首页 > 代码库 > ArcEngine和GDAL读写栅格数据机制对比（二）—— IPixelBlock读写栅格
ArcEngine和GDAL读写栅格数据机制对比（二）—— IPixelBlock读写栅格
以下是设定一个矩形框，用IPixelBlock将256*256瓦片tile拼接成一个整块影像的代码，row1, col1, row2, col2是一个矩形框行列号范围。level是瓦片的金字塔等级。这里的瓦片已经下载完毕，位于domSavePath文件夹下。
1 //选择的Google瓦块的行列号范围 2 int row1, col1, row2, col2; 3 int nTileSize = 256; 4 row1 = topLeft.Row; 5 col1 = topLeft.Col; 6 row2 = bottomRight.Row; 7 col2 = bottomRight.Col; 8 //拼接影像大小 9 int nImgSizeX = (col2 - col1 + 1) * nTileSize;10 int nImgSizeY = (row2 - row1 + 1) * nTileSize;11 12 double leftlon = (((col1 * 20037508.343) * 2.0) / (Math.Pow(2.0, (double)level - 1.0))) - 20037508.343;13 double toplat = 20037508.343 - (((row1 * 20037508.343) * 2.0) / (Math.Pow(2.0, (double)level - 1.0)));14 double pixel = 40075016.686 / (nTileSize * Math.Pow(2.0, (double)level - 1.0));15 //拼接图像的左上角点，WebMecator投影16 IPoint origin = new PointClass();17 origin.PutCoords(leftlon, toplat);18 //创建拼接图像19 IRasterDataset mergeRasterDs = CreateRasterDataset(domSavePath, "Full.tif", origin, nImgSizeX, nImgSizeY, pixel, pixel, 3);20 21 for (int ii = row1; ii <= row2; ii++)22 {23 for (int jj = col1; jj <= col2; jj++)24 {25 //瓦片的名称26 string tileName = ii.ToString().PadLeft(8, ‘0‘) + "_" + jj.ToString().PadLeft(8, ‘0‘) + "." + _fileEndExtent;27 string FilePath = domSavePath + @"\" + tileName;28 if (!File.Exists(FilePath))29 {30 continue;31 }32 //读取瓦片数据集33 IRasterDataset tileRasterDs = OpenFileRasterDataset(domSavePath, tileName);34 IRasterDataset2 tileRasterDs2 = tileRasterDs as IRasterDataset2;35 IRaster tileRaster = tileRasterDs2.CreateFullRaster();36 //设置瓦片像素快大小37 IPnt tileBlockSize = new PntClass();38 tileBlockSize.SetCoords(256, 256);39 IPixelBlock3 readPixelblock = tileRaster.CreatePixelBlock(tileBlockSize) as IPixelBlock3;40 //瓦块所在的左上角点41 IPnt tileTopleftCorner = new PntClass();42 tileTopleftCorner.SetCoords(0, 0);43 tileRaster.Read(tileTopleftCorner, readPixelblock as IPixelBlock);44 45 //If you need to set NoData for some of the pixels, you need to set it on band 46 //to get the raster band.47 //IRasterBandCollection rasterBands = (IRasterBandCollection)rasterDataset;48 //IRasterBand rasterBand;49 //IRasterProps rasterProps;50 //rasterBand = rasterBands.Item(0);51 //rasterProps = (IRasterProps)rasterBand;52 //Set NoData if necessary. For a multiband image, a NoData value needs to be set for each band.53 //rasterProps.NoDataValue = http://www.mamicode.com/255;>54 55 //从数据集中读取IRaster56 IRasterDataset2 mergeRasterDs2 = mergeRasterDs as IRasterDataset2;57 IRaster mergeRaster = mergeRasterDs2.CreateFullRaster();58 59 //Create a pixel block using the weight and height of the raster dataset. 60 //If the raster dataset is large, a smaller pixel block should be used. 61 //Refer to the topic "How to access pixel data using a raster cursor".62 IPnt blocksize2 = new PntClass();63 blocksize2.SetCoords(256, 256);64 IPixelBlock3 writePixelblock = mergeRaster.CreatePixelBlock(tileBlockSize) as IPixelBlock3;65 66 System.Array pixelsTarget;67 System.Array pixelsOrigin;//瓦块的像素坐标68 for (int iplane = 0; iplane < 3; iplane++)69 {70 pixelsOrigin = (System.Array)readPixelblock.get_PixelData(iplane);71 pixelsTarget = (System.Array)writePixelblock.get_PixelData(iplane);72 for (int i = 0; i < 256; i++)73 {74 for (int j = 0; j < 256; j++)75 {76 object obj = pixelsOrigin.GetValue(i, j);77 pixelsTarget.SetValue(obj, i, j);78 }79 }80 writePixelblock.set_PixelData(iplane, (System.Array)pixelsOrigin);81 }82 //瓦块偏移左上角的像素值83 int nOffsetX = (jj - col1) * nTileSize;84 int nOffsetY = (ii - row1) * nTileSize;85 //定义pixel block左上角点坐标，执行写入.86 IPnt upperLeft = new PntClass();87 upperLeft.SetCoords(nOffsetX, nOffsetY);88 89 //写入拼接影像中90 IRasterEdit mergeRasterEdit = (IRasterEdit)mergeRaster;91 mergeRasterEdit.Write(upperLeft, (IPixelBlock)writePixelblock);92 93 //释放mergeRasterEdit引用.94 System.Runtime.InteropServices.Marshal.ReleaseComObject(mergeRasterEdit);95 }96 }调用的CreateRasterDataset方法的代码如下：
1 public static IRasterDataset CreateRasterDataset(string path, string fileName, IPoint origin, int width, int height, double xCell, double yCell, int NumBand) 2 { 3 try 4 { 5 IRasterWorkspace2 rasterWs = OpenRasterWorkspace(path); 6 //定义空间参考 7 string prj = "PROJCS[\"Popular Visualisation CRS / Mercator\",GEOGCS[\"Popular Visualisation CRS\",DATUM[\"Popular_Visualisation_Datum\",SPHEROID[\"Popular_Visualisation_Sphere\",6378137.0,0.0]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]],PROJECTION[\"Mercator_1SP\"],PARAMETER[\"false_easting\",0.0],PARAMETER[\"false_northing\",0.0],PARAMETER[\"central_meridian\",0.0],PARAMETER[\"scale_factor\",1.0],UNIT[\"Meter\",1.0]]"; 8 9 ISpatialReference sr = CreateWebMector();10 if (sr == null)11 {12 sr = new UnknownCoordinateSystemClass();13 }14 IRasterDataset rasterDataset = null;15 if (!File.Exists(string.Format(@"{0}\{1}", path, fileName)))16 {17 //创建TIFF格式栅格数据.18 rasterDataset = rasterWs.CreateRasterDataset(fileName, "TIFF",19 origin, width, height, xCell, yCell, NumBand, rstPixelType.PT_UCHAR, sr,20 true);21 }22 else23 {24 throw new ArgumentException("栅格数据已经存在");25 }26 return rasterDataset;27 }28 catch (Exception ex)29 {30 System.Diagnostics.Debug.WriteLine(ex.Message);31 return null;32 }33 }调用的OpenRasterWorkspace方法代码：
1 public static IRasterWorkspace2 OpenRasterWorkspace(string PathName) 2 { 3 //This function opens a raster workspace. 4 try 5 { 6 IWorkspaceFactory workspaceFact = new RasterWorkspaceFactoryClass(); 7 return workspaceFact.OpenFromFile(PathName, 0) as IRasterWorkspace2; 8 } 9 catch (Exception ex)10 {11 System.Diagnostics.Debug.WriteLine(ex.Message);12 return null;13 }14 }
ArcEngine和GDAL读写栅格数据机制对比（二）—— IPixelBlock读写栅格
声明：以上内容来自用户投稿及互联网公开渠道收集整理发布，本网站不拥有所有权，未作人工编辑处理，也不承担相关法律责任，若内容有误或涉及侵权可进行投诉： 投诉/举报 工作人员会在5个工作日内联系你，一经查实，本站将立刻删除涉嫌侵权内容。