[GRASS5] Rethinking regions (was: Re: Grass GUI)

[Carl Worth]

On Mar 22, Eric G. Miller wrote:
 > On Fri, Mar 22, 2002 at 07:00:30PM +0000, Glynn Clements wrote:
 > > 
 > > For the case where there is a single input map, it would be possible
 > > to use that map's settings, although that would require explicitly
 > > generating a new clipped and/or resampled map if you didn't want to
 > > use the map's settings. And what if there are several input maps? Use
 > > their union? Or intersection? What about the resolution?
 > 
 > For comparison: Arc/Info GRID uses Maxof/Maxof by default.  That is,
 > if an analysis region and resolution are unspecified, then it uses
 > the maximum extents and maximum (really lowest?) resolution of the
 > inputs.

Right. I've never used Arc/Info, but this sounds like exactly the
right idea. It follows the principle of never throwing away
information without a specific user request.

Glynn mentioned earlier that it would be painful to constantly be
rescaling or clipping maps. This could be mitigated by adding
clip=<region> res=<resolution> operators to the command-line of the
appropriate r.* commands.

And, it still does make sense to allow the user to specifically
provide a region that will be persistently by future r.* commands. So,
that could still happen. But, in my mind, that must be a specific user
request, and should not be equated with things like d.zoom as is
currently the case. Maybe we could drop g.region and make two new
commands, r.region and d.region? That would satisfy me I think.

-Carl

-- 
Carl Worth                                        
USC Information Sciences Institute                 cworth at east.isi.edu
3811 N. Fairfax Dr. #200, Arlington VA 22203		  703-812-3725