AE的raster处理.doc

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);

}

6．2如何创建一个栅格数据
public IRasterDataset CreateFileRasterDataset(string directoryName, string fileName)
        {
            // This function creates a new img file in the given workspace
            // and then assigns pixel values
            try
            {
                IRasterDataset rasterDataset = null;
                IPoint originPoint = new PointClass();
                originPoint.PutCoords(0, 0);
                // Create the dataset
                IRasterWorkspace2 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; //之后他代表第一波段（实际只有一个波段）纵横代码
                IPixelBlock3 pixelBlock3 = null; //承载栅格影像数据的块（内存块吗。。）
                IPnt pixelBlockOrigin = null;
                IPnt pixelBlockSize = null;
                IRasterBandCollection rasterBandCollection;
                IRasterProps rasterProps;

                // QI for IRawPixels and IRasterProps
                rasterBandCollection = (IRasterBandCollection)rasterDataset;
                rawPixels = (IRawPixels)rasterBandCollection.Item(0);
                rasterProps = (IRasterProps)rawPixels;

                // Create pixelblock 创建像素块
                pixelBlockOrigin = new DblPntClass();
                pixelBlockOrigin.SetCoords(0, 0);
                pixelBlockSize = new DblPntClass();
                pixelBlockSize.SetCoords(rasterProps.Width, rasterProps.Height);
                pixelBlock3 = (IPixelBlock3)rawPixels.CreatePixelBlock(pixelBlockSize);
// 上述函数为参数为IPnt Size，返回值为IPixelBlock
                // Read pixelblock 读取像素块，虽然它是由rawPixels创造的
                rawPixels.Read(pixelBlockOrigin, (IPixelBlock)pixelBlock3);
                // Get pixeldata array
                System.Object[,] pixelData;
                pixelData = (System.Object[,])pixelBlock3.get_PixelDataByRef(0); //参数int plane
                // Loop through all the pixels and assign value
                for (int i = 0; i < rasterProps.Width; i++)
                    for (int j = 0; j < rasterProps.Height; j++)
                        pixelData[i, j] = (i * j) % 255;

                // Write the pixeldata back
                System.Object cachePointer;
                cachePointer = rawPixels.AcquireCache();
                rawPixels.Write(pixelBlockOrigin, (IPixelBlock)pixelBlock3);
                rawPixels.ReturnCache(cachePointer);
                // Return raster dataset
                return rasterDataset;
            }
            catch (Exception ex)
            {
                System.Diagnostics.Debug.WriteLine(ex.Message);
                return null
            }
        }

        public IRasterWorkspace2 CreateRasterWorkspace(string pathName)
        {
            // Create RasterWorkspace
            IWorkspaceFactory workspaceFactory = new RasterWorkspaceFactoryClass();
            return workspaceFactory.OpenFromFile(pathName, 0) as IRasterWorkspace2;
        }
6．3依旧是生成栅格文件
public IRasterDataset CreateRasterDataset(string Path, string FileName)
{
try
{
//Create raster workspace. This example also works with any other workspaces that support raster data such as a file geodatabase (FGDB) workspace.
//Access the workspace and the SDE workspace.
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 dimension 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 grid format.
IRasterDataset rasterDataset = rasterWs.CreateRasterDataset(FileName, "GRID",
origin, width, height, xCell, yCell NumBand, rstPixelType.PT_UCHAR, sr,
true);
//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, NoData value needs to be set for each band.
rasterProps.NoDataValue = 255;
//Create a raster from the dataset.
IRaster raster = rasterDataset.CreateDefaultRaster();

//Create a pixel block.
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 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;
}
}
来自http://bbs.esrichina-
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);

栅格数据重分类 (2009-01-10 10:10:09)
标签：栅格 重分类 分类：AE二次开发

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 !=