[GRASS-dev] lib/vask [i.points replacement]

[Michael Barton]

> From: Glynn Clements <glynn at gclements.plus.com>
> Date: Tue, 27 Jun 2006 16:49:51 +0100
> To: Michael Barton <michael.barton at asu.edu>
> Cc: Hamish <hamish_nospam at yahoo.com>, <grass-dev at grass.itc.it>
> Subject: Re: [GRASS-dev] lib/vask  [i.points replacement]
> 
> 
> As for processing multiple maps: the calculations involved in
> computing the projection from the GCPs are trivial (in terms of CPU
> usage) compared to the actual projection. It wouldn't be noticeably
> less efficient to have a script call the projection utility once for
> each map.
> 
> If you had an r.rectify command (or an extended r.proj) which
> rectified a single map using an explictly-specified GCP file, it
> shouldn't be much work to re-implement i.rectify as a script which
> runs r.rectify on each map in the REF file, using the POINTS file from
> the "group" directory.

I was thinking of having it work more like g.remove. You could simply list a
set of maps in the input argument. e.g.,

r.rectify input=map[,map,map,...] points=file location=source_location
mapset=source_mapset method=[method (default to 1st order)]

either have a v.rectify that works the same way (currently v.transform only
works with maps in the same mapset for source and target) or have a
g.rectify that would replace input= with vect= and rast=



> 
> Rectifying /out/ of the current mapset might be tricker, but that
> particular behaviour is arguably a bug which should be fixed.

agreed

> 
> Aside:
> 
> I've wondered whether it would be worth having a general-purpose
> "g.multi" command which executes a command "template" on multiple
> maps. This first occurred to me in the context of handling colour
> images as R/G/B channels; i.e. having a g.rgb command which would be
> used like e.g. "g.rgb r.rescale in=inmap.% out=outmap.% ...", where
> the % would be replaced with r/g/b on each run.
> 

Interesting, but is this necessary when you can have multiple inputs?

Michael

__________________________________________
Michael Barton, Professor of Anthropology
School of Human Evolution & Social Change
Center for Social Dynamics and Complexity
Arizona State University

phone: 480-965-6213
fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton