[gdal-dev] Problems with large ASTER GeoTIFF

[Jean-Roc Morreale]

Hi,

You can do all these operation in one command :

gdal_translate -of PNG -srcwin xoff yoff xsize ysize "input.tif" 
"output.png"

Are you sure of your scrwin parameters ?

Le 2014-04-14 16:16, Nicole Stoffels a écrit :
> Dear Gdal-List,
> 
> I have a large ASTER file (downloaded from
> http://www.eea.europa.eu/data-and-maps/data/eu-dem#tab-european-data)
> in the GeoTIFF-format. It is compressed with LZW. What I want to do
> is:
> 
> 1. unpack it
> 2. seperate a smaller region from it
> 3. convert this regional GeoTIFF to a PNG
> 
> What I am doing:
> 
> $ gdal_translate -co COMPRESS=NONE EUD_CP-DEMS_6500035000-AA.tif 
> tmp1.tif
> 
> $ gdal_translate -srcwin 6500 3300 1000 1000 tmp1.tif tmp2.tif
> 
> $ gdal_translate -of PNG tmp2.tif tmp2.png
> 
> When I display the info with gdalinfo the first step seems to produce
> a decompressed file. The line COMPRESSION=LZW is not there anymore.
> However, if I want to display the min and max with gdalinfo, I get the
> following error.
> 
> ERROR 1: Failed to compute min/max, no valid pixels found in sampling.
> 
> I thought that the file might be too large, but if I change the
> data_type from float 32 to e.g. Int16 I get 0 as min and max value.
> That's why I assume that already the first gdal_translate does not
> work as I actually want it to work.
> 
> The other two transformations work without error messages. However, in
> the end I get a black png.
> 
> I have tried all types of transformation with various options. But as
> I am new in the subject and do not know much about gdal, I have no
> further ideas how to generate a file from my large GeoTIFF to continue
> working with.
> 
> I hope someone has an idea, what's going wrong with my
> gdal_translations. Thanks very much in advance.
> 
> Best regards
> Nicole