[GRASS-dev] wxGUI: align to resolution by default

Markus Metz markus.metz.giswork at gmail.com
Thu Jan 5 13:43:08 PST 2017

On Thu, Jan 5, 2017 at 11:04 AM, Martin Landa <landa.martin at gmail.com>
> Hi,
> 2017-01-05 8:30 GMT+01:00 Moritz Lennert <mlennert at club.worldonline.be>:
> >>What do you think? Ma
> >
> >
> > See the arguments at
> > https://trac.osgeo.org/grass/ticket/1745
> hm, I found two reasons there:
> 1) Using '-a' breaks that by rounding - not surprissing
> 2) by default GRASS should try to do the least-damaging thing
> Well I used -a flag everytime when setting up region based on vector
> and raster data. I still think that it could be default in wxGUI. In
> 99% you want to preserve resolution. Ma

99% I also want to preserve grid geometry and avoid grid shift. A simple
example is SRTM. Import an SRTM tile with 3 arcsec resolution, then set the
region to the SRTM tile. Now set the region with g.region -a res=00:00:03
and compare the extents. They will be shifted by half a pixel and no longer
match the SRTM tile.

I am opting for 2) by default GRASS should try to do the least-damaging

Markus M

> --
> Martin Landa
> http://geo.fsv.cvut.cz/gwiki/Landa
> http://gismentors.cz/mentors/landa
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