[gdal-dev] TIF + TFW to GeoTIFF without decompression/recompression

[Even Rouault]

(Re-adding gdal-dev)

Le 21/09/2021 à 13:04, Andrea Giudiceandrea a écrit :
> Il 20/09/2021 11:28, Even Rouault ha scritto:
>> No, this is not implemented.  As you mention below gdal_edit, you 
>> could likely do a small script (or an enhancement of gdal_edit that 
>> has a -worldfile {filename} option)) to call SetGeoTransform() with a 
>> geotransform computed from the worldfile content
>
> Hi Even,
> thank you for your suggestion.
>
> Having a -worldfile option for gdal_edit would be good, it would also 
> good to have also an option to use the georeferencing parameters from 
> a PAM sidecar file.
>
> I still think the right thing would be to make sure gdal_translate 
> don't do a decompression/recompression cycle if not needed (i.e. when 
> the src raster is a TIFF ad the dst raster is GeoTIFF and no image 
> manipulation options are specified), maybe adding a special option for 
> this case (or a special value for the COMPRESSION option), so the 
> current default behaviour would be preserved.
I can't think of any major theoretical or practical obstacle in doing 
that, apart from actually coding it, as it will be a completely new code 
path in the GeoTIFF driver, which is a non-trivial one.
>
> Anyway, the following minimal Python script (complete code at [1]) 
> just do what I need (i.e. copy the src tif file to a new dst one and 
> copy the georeference information from src to dst):
> **
> shutil.copyfile(src, dst)
>
> src = gdal.Open(src)
>
> spatialref = src.GetSpatialRef()
> geotransform = src.GetGeoTransform()
> src = None
>
> dst = gdal.Open(dst,1)
> dst.SetSpatialRef(spatialref)
> dst.SetGeoTransform(geotransform)
> dst = None
> **
>
> or using GetGCPSpatialRef() / GetGCPs() and SetGCPs() for a 
> georeference with GCPs and not a geotransform.
>
> How can I reliably check if the src raster has a georeference with 
> GCPs or with a geotransform so I can appply the correct georeference 
> to the dst raster?
GCPs and geotransform will generally be exclusive (in GeoTIFF they are), 
so you can for example test if GetGCPs() returns something and use 
SetGCPs() then, and otherwise do the above
>
> Thank you again.
>
> Andrea Giudiceandrea
>
>
> [1] 
> https://gist.github.com/agiudiceandrea/2f0ef1e65858de1a35ef4b27b674c4ce

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