[GRASS5] [bug #3704] (grass) d.rast.arrow does not save a line in the monitor history

[Michael Barton]

A negative magnitude is not necessarily an error, but could have real
meaning.

Michael
__________________________________________
Michael Barton, Professor of Anthropology
School of Human Evolution and Social Change
Arizona State University
Tempe, AZ 85287-2402

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



> From: Daniel Calvelo Aros <dcalvelo at minag.gob.pe>
> Reply-To: <daniel.calvelo at minag.gob.pe>
> Date: Wed, 12 Oct 2005 10:02:02 -0500
> To: Hamish <hamish_nospam at yahoo.com>, Michael Barton <michael.barton at asu.edu>
> Cc: <grass-bugs at intevation.de>, <david.p.finlayson at gmail.com>,
> <grass5 at grass.itc.it>
> Subject: Re: [GRASS5] [bug #3704] (grass) d.rast.arrow does not save a line in
> the monitor history
> 
> From: Hamish <hamish_nospam at yahoo.com>
> Sent: Wed, 12 Oct 2005 19:05:02 +1300
>> 
>> Done & in CVS.
>> 
>> d.rast.arrow now can take a raster map for arrow magnitude and there
>> is a new skip option to only draw arrows every Nth cell.
>> 
>> screenshot showing raster elevation level, with arrow direction and size
>> controlled by aspect and slope maps (created with r.slope.aspect); skip
>> factor set to only draw every third cell; and grid color set to "none":
>> 
>>   http://bambi.otago.ac.nz/hamish/grass/d_rast_arrow_magnitude.png
>> 
>> The question remains what to do if fed negative magnitudes. Right
>> now I have it skipping over that arrow (as it does for NULL values),
>> but it could take the absolute value or rotate the arrow 180 degrees.
> 
> I'd say keep the current skip, but issue a warning; whatever the cartographer
> needs to do he can using r.mapcalc (tell him in the warning and the docs).
> 
> The other possibility is to add an option, but I've the impression it somehow
> reduces flexibility...
> 
> Daniel.