[GRASS-user] vectors: how to find the gravitation centre of point data ?

["Peter Löwe"]

[...]
> > is there an easy way to derive the centre of a cloud of points ?
> > 
> > I am aware that the set of vector points ("cloud of points") could be
> > used to stake out a polygon/boundary and use v.centroid etc etc to
> > derive in turn its' centroid, but I am hoping for an easier solution
> > .. ?
> > 
> > This issue stems from working with v.to.db: currently it is not
> > possible to upload xy coordinates for "multiploygons" into a
> > database, i.e: Within a vector layer, there might be several
> > boundaries which all share the same category value. If the
> > "gravitational centre/ super-centroid" for these boundaries could be
> > (conveniently) calculated, the v.to.db issue could be taken care of.
> 
> 
> Why not use v.dissolve on these polygons and then get the centroids of 
> the result ?

This option fails if the polygons don't have common borders. An example for this would be multiple polygons describing spatial exclaves of a territory/county/soil type, etc. 

> Another (very wild) guess: what about the mean of the coordinates of the 
> individual polygons' centroids ?

That would be great if it could be automated.

Peter

> 
> Moritz

-- 
Dr. Peter Löwe
<peter.loewe at gmx.de>





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