[GRASS-user] Region definition in Grass 6.1 (and 6.1 cvs)

[Michael Barton]

Thanks for helping clarify this Maciej. A couple more items below.

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

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


> 
> Correct. All commands called from gis.m should inherit region set using
> other gis.m tools. And all commands called from Grass terminal should
> inherit region set using other tools called from terminal.
> 
> Only I think it's correct - gis.m own CLI and Grass terminal CLI are 2
> different beasts.
> 
>> but most important: If you zoom in and make some action (for example
>> r.to.vect) it will affect ONLY on zoomed fragment

IMPORTANT CLARIFICATION: Region zooming in the display generally ONLY
affects that display and related tools IN THAT DISPLAY. Most system wide
commands (e.g., r.to.vect) will respond to the current setting in the WIND
file, not the dynamic region setting in the display. This is because we are
trying to avoid having any particular display affect the system-wide WIND
file. 

So if you are running a system-wide command (i.e., not tied to a display,
its toolbar, or its layer tree) you need to make any desired region settings
via g.region. It doesn't matter whether g.region is run from the command
line or from a menu selection. Alternatively, you can display the region you
want, then select 'set WIND file from displayed region' from the menu button
on the display toolbar. If you just zoom interactively to somewhere in the
display without setting the WIND file, the region-related effects of a
system-wide command may not be what you want.

We may want to think about this more. Would it be better for a system-wide
command to affect the region set by g.region or the region displayed in a
particular display? Which display? How to make sure it is what you  want?


> 
> Correct IMHO (see above).
> 
>> try to change resolution from GUI (eg menu or GUI command line)
> 
> I tried. Behaves as expected (anything wrong for you?).
> 
> Maciek
> 
> P.S.
> 
> There is 1 bad thing happening here though - I can see that gis.m zoom
> tool doesn't preserve resolution:
> 
>> before:
>> nsres:      5
>> ewres:      5
> 
>> after:
>> nsres:      4.99846809
>> ewres:      4.99936821

This is a rounding issue due to not setting the -a flag in the interactive
zooming tools. There are some issues to this. I promised Maciej that I'd try
again to see if this can be done without messing up something else.

Michael

> 
> This shouldn't happen IMHO. I'll let Michael know about it.
> 
> Thanks.
> 
>