<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Don't forget:<div><br class="webkit-block-placeholder"></div><div>SELECT ST_IsValid(<span class="Apple-style-span" style="color: rgb(84, 0, 0); ">'MultiPolygon( ((0 0,0 3,3 3,3 0,0 <span class="Apple-style-span" style="color: rgb(0, 0, 0); ">0)),((11,1 4,4 4,4 1,1 1)))') --> FALSE</span></span></div><div><br class="webkit-block-placeholder"></div><div>P.</div><div><br><div><div>On Jan 11, 2008, at 1:19 AM, Guido Lemoine wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">SELECT ST_Area(ST_Intersection(GeomFromText('Polygon((0 0,0 3,3 3,3 0,0 <br>0))'),<br>GeomFromText('Polygon((1 1,1 4,4 4,4 1,1 1))'))) --> 4 (QED)<br><br>SELECT ST_Area(ST_Union(GeomFromText('Polygon((0 0,0 3,3 3,3 0,0 0))'),<br>GeomFromText('Polygon((1 1,1 4,4 4,4 1,1 1))'))) --> 14<br><br><br><br>Paul Ramsey wrote:<br><blockquote type="cite">ST_Area(ST_Intersection(g1,g2)) ?<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">On Jan 10, 2008, at 8:23 AM, <a href="mailto:olivier.amram@free.fr">olivier.amram@free.fr</a> wrote:<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"><blockquote type="cite">Yes, but how do you calculate the area of the intersection ?<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">Olivier.<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">Selon Guido Lemoine <<a href="mailto:guido.lemoine@jrc.it">guido.lemoine@jrc.it</a>>:<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Your multipolygon is simply two rings of 3 by 3. Defining them<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">as multipolygon does do nothing for intersection, so the area is 18<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">(which is 9 + 9). You need to look up what intersection means.<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">For me, the intersection of the 2 polygons is the common area,<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">which is 4.<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">GL<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><a href="mailto:olivier.amram@free.fr">olivier.amram@free.fr</a> wrote:<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Hi,<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">I'd like to compute the total area of polygon that intersects with <br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">another<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">polygon<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Polygon(0 0,0 3,3 3,3 0,0 0)<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Polygon(1 1,4 1,4 4,1 4,1 1)<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">The total area is 14 but I don't find a solution to compute this <br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">value.<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">e.g. SELECT Area(GeomFromText('MultiPolygon( ((0 0,0 3,3 3,3 0,0 <br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">0)),((1<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">1,1 4,4<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">4,4 1,1 1)))')) --> 18<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Have you any idea ?<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Thank,<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Olivier.<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">_______________________________________________<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">postgis-users mailing list<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><a href="mailto:postgis-users@postgis.refractions.net">postgis-users@postgis.refractions.net</a><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><a href="http://postgis.refractions.net/mailman/listinfo/postgis-users">http://postgis.refractions.net/mailman/listinfo/postgis-users</a><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">-- <br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">----------------------------------------------------------------<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Guido Lemoine<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Joint Research Centre, European Commission<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Institute for the Protection and Security of the Citizen (IPSC)<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Support to External Security<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Via E. Fermi, 2749 TP 267 Ispra 21027 (VA), Italy<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Tel. +39 0332 786239 (direct line) Fax. +39 0332 785154<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">WWW: <a href="http://ses.jrc.it">http://ses.jrc.it</a><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">----------------------------------------------------------------<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Disclaimer:<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Views expressed are those of the individual and do not represent<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">the views of the European Commission<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">_______________________________________________<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">postgis-users mailing list<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><a href="mailto:postgis-users@postgis.refractions.net">postgis-users@postgis.refractions.net</a><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><a href="http://postgis.refractions.net/mailman/listinfo/postgis-users">http://postgis.refractions.net/mailman/listinfo/postgis-users</a><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">_______________________________________________<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">postgis-users mailing list<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><a href="mailto:postgis-users@postgis.refractions.net">postgis-users@postgis.refractions.net</a><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><a href="http://postgis.refractions.net/mailman/listinfo/postgis-users">http://postgis.refractions.net/mailman/listinfo/postgis-users</a><br></blockquote></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">_______________________________________________<br></blockquote><blockquote type="cite">postgis-users mailing list<br></blockquote><blockquote type="cite"><a href="mailto:postgis-users@postgis.refractions.net">postgis-users@postgis.refractions.net</a><br></blockquote><blockquote type="cite"><a href="http://postgis.refractions.net/mailman/listinfo/postgis-users">http://postgis.refractions.net/mailman/listinfo/postgis-users</a><br></blockquote><blockquote type="cite"><br></blockquote><br>-- <br>----------------------------------------------------------------<br>Guido Lemoine<br>Joint Research Centre, European Commission<br>Institute for the Protection and Security of the Citizen (IPSC)<br>Support to External Security<br>Via E. Fermi, 2749 TP 267 Ispra 21027 (VA), Italy<br>Tel. +39 0332 786239 (direct line) Fax. +39 0332 785154<br>WWW: <a href="http://ses.jrc.it">http://ses.jrc.it</a><br>----------------------------------------------------------------<br>Disclaimer:<br>Views expressed are those of the individual and do not represent <br>the views of the European Commission<br><br><br>_______________________________________________<br>postgis-users mailing list<br><a href="mailto:postgis-users@postgis.refractions.net">postgis-users@postgis.refractions.net</a><br>http://postgis.refractions.net/mailman/listinfo/postgis-users<br></blockquote></div><br></div></body></html>