转自原文

两个星期以来一直与栅格数据打交道，对AO的栅格部分应该有了一定的理解，下面是自己的一点体会，希望高手指教：－）

1、栅格数据的存储类型

栅格数据一般可以存储为ESRI GRID（由一系列文件组成），TIFF格式（包括一个TIF文件和一个AUX文件），IMAGINE Image格式 在AE中一般调用ISaveAs接口来保存栅格数据

2、栅格数据集和栅格编目的区别

一个栅格数据集由一个或者多个波段（RasterBand）的数据组成，一个波段就是一个数据矩阵。对于格网数据（DEM数据）和单波段的影像数据，表现为仅仅只有一个波段数据的栅格数据集，而对于多光谱影像数据则表现为具有多个波段的栅格数据集

栅格编目（RasterCatalog）用于显示某个研究区域内各种相邻的栅格数据，这些相邻的栅格数据没有经过拼接处理合成一副大的影像图

3、IRasterWorkspaceEx与IRasterWorkspace ,IRsterWorkspace2的区别

1).IRasteWorkspaceEx接口主要是用来读取GeoDatabase中的栅格数据集和栅格编目

2) . IRasterWorkspace ,IRsterWorkspace2主要是用来读取以文件格式存储在本地的栅格数据

4、加载栅格数据（以存储在本地的栅格数据文件为例）

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if (rastDataset == null){Console.WriteLine("Could not open the raster dataset.");return;}

5、如何读取栅格数据的属性和遍历栅格数据

栅格数据的属性包括栅格大小，行数，列数，投影信息，栅格范围等等，见下面代码

（假设当前加载的栅格文件栅格值存储方式为：UShort类型）

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());}}

6、如何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();try{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……………………..}Catch(Exception ex){Throw new Argumention(ex.Message);}

 

2)．IExtractionOp接口(调用此接口前，应该先检查空间许可)

IExtractionOp extraction = new RasterExtractionOpClass();try{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");}}catch (Exception ex){MessageBox..Show(Ex.message);}

 

7．栅格数据重采样

栅格数据的重采样主要基于三种方法：最邻近采样（NEAREST），双线性

ILINEAR）和三次卷积采样（CUBIC）。

（1）.最邻近采样：它用输入栅格数据中最临近栅格值作为输出值。因此，在重采

样后的输出栅格中的每个栅格值, 都是输入栅格数据中真实存在而未加任何改变的值。这种方法简单易用，计算量小，重采样的速度最快。

（2）.双线性采样：此重采样法取待采样点（x，y）点周围四个邻点，在y方向（或X方向）内插两次，再在x方向（或y方向）内插一次，得到（x，y）点的栅格值。

（3）.三次卷积采样：这是进一步提高内插精度的一种方法。它的基本思想是增加邻点来获

得最佳插值函数。取待计算点周围相邻的16个点，与双线性采样类似，可先在某一方向上内插，如先在x方向上，每四个值依次内插四次，再根据四次的计算结果在y方上内插，最终得到内插结果

代码示例：采用双线性采样

IRasterGeometryProc rasterGeometryProc = new RasterGeometryProcClass();rasterGeometryProc.Resample(rstResamplingTypes.RSP_CubicConvolution, newCellSize, clipRaster);public static IRasterLayer SetViewShedRenderer(IRaster pInRaster,string sField,string sPath){IRasterDescriptor pRD = new RasterDescriptorClass();pRD.Create(pInRaster, new QueryFilterClass(), sField);IReclassOp pReclassOp = new RasterReclassOpClass();IGeoDataset pGeodataset=pInRaster as IGeoDataset;IRasterAnalysisEnvironment pEnv = pReclassOp as IRasterAnalysisEnvironment;IWorkspaceFactory pWSF=new RasterWorkspaceFactoryClass();IWorkspace pWS = pWSF.OpenFromFile(sPath, 0);pEnv.OutWorkspace = pWS;object objSnap = null;object objExtent = pGeodataset.Extent;pEnv.SetExtent(esriRasterEnvSettingEnum.esriRasterEnvValue, ref objExtent, ref objSnap);pEnv.OutSpatialReference = pGeodataset.SpatialReference;IRasterLayer pRLayer = new RasterLayerClass();IRasterBandCollection pRsBandCol = pGeodataset as IRasterBandCollection;IRasterBand pRasterBand = pRsBandCol.Item(0);pRasterBand.ComputeStatsAndHist();IRasterStatistics pRasterStatistic = pRasterBand.Statistics;double dMaxValue = pRasterStatistic.Maximum ;double dMinValue = pRasterStatistic.Minimum ;INumberRemap pNumRemap = new NumberRemapClass();pNumRemap.MapRange(dMinValue, 0, 0);pNumRemap.MapRange(0, dMaxValue, 1);IRemap pRemap = pNumRemap as IRemap;IRaster pOutRaster = pReclassOp.ReclassByRemap(pGeodataset, pRemap, false) as IRaster ;pRLayer.CreateFromRaster(pOutRaster);return pRLayer;}

栅格图层和矢量图层的属性表浏览

if (pLyr is IFeatureLayer){DataTable pTable = new DataTable();IFeatureLayer pFealyr = pLyr as IFeatureLayer;IFeatureClass pFCls = pFealyr.FeatureClass;string shape = "";if (pFCls.ShapeType == esriGeometryType.esriGeometryPoint)shape = "Point";else if (pFCls.ShapeType == esriGeometryType.esriGeometryPolyline)shape = "Polyline";else if (pFCls.ShapeType == esriGeometryType.esriGeometryPolygon)shape = "Polygon";for (int i = 0; i < pFCls.Fields.FieldCount; i++){pTable.Columns.Add(pFCls.Fields.get_Field(i).Name);}IFeatureCursor pCursor = pFCls.Search(null, false);int ishape = pFCls.Fields.FindField("Shape");IFeature pFea = pCursor.NextFeature();while (pFea != null){DataRow pRow = pTable.NewRow();for (int i = 0; i < pFCls.Fields.FieldCount; i++){if (i == ishape){pRow[i] = shape;continue;}pRow[i] = pFea.get_Value(i).ToString();}pTable.Rows.Add(pRow);pFea = pCursor.NextFeature();}dataGridView1.DataSource = pTable;}else if (pLyr is IRasterLayer){IRasterLayer pRlyr = pLyr as IRasterLayer;IRaster pRaster = pRlyr.Raster;IRasterProps pProp = pRaster as IRasterProps;pProp.PixelType = rstPixelType.PT_LONG;if (pProp.PixelType == rstPixelType.PT_LONG){IRasterBandCollection pBcol = pRaster as IRasterBandCollection;IRasterBand pBand = pBcol.Item(0);ITable pRTable = pBand.AttributeTable;DataTable pTable = new DataTable();for (int i = 0; i < pRTable.Fields.FieldCount; i++)pTable.Columns.Add(pRTable.Fields.get_Field(i).Name);ICursor pCursor= pRTable.Search(null, false);IRow pRrow= pCursor.NextRow();while (pRrow != null){DataRow pRow = pTable.NewRow();for (int i =0 ;i

 

创建栅格数据集

CreateRasterDataset C#public IRasterDataset CreateFileRasterDataset(string directoryName, string fileName){// This function creates a new img file in the given workspace// and then assigns pixel valuestry{IRasterDataset rasterDataset = null;IPoint originPoint = new PointClass();originPoint.PutCoords(0, 0);// Create the datasetIRasterWorkspace2 rasterWorkspace2 = null;rasterWorkspace2 = CreateRasterWorkspace(directoryName);rasterDataset = rasterWorkspace2.CreateRasterDataset(fileName, "IMAGINE Image", originPoint, 200, 100, 1, 1, 1, rstPixelType.PT_UCHAR, new UnknownCoordinateSystemClass(), true);IRawPixels rawPixels = null;IPixelBlock3 pixelBlock3 = null;IPnt pixelBlockOrigin = null;IPnt pixelBlockSize = null;IRasterBandCollection rasterBandCollection;IRasterProps rasterProps;// QI for IRawPixels and IRasterPropsrasterBandCollection = (IRasterBandCollection)rasterDataset;rawPixels = (IRawPixels)rasterBandCollection.Item(0);rasterProps = (IRasterProps)rawPixels;// Create pixelblockpixelBlockOrigin = new DblPntClass();pixelBlockOrigin.SetCoords(0, 0);pixelBlockSize = new DblPntClass();pixelBlockSize.SetCoords(rasterProps.Width, rasterProps.Height);pixelBlock3 = (IPixelBlock3)rawPixels.CreatePixelBlock(pixelBlockSize);// Read pixelblockrawPixels.Read(pixelBlockOrigin, (IPixelBlock)pixelBlock3);// Get pixeldata arraySystem.Object[,] pixelData;pixelData = (System.Object[,])pixelBlock3.get_PixelDataByRef(0);// Loop through all the pixels and assign valuefor (int i = 0; i < rasterProps.Width; i++)for (int j = 0; j < rasterProps.Height; j++)pixelData[i, j] = (i * j) % 255;// Write the pixeldata backSystem.Object cachePointer;cachePointer = rawPixels.AcquireCache();rawPixels.Write(pixelBlockOrigin, (IPixelBlock)pixelBlock3);rawPixels.ReturnCache(cachePointer);// Return raster datasetreturn rasterDataset;}catch (Exception ex){System.Diagnostics.Debug.WriteLine(ex.Message);return null;}}public IRasterWorkspace2 CreateRasterWorkspace(string pathName){// Create RasterWorkspaceIWorkspaceFactory workspaceFactory = new RasterWorkspaceFactoryClass();return workspaceFactory.OpenFromFile(pathName, 0) as IRasterWorkspace2;}public IRasterDataset tin2raster(string tempBathyTIN,string geoPath, string gridName){string tinFolder = System.IO.Path.GetDirectoryName(tempBathyTIN);string tinName = System.IO.Path.GetFileName(tempBathyTIN);IRasterDataset rasterDataset = new RasterDatasetClass();try{string rasterPath = System.IO.Path.GetDirectoryName(geoPath);IWorkspaceFactory TinWF = new TinWorkspaceFactory();ITinWorkspace TinWK = TinWF.OpenFromFile(tinFolder,0)as ITinWorkspace;ITinAdvanced2 tinAd = TinWK.OpenTin(tinName) as ITinAdvanced2;IEnvelope extent = tinAd.Extent;IPoint origin = extent.LowerLeft;origin.X = origin.X - (5 * 0.5);origin.Y = origin.Y - (5 * 0.5);int nCol = (int)Math.Round(extent.Width / 5) + 1;int nRow = (int)Math.Round(extent.Height / 5) +1;ISpatialReference2 spatialRef = (ISpatialReference2)extent.SpatialReference;IWorkspaceFactory rasterWF = new RasterWorkspaceFactoryClass();IRasterWorkspace2 workSpace = (IRasterWorkspace2)rasterWF.OpenFromFile(rasterPath,0);rasterDataset = workSpace.CreateRasterDataset(gridName, "GRID", origin,nCol,nRow,5,5,1,ESRI.ArcGIS.Geodatabase.rstPixelType.PT_FLOAT, spatialRef,true);IRasterBandCollection bandColl = (IRasterBandCollection) rasterDataset;IRasterBand rasterBand = bandColl.Item(0);IRawPixels rawPixels = (IRawPixels)rasterBand;IPnt blockSize = new DblPntClass();blockSize.X = nCol;blockSize.Y = nRow;IPixelBlock3 pixelBlock = (IPixelBlock3)rawPixels.CreatePixelBlock(blockSize);ITinSurface tinSurface = (ITinSurface)tinAd;IRasterProps rasterProps = (IRasterProps)rawPixels;object nodataFloat;//long nodataInt;object val = pixelBlock.get_PixelDataByRef(0);MessageBox.Show(val.ToString());double cellsize = 5;origin.X = origin.X + (5 * 0.5);origin.Y = origin.Y + (5 * nRow) - (5 * 0.5);nodataFloat = Convert.ToDouble(rasterProps.NoDataValue.ToString());tinSurface.QueryPixelBlock(origin.X,origin.Y,cellsize,cellsize,esriRasterizationType.esriElevationAsRaster,nodataFloat,val);IPnt offset = new DblPntClass();offset.X = 0;offset.Y = 0;rawPixels.Write(offset,pixelBlock as IPixelBlock);}catch(Exception ex){MessageBox.Show(ex.ToString());}return rasterDataset;}