[Manifold-l] merge points to areas

[Simon Greener (SpatialDB Advisor)]

On Wed, 10 Oct 2007 06:53:08 +1100, Bob Heitzman <rheitzman at gmail.com>  
wrote:

> I have a drawing containing points on a common grid and in dense groups,
> like blobs of mould I suppose, for want of a better description.
>
> I need to be able to coalesce these into areas, one per group. In  
> principle
> it's just a complex hull function, however, I want the complex hull of
> each group and not the whole drawing. If there were a small number of  
> groups I could select each by hand, but there are several hundred...
>
> Any suggestions as to how to automate this?

What defines a group? An attribute or the fact that they are "spatially  
correlated"?

If the latter, have you considered converting the drawing to a surface  
(via kriging or some such) then identifying the groups by spatial sql (eg  
one of the raster extension functions such as HeighMaj with a 9x9 window)?

regards
Simon
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