[Gdal-dev] Warping of large files

Asger Petersen asger at jo-informatik.dk
Mon Apr 18 07:12:59 EDT 2005

>> Of course i could chop the files into pieces small enough to use 
>> Gtiff and then mosaik them in Mapserver, but I would really prefer 
>> keeping them in one piece.

> I can understand your reluctance to create tiled geotiff's but it is a

> very fast, and relatively easy solution. If your > images are color, 
> try to make them into a palettized (pseudo color) image. Possibly 
> limit the number of colors in the palette to less than 255 if you have
other colors required for overlays in your map file. Use a tileindex,
and use overviews (gdaladdo). In my limited testing a couple years ago
this approached provided the fastest performance for serving imagery off
my system.

We have done that in another project, but this time it is necessary to
use a compressed format because of the size of data. Therefore we are
considering using a mosaic of ecw-compressed files instead of GTiff.

At the moment I have some troubles getting FWTools 0.9.7 to work
properly when compressing to ecw format. It just crashes:

C:\>gdal_translate -of ECW -srcwin 0 0 500 500 -a_srs srs.txt in.jp2
out.ecw Input file size is 67500, 45000 0.

Then Windows shows a popup with the message: "gdal_translate.exe has
encountered a problem and needs to close.  We are sorry for the

Has anyone seen this one before?


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