[GRASS-user] Region setting correction

[Michael Barton]

I wanted to correct a few things I just said about  region settings.

1. If you run g.region from the command line‹either with arguments (e.g.,
g.region ­p) or without arguments so that it starts one of the autogenerated
GUI dialogs‹it sets and/or reports on the values in the WIND file. This is
the way I described it a few minutes ago.
2. BUT, if you run g.region from the menu, there is anomalous behavior that
may be the cause of considerable and repeated confusion. G.region started
from the menus will REPORT (i.e., with ­p set) on the region of the
currently active display window (i.e., whichever display currently has the
focus). If you try to set something with g.region run from the menu, it
seems to have NO EFFECT on a display OR on the WIND file.
3. However, if you set something from a g.region dialog run from the menu
AND select Œzoom to current region¹ from the menu button on the toolbar, the
display will match the g.region settings‹even though this is NOT in the WIND
file. 
4. If you set something from a g.region dialog started from the command line
(or issue a g.region command with arguments) and select Œzoom to current
region¹ from the menu button on the toolbar, it will have NO EFFECT on the
display zooming. 
5. If you zoom interactively in a map display and select Œset current region
(WIND file) to match display¹, this WILL change the  WIND file to match the
display (check by running g.region ­p from the command line). At this point,
it can insert some rounding error in resetting the WIND file to match the
display. I think this is what Maciek is seeing. I tried changing to a
g.region ­a (align to current region) and it had no effect on this rounding
error.

The map display interactive zooming and zoom menu button are behaving as
they should. 

1. Interactive zooming affects a dynamic region ONLY for that display and
DOES NOT affect the WIND file
2. Selecting Œzoom to current region¹ DOES change the display to match the
settings of g.region run from the menu‹but NOT from the command line.
3. Selecting Œset current region (WIND file)...¹ DOES change the WIND file
to match the display.

BUT (and a very confusing one at that), g.region run from the command line
and g.region run from the menus do NOT always behave the same way with
regard to the interactive zooming in a display. I have no idea why this is
so. Maybe someone else can enlighten me.

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


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