[GRASS-dev] Re: [GRASS-user] commercial use of GRASS in Australia

[Hamish]

David Hine wrote:
> Telstra is the largest telco in Australia and was once fully owned by the
> federal government as part of the post office. They used GRASS for
> analysis.. as below GRASS only in research institutions.. Not in this case.
..
> >From http://www.pcworld.idg.com.au/index.php/id;1787316484 


I was expecting to see v.net.*, but from the methodology in the paper they used
v.distance. And they mention lat/lon a lot.

Perhaps it is time to revisit GForge bug #378:
 http://wald.intevation.org/tracker/?func=detail&group_id=21&aid=378&atid=204

Apparently they double-checked the results with published values, and a
distance given in decimal degrees is obviously wrong, so I don't think they
made any mistakes. My guess is that they actually reprojected the lat/lons for
the processing or created a v.dist output=line_segments map and used something
like d.what.vect (which does use geodetic distance) to extract the distances.


Regardless, it would be nice to fix 'v.distance upload=dist,to_along' to use
geodetic distance; check the nearest feature calculation isn't biasing to
features in the N-S plane at high latitudes; and more generally make the vector
modules & libraries more Lat/Lon aware.

Or start adding checks into the code of any module which could output a
misleading result:

if (G_projection () == PROJECTION_LL)
  G_fatal_error(
      _("%s works in Euclidean space. Please project your data."),
      G_program_name() );


Hamish


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