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<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>Numerical differences in, for example, buffer:</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p><FONT face="Times New Roman" size=3></FONT></o:p> </P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>I noticed numerical differences between an sql statement through the ogr library versus directly through postgreSQL (I thought the sqlexecute goes through?). Has anyone noticed these differences as well? In the following dataset these numerical differences produce sort of ears that are equal to the radius of the buffer (so not really negligible and quite visible).</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><o:p><FONT face="Times New Roman" size=3></FONT></o:p> </P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>Here is an example (other number combinations are less visible, but still produce errors):</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><o:p><FONT face="Times New Roman" size=3></FONT></o:p> </P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>Buffer of Point(3.0 -3.7) results:</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><o:p><FONT face="Times New Roman" size=3></FONT></o:p> </P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>C:\Program Files\FWTools0.9.9>ogr2ogr -f "ESRI Shapefile" -sql "SELECT buffer(Ge</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>omFromText('POINT(3.0 -3.7)'), 1.0,4)" buffer.shp "PG:user=postgres password=xxx </FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>dbname=xxx host=localhost port=5432"</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><o:p><FONT face="Times New Roman" size=3></FONT></o:p> </P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>In numbers:</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>4.0000000000000000,-3.6999999999999957</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>3.9238604590292496,-4.0820349338195641</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>3.6289817765446712,-4.2508567811706746</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>3.3826834323961990,-4.6238413855257363</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>3.0000000000437552,-4.7000000000000002</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>2.6173153755938636,-4.6238413855600982</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>2.2928932188610727,-4.2508567812341678</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>2.0761204675187801,-4.0820349339023796</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>2.0000000000000000,-3.7000000000716033</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>2.0761204674499845,-2.0673165677282341 … ear 1 … should be around 2.07.., -3.06..</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>2.2928932187340854,-2.9928932188928199</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>2.6173153754279466,-2.7761192754430666</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>2.9999999998653095,-2.6999999999999957</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>3.3826834322302819,-2.7761192753399788</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>3.6289817810754332,-2.9928932187023385</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>3.9238604586694903,-2.0673165674793625 … ear 2 … should be around 3.92.., -3.06..</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>4.0000000000000000,-3.6999999998204118</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>4.0000000000000000,-3.6999999999999957</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><o:p><FONT face="Times New Roman" size=3></FONT></o:p> </P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>Initially, I thought this might be a PostGIS or Geos issue, so I tested the same sql </FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>statement directly in PostgreSQL using:</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><o:p><FONT face="Times New Roman" size=3></FONT></o:p> </P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>SELECT AsText(buffer(GeomFromText('POINT(3.0 -3.7)'), 1.0,4))</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><o:p><FONT face="Times New Roman" size=3></FONT></o:p> </P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>"POLYGON((</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>4 -3.7</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>3.92387953251558 -4.08268343235472</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>3.70710678120242 -4.40710678117067</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>3.3826834323962 <SPAN style="mso-spacerun: yes"> </SPAN>-4.6238795324984</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>3.0000000000449 <SPAN style="mso-spacerun: yes"> </SPAN>-4.7</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>2.61731656768676 -4.62387953253276</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>2.29289321886107 -4.40710678123417</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>2.07612046751878 -4.08268343243768</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>2<SPAN style="mso-spacerun: yes"> </SPAN><SPAN style="mso-spacerun: yes"> </SPAN>-3.70000000008979</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>2.07612046745006 -3.31731656772824</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>2.29289321873409 -2.99289321889282</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>2.61731656752084 -2.77612046753596</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>2.99999999986531 -2.7</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>3.38268343223028 -2.77612046743287</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>3.70710678107543 -2.99289321870234</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>3.92387953244686 -3.31731656747936</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>4 <SPAN style="mso-spacerun: yes"> </SPAN>-3.69999999982041</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>4 <SPAN style="mso-spacerun: yes"> </SPAN>-3.7</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>))"</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><o:p><FONT face="Times New Roman" size=3></FONT></o:p> </P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>The PostGIS buffer function did not reproduce the ears on the buffer. Also, </FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>overall there are some differences between the datasets created through ogr2ogr </FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>versus directly in PostgreSQL. The shapefile is not really an issue since I also tested reading the results directly through ogr ...</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><o:p><FONT face="Times New Roman" size=3></FONT></o:p> </P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>...any hints/help is appreciated!</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><o:p><FONT face="Times New Roman" size=3></FONT></o:p> </P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>Thanks,</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>Thomas</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><o:p><FONT face="Times New Roman" size=3> </FONT></o:p></P></DIV><p>
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