[GRASSLIST:3110] weighted Thiessen polygons

Michael Barton michael.barton at asu.edu
Tue Apr 6 12:03:30 EDT 2004

On Monday, April 5, 2004, at 10:01  PM, Multiple recipients of list 

> From: "Colin Nielsen" <nielsen at myrealbox.com>
> Date: Mon Apr 5, 2004  5:13:58  PM America/Phoenix
> To: hamish_nospam at yahoo.com
> Cc: GRASSLIST at baylor.edu
> Subject: [GRASSLIST:3100] Re: Xtent Modelling (wieghted Thieseen)
> I'm an archaeologist trying to determine possible 
> territories/influence around sites. I want to give certain sites a 
> greater weight of influence than others (such as a capital city vs a 
> small farm). It would be relatively easy to impliment from a 
> programmers point of view. Instead of drawing the boundary at 50% 
> between the sites put it at 70% or whatever based on the wieghting. I 
> was just hoping someone had already done this. Yes/ no?
> -Colin

I am also an archaeologist. The short answer is no. No one has produced 
for GRASS a kind of weighted Voronoi/Thiessen routine that you describe.

I understand what you want to do, and agree that it could be useful. 
However, I'm not sure that a Voronoi diagram is what you need. 
Remember, if you use a weighting variable to change the distance at 
which splits are made between sites, it changes it in all directions. 
For a small site, the distance might need to be 30% in one direction, 
but 50% in another. The program would need to work this out. Maybe you 
could actually draw something this way that completely fills space like 
Voronoi diagrams, but I worry that there would be trouble with the 
vertices. Of course, maybe it is just my faulty imagination first thing 
in the morning.

Michael Barton
Michael Barton, Professor & Curator
Department of Anthropology
Arizona State University
Tempe, AZ  85287-2402

voice: 480-965-6262; fax: 480-965-7671

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