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<TITLE>Re: [postgis-users] What is the tolerance parameter for simplify?</TITLE>
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<DIV id=idOWAReplyText51609 dir=ltr>
<DIV dir=ltr><FONT face=Arial color=#000000 size=2>Having simplify use the units
of the projection probably was easier to implement but what does it really mean
to use a 1/10 of a degree of tolerance? Why doesn't postgis allow the use of
more reasonable values say meters? Why don't more functions work more like
distance_spheroid (where you provide a spheroid to use for computation)? I
ran into the same problem with area. What possible use is there knowing the
degrees^2 of a polygon? It would seem that with the SRID and the proper spheroid
more intuitive values could be used for functions like area and simplify and
area. To compute areas for my data I know have to read my data out of the
database, reproject it and compute my values. It would be much more
convenient and less error prone if the database could do this for
me.</FONT></DIV>
<DIV dir=ltr> </DIV>
<DIV dir=ltr><FONT face=Arial color=#000000 size=2>So what are the reasons for
not providing this type of functionality in the database?</FONT></DIV>
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<DIV dir=ltr><FONT face=Arial size=2>-e</FONT></DIV></DIV>
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<FONT face=Tahoma size=2><B>From:</B> strk@refractions.net
[mailto:strk@refractions.net]<BR><B>Sent:</B> Tue 1/4/2005 1:23 AM<BR><B>To:</B>
Ethan Alpert<BR><B>Cc:</B>
postgis-users@postgis.refractions.net<BR><B>Subject:</B> Re: [postgis-users]
What is the tolerance parameter for simplify?<BR></FONT><BR></DIV>
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<P><FONT size=2>On Mon, Jan 03, 2005 at 05:41:02PM -0700, Ethan Alpert
wrote:<BR>> Just curious what the units are. I have geometries in SRID 4326
(lat/lon<BR>> wgs84) so what units would the tolerance parameter be in when
calling<BR>> simplify?<BR>> <BR>> Thanks,<BR>> <BR>>
-e<BR><BR>It would be the units of the projection.<BR>Decimal degrees in your
case.<BR><BR>--strk;<BR><BR>For standing up against patentability of
software,<BR><BR> Thank You, Poland!<BR><BR>Read the
intervention: <A
href="http://kwiki.ffii.org/ConsPolon041221En">http://kwiki.ffii.org/ConsPolon041221En</A><BR>Send
your thanks:
thankyoupoland.info<BR>Read/do more:
<A
href="http://www.noepatents.org/">http://www.noepatents.org/</A><BR></FONT></P></DIV>
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