Hi All, Recently I am trying to write float type data into a raster using the function named WriteRaster in GDAL. However, I found that the data written into the image does not make sense.
I tried to track down the issue from the very beginning, I found that the values predicted by the non-GDAL part are correct which ranges from 0.0 to 1000.0. However, the values written into the image seems not right. I "info"ed some pixels in ArcGIS, and found that some of the values are correct, but some are incredibly large (> 1,000,000,000) or -0.0. Beneath are the two function I created using C# to wrap up the create raster and write data to raster operations. Would you please review the code and let me know if you find anything wired? The dataType I passed in the following function is DataType.GDT_Float64. /// <summary> /// Function of CreateImage /// </summary> /// <param name="width">the width of the image</param> /// <param name="height">the height of the image</param> /// <param name="band">the band number of the image</param> /// <param name="dataType">the dataType of the image</param> /// <param name="fileName">the filepath of the image</param> /// <param name="Projection">the projection of the image</param> /// <param name="geotrans">the extent of the image</param> /// <returns>true if the file is created successfully, false otherwise</returns> public bool CreateImage(int width, int height, int band, OSGeo.GDAL.DataType dataType, string fileName, string Projection, double[] geotrans) { try { OSGeo.GDAL.Gdal.AllRegister(); OSGeo.GDAL.Driver poDriver = OSGeo.GDAL.Gdal.GetDriverByName("GTiff"); if (System.IO.Path.GetExtension(fileName) == ".img") poDriver = OSGeo.GDAL.Gdal.GetDriverByName("HFA"); OSGeo.GDAL.Dataset poDstDs = poDriver.Create(fileName, width, height, band, dataType, null); poDstDs.SetProjection(Projection); poDstDs.SetGeoTransform(geotrans); //****Added by ZLu on 08/03/2012**** poDstDs.Dispose(); return true; } catch { return false; } } /// <summary> /// Function of WriteData2File /// </summary> /// <param name="LCx">the column index of left corner</param> /// <param name="LCy">the row index of left corner</param> /// <param name="width">the width of the rectangle</param> /// <param name="height">the length of the rectangle</param> /// <param name="fileName">the fileName where the data will be saved</param> /// <returns>true, if the data is added correctly, false otherwise.</returns> public bool WriteData2File(int LCx, int LCy, int width, int height, int band, double[] Data, string fileName) { OSGeo.GDAL.Driver imgDriver = OSGeo.GDAL.Gdal.GetDriverByName("GTiff"); string extension = System.IO.Path.GetExtension(fileName); if (extension == ".img") imgDriver = OSGeo.GDAL.Gdal.GetDriverByName("HFA"); if (imgDriver == null) throw new Exception("The file type is not supported!"); OSGeo.GDAL.Dataset ds = OSGeo.GDAL.Gdal.Open(fileName, OSGeo.GDAL.Access.GA_Update); int[] bandMap = new int[] { 1, 1, 1}; try { ds.WriteRaster(LCx, LCy, width, height, Data, width, height, 1, bandMap, 1, 1, 1); //ds.WriteRaster(LCx, LCy, width, height, Data, width, height, band, 0, 0, 0); ds.Dispose(); return true; } catch { return false; } } Thank you so much and wish you have a nice weekend. Zhenyu -- Zhenyu Lu SUNY-ESF
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