[GRASS-user] Re: [GRASS-dev] d.barb: call for testing

[Dylan Beaudette]

Nice work! 

I had been thinking about using this type of graphic to describe the potential 
movement of water/sediment flux along landscape gradients for some time now... 
With a little bit of tinkering around, I was able to get a figure that matched 
my mental picture:

http://basho.dyndns.org/~dylan/temp/d.barb_terrain_example.jpg

Colors represent mean curvature, contours are every 10 meters, white lines are 
from r.flow, arrow direction is from an aspect map, arrow length is scaled by 
the compound topographic index.

Thanks!

Dylan


On Wednesday, April 27, 2011, Hamish wrote:
> Hi,
> 
> I have added a new C module in the addons svn which will draw wind barbs,
> straw plots, and arrow plots from a raster array or sparse vector point
> data. It can use either direction + magnitude, or u + v components as the
> input, and can produce a legend key.
> 
> Some of this functionality is already covered by d.rast.arrow and d.vect,
> but I thought I'd bring it together into a dedicated tool and add some
> commonly needed options.
> 
> It's still a work in progress, and there are still a few things on the
> todo list, but I think it's ready to get some testing now.
> 
> Once the bugs are out and the design & feature set have been finalized
> I'd port it to grass7 and hope to add it to the main distribution + GUI.
> (One weird thing I notice is that in the tcl/tk GUI the legend_at=
> option appears as a tick box not a text entry field. ?)
> 
> 
>   http://grass.osgeo.org/wiki/GRASS_AddOns#d.barb
>   http://trac.osgeo.org/grass/browser/grass-addons/display/d.barb
> 
> screenshot:  (style=arrow)
>   http://bambi.otago.ac.nz/hamish/grass/screenshots/narr-
a_221_20100629_1800_000_10m_winds.png
> 
> 
> maybe g.extension works to install it if you compiled grass yourself?
>  (I haven't tried installing it that way yet)
> 
> comments, wishes, & criticisms welcome.  usage follows, see the help
> page for more explanation & examples.
> 
> 
> Hamish
> 
> 
> 
> --------------------------------------
> 
> GRASS65> d.barb --help
> 
> Description:
>  Draws flow barbs.
> 
> Keywords:
>  
> 
> Usage:
>  d.barb [-r] [direction=name] [magnitude=name] [u=name] [v=name]
>    [input=name] [layer=value] [style=string] [color=name] [skip=value]
>    [scale=value] [peak=value] [aspect_type=string]
>    [legend_at=x,y[,x,y,...]] [legend_velo=value[,value,...]]
>    [legend_fontsize=value] [--verbose] [--quiet]
> 
> Flags:
>   -r   Rotate direction 180 degrees
>         Useful for switching between atmospheric and oceanographic 
conventions
>  --v   Verbose module output
>  --q   Quiet module output
> 
> Parameters:
>         direction   Raster map (or attribute column) containing velocity 
direction
>         magnitude   Raster map (or attribute column) containing velocity 
magnitude
>                 u   Raster map (or attribute column) containing u-component 
of velocity
>                 v   Raster map (or attribute column) containing v-component 
of velocity
>             input   Name of input vector map
>             layer   Layer number
>                      A single vector map can be connected to multiple 
database tables. This number determines which table to use.
>                     default: 1
>             style   Style
>                     options: arrow,barb,straw
>                     default: arrow
>             color   Color
>                      Either a standard color name or R:G:B triplet
>                     default: black
>              skip   Draw arrow every Nth grid cell
>                     default: 10
>             scale   Scale factor for arrow rendering
>                     default: 1.0
>              peak   Maximum value for scaling (overrides map's maximum)
>       aspect_type   Direction map aspect type
>                     options: cartesian,compass
>                     default: cartesian
>         legend_at   Screen percentage for legend barb ([0,0] is bottom-left)
>                      Draws a single barb and exits
>                     options: 0-100
>                     default: 10.0,10.0
>       legend_velo   Velocity for legend key arrow
>   legend_fontsize   Font size used in legend
>                     default: 14
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> 


-- 
Dylan E. Beaudette
USDA-NRCS Soil Scientist
California Soil Resource Lab
http://casoilresource.lawr.ucdavis.edu/