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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>The easy answer is if was done in ArcView
3.x then the methodology can be duplicated in PostGIS. All you would need to
do is view the avenue code and recreate with the functions available in
PostGIS. Looping and iterations could be hard but not impossible.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>The hard question is what is the status of
the avenue code? If it is copyrighted then you are stuck without the
permission of the owner.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Bruce Rindahl<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
postgis-users-bounces@postgis.refractions.net
[mailto:postgis-users-bounces@postgis.refractions.net] <b><span
style='font-weight:bold'>On Behalf Of </span></b>William Andersen<br>
<b><span style='font-weight:bold'>Sent:</span></b> Wednesday, July 05, 2006
11:44 AM<br>
<b><span style='font-weight:bold'>To:</span></b> <st1:PersonName w:st="on">PostGIS
Users Discussion</st1:PersonName><br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [postgis-users]
Amoeba Hulls</span></font><o:p></o:p></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>Paul, Steve,<br>
<br>
Thanks for the quick replies, unfortunately it's pretty hard to tell from those
images if they match.<br>
<br>
I've done some more digging and it turns out that these shapes were created in
Arcview 3.x. The notes I have say... <br>
<br>
> This approach selects a number of the outliers and joins the extreme
points using elliptical arcs. <br>
> The arcs are all created in a direction moving out from the store.<br>
<br>
However, I dont see customer points at the discontinuities in the hulls, so it
appears that the "extreme points" are perhaps interpolated. <br>
<br>
<br>
Will<o:p></o:p></span></font></p>
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<p class=MsoNormal><span class=gmailquote><font size=3 face="Times New Roman"><span
style='font-size:12.0pt'>On 7/5/06, <b><span style='font-weight:bold'>Paul
Ramsey</span></b> <<a href="mailto:pramsey@refractions.net">pramsey@refractions.net</a>>
wrote:</span></font></span><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>William,<br>
<br>
It doesn't look like this is a standard algorithm, but more likely a<br>
particular empirical technique provided by the particular software you<br>
were using. So substituting some other technique might yield a <br>
different shape entirely... do any of the techniques mentioned here<br>
<<a
href="http://www.geospatial-online.com/geospatialsolutions/article/articleDetail.jsp?id=1348">http://www.geospatial-online.com/geospatialsolutions/article/articleDetail.jsp?id=1348
</a>><br>
sound like what was done to your data?<br>
<br>
Paul<br>
<br>
William Andersen wrote:<br>
><br>
> I'm fairly new to postgis, and working to automate a number of<br>
> processes.<br>
><br>
> We are trying to compute market area polygons that look like the <br>
> attached image. These were created by some older software.<br>
><br>
><br>
> They are referred to as Amoeba Hulls, and they contain 80% of a<br>
> store's customers. However I can't find any solid documentation that <br>
> would allow me to reproduce them.<br>
><br>
> Does anyone have any ideas how these shapes are created or an<br>
> alternate name that I might be able to google? Additionally, we may<br>
> be in a position to finance the development of this feature. <br>
><br>
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