[gdal-dev] gdalwarp and image size change

[erik]

Hi,

I'm new to gdal, geotiffs & stuff, so sorry if this all seems obvious.
I've been trying to reproject a geotiff from "+proj=utm +zone=29 +ellps=intl
+units=m +no_defs" (European 1950, zone 29 - Portugal) to WGS84.

gdalwarp -s_srs "+proj=utm +zone=29 +ellps=intl +units=m +no_defs" -t_srs
"+proj=latlong +datum=WGS84" map.tif map3.tif

The original file is 5366 x 3387
but ... the reprojected file is 5695 x 2863

With the naked eye I can't see much change. Is this behaviour normal?

Concerning the original file, it was built with gcp's in gdal_translate and
then warped in the original projection. Maybe this isn't enough? In the
ozi2geotiff.py script I see he does a second translate with several creation
options (-co) for tiled, block(x,y)size, compress and predictor. As well as
some other stuff with convert, listgeo and geotifcp.

Thanks,
Erik.
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