[gdal-dev] compressed GTiff large file size?

[Even Rouault]

On mardi 30 mai 2017 17:44:18 CEST MUTLU OZDOGAN wrote:
> Dear Developers
> 
> I have two multi-band geotiff files (each about 2 GB in size uncompressed)
> that I would like to mosaic using gdal_merge.py.  These files make up two
> halves of a single Landsat footprint so when joined should create a single
> mosaicked image.  I checked the corner coordinates and they seem correct. 
> However, when I use the gdal_merge.py command with the -co “COMPRESS=LZW”
> option, the final file size ends up being a ~100 GB which does not make any
> sense.  Any ideas about what is going on?  I checked the image dimensions
> and they seem to be correct and should result in a file that is about 4.5
> GB in size uncompressed so the compressed version should be at least this
> size if not smaller.

Mutlu,

Asy you noticed, gdal_merge.py strategy is not necessarily optimal regarding minimizing file 
size in case of compression

So I'd recommend using a workflow like :

gdalbuildvrt tmp.vrt landsat1 landsat2
gdal_translate tmp.vrt merged.tif -co COMPRESS=LZW -co TILED=YES


Even


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