基于Dataset
public CPLErr ReadRaster(int xOff, int yOff, int xSize, int ySize, byte[] buffer, int buf_xSize, int buf_ySize, int bandCount, int[] bandMap, int pixelSpace, int lineSpace, int bandSpace)
int[] dataArray = new int[srcWidth * srcHeight * bandCount];
xOff和yOff是指偏移量，即从影像的左上角起始坐标（xOff,yOff）开始读取数据。
xSize和ySize是指读取图像数据的行列数，即宽度和高度，单位都是像素。
Buffer是图像数据缓存区域（数组），要根据文件类型重新定义 const char* GDALGetDataTypeName(poBand->GetRasterDataType()) 。
buf_xSize和buf_ySize是缓存区的大小，默认的GDAL支持重采样，它们须与buffer申请的大小保持一致，通过这两个参数可以控制影像的缩放，如果它们小于xSize和ySize就是将原图缩小，反之如果它们大于xSize和ySize就是将原图放大。
pixelSpace和lineSpace一般默认取0即可。ReadRaster最后三个参数全是0，默认按照波段顺序存储 。
pixelSpace设置成1，则隔一个像素点读取一个像素点的方式读取图像。
Ds.ReadRaster(0, 0, srcWidth, srcHeight, dataArray, srcWidth, srcHeight, bandCount, bandArray, 0, 0, 0);
public CPLErr WriteRaster(int xOff, int yOff, int xSize, int ySize, byte[] buffer, int buf_xSize, int buf_ySize, int pixelSpace, int lineSpace)
/// <summary>
/// GDAL栅格转换为位图
/// </summary>
/// <param name="ds">GDAL Dataset</param>
/// <param name="showRect">显示区域</param>
/// <param name="bandlist">需要显示的波段列表</param>
/// <returns>返回Bitmap对象</returns>
public Bitmap GetImage(OSGeo.GDAL.Dataset ds, Rectangle showRect, int[] bandlist)
{
int imgWidth = ds.RasterXSize; //影像宽
int imgHeight = ds.RasterYSize; //影像高
float ImgRatio = imgWidth / (float)imgHeight; //影像宽高比
//获取显示控件大小
int BoxWidth = showRect.Width;
int BoxHeight = showRect.Height;
float BoxRatio = imgWidth / (float)imgHeight; //显示控件宽高比
//计算实际显示区域大小，防止影像畸变显示
int BufferWidth, BufferHeight;
if (BoxRatio >= ImgRatio)
{
BufferHeight = BoxHeight;
BufferWidth = (int)(BoxHeight * ImgRatio);
}
else
{
BufferWidth = BoxWidth;
BufferHeight = (int)(BoxWidth / ImgRatio);
}
//构建位图
Bitmap bitmap = new Bitmap(BufferWidth, BufferHeight, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
if (bandlist.Length == 3) //RGB显示
{
int[] r = new int[BufferWidth * BufferHeight];
Band band1 = ds.GetRasterBand(bandlist[0]);
band1.ReadRaster(0, 0, imgWidth, imgHeight, r, BufferWidth, BufferHeight, 0, 0); //读取图像到内存
//为了显示好看，进行最大最小值拉伸显示
double[] maxandmin1 = { 0, 0 };
band1.ComputeRasterMinMax(maxandmin1, 0);
int[] g = new int[BufferWidth * BufferHeight];
Band band2 = ds.GetRasterBand(bandlist[1]);
band2.ReadRaster(0, 0, imgWidth, imgHeight, g, BufferWidth, BufferHeight, 0, 0);
double[] maxandmin2 = { 0, 0 };
band2.ComputeRasterMinMax(maxandmin2, 0);
int[] b = new int[BufferWidth * BufferHeight];
Band band3 = ds.GetRasterBand(bandlist[2]);
band3.ReadRaster(0, 0, imgWidth, imgHeight, b, BufferWidth, BufferHeight, 0, 0);
double[] maxandmin3 = { 0, 0 };
band3.ComputeRasterMinMax(maxandmin3, 0);
int i, j;
for (i = 0; i < BufferWidth; i++)
{
for (j = 0; j < BufferHeight; j++)
{
int rVal = Convert.ToInt32(r[i + j * BufferWidth]);
rVal = (int)((rVal - maxandmin1[0]) / (maxandmin1[1] - maxandmin1[0]) * 255);
int gVal = Convert.ToInt32(g[i + j * BufferWidth]);
gVal = (int)((gVal - maxandmin2[0]) / (maxandmin2[1] - maxandmin2[0]) * 255);
int bVal = Convert.ToInt32(b[i + j * BufferWidth]);
bVal = (int)((bVal - maxandmin3[0]) / (maxandmin3[1] - maxandmin3[0]) * 255);
Color newColor = Color.FromArgb(rVal, gVal, bVal);
bitmap.SetPixel(i, j, newColor);
}
}
}
else //灰度显示
{
int[] r = new int[BufferWidth * BufferHeight];
Band band1 = ds.GetRasterBand(bandlist[0]);
band1.ReadRaster(0, 0, imgWidth, imgHeight, r, BufferWidth, BufferHeight, 0, 0);
double[] maxandmin1 = { 0, 0 };
band1.ComputeRasterMinMax(maxandmin1, 0);
int i, j;
for (i = 0; i < BufferWidth; i++)
{
for (j = 0; j < BufferHeight; j++)
{
int rVal = Convert.ToInt32(r[i + j * BufferWidth]);
rVal = (int)((rVal - maxandmin1[0]) / (maxandmin1[1] - maxandmin1[0]) * 255);
Color newColor = Color.FromArgb(rVal, rVal, rVal);
bitmap.SetPixel(i, j, newColor);
}
}
}
return bitmap;
}读写影像数据（基于Band）
public CPLErr ReadRaster(int xOff, int yOff, int xSize, int ySize, byte[] buffer, int buf_xSize, int buf_ySize, int pixelSpace, int lineSpace)