public bool ContourGenerate(string dstVectorFilename, string strAtrrName, Dataset pInDataset, int nBandIndex = 1, double[] dLevelIntervals = null, double dLevelBase = 0, bool isPolygon = true, string driverName = "GeoJSON")
{
if (pInDataset == null)
{
return(false);
}
//提取图像参数值
int nDemWidth = pInDataset.RasterXSize; //获取图像宽
int nDemHeight = pInDataset.RasterYSize; //获取图像高
int nCount = pInDataset.RasterCount; //波段数
//读取图像数据波段
Band poBand = pInDataset.GetRasterBand(nBandIndex);
float[] pData = new float[nDemWidth * nDemHeight];
CPLErr err = poBand.ReadRaster(0, 0, nDemWidth, nDemHeight, pData, nDemWidth, nDemHeight, 4, 0);
if (err == CPLErr.CE_Failure)
{
Gdal.GDALDestroyDriverManager();
Console.WriteLine("读取DEM图像数据时出错！");
return(false);
}
//判断图像中是否有异常值，并获取异常值实际值
float fNoData = 0;
int nIdx;
for (int i = 0; i < nDemHeight; i++)
{
for (int j = 0; j < nDemWidth; j++)
{
nIdx = i * nDemWidth + j;
if (pData[nIdx] <= -9999)
{
fNoData = pData[nIdx];
}
}
}
//创建矢量图
OSGeo.OGR.Driver poDriver = Ogr.GetDriverByName(driverName);
if (poDriver == null)
{
Console.WriteLine(driverName + " driver not available.");
return(false);
}
//载入数据源
DataSource poDS = poDriver.CreateDataSource(dstVectorFilename, null);
if (poDS == null)
{
Console.WriteLine("Creation of output file failed.");
return(false);
}
SpatialReference poSpatialRef = new SpatialReference(pInDataset.GetProjectionRef());
Layer poLayer = poDS.CreateLayer("Contour", poSpatialRef, wkbGeometryType.wkbLineString, null);
if (poLayer == null)
{
Console.WriteLine("Layer creation failed.");
return(false);
}
if (strAtrrName == "")
{
strAtrrName = "Elevation";
}
FieldDefn oFieldDef = new FieldDefn(strAtrrName, FieldType.OFTInteger); //在矢量图中创建高程值字段
if (poLayer.CreateField(oFieldDef, 1) != Ogr.OGRERR_NONE)
{
Console.WriteLine("创建矢量图层属性表失败！");
poDS.Dispose();
pInDataset.Dispose();
return(false);
}
//组装参数
List <string> lstOptions = new List <string>()
{
};
if (dLevelIntervals == null)
{
lstOptions.Add("LEVEL_INTERVAL=" + 0);
}
else
{
if (dLevelIntervals.Length == 1)
{
lstOptions.Add("LEVEL_INTERVAL=" + dLevelIntervals[1]);
}
else
{
lstOptions.Add("FIXED_LEVELS=[" + string.Join(",", dLevelIntervals) + "]");
}
}
lstOptions.Add("LEVEL_BASE=" + dLevelBase);
lstOptions.Add("NODATA=" + fNoData);
lstOptions.Add("POLYGONIZE=" + (isPolygon ? "YES" : "NO"));
if (isPolygon)
{
lstOptions.Add("ELEV_FIELD_MAX=0");
lstOptions.Add("ELEV_FIELD_MIN=0");
}
//根据图像波段生成矢量图等高线
//Gdal.ContourGenerate(pInRasterBand, dfContourInterval, 0, 0, null, 1, fNoData, poLayer, -1, 0, null, null);
//string[] options = new string[] { "LEVEL_INTERVAL=" + 5, "LEVEL_BASE=" + 5, "NODATA=" + fNoData, "POLYGONIZE=YES", "ELEV_FIELD_MIN=0", "ELEV_FIELD_MAX=0", "FIXED_LEVELS=[20,30,40,50,60,100]" };
Gdal.ContourGenerateEx(poBand, poLayer, lstOptions.ToArray(), null, null);
//释放资源
poDS.Dispose();
poLayer.Dispose();
poDriver.Dispose();
pInDataset.Dispose();
return(true);
}
