ArcEngine栅格影像开发.doc

1栅格数据处理常用到的接口：IRasterIRatserLayerIRasterDatasetIInterpolationOp IGeoDatasetIPixelBlock2 IPnt IRawPixels(read)IRaster(read)2. 加载栅格数据(1) 直接用IRasterLayer接口打开一个栅格文件并加载到地图控件IRasterLayer rasterLayer = new RasterLayerClass();rasterLayer.CreateFromFilePath(fileName); / fileName指存本地的栅格文件路径axMapControl1.AddLayer(rasterLayer, 0);(2) 用IRasterDataset接口打开一个栅格数据集IWorkspaceFactory workspaceFactory = new RasterWorkspaceFactory();IWorkspace workspace;workspace = workspaceFactory.OpenFromFile(inPath, 0); /inPath栅格数据存储路径if (workspace = null)Console.WriteLine(Could not open the workspace.);return;IRasterWorkspace rastWork = (IRasterWorkspace)workspace;IRasterDataset rastDataset;rastDataset= rastWork.OpenRasterDataset(inName);/inName栅格文件名3. 读取栅格数据的属性和遍历栅格数据IRasterProps rasterProps = (IRasterProps)clipRaster;int dHeight = rasterProps.Height;/当前栅格数据集的行数int dWidth = rasterProps.Width; /当前栅格数据集的列数double dX = rasterProps.MeanCellSize().X; /栅格的宽度double dY = rasterProps.MeanCellSize().Y; /栅格的高度IEnvelope extent=rasterProps.Extent; /当前栅格数据集的范围rstPixelType pixelType=rasterProps.PixelType; /当前栅格像素类型IPnt pntSize = new PntClass();pntSize.SetCoords(dX, dY);IPixelBlock pixelBlock = clipRaster.CreatePixelBlock(pntSize);IPnt pnt = new PntClass();for (int i = 0; i dHeight; i+)for (int j = 0; j dWidth; j+)pnt.SetCoords(i, j);clipRaster.Read(pnt, pixelBlock);if (pixelBlock != null)object obj = pixelBlock.GetVal(0, 0, 0);MessageBox.Show( Convert.ToUInt32(obj).ToString();4. 提取指定的范围的栅格数据提取指定范围内的栅格数据通常用两种方法IRasterLayerExport(esriCarto), IExtractionOp, IExtractionOp2 (esriSpatialAnalyst)，IRasterLayerExport接口提供的栅格数据提取功能有限，只能以矩形范围作为提取范围，而IExtractionOp接口提供了多边形，圆，属性，矩形等几种形式作为提取栅格数据.(1).IRasterLayerExport接口IRasterLayerExport rLayerExport = new RasterLayerExportClass();rLayerExport.RasterLayer = rasterLayer;/ rasterLayer指当前加载的栅格图层rLayerExport.Extent = clipExtent;/clipExtent指提取栅格数据的范围if (proSpatialRef != null)rLayerExport.SpatialReference = proSpatialRef;/ proSpatialRef当前栅格数据的投影信息IWorkspaceFactory pWF = new RasterWorkspaceFactoryClass();IWorkspace pRasterWorkspace = pWF.OpenFromFile(_folder, 0);/ _folder指栅格文件保存路径IRasterDataset outGeoDataset = rLayerExport.Export(pRasterWorkspace, code, strRasterType);/调用ISaveAs接口将导出的数据集保存.(2) IExtractionOp接口(调用此接口前，应该先检查空间许可)IExtractionOp extraction = new RasterExtractionOpClass();IGeoDataset geoDataset = extraction.Rectangle(IGeoDataset)clipRaster, clipExtent, true);IRaster raster = geoDataset as IRaster;if (raster != null)IWorkspaceFactory WF = new RasterWorkspaceFactoryClass();IWorkspace rasterWorkspace = WF.OpenFromFile(_folder, 0);ISaveAs saveAs = (ISaveAs)raster;saveAs.SaveAs(“Result.tif”, rasterWorkspace, TIFF);5. 创建栅格数据需要用到的接口有：IWorkspaceFactory, IRasterWorkspace2, IPoint, IRasterDataset, 实例代码如下：IWorkspaceFactory pWSF=new RasterWorkspaceFactoryClass();IRasterWorkspace pRasWS=pWSF.OpenFromFile(pFileName,0);IRasterWorkspace2 pRasWS2=pRasWS as IRasterWorkspace2;IPoint pOrigin=new PointClass();pOrigin.PutCoords(0,0);IRasterDataset pOutDS=pRasWS2.CreateRasterDataset(“test.tif”,”TIFF”,pOrigin,512,512,2,2,3,PT_FLOAT,null,true);6. 创建并设置单元格的值public IRasterDataset CreateRasterDataset2(string pRasterFile)trystring pDir = System.IO.Path.GetDirectoryName(pRasterFile);string pFileName = System.IO.Path.GetFileNameWithoutExtension(pRasterFile);IWorkspaceFactory pWsF = new RasterWorkspaceFactoryClass();IRasterWorkspace2 pRWs = pWsF.OpenFromFile(pDir, 0) as IRasterWorkspace2;/定义数据集投影ISpatialReference pSpatialRef = GetSpatialRef();double XLeftCorner = GetMapLeftX();double YBottomCorner = GetMapBottomY();double YTopCorner = GetMapTopY();double XRightCorner = GetMapRightX();/定义数据集的行列数、像元大小、波段数int pRows = GetRows();int pCols = GetColumns();double xCell = GetCellXSize();double yCell = GetCellYSize();int NumBand = 1;/修正起始点坐标IPoint pOrignPt = new PointClass();double dX = XLeftCorner - xCell / 2;double dY = YBottomCorner + yCell / 2;pOrignPt.PutCoords(dX, dY);/定义栅格数据集为GRID格式IRasterDataset pRDs = pRWs.CreateRasterDataset(pFileName, GRID, pOrignPt, pCols, pRows, xCell, yCell, NumBand, rstPixelType.PT_FLOAT, pSpatialRef, true);IRasterBandCollection pRBandCollection = pRDs as IRasterBandCollection;IRasterBand pRBand = pRBandCollection.Item(0);IRasterProps pRProp = pRBand as IRasterProps;IPnt pBlockSize = new PntClass();IEnvelope pEnvelope = pRProp.Extent;pBlockSize.SetCoords(pEnvelope.Width, pEnvelope.Height);IRasterDataset2 pRDs2 = pRDs as IRasterDataset2;IRaster pRaster = pRDs2.CreateFullRaster();IRaster2 pRaster2 = pRaster as IRaster2;IPixelBlock pixelBlock = pRaster2.CreateCursorEx(pBlockSize).PixelBlock;int w = pixelBlock.Width;int h = pixelBlock.Height;/read the first pixel blockIPnt topleftCorner = new PntClass();topleftCorner.SetCoords(XLeftCorner, YTopCorner);pRaster.Read(topleftCorner, pixelBlock);IPixelBlock3 pixelBlock3 = pixelBlock as IPixelBlock3;System.Array pixels = (System.Array)pixelBlock3.get_PixelData(0);for (int i = 0; i w; i+)for (int j = 0; j h; j+)if(i = j)pixels.SetValue(i*j, i, j); pixelBlock3.set_PixelData(0, (System.Object)pixels);/write the modified pixel block to the raster datasetIRasterEdit rasterEdit = (IRasterEdit)pRaster;rasterEdit.Write(topleftCorner, pixelBlock);/Release rasterEdit explicitly.System.Runtime.InteropServices.Marshal.ReleaseComObject(rasterEdit);return pRDs;catch (Exception ex)System.Diagnostics.Debug.WriteLine(ex.Message);return null;7. 使用多边形裁剪影像Public Function ClipRasterByPolgon(pInGeoDataset As IGeoDataset, pPolygon As IPolygon) As IRaster Dim pRaster As IRaster If TypeOf pInGeoDataset Is IRasterLayer Then Dim pRasterlayer As IRasterLayer Set pRasterlayer = pInGeoDataset Set pRaster = pRasterlayer.Raster ElseIf TypeOf pInGeoDataset Is IRasterDataset Then Dim pRasterDataset As IRasterDataset Set pRasterDataset = pInGeoDataset Set pRaster = pRasterDataset.CreateDefaultRaster ElseIf TypeOf pInGeoDataset Is IRaster Then Set pRaster = pInGeoDataset Else Exit Function End If Dim pInputDataset As IGeoDataset Set pInputDataset = pRaster Dim pExtractionOp As IExtractionOp Set pExtractionOp = New RasterExtractionOp Dim pRasterAnalys