[postgis-users] Amoeba Hulls
pramsey at refractions.net
Wed Jul 5 12:50:12 PDT 2006
I think that is a good start, but as you note, sharp radius changes
would be baaad. William's example also has inflexions in the boundary
where no points exist at all, which is interesting.
Stephen Woodbridge wrote:
> Would you not just connect the dots, like this.
> 1) determine the 80% points, say by distance or whatever
> 2) order the points by radial angle increasing and radius decreasing
> 3) use something like a window say plus/minus 1/2 degree and select the
> maximum radius in the window and add that point to the polygon
> 4) step 1/2 degree and repeat 3)
> 5) close the polygon
> You probably need to have some special handling if there is a sudden
> change in radius to make sure no points get clicked out of the polygon.
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