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I want to change projections for images using gdal bindings for c#. Gdal_translate seems like just renaming of projection (using a_srs parameter), but not reprojecting, so I used gdalwarp with s_srs parameter for that task. It's pretty clear what to pass to the Gdal.wrapper_GDALTranslate function: path to the destination file, dataset of the input file and some minor stuff. It also has more or less clear documentation. But for gdalwarp there are 3 kinds of different methods:

Gdal.wrapper_GDALWarpDestName(string dest, int object_list_count, 
SWIGTYPE_p_p_GDALDatasetShadow poObjects,
GDALWarpAppOptions warpAppOptions, Gdal.GDALProgressFuncDelegate callback,
string callback_data); //returns Dataset

Gdal.wrapper_GDALWarpDestDS(Dataset dstDS, int object_list_count,
SWIGTYPE_p_p_GDALDatasetShadow poObjects, GDALWarpAppOptions warpAppOptions,
Gdal.GDALProgressFuncDelegate callback, string callback_data); //returns int

Gdal.AutoCreateWarpedVRT(Dataset src_ds, string src_wkt, string dst_wkt, 
ResampleAlg eResampleAlg, double maxerror); //returns Dataset

It's absolutely not clear what these functions do and how they do it. Docs on gdalwarp page don't have any of these. I also don't understand the parameters: there is no input file or dataset parameter, only destination ones; the SWIGTYPE_p_p_GDALDatasetShadow class, which also doesn't have docs (there are not a single word about "shadow" either).

Summarizing, I'd like to hear some explanations about how this funcs work and how to make them work as binary gdalwarp.exe does.

  • Please do not include answers within your questions. It is fine to self-answer using the area provided for answers. I recommend that you cut/paste what is below the line in your question into an answer. – PolyGeo Oct 24 '18 at 23:12
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Using How to use wrapper_GDALWarpDestName in C#, I managed to write working method, that works like console GdalWarp does.

public static bool GdalWarp(string inputFile, string outputFile, string[] options, OSGeo.GDAL.Gdal.GDALProgressFuncDelegate callback)
{
    using (Dataset inputDataset = Gdal.Open(inputFile, Access.GA_ReadOnly))
    {
        IntPtr[] ptr = {Dataset.getCPtr(inputDataset).Handle};
        GCHandle gcHandle = GCHandle.Alloc(ptr, GCHandleType.Pinned);
        Dataset result = null;
        try
        {
            SWIGTYPE_p_p_GDALDatasetShadow dss = new SWIGTYPE_p_p_GDALDatasetShadow(gcHandle.AddrOfPinnedObject(), false, null);
            result = Gdal.wrapper_GDALWarpDestName(outputFile, 1, dss, new GDALWarpAppOptions(options), callback, null);
        }
        catch (Exception) { return false; }
        finally
        {
            gcHandle.Free();
            result.Dispose();
        }
    }
    return true;
}
  • I'm curious what your GDALProgressFuncDelegate looks like – gisdude Oct 31 at 15:59

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