[GRASS-user] Re: BAnk and ditch symbols in grass (or other Open Source GIS)

[Michael Barton]

Sounds like good ideas when you get a chance to move ahead with them. Maybe someone will be able to help you on this.

Michael

On Aug 24, 2010, at 7:14 PM, Hamish wrote:

>> Michael wrote:
>>> I wonder if an enterprising programmer could start with the
>>> d.rast.arrow code and use it to allow different symbols than
>>> arrows?
>> 
>> FYI I am already well underway on that, have half-written a new
>> module called d.barb. Primarily for drawing wind barbs on met
>> maps, but also allows things like straws instead of arrows.
>> 
>> input is either from a raster map array like d.rast.arrow, or
>> a vector map with direction and magnitude taken from the points'
>> attribute table.
> 
> (I should mention that I've been "well underway" on that for more than
> a year, it's been stalled while I waited for a job to come up that needed
> it so I could justify my time. I hesitated to put it into addons svn
> as it is still pre-alpha, but if anyone wants to collaborate on it I'm
> happy to put it up there)
> 
> 
> as for the hatched lines for banks and depressions, continuing on with the
> idea of using 'v.split length=' in a loop with length taken from each line
> segment's attribute table to set the density, then 'v.to.points -v' to pull
> out the vertices, then something to upload the tangent slope of the line
> at each vertex to that point's attribute table, then using 'd.vect size_column= rotate_column=' to render a symbol (centered at 0,0) at 90+20
> degrees to the line, of the appropriate length (negative length could be
> right side of line instead of left, copy idea for that from v.lrs.segment?).
> 
> and so for different line segments you get different hatching styles.
> 
> not really automatic, but enough for a prototype or one-off proof of
> concept before getting into it with a full module.
> 
> ?
> Hamish
> 
> 
> 
>