[gdal-dev] GTiff optimisation

[Etienne Tourigny]

Bonjour Yves,


I think that gdalwarp is not optimized for saving compressed geotiffs, you would have to do that in a second step. This topic has been addressed in this list not long ago.


Anyway, you should be using gdal_translate (with a_srs flag) instead for this 
task, as you are just adding georeferencing information, not 
re-projecting the data.

something like gdal_translate -co "COMPRESS=PACKBITS" -co "PHOTOMETRIC=MINISWHITE" -co "NBITS=1" -a_srs "EPSG:2154" input.tif output.tif

Etienne



----- Original Message -----
From: Yves Jacolin <yjacolin at free.fr>
To: gdal-dev <gdal-dev at lists.osgeo.org>
Cc: 
Sent: Tuesday, August 30, 2011 8:22:46 AM
Subject: [gdal-dev] GTiff optimisation

Hello,

I am converting GTiff to GTiff in order to add projection and georeferencing 
information in the header. I am using gdalwarp with some flags, mailny -co 
flags. I have some question about this.

Here is my command line:

gdalwarp -co "COMPRESS=PACKBITS" -co "PHOTOMETRIC=MINISWHITE" -co "NBITS=1" -
s_srs "EPSG:2154" -t_srs "EPSG:2154" input.tif output.tif

1.  File size: input.tif and output.tif have different file size, output file is 
50 % bigger than the input file. Is it normal?

2. If I use gdalinfo on my output file, I have no information about MINISWHITE 
parameter while I have it in the input file. Am I using this creation option 
correctly? This issue could be related to the first item?

3. I also have a "AREA_OR_POINT=Area" item in my output from gdalinfo, what 
does it means?

gdal version: GDAL 1.7.3, released 2010/11/10

thanks,

Y.
-- 
Yves Jacolin

http://yjacolin.gloobe.org
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