C#使用GDAL读取与创建影像

╰+攻爆jí腚メ 2022-08-14 00:49 353阅读 0赞

C\#下GDAL的使用这里就不多赘述了，参见上一篇博客。

代码中都加了注释，这里就不再一一叙述了，代码如下：

class FloodSimulation
        {
            #region 类成员变量
    
            public Dataset m_DEMDataSet;            //DEM数据集
            public Dataset m_FloodSimulatedDataSet; //洪涝淹没范围数据集
            public int m_XSize;                     //数据X方向栅格个数
            public int m_YSize;                     //数据Y方向栅格个数
            public double m_AreaFlooded;            //水面面积
            public double m_WaterVolume;            //淹没水体体积
            public double[] m_FloodBuffer;          //填充缓冲区（洪涝淹没范围）
            public double[] m_DEMdataBuffer;           //DEM数据缓冲
    
            /* 这里的GeoTransform(影像坐标变换参数)的定义是：通过像素所在的行列值得到其左上角点空间坐标的运算参数
                例如:某图像上(P,L)点左上角的实际空间坐标为：
                Xp = GeoTransform[0] + P * GeoTransform[1] + L * GeoTransform[2];
                Yp = GeoTransform[3] + P * GeoTransform[4] + L * GeoTransform[5];                                                                     */
            public double[] m_adfGeoTransform;   
    
            #endregion
            
            //构造函数
            public FloodSimulation()
            {
                m_adfGeoTransform = new double[6];
            }
    
            /// <summary>
            /// 加载淹没区DEM,并创建淹没范围影像
            /// </summary>
            /// <param name="m_DEMFilePath">DEM文件路径</param>
            /// <returns></returns>
            public void loadDataSet(string m_DEMFilePath)
            {
                m_DEMDataSet = Gdal.Open(m_DEMFilePath, Access.GA_ReadOnly);
                //获取X、Y方向栅格数
                m_XSize = m_DEMDataSet.RasterXSize;
                m_YSize = m_DEMDataSet.RasterYSize;
                
                //读取DEM数据到内存中
                Band m_DEMBand = m_DEMDataSet.GetRasterBand(1); //获取第一个波段
                m_DEMdataBuffer = new double[m_XSize * m_YSize];
                m_DEMBand.ReadRaster(0, 0, m_XSize, m_YSize, m_DEMdataBuffer, m_XSize, m_YSize, 0, 0);
    
                //淹没范围填充缓冲区
                m_FloodBuffer = new double[m_XSize * m_YSize];
                //获取影像坐标转换参数
                m_DEMDataSet.GetGeoTransform(m_adfGeoTransform); 
    
                //创建洪涝淹没范围影像
                string m_FloodImagePath = System.IO.Path.GetDirectoryName(System.Windows.Forms.Application.ExecutablePath) + "\\FloodSimulation\\FloodedRegion.tif";
                if (System.IO.File.Exists(m_FloodImagePath))
                {
                    System.IO.File.Delete(m_FloodImagePath);
                }
                //在GDAL中创建影像,先需要明确待创建影像的格式,并获取到该影像格式的驱动
                OSGeo.GDAL.Driver driver = Gdal.GetDriverByName("GTiff");
                //调用Creat函数创建影像
                m_FloodSimulatedDataSet=driver.Create(m_FloodImagePath, m_XSize, m_YSize, 1, DataType.GDT_CFloat32, null);
                //设置影像属性
                m_FloodSimulatedDataSet.SetGeoTransform(m_adfGeoTransform); //影像转换参数
                m_FloodSimulatedDataSet.SetProjection(m_DEMDataSet.GetProjection()); //投影
                //将影像数据写入内存
                m_FloodSimulatedDataSet.GetRasterBand(1).WriteRaster(0, 0, m_XSize, m_YSize, m_FloodBuffer, m_XSize, m_YSize, 0, 0);
                m_FloodSimulatedDataSet.GetRasterBand(1).FlushCache();
                m_FloodSimulatedDataSet.FlushCache();
    
            }
    
            /// <summary>
            /// 从像素空间转换到地理空间
            /// </summary>
            /// <param name="adfGeoTransform">影像坐标变换参数</param>
            /// <param name="pixel">像素所在行</param>
            /// <param name="line">像素所在列</param>
            /// <param name="x">X</param>
            /// <param name="y">Y</param>
            public void  imageToGeoSpace( double [] m_GeoTransform, int pixel,int line, out double X,out double Y )
            {
                X = m_GeoTransform[0] + pixel * m_GeoTransform[1] + line * m_GeoTransform[2];
                Y = m_GeoTransform[3] + pixel * m_GeoTransform[4] + line * m_GeoTransform[5];
            }
    
            /// <summary>
            /// 从地理空间转换到像素空间
            /// </summary>
            /// <param name="adfGeoTransform">影像坐标变化参数</param>
            /// <param name="x">X</param>
            /// <param name="y">Y</param>
            /// <param name="pixel">像素所在行</param>
            /// <param name="line">像素所在列</param>
            public void geoToImageSpace(double[] m_GeoTransform, double x, double y, out int pixel, out int line)
            {
                line = (int)((y * m_GeoTransform[1] - x * m_GeoTransform[4] + m_GeoTransform[0] * m_GeoTransform[4] - m_GeoTransform[3] * m_GeoTransform[1]) / (m_GeoTransform[5] * m_GeoTransform[1] - m_GeoTransform[2] * m_GeoTransform[4]));
                pixel = (int)((x - m_GeoTransform[0] - line * m_GeoTransform[2]) / m_GeoTransform[1]);
            }
        }

因项目需要做洪涝模拟，所以采用GDAL使用C\#编写了FloodSimulation类，后面再一步步完善这个类。