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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 = 255;
54
55 //从数据集中读取IRaster
56 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 else
23 {
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
标签：style blog http io color ar os sp for
原文地址：http://www.cnblogs.com/yhlx125/p/4088795.html
