[GRASS-user] Re: grass-user Digest, Vol 52, Issue 55

[Michael Barton]

On Aug 24, 2010, at 3:34 AM, grass-user-request at lists.osgeo.org wrote:

> Date: Mon, 23 Aug 2010 17:20:19 -0700 (PDT)
> From: Hamish <hamish_b at yahoo.com>
> Subject: Re: [GRASS-user] BAnk and ditch symbols in grass (or other
>        Open    Source GIS)
> To: grass-user at lists.osgeo.org, Dr Tim Southern
>        <tim.southern at talktalk.net>
> Message-ID: <573534.70593.qm at web110016.mail.gq1.yahoo.com>
> Content-Type: text/plain; charset=iso-8859-1
> 
> Tim wrote:
>> I am an archaeologist mainly working within woodlands and
>> need to be be able to display in grass of similar GIS the
>> location of woodland banks and their associated
>> ditches.? There is a standard set of symbols for this
> 
> any online link to an image of what they look like?
> 
> 
>> but is there a way of actually getting GRASS or other GIS to
>> implement these.
> 
> are they point symbols or line styles?
> 
> point symbols:
>  http://grass.osgeo.org/wiki/IconSymbols
> 
> line styles are more tricky, but I would not say impossible.
> 
>> If not has anyone any ideas on how to write the appropriate
>> code or adapt other code to do it.? My initial thoughts
>> were to digitize the location of the features to a vector
>> map.?
> 
> e.g. the fish on the above wiki page was "digitized" from the
> QGIS .svg symbol in Inkscape, then a little B?zier curve math
> to make the x,y points,
>  http://grass.osgeo.org/wiki/Symb-fish
> 
> the "classic" model for this is the CERL castle graphic for
> d.graph (see d.graph/grass_logo.txt in the source code),
> initially drawn on graph paper and then transfered.
> 
> 
> 
>> As a vector it has direction and therefore if a
>> standard was adopted say for example if a ditch existed it
>> was on the rhs of the vector and the dashes marking the bank
>> could then be placed on the lhs.
> 
> so you mean like cliff polylines rendered by Mapnik for
> OpenStreetMap:  http://wiki.openstreetmap.org/wiki/Cliff
> 
> e.g.
> http://www.openstreetmap.org/?lat=-44.1026&lon=-176.5281&zoom=13&layers=M
> 
> ?
> 
> see also geology/strike_triangle:
>  http://grass.osgeo.org/wiki/IconSymbols#New
> 
> grass vector lines have direction, so setting them as true-left
> and right bank can be easily done. (see `d.vect display=dir`)
> 
> 
>> Eventually the information about the profile of the bank
>> and ditch needs to be analyzed statistically so having the
>> information within a data base makes good sense.
> 
> should be pretty easy if lines were as a vector map. a number
> of tools exist for it.
> 
> 
> regards,
> Hamish

I wonder if an enterprising programmer could start with the d.rast.arrow code and use it to allow different symbols than arrows?

Michael