[GRASS-dev] Re: gis.m: resolution not preserved

[Michael Barton]

Maciek,

Perhaps something has changed. But when I discovered this behavior in
explore mode, I also did a bunch of tests in normal mode and looked at the
code. AFAICT, normal mode does not change resolution--though sometimes it
can get confusing as to what is happening between the different modes. Could
you please test it further and see if this is really happening and under
what circumstances.

Michale
__________________________________________
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


> From: Maciej Sieczka <tutey at o2.pl>
> Date: Fri, 18 Aug 2006 18:18:14 +0200
> To: Michael Barton <michael.barton at asu.edu>
> Cc: grass-dev <grass-dev at grass.itc.it>, Jarek Jasiewicz <jarekj at amu.edu.pl>
> Subject: Re: gis.m: resolution not preserved
> 
> Michael Barton napisa?(a):
>> I posted a message on this over a week ago and got no reply.
>> 
>> <http://grass.itc.it/pipermail/grass-dev/2006-August/024866.html>
>> 
>> I also discovered this and thought it was a bug at first. But when I looked
>> at the code (this new 'explore mode' was developed by Cedric Shock), I
>> realized that it was intentional.
>> 
>> That is, it is dynamically changing resolution to speed display times as you
>> zoom in and out.
>> 
>> I asked if this is what we wanted or not. There are advantages and
>> disadvantages. It needs to be documented in any case, of course.
> 
> Michael,
> 
> OK as to "explore" mode. BUT, there is still another issue - that the
> resolution is not preserved after zooming in gis.m in "normal" mode. Did
> you try to reproduce it? Could you fix it?
> 
> I'm reffering to the following part of my email:
> 
>>> Start Grass in spearfish.
>>> 
>>> # terminal:
>>> g.region rast=slope -a
>>> 
>>> # gis.m
>>> add raster 'slope'
>>> display it
>>> 
>>> # gis.m CLI
>>> g.region -g
>>> 
>>> n=4928030
>>> s=4913690
>>> w=589980
>>> e=609000
>>> nsres=30
>>> ewres=30
>>> rows=478
>>> cols=634
>>> 
>>> # gis.m
>>> zoom in/out a bit
>>> 
>>> # gis.m CLI
>>> g.region -g
>>> n=4925065.04215
>>> s=4921067.9817
>>> w=593703.886256
>>> e=599027.771749
>>> nsres=30.05308609
>>> ewres=30.07844911
>>> rows=133
>>> cols=177
>>> 
>>> As you see, the resolution is not preserved.
> 
>>> I tried adding -a for g.region calls in mapcanvas.tcl and it seems to
>>> solve the problem, but I'm not entirely sure which g.region calls really
>>> require it, and which should be be left without it.
> 
>>> Also, it seems that rastnum.tcl and georect.tcl would require same fix (?).
> 
> Maciek