[gdal-dev] gdal_translate: set the CRS makes the output 10 times bigger

[Andrés Maneiro]

Thanks Even for the response, I suppose it has to do with your 
suggestions, but I don't know why, as I don't see any compression 
algorithm within gdalinfo output :/

Here the output of gdalinfo on the original tiff:

Driver: GTiff/GeoTIFF
Files: 120135.tif
Size is 12261, 9595
Coordinate System is:
PROJCS["UTM Zone 29N",
     GEOGCS["ED_1950_16",
         DATUM["ED_1950_16",
             SPHEROID["International 1909",6378388,297.0000535480247]],
         PRIMEM["Greenwich",0],
         UNIT["degree",0.0174532925199433]],
     PROJECTION["Transverse_Mercator"],
     PARAMETER["latitude_of_origin",0],
     PARAMETER["central_meridian",-9],
     PARAMETER["scale_factor",0.9996],
     PARAMETER["false_easting",500000],
     PARAMETER["false_northing",0],
     UNIT["metre",1,
         AUTHORITY["EPSG","9001"]]]
Origin = (560152.010000000009313,4794483.370000000111759)
Pixel Size = (0.035418645400000,-0.035419541800000)
Metadata:
   TIFFTAG_SOFTWARE=IMAGINE TIFF Support
Copyright 1991 - 1999 by ERDAS, Inc. All Rights Reserved
@(#)$RCSfile: etif.c $ $Revision: 1.10.1.9.1.9.2.11 $ $Date: 2004/09/15 
18:42:01EDT $
   TIFFTAG_XRESOLUTION=1
   TIFFTAG_YRESOLUTION=1
   TIFFTAG_RESOLUTIONUNIT=1 (unitless)
   AREA_OR_POINT=Area
Image Structure Metadata:
   INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (  560152.010, 4794483.370) (  8d15'30.35"W, 43d17'59.98"N)
Lower Left  (  560152.010, 4794143.519) (  8d15'30.49"W, 43d17'48.97"N)
Upper Right (  560586.278, 4794483.370) (  8d15'11.08"W, 43d17'59.86"N)
Lower Right (  560586.278, 4794143.519) (  8d15'11.22"W, 43d17'48.84"N)
Center      (  560369.144, 4794313.445) (  8d15'20.78"W, 43d17'54.41"N)
Band 1 Block=64x64 Type=Byte, ColorInterp=Palette
   Image Structure Metadata:
     NBITS=1
   Color Table (RGB with 2 entries)
     0: 0,0,0,255
     1: 255,255,255,255


On 02/06/11 20:07, Even Rouault wrote:
> Le jeudi 02 juin 2011 20:00:15, Andrés Maneiro a écrit :
>> Hello devs,
>>
>> I'm playing with GDAL to set the CRS of a set of geotiff files I was
>> given to upload them to geoserver later.
>>
>> These files, were generated using ArcGIS and it seems that the CRS set
>> in the geotiff file header is not standar (at least, my geoserver
>> doesn't recognize them). What I did:
>>
>>    gdal_translate -a_srs "EPSG:23029" original.tif output.tif
>>
>> After doing that, the size of the output is 5/10 times bigger than input
>> (in some cases: from 10Mb to almost 110Mb). The only thing I see as
>> different -using gdalinfo on both files- is the "Color Table". The
>> former has 2 entries and the output has 256. Don't know if it's the
>> source of the problem, just let you know in case it is useful.
>
> Hum, it's likely that your original.tif was compressed. gdal_translate without
> argument will generate an uncompressed file.
>
> What is the output of gdalinfo on original.tif ? If you see a COMPRESS=
> metadata keywords, you can try reusing it as a creation option.
>
> It is also likely that your original.tif is a 1bit file.
>
> So, guess blindly, I would try :
>
> gdal_translate -a_srs "EPSG:23029" original.tif output.tif -co NBITS=1 -co
> COMPRESS=PACKBITS
>
>>
>> So, my question is: how could I generate an output file, with CRS set
>> and with roughly the same size of the original?
>>
>> best,
>> amaneiro
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