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

[Michael Barton]

This is great. Thanks much. Following up on the rest of the thread (not
reproduced here), this is moving toward a very useful new visualization
tool, especially if arrow magnitude (width or length, but maybe width is
better because of length limits imposed by grid sizes) can be read from
another map.

Currently, the arrows fill grid cells, set by the region resolution.
However, to be useful in a wider variety of uses (e.g., wind directions,
cost surface/travel visualization, animal movements/migration modeling, flow
intensities across channels, etc.) it would be useful to be able to drape a
map of arrows at a coarse resolution over a relief map (or nviz topography)
at a much higher resolution. I can't think of any way to do this, but maybe
someone out there can.

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

voice: 480-965-6262; fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton


> From: Harmish Bowman via RT <grass-bugs at intevation.de>
> Reply-To: Harmish Bowman via RT <grass-bugs at intevation.de>
> Date: Fri,  7 Oct 2005 02:38:27 +0200 (CEST)
> To: <david.p.finlayson at gmail.com>
> Cc: <grass5 at grass.itc.it>
> Subject: [GRASS5] [bug #3704] (grass) d.rast.arrow does not save a line in the
> monitor history
> 
> Ok, d.rast.arrow and d.rast.num are now added to the display monitor history
> list and should survive redraw, PNG export, zoom, etc.
> 
> 
> Also for d.rast.arrow I've added support for compass based aspect maps
> (degrees clockwise from north) and 360 degree resolution instead of D8 (where
> applicable).
> 
> i.e.
>  grass aspect maps:    1 deg resolution
>  compass aspect maps:  1 deg resolution
>  AGNPS aspect maps:    D8 resolution (45 degrees)
>  ANSWERS aspect maps:  15 degree resolution
> 
> 
> Two things to think about:
> - How to visualize MDF directional flow created by r.terraflow?
> 
> - With a little more effort, arrow size (magnitude) could be read
>   from a second raster map, perhaps with a default scaling factor which
>   could take the max of the raster range to be 10x the cell width.
>   i.e. Eulerian velocity fields!
> 
> 
> screenshot:
>   http://bambi.otago.ac.nz/hamish/grass/d_rast_arrow_360.png
> 
> 
> 
> enjoy,
> Hamish
> 
> 
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