ArcEngine 栅格数据总结

Posted 2023-02-15 杨千羽

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				<p id="breadcrumbs"><span><span><a href="https://www.giserdqy.com/">首页</a> » <span><a href="https://www.giserdqy.com/arcengine/">ArcEngine</a> » <span class="breadcrumb_last" aria-current="page">ArcEngine 栅格数据 总结</span></span></span></span></p>					<h1 class="post-title">ArcEngine 栅格数据 总结</h1>
				
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				<p class="post-byline">by <a href="https://www.giserdqy.com/author/dqy/" title="由giser发布" rel="author">giser</a> · 2019-04-05</p>

				
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本文大部分内容参考AO帮助文档和ArcMap帮助文档，大家实际使用中遇到的问题也可以在本帖下方留言交流，谢谢！
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基础知识

栅格数据基础知识：传送门

栅格数据是由一系列等间距的格网矩阵组成，用来表达完整的主题、光谱、图像信息。
栅格数据模型分为栅格数据集（Raster dataset）、栅格目录（Raster catalog）、镶嵌数据集（Mosaic dataset）。他们以文件系统、个人地理数据库、文件地理数据库、企业地理数据库为数据源进行存储。

栅格数据集也就是我们经常所得的jpg、tif文件等， ArcGIS 将这些栅格数据抽象为 RasterDataset，栅格数据集就代表了磁盘中的一个文件，它由一个或多个波段组成。在使用栅格数据集的时候，栅格数据会被转换成 IMG 文件存储在数据库中。我们可以对栅格数据集进行一些操作，如改变空间参考，建立影像金字塔等。

栅格目录，正如其名字一样是一个目录，跟书的目录相似，它记录了一个或者多个栅格数据集，每一个栅格数据集都作为一条记录存储在栅格目录中。栅格目录对栅格数据集的管理有两种方式，托管和非托管。托管方式的时候，栅格数据是存储在数据库中，非托管的时候，栅格目录记录了栅格数据集的路径，也就是栅格数据并没有存储在数据库中。当我们删除一条记录的时候，对我们的栅格数据没有任何影响。

镶嵌数据集可以说是栅格数据集和栅格目录的混合技术，它的存储方式和栅格目录类似，但是在使用的时候和普通的栅格数据集是一样的，镶嵌数据集用于管理和发布海量多分辨率，多传感器影像，对栅格数据提供了动态镶嵌和实时处理的功能。
对文件地理数据库、个人地理数据库和 ArcSDE 地理数据库中的栅格存储加以比较：

 //Open a file geodatabase workspace as RasterWorkspace.
static IRasterWorkspaceEx OpenFGDB(string FGDBPath)
    //FGDBPath string example: c:\\data\\raster.gdb.
    IWorkspaceFactory2 workspaceFactory = new FileGDBWorkspaceFactoryClass();
    return (IRasterWorkspaceEx)workspaceFactory.OpenFromFile(FGDBPath, 0);
//Open an ArcSDE workspace as RasterWorkspace.
static IRasterWorkspaceEx OpenSDE(string conString)
    //conString example: SERVER=ais;INSTANCE=9200;VERSION=sde.DEFAULT;USER=raster;PASSWORD=raster.
    IWorkspaceFactory2 workspaceFactory = new SdeWorkspaceFactoryClass();
    return (IRasterWorkspaceEx)workspaceFactory.OpenFromString(conString, 0);
//Open an accessed workspace as RasterWorkspace.
static IRasterWorkspaceEx OpenAccess(string PGDBPath)
    //FGDBPath string example: c:\\data\\rasters.mdb.
    IWorkspaceFactory2 workspaceFactory = new AccessWorkspaceFactoryClass();
    return (IRasterWorkspaceEx)workspaceFactory.OpenFromFile(PGDBPath, 0);
//Open a file workspace as RasterWorkspace.
static IRasterWorkspace OpenFileWorkspace(string wsPath)
    //wsPath example: c:\\data\\rasters.
    IWorkspaceFactory workspaceFact = new RasterWorkspaceFactoryClass();
    return (IRasterWorkspace)workspaceFact.OpenFromFile(wsPath, 0);

打开栅格数据集

 IRasterDataset rasterDataset = rasterWorkspace.OpenRasterDataset(datasetName);

 IRasterDataset rasterDataset = rasterWorkspaceEx.OpenRasterDataset(datasetName);

创建栅格数据集

Creating a raster dataset（创建以文件存储的栅格数据集，如TIFF）
1)Create a workspace.创建工作空间
2)Create a TIFF file with specified width, height, pixel type, cell size, and other necessary dimensions.创建一个TIFF文件，并指定它的宽度,高度,像素类型、像元大小和其他必要的维度。
3)Use the IPixelBlock and IRasterEdit interfaces to edit the pixel values.使用IPixelBlock 和 IRasterEdit 接口来编辑像元的值。

 public static IRasterDataset CreateRasterDataset(string Path, string FileName)
    try
    
        IRasterWorkspace2 rasterWs = OpenRasterWorkspace(Path);
        //Define the spatial reference of the raster dataset.
        ISpatialReference sr = new UnknownCoordinateSystemClass();
        //Define the origin for the raster dataset, which is the lower left corner of the raster.
        IPoint origin = new PointClass();
        origin.PutCoords(15.0, 15.0);
        //Define the dimensions of the raster dataset.
        int width = 100; //This is the width of the raster dataset.
        int height = 100; //This is the height of the raster dataset.
        double xCell = 30; //This is the cell size in x direction.
        double yCell = 30; //This is the cell size in y direction.
        int NumBand = 1; // This is the number of bands the raster dataset contains.
        //Create a raster dataset in TIFF format.
        IRasterDataset rasterDataset = rasterWs.CreateRasterDataset(FileName, "TIFF", 
			origin, width, height, xCell, yCell, NumBand, rstPixelType.PT_UCHAR, sr,
            true);
        //If you need to set NoData for some of the pixels, you need to set it on band 
        //to get the raster band.
        IRasterBandCollection rasterBands = (IRasterBandCollection)rasterDataset;
        IRasterBand rasterBand;
        IRasterProps rasterProps;
        rasterBand = rasterBands.Item(0);
        rasterProps = (IRasterProps)rasterBand;
        //Set NoData if necessary. For a multiband image, a NoData value needs to be set for each band.
        rasterProps.NoDataValue = 255;
        //Create a raster from the dataset.
        IRaster raster = rasterDataset.CreateFullRaster();
        //Create a pixel block using the weight and height of the raster dataset. 
        //If the raster dataset is large, a smaller pixel block should be used. 
        //Refer to the topic "How to access pixel data using a raster cursor".
        IPnt blocksize = new PntClass();
        blocksize.SetCoords(width, height);
        IPixelBlock3 pixelblock = raster.CreatePixelBlock(blocksize)as IPixelBlock3;
        //Populate some pixel values to the pixel block.
        System.Array pixels;
        pixels = (System.Array)pixelblock.get_PixelData(0);
        for (int i = 0; i < width; i++)
            for (int j = 0; j < height; j++)
                if (i == j)
                    pixels.SetValue(Convert.ToByte(255), i, j);
                else
                    pixels.SetValue(Convert.ToByte((i * j) / 255), i, j);
        pixelblock.set_PixelData(0, (System.Array)pixels);
        //Define the location that the upper left corner of the pixel block is to write.
        IPnt upperLeft = new PntClass();
        upperLeft.SetCoords(0, 0);
        //Write the pixel block.
        IRasterEdit rasterEdit = (IRasterEdit)raster;
        rasterEdit.Write(upperLeft, (IPixelBlock)pixelblock);
        //Release rasterEdit explicitly.
        System.Runtime.InteropServices.Marshal.ReleaseComObject(rasterEdit);
        return rasterDataset;
    
    catch (Exception ex)
    
        System.Diagnostics.Debug.WriteLine(ex.Message);
        return null;
    
public static IRasterWorkspace2 OpenRasterWorkspace(string PathName)
    //This function opens a raster workspace.
    try
    
        IWorkspaceFactory workspaceFact = new RasterWorkspaceFactoryClass();
        return workspaceFact.OpenFromFile(PathName, 0)as IRasterWorkspace2;
    
    catch (Exception ex)
    
        System.Diagnostics.Debug.WriteLine(ex.Message);
        return null;

Creating a raster dataset in a geodatabase（创建以GDB存储的栅格数据集，如GRID）
1)Create a file geodatabase workspace factory.创建哥FGDB的工作工厂对象。
2)Create a raster workspace and query IRasterWorkspaceEx.创建一个栅格工作空间对象并且转换到IRasterWorkspaceEx对象上
3)Define the storage and raster properties using the RasterStorageDef and RasterDef classes. 利用RasterStorageDef 和RasterDef 类定义栅格数据集的存储和栅格属性。
4)Create the dataset using the CreateRasterDataset method.利用CreateRasterDataset方法创建栅格数据集。

 IWorkspaceFactory wsf = new FileGDBWorkspaceFactoryClass();
IRasterWorkspaceEx ws = (IRasterWorkspaceEx)wsf.OpenFromFile(@"c:\\temp\\fgdb.gdb", 0);
//Define the raster storage.
IRasterStorageDef storage = new RasterStorageDefClass();
storage.Tiled = true;
storage.TileHeight = 128;
storage.TileWidth = 128;
//Define the spatial reference.
IRasterDef rasterDef = new RasterDefClass();
rasterDef.SpatialReference = new UnknownCoordinateSystemClass();
//Create data.
IRasterDataset rasterDs = ws.CreateRasterDataset("newraster", 3,
rstPixelType.PT_SHORT, storage, "sde.DEFAULT", rasterDef, null);

访问HDF和NIFF数据的子集

一些栅格格式,如分层数据格式(HDF),可以在单个文件中包含多个subdatasets。访问HDF subdatasets使用IRasterDatasetJukebox接口,请参见下面的代码示例:

 IWorkspaceFactory wsf = new FileGDBWorkspaceFactoryClass();
IRasterWorkspaceEx ws = (IRasterWorkspaceEx)wsf.OpenFromFile(@"c:\\temp\\fgdb.gdb", 0);
//Define the raster storage.
IRasterStorageDef storage = new RasterStorageDefClass();
storage.Tiled = true;
storage.TileHeight = 128;
storage.TileWidth = 128;
//Define the spatial reference.
IRasterDef rasterDef = new RasterDefClass();
rasterDef.SpatialReference = new UnknownCoordinateSystemClass();
//Create data.
IRasterDataset rasterDs = ws.CreateRasterDataset("newraster", 3,
rstPixelType.PT_SHORT, storage, "sde.DEFAULT", rasterDef, null);

读取JPEG EXIF扩展标记信息

 public static void JPEG_EXIFtag(IRasterDataset exifDataset)
    //exifDataset represents a raster dataset opened from a JPEG file that has EXIF tags.
    IDataset dataset = (IDataset)exifDataset;
    //Get the EXIF tags and the associated values.
    IPropertySet propertySet = dataset.PropertySet;    
	System.Object tag_names;
    System.Object tag_values;
    propertySet.GetAllProperties(out tag_names, out tag_values);
    string[] stringNames = (string[])tag_names;
    object[] stringValues = (object[])tag_values;
    for (int i = 0; i < stringNames.Length - 1; i++)    
	
		System.Console.WriteLine(stringNames[i]);
		System.Console.WriteLine(stringValues[i]);

读取像素数据

使用光栅游标访问像素数据

 public static void UsingRasterCursorWithPixelBlock(IRasterDataset2 rasterDs)
    try
    
        //Create a raster. 
        IRaster2 raster2 = rasterDs.CreateFullRaster()as IRaster2;
        //Create a raster cursor with a system-optimized pixel block size by passing a null.
        IRasterCursor rasterCursor = raster2.CreateCursorEx(null);
        //Use the IRasterEdit interface.
        IRasterEdit rasterEdit = raster2 as IRasterEdit;
        //Loop through each band and pixel block.
        IRasterBandCollection bands = rasterDs as IRasterBandCollection;
        IPixelBlock3 pixelblock3 = null;
        long blockwidth = 0;
        long blockheight = 0;
        System.Array pixels;
        IPnt tlc = null;
        object v;
        long bandCount = bands.Count;
        do
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ArcEngine 栅格数据总结

基础知识

类图

栅格数据接口使用示例

打开栅格数据工作空间

打开栅格数据集

创建栅格数据集

访问HDF和NIFF数据的子集

读取JPEG EXIF扩展标记信息

读取像素数据

ArcEngine 栅格数据 总结

ArcEngine 栅格数据总结