//保存TIN文件
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pTinEdit.SaveAs(tinFileName, ref vtMissing);
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pTinEdit.StopEditing(true);
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5.动态变化DEM、TIN的渲染样式
动态变化DEM、TIN的渲染样式其实是根据用户的设定重新生成对应的渲染样式而已,这里就不贴代码了,具体的可以参考程序。
6.矢量图层叠加到TIN模型
矢量图层叠加到TIN模型,其实是改变图层的属性,将图层中对应的ILayerExtensions接口变为I3DProperties接口,然后将I3DProperties. BaseSurface属性设为TIN图层表面数据。具体代码如下:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
代码
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/**//// <summary>
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/// 将矢量图层叠加到TIN模型上
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/// </summary>
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/// <param name="pLayer">要叠加的图层</param>
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/// <param name="pSceneControl">三维控件</param> 6
public void setLayerToTIN(ILayer pLayer, AxSceneControl pSceneControl)
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{
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I3DProperties p3DProperties;
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p3DProperties = get3DProps(pLayer);
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p3DProperties.BaseOption = esriBaseOption.esriBaseSurface;
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ISurface pSurface = getTinlayer(pSceneControl).Dataset as ISurface;
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p3DProperties.BaseSurface = pSurface;
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p3DProperties.Apply3DProperties(pLayer);
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}
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/**//// <summary>
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/// 恢复到平常样式
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/// </summary>
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/// <param name="pLayer"></param>
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/// <param name="pSceneControl"></param>21
public void setLayerOutTIN(ILayer pLayer, AxSceneControl pSceneControl)
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{
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I3DProperties p3DProperties;
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p3DProperties = get3DProps(pLayer);
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p3DProperties.BaseOption = esriBaseOption.esriBaseExpression;
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p3DProperties.Apply3DProperties(pLayer);
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}
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/**//// <summary>
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/// 获得普通要素图层的3D属性
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/// </summary>
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/// <param name="pLayer">普通矢量图层</param>
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/// <returns></returns>34
public I3DProperties get3DProps(ILayer pLayer)
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{
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ILayerExtensions pLayerExts = pLayer as ILayerExtensions;
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if (pLayerExts != null)
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{
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for (int i = 0; i < pLayerExts.ExtensionCount; i++)
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{
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I3DProperties p3DProps = pLayerExts.get_Extension(i) as I3DProperties;
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if (p3DProps != null)
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return p3DProps;
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}
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}
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return null;
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}
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/**//// <summary>
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/// 返回TIN数据图层
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/// </summary>
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/// <param name="pSceneControl">三维控件</param>
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/// <returns></returns>54
public ITinLayer getTinlayer(AxSceneControl pSceneControl)
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{
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ITinLayer pTinlayer = null;
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IScene map = pSceneControl.Scene;
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if (map == null)
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return null;
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for (int i = 0; i < map.LayerCount; i++)
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{
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ILayer lyr = map.get_Layer(i);
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if (lyr is ITinLayer)
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{
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pTinlayer = lyr as ITinLayer;
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break;
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}
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}
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return pTinlayer;
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}
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7.总结
至此,关于TIN的一些介绍就到这告一段落,文中没有阐述清楚的部分可以参看程序中的代码。当然,其中不足之处还请各位留言批评指正。