[Gdal-dev] r.out.gdal vs gdal_translate vs gdalwarp

[Maciej Sieczka]

Hi!

I'm really puzzled. Please can somebody look into this?

I tried to simplify the case a bit. Let's leave out r.out.gdal for a
moment and stick to GDAL commands only. A sample vegcover3.tif is
attached, but you should be able to reproduce the issue with any tiff
out there.

The sample size is 28628 bytes.



Try the following on the sample:

$ gdal_translate vegcover3.tif vegcover3_gt.tif

vegcover3_gt.tif size is 28628 bytes. Identical to input. OK.

$ gdalwarp vegcover3.tif vegcover3_gw.tif

vegcover3_gw.tif size is 36336 bytes. That's 27% bigger than the input!

But why? I can't see a reason there should be any difference. gdalwarp
is supposed to do a raw copy of the input if no switches present; or
isn't it? Maybe I'm just missing something.

Maciek
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