Leonardo, An SRID is mostly useful to say your data is in a specified coordinate/datum/projection/etc system and therefore since your spatial reference system is known it can be transformed into another system using transform etc. Sometimes the spatial reference system you get your data in is not the most useful for your analysis, so you transform to another e.g if you get data in degrees and you do analysis in meters.
Here are a couple of links that may be useful. http://www.sharpgis.net/2007/05/05/SpatialReferencesCoordinateSystemsPro jectionsDatumsEllipsoidsConfusing.aspx These last couple I wrote just because people ask me these questions all the time. Let me know if I made any possibly fallacious statements. I always feel like a fish out of water so to speak in this area. http://www.bostongis.com/?content_name=srid#82 http://www.bostongis.com/postgis_geomfromtext.snippet http://www.bostongis.com/postgis_pointfromtext_linefromtext_etc.snippet http://www.bostongis.com/?content_name=postgis_tut03#30 (the section about transforming to another spatial reference system) Hope that helps, Regina -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Leonardo Mateo Sent: Tuesday, June 12, 2007 4:43 PM To: PostGIS Users Discussion Subject: Re: [postgis-users] Polygon from a set of points On 6/12/07, Kevin Neufeld <[EMAIL PROTECTED]> wrote: > I see. Yes, it's certainly possible. Since you are coming straight from > text, I think the easiest for you would be to use geomfromtext() method. > > SELECT GeomFromText('POLYGON((-67.84208673890122 -31.89216012405324, > -67.84097873325344 -31.8878559482676, ...))'); > > Note: you can optionally add the SRID of the projection you are in as a > second parameter if you plan on performing any projection operations. > > Is that what you were after? Thanx!!! That was exactly what I was after. By the way, sorry for the cross posting, but I don't quite understand the what the SRID is for. PostGIS docs are not really useful on this topic. Do you know some URL or something where I can read about? Or maybe I should start another thread for this? Thanx a lot for your time, and sorry for the very basic questions. -- Leonardo Mateo. There's no place like ~ _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users ----------------------------------------- The substance of this message, including any attachments, may be confidential, legally privileged and/or exempt from disclosure pursuant to Massachusetts law. It is intended solely for the addressee. If you received this in error, please contact the sender and delete the material from any computer. _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
