[GRASS-user] V.distance

GRASS GRASS user
1

What algorithm does V.distance use for calculations?

Richard Chirgwin

2

On Jan 8, 2008 11:54 PM, Richard Chirgwin <rchirgwin@ozemail.com.au> wrote:

What algorithm does V.distance use for calculations?

For cartesian coordinate systems it currently uses 2D/3D Pythagoras.
Vect_line_distance() in
http://trac.osgeo.org/grass/browser/grass/trunk/lib/vector/Vlib/line.c

For LatLong it uses geodesic distance calculation (reference):
  Vect_line_geodesic_length() in
  http://trac.osgeo.org/grass/browser/grass/trunk/lib/vector/Vlib/line.c
which calls
  http://trac.osgeo.org/grass/browser/grass/trunk/lib/gis/geodist.c

Markus

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