[postgis-users] Amoeba Hulls

[Paul Ramsey]

So my guess is that you use drive-time to segment your population of 
customers relative to the store into the "nearest X%" and then draw a 
"shape" around that cloud of points.  And drawing the shape is the "fun" 
part.

William Andersen wrote:
> It appears to be the same as this functionality in Business Analyst
> 
> http://www.esri.com/software/arcgis/extensions/businessanalyst/about/customer-market.html 
> <http://www.esri.com/software/arcgis/extensions/businessanalyst/about/customer-market.html>
> 
> I thought this was done using some older version of Arcview, but i'm not 
> very familiar with esri's offerings.
> 
> Will
> 
> On 7/5/06, *Paul Ramsey * <pramsey at refractions.net 
> <mailto:pramsey at refractions.net>> wrote:
> 
>     This wouldn't be in vanilla arcview, was it in Network Analyst? The top
>     80% of points by drive distance might yield this shape.  Finding the
>     points would be straightforward, and then the hull building would be the
>     hand-waving part.
> 
>     P
> 
>     William Andersen wrote:
>      > Paul, Steve,
>      >
>      > Thanks for the quick replies, unfortunately it's pretty hard to tell
>      > from those images if they match.
>      >
>      > I've done some more digging and it turns out that these shapes were
>      > created in Arcview 3.x. The notes I have say...
>      >
>      >  > This approach selects a number of the outliers and joins the
>     extreme
>      > points using elliptical arcs.
>      >  > The arcs are all created in a direction moving out from the
>     store.
>      >
>      > However, I dont see customer points at the discontinuities in the
>     hulls,
>      > so it appears that the "extreme points" are perhaps interpolated.
>      >
>      >
>      > Will
>      >
>      > On 7/5/06, *Paul Ramsey* < pramsey at refractions.net
>     <mailto:pramsey at refractions.net>
>      > <mailto:pramsey at refractions.net
>     <mailto:pramsey at refractions.net>>> wrote:
>      >
>      >     William,
>      >
>      >     It doesn't look like this is a standard algorithm, but more
>     likely a
>      >     particular empirical technique provided by the particular
>     software you
>      >     were using.  So substituting some other technique might yield a
>      >     different shape entirely... do any of the techniques
>     mentioned here
>      >    
>     <http://www.geospatial-online.com/geospatialsolutions/article/articleDetail.jsp?id=1348
>      >     <
>     http://www.geospatial-online.com/geospatialsolutions/article/articleDetail.jsp?id=1348>>
>      >     sound like what was done to your data?
>      >
>      >     Paul
>      >
>      >     William Andersen wrote:
>      >      >
>      >      > I'm fairly new to postgis, and working to automate a number of
>      >      > processes.
>      >      >
>      >      > We are trying to compute market area polygons that look
>     like the
>      >      > attached image. These were created by some older software.
>      >      >
>      >      >
>      >      > They are referred to as Amoeba Hulls, and they contain 80%
>     of a
>      >      > store's customers. However I can't find any solid
>     documentation that
>      >      > would allow me to reproduce them.
>      >      >
>      >      > Does anyone have any ideas how these shapes are created or an
>      >      > alternate name that I might be able to google?
>     Additionally, we may
>      >      > be in a position to finance the development of this feature.
>      >      >
>      >     _______________________________________________
>      >     postgis-users mailing list
>      >     postgis-users at postgis.refractions.net
>     <mailto:postgis-users at postgis.refractions.net>
>      >     <mailto:postgis-users at postgis.refractions.net
>     <mailto:postgis-users at postgis.refractions.net>>
>      >     http://postgis.refractions.net/mailman/listinfo/postgis-users
>      >
>      >
>      >
>      >
>     ------------------------------------------------------------------------
>      >
>      > _______________________________________________
>      > postgis-users mailing list
>      > postgis-users at postgis.refractions.net
>     <mailto:postgis-users at postgis.refractions.net>
>      > http://postgis.refractions.net/mailman/listinfo/postgis-users
> 
>     _______________________________________________
>     postgis-users mailing list
>     postgis-users at postgis.refractions.net
>     <mailto:postgis-users at postgis.refractions.net>
>     http://postgis.refractions.net/mailman/listinfo/postgis-users
> 
> 
> 
> ------------------------------------------------------------------------
> 
> _______________________________________________
> postgis-users mailing list
> postgis-users at postgis.refractions.net
> http://postgis.refractions.net/mailman/listinfo/postgis-users