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

[Michael Barton]

Hamish,

This looks great. I could have really used this in a paper on modeling
Viking seafaring last year. But we are going to do another one soon, so I'll
have a chance to try this out.

With respect to negative magnitudes, I like your idea. It would accurately
visually indicate the data. An alternate color would make it stand out even
more, but that probably complicates things too much.

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: Hamish <hamish_nospam at yahoo.com>
> Date: Wed, 12 Oct 2005 19:05:02 +1300
> To: 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
> 
> [d.rast.arrow too cluttered to be useful]
> 
>>> g.region rast=source_map
>>> d.rast source_map
>>> g.region res=  (res * 16)
>>> d.rast.arrow ...
>>> 
>>> perhaps that leads to aliasing problems?
>> 
>> This seems to work, but it is clunky. I could of course script a way
>> to change resolution, display arrows, and change it back again.
>> However, I wonder if this is desirable enough, when you make your
>> improvements to d.rast.arrow, that it is worthwhile to include a
>> (temporary) resolution setting in the module itself?
> 
> 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.
> 
> 
> enjoy,
> Hamish