<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman,new york,times,serif;font-size:12pt"><div>hi<br>I'm so sorry. i was so mad because i didn't find ST_IsValidReason function myself. <br>Thanks to PostGIS and its developers, it works nice.<br>Also, i found an option in OpenJump for validating features.<br><br>Best Regards<br><br></div><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><br><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><font face="Tahoma" size="2"><hr size="1"><b><span style="font-weight: bold;">From:</span></b> Saka Royban <sakaroyban@yahoo.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> Thu, December 30, 2010 11:57:42 AM<br><b><span style="font-weight:
bold;">Subject:</span></b> Re: [postgis-users] How buffer trick validates features?<br></font><br>
<meta http-equiv="x-dns-prefetch-control" content="off"><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;">Thanks a lot Mr. Ramsey<br>one more question: is there a way to understand what is wrong with invalid feature? i.e. any software, package, etc.<br><br>sorry for simple questions. I'm a beginner.<br>Regards<br><div><br></div><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><br><div style="font-family: arial,helvetica,sans-serif; font-size: 13px;"><font face="Tahoma" size="2"><hr size="1"><b><span style="font-weight: bold;">From:</span></b> Paul Ramsey <pramsey@opengeo.org><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> Thu, December 30, 2010 12:00:14 AM<br><b><span style="font-weight: bold;">Subject:</span></b> Re:
[postgis-users] How buffer trick validates features?<br></font><br>
In order to buffer a feature you have to create a new set of line work<br>then build a polygon from that. If the new set of linework is the old<br>set, the built feature looks much line the old one. But because it's<br>built by the database (by GEOS, in this case) it is built according to<br>the known topology rules we want, and hence is more likely to be<br>valid.<br><br>P.<br><br>On Wed, Dec 29, 2010 at 12:21 PM, Saka Royban <<a rel="nofollow" ymailto="mailto:sakaroyban@yahoo.com" target="_blank" href="mailto:sakaroyban@yahoo.com">sakaroyban@yahoo.com</a>> wrote:<br>> Hi all.<br>> I was reviewing postgis workshop presented in FOSS4G 2007. it presents a<br>> trick like this for making invalid features valid:<br>> UPDATE bc_voting_areas<br>> SET the_geom = ST_Buffer(the_geom, 0.0)<br>> WHERE gid = 4897;<br>><br>> I'm wondering how it works in background!!!. I mean how buffering with zero<br>> distance makes features
valid?<br>> what is in buffer
function?<br>><br>> Regards<br>><br>><br>> _______________________________________________<br>> postgis-users mailing list<br>> <a rel="nofollow" ymailto="mailto:postgis-users@postgis.refractions.net" target="_blank" href="mailto:postgis-users@postgis.refractions.net">postgis-users@postgis.refractions.net</a><br><span><span>> <a target="_blank" href="http://postgis.refractions.net/mailman/listinfo/postgis-users">http://postgis.refractions.net/mailman/listinfo/postgis-users</a></span></span><br>><br>><br>_______________________________________________<br>postgis-users mailing list<br><a rel="nofollow" ymailto="mailto:postgis-users@postgis.refractions.net" target="_blank" href="mailto:postgis-users@postgis.refractions.net">postgis-users@postgis.refractions.net</a><br><a rel="nofollow" target="_blank"
href="http://postgis.refractions.net/mailman/listinfo/postgis-users">http://postgis.refractions.net/mailman/listinfo/postgis-users</a><br></div></div>
</div><br>
<meta http-equiv="x-dns-prefetch-control" content="on"></div></div></div><br>
</body></html>