[GRASS-user] Help needed in creating a thematic map

RAVI KUMAR ravivundavalli at yahoo.com
Sat Mar 21 18:40:16 EDT 2009


Hi,
have you tried Qgis, which also comes with built in GRASS features.
Digitisation and attribution is quite easy in Qgis.
Ravi Kumar


--- On Sun, 3/22/09, Markus Neteler <neteler at osgeo.org> wrote:

> From: Markus Neteler <neteler at osgeo.org>
> Subject: Re: [GRASS-user] Help needed in creating a thematic map
> To: "Thomas Adams" <Thomas.Adams at noaa.gov>
> Cc: "grass-user" <grass-user at lists.osgeo.org>
> Date: Sunday, March 22, 2009, 1:38 AM
> Thomas,
> 
> On Sun, Mar 8, 2009 at 4:03 AM, Thomas Adams
> <Thomas.Adams at noaa.gov> wrote:
> > List:
> >
> > I need to create a map in GRASS like the attached map.
> This needs to be done
> > on a daily basis, and it needs to be created by those
> who have little GIS or
> > GRASS knowledge or experience. The critical aspect is
> to manually
> > draw/digitize the critical "likely" or
> "possible" areas. And I am struggling
> > with v.digit doing this, but it's not the main
> problem.
> 
> (which v.digit do you use?)
> Perhaps Featureserver would be a good idea here:
> http://featureserver.org/
> http://www.paolocorti.net/2008/02/21/a-day-with-featureserver-1/
> 
> (random demo: http://dev.riverchange.org/featureserver/
>  use the + at top right to activate WMS
>  SHIFT-left-mouse-button to zoom in via box
> )
> 
> Or the new digitizer in GRAS 6.4:
> http://grass.osgeo.org/screenshots/vector.php
> -> New vector digitizer tool with advanced editing
> features
> 
> > The key issue is
> > attaching attribute data to the polygonal regions that
> define the period
> > over which the "likely" or
> "possible" areas apply, as the graphic shows.
> 
> Both Featureserver and GRASS digitizer support this.
> 
> > ALSO, the boundary data and the attributes (the valid
> Date period) need to
> > be exported to an ascii text file which is then
> ftp'ed to a central location
> 
> (new) v.out.ascii export attributes in point mode. You
> could export
> the ASCII data in "standard" format, then convert
> centroids to points
> and in a second run of v.out.ascii export attributes.
> 
> > — the end users use their own software to combine
> other such files to create
> > a graphic (actually the one I am showing). Now,
> combining the exported data
> > into the format needed by the end user is not an
> issue,
> 
> At this point I would export SHAPE format which includes
> the attributes
> in the DBF table.
> 
> > it's really a matter
> > of how to most efficiently (easily) get the Starting
> and Ending dates into
> > the attributes of the polygons.
> 
> I would just use two columns in the attribute table.
> 
> > Also, should I try to use a separate vector
> > map for each polygon of the same type
> ("likely" or "possible") or should
> > they be in different layers?
> 
> IMHO yes.
> 
> > I'll have to write detailed instructions covering
> how to do this, but I need
> > to know how to do this first!
> >
> > I'm very open to suggestions…
> 
> Hope this helps,
> Markus
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