ArcEngine修改像素值与像元值

这里要注意的是单波段的栅格数据，比如dem一般是不能修改像素值的。而dem的像元值一般代表它的高程。这里的把我研究的高程数据的像元值全部改成了0和1。它要注意的是由于修改像素是直接在原数据上直接修改，所以完成后原数据就会没有了，所以大家可以先复制一下原数据再做。

一。改变栅格数据像素值

 public void ChangeRasterValue(IRasterDataset2 pRasterDatset)        {            IRaster2 pRaster2 = pRasterDatset.CreateFullRaster() as IRaster2;            IPnt pPntBlock = new PntClass();            pPntBlock.X = 128;            pPntBlock.Y = 128;            IRasterCursor pRasterCursor = pRaster2.CreateCursorEx(pPntBlock);            IRasterEdit pRasterEdit = pRaster2 as IRasterEdit;            if (pRasterEdit.CanEdit())            {                IRasterBandCollection pBands = pRasterDatset as IRasterBandCollection;                IPixelBlock3 pPixelblock3 = null;                int pBlockwidth = 0;                int pBlockheight = 0;                System.Array pixels;                IPnt pPnt = null;                object pValue;                long pBandCount = pBands.Count;                //获取Nodata                //IRasterProps pRasterPro = pRaster2 as IRasterProps;                //object pNodata = pRasterPro.NoDataValue;                do                {                    pPixelblock3 = pRasterCursor.PixelBlock as IPixelBlock3;                    pBlockwidth = pPixelblock3.Width;                    pBlockheight = pPixelblock3.Height;                    for (int k = 0; k < pBandCount; k++)                    {                        pixels = (System.Array)pPixelblock3.get_PixelData(k);                        for (int i = 0; i < pBlockwidth; i++)                        {                            for (int j = 0; j < pBlockheight; j++)                            {                                pValue = pixels.GetValue(i, j);                                if (Convert.ToInt32(pValue) == 0 && isFlood[j, i] == true)                                {                                    pixels.SetValue(Convert.ToByte(50), i, j);                                }                            }                        }                        pPixelblock3.set_PixelData(k, pixels);                    }                    pPnt = pRasterCursor.TopLeft;                    pRasterEdit.Write(pPnt, (IPixelBlock)pPixelblock3);                }                while (pRasterCursor.Next());                System.Runtime.InteropServices.Marshal.ReleaseComObject(pRasterEdit);                MessageBox.Show("done");            }        }

还有就是根据IRaster2修改像素值

                IRasterBandCollection rasterbands = (IRasterBandCollection)pRasterDataset;                IRasterBand rasterband = rasterbands.Item(0);                IRawPixels rawpixels = (IRawPixels)rasterbands.Item(0);                IRasterProps rasterpro = (IRasterProps)rasterband;                IRasterDataset2 rasterDataset2 = (IRasterDataset2)pRasterDataset;                IRaster raster = rasterDataset2.CreateFullRaster();                IRaster2 raster2 = (IRaster2)raster;                IPnt pBlockSize1 = new PntClass();                IEnvelope envelope = rasterpro.Extent;                pBlockSize1.SetCoords(envelope.Width, envelope.Height);                IPixelBlock pixelBlock = raster2.CreateCursorEx(pBlockSize1).PixelBlock;                int w = pixelBlock.Width;                int h = pixelBlock.Height;                //read the first pixel block                IPnt topleftCorner = new PntClass();                topleftCorner.SetCoords(0, 0);                raster.Read(topleftCorner, pixelBlock);                //modify one pixel value at location (assume the raster has a pixel type of uchar)                IPixelBlock3 pixelBlock3 = (IPixelBlock3)pixelBlock;                System.Array pixels = (System.Array)pixelBlock3.get_PixelData(0);                for (int finalX = 0; finalX < pRows; finalX++)                {                    for (int finalY = 0; finalY < pColumns; finalY++)                    {                        if (isFlood[finalX, finalY] == true)                        {                            pixels.SetValue(Convert.ToByte(100), finalY, finalX);                        }                        //else                        //{                        //    pPixelData.SetValue(0, finalY, finalX);                        //}                    }                }                pixelBlock3.set_PixelData(0, (System.Object)pixels);                //write the modified pixel block to the raster dataset                IRasterEdit rasterEdit = (IRasterEdit)raster;                rasterEdit.Write(topleftCorner, pixelBlock);

二，栅格数据重分类，即修改栅格值

public void reclass(IRaster pRaster, double weight)        {            //int trueCount = 0;            //int falseCount = 0;            IRasterProps rasterProps = (IRasterProps)pRaster;            //设置栅格数据起始点            IPnt pBlockSize = new Pnt();            pBlockSize.SetCoords(rasterProps.Width, rasterProps.Height);            //获取整个范围            IPixelBlock pPixelBlock = pRaster.CreatePixelBlock(pBlockSize);            // IPixelBlock3 pPixelBlock = (IPixelBlock3)pRaster.CreatePixelBlock(pBlockSize);            //左上点坐标            IPnt tlp = new Pnt();            tlp.SetCoords(0, 0);            //读入栅格            IRasterBandCollection pRasterBands = pRaster as IRasterBandCollection;            IRasterBand pRasterBand = pRasterBands.Item(0);            IRawPixels pRawPixels = pRasterBands.Item(0) as IRawPixels;            pRawPixels.Read(tlp, pPixelBlock);            //将pixel的值组成数组            System.Array pSafeArray = pPixelBlock.get_SafeArray(0) as System.Array;            for (int y = 0; y < rasterProps.Height; y++)            {                for (int x = 0; x < rasterProps.Width; x++)                {                    //int value = Convert.ToInt32(pSafeArray.GetValue(x, y));                    //Byte value = Convert.ToByte(pSafeArray.GetValue(x, y));                    //if (value != 0 && isFlood[y, x] == false)                    //{                    //    pSafeArray.SetValue((Byte)(value * weight), x, y);                    //}                    if (isFlood[y, x] == true)                    {                        pSafeArray.SetValue(1, x, y);                        //trueCount++;                    }                    else                    {                        pSafeArray.SetValue(0, x, y);                        //falseCount++;                    }                }            }            pPixelBlock.set_SafeArray(0, pSafeArray);            //编辑raster,将更新的值写入raster中            IRasterEdit rasterEdit = pRaster as IRasterEdit;            rasterEdit.Write(tlp, pPixelBlock);            rasterEdit.Refresh();            int Fcount=0;            //m_map.AddLayer            //MessageBox.Show("ok");            //double result = Convert.ToDouble(pSafeArray.GetValue(100, 99));                   }