[GRASS-dev] any special reason why choice of raster compression method is done via environmental variable ?

Moritz Lennert mlennert at club.worldonline.be
Mon Dec 9 21:47:37 PST 2019

On 9/12/19 22:50, Markus Metz wrote:
>   Hi Moritz,
> On Wed, Dec 4, 2019 at 10:28 AM Moritz Lennert 
> <mlennert at club.worldonline.be <mailto:mlennert at club.worldonline.be>> wrote:
>  >
>  > Hi Markus,
>  >
>  > In recent days, I've been confronted several times with the issue of
>  > people trying to share data among themselves, but using different
>  > versions of GRASS, and so raster data compressed in a more recent
>  > version of GRASS was not usable in an older version of GRASS.
>  >
>  > Now, I agree that generally the solution is to tell people to use the
>  > latest and greatest, but this is not always possible / it is not
>  > necessarily highest on the list of priorities of people to see how they
>  > can install the latest version of GRASS within their particular 
> environment.
>  >
>  > Obviously, those with the latest version of GRASS can simple recompress
>  > using ZLIB. However, compression method is defined as an environment
>  > variable. This is somewhat daunting to many MS Windows users out there.
>  > Is there any specific reason that lead to the choice of not using a
>  > parameter to allow the choice of compression method (possibly to
>  > override a default that is still defined by an environment variable) ?
> Such a parameter would need to be added to every module creating raster 
> output.

My request is more linked to use cases where one would like to share 
data (e.g. with r.pack) with other GRASS GIS users who do not 
necessarily have access to the same compression method, not necessarily 
to changing the default compression method. I was just wondering whether 
it might be easily possible to just implement r.compress method= as a 
quick way to recompress a specific map with a chosen method, overriding 
the default method. Currently, to do that, you have to change the 
default method by changing the env variable, run r.compress, then change 
the variable back to the value one wishes generally to use as default.

Obviously, you can always just export as tiff and share that, but that 
just feels less elegant. Anyway, this is probably somewhat of a luxury 
problem :-)


More information about the grass-dev mailing list