///

/// GDAL栅格转换为位图

///

/// GDAL Dataset

/// 显示区域

/// 需要显示的波段列表

/// 返回Bitmap对象

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;

}

主函数调用

private void ImageShow()

{

string filename="";

OpenFileDialog dlg = new OpenFileDialog();

dlg.Filter = "Tiff文件|*.tif|Erdas img文件|*.img|Bmp文件|*.bmp|jpeg文件|*.jpg|所有文件|*.*";

if (dlg.ShowDialog() == DialogResult.OK)

{

filename = dlg.FileName;

}

if (filename == "")

{

MessageBox.Show("影像路径不能为空");

return;

}

OSGeo.GDAL.Dataset ds= Gdal.Open(filename, Access.GA_ReadOnly);

if(ds==null)

{

MessageBox.Show("影像打开失败");

return;

}

Rectangle pictureRect = new Rectangle();

pictureRect.X = 0;

pictureRect.Y = 0;

pictureRect.Width = this.pictureBox1.Width;

pictureRect.Height = this.pictureBox1.Height;

int[] disband = {3,2,1};

Bitmap bitmap = GetImage(ds, pictureRect, disband);   //遥感影像构建位图

pictureBox1.Image = bitmap;                   //将位图传递给PictureBox控件进行显示

}