[gdal-dev] Options of gdalwarp not all exposed in the GDAL Python gdal.Warp ?

[Thomas Gratier]

Hello all,

Due to question at
https://gis.stackexchange.com/questions/398223/how-to-remap-gdal-options-from-string-version-to-a-dictionary-version
I've taken a look at code

When trying to use gdal.Warp from Python, most options are supported but
some seems to be missing
Although an approach with only `gdal.Warp(dest, origin,
options='-overwrite')` can work without code change,
the dict approach like below seems to be simpler from a Python perspective

kwargsoptions = {"overwrite": True} # particular key does not exist, just
for the explanation
gdal.Warp(dest, origin, **kwargsoptions)

Below are the command options I only found in gdalwarp command line but
absent in the WarpOptions (from doc
https://gdal.org/programs/gdalwarp.html#cmdoption-gdalwarp-r)

[-ct string]
[-novshiftgrid]
[-refine_gcps tolerance [minimum_gcps]]
[-ovr level|AUTO|AUTO-n|NONE]
[-srcalpha|-nosrcalpha]
[-q]
[-if format]*
[-overwrite]
[-oo NAME=VALUE]*
[-doo NAME=VALUE]*

-srcalpha is present but not it counterpart -nosrcalpha

In gdal.py code, there are references to resampling option not in the doc
e.g below excerpt
(from
https://github.com/OSGeo/gdal/blob/master/gdal/swig/python/osgeo/gdal.py#L588)
.

elif resampleAlg == GRIORA_Bilinear:
    new_options += ['-rb']
elif resampleAlg == GRIORA_Cubic:
    new_options += ['-rc']
elif resampleAlg == GRIORA_CubicSpline:
    new_options += ['-rcs']

It may to need to be removed if looking at
https://gdal.org/programs/gdalwarp.html#cmdoption-gdalwarp-r
e.g (no -rcs, -rb or -rc options) except maybe for compatibility reason

I will try to make a PR. The main issue is more about naming for each
option.
I also don't know if command line and Python API "unsync" is due to
evolution, to intended API choices or other reasons.

I also only discuss here the gdal.Warp options but I suppose there are
maybe other Python tools ported from RFC 59
https://gdal.org/development/rfc/rfc59_utilities_as_a_library.html that may
have the same "unsync" issue.
Did not look at the moment


Regards

Thomas Gratier
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