<html><body><div style="color:#000; background-color:#fff; font-family:verdana, helvetica, sans-serif;font-size:10pt"><div><span>Hi Andrea,</span></div><div><br><span></span></div><div><span>I'm still working on this issue. To my knowledge there are no Collections. The GeometryType on all records in both tables is POLYGON. So I expect the LINESTRING error to be an internal issue where I'm unable to detect or prevent this from happening.</span></div><div><span><br></span></div><div><span>I you or anybody else has some idea's please let me know.</span></div><div><br><span></span></div><div><span>thanks,</span></div><div><span>Ge</span></div><div><br></div><div style="font-family: verdana, helvetica, sans-serif; font-size: 10pt;"><div style="font-family: times new roman, new york, times, serif; font-size: 12pt;"><font face="Arial" size="2"><hr size="1"><b><span style="font-weight:bold;">From:</span></b> Andrea Peri <aperi2007@gmail.com><br><b><span
style="font-weight: bold;">To:</span></b> PostGIS Users Discussion <postgis-users@postgis.refractions.net><br><b><span style="font-weight: bold;">Sent:</span></b> Thursday, September 22, 2011 12:02 PM<br><b><span style="font-weight: bold;">Subject:</span></b> Re: [postgis-users] ST_Insersection problem<br></font><br>
<div id="yiv1131984839"><pre>>Hello Group,<br>>We are using "POSTGIS="1.5.1" GEOS="3.2.2-CAPI-1.6.2" PROJ="Rel. 4.7.1, 23 September 2009" LIBXML="2.7.6" USE_STATS" and having a problem with ST_Intersection().<br>
>Given the following query<br>>select count(st_intersection(tbl_a.the_geom,tbl_b.the_geom)) from tbl_a, tbl_b;<br>>will result in this error message<br>>NOTICE: TopologyException: found non-noded intersection between LINESTRING (62723.7 426635, 62722.5 426634) and LINESTRING (62723.7 426635, 62726.2 426632) at 62723.7 426635<br>
>ERROR: GEOS Intersection() threw an error!<br>>SQL status:XX000<br>><br>>After the NOTICE message we expect the query to continue but it doesn't. Both tables have all records st_isvalid='t'.<br>><br>
>Does anyone know a solution or workaround for this problem?<br>><br>>Thanks,<br><br>Hi,<br>I give my 2ct. :)<br>The problemyou report is not really a problem of postgis, but instead is a problem of the finite arithmetic use by the pcs and of the methematical algorithm used .<br>
<br>I have every time the error you report.<br>Please notice I run about 10-20 million records of geometry and some geometry has also 1 million vertex :)<br><br>Is a nightmare.<br>But this is the beautiful and the hell of the arithmetic finite .<br>
<br>To resolve this you must detect at every step what happened and filter they using specific "where" clause or CASE operators.<br><br>Is pretty easy,<br>you will see often it return a Collection, and you get only the lines or the polys from that, again<br>
you can filter out the empty geometry.<br>After this long path you will have a good procedure to clean all the problem of a real intersection on a arithmetic finite machine.<br><br>Regards,<br>Andrea Peri.<br><br></pre><br clear="all">
<br>-- <br>-----------------<br>Andrea Peri<br>. . . . . . . . . <br>qwerty אטלעש<br>-----------------<br><br>
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