This tutorial will show you how to do exactly what you want with rasters: http://trac.osgeo.org/postgis/wiki/WKTRasterTutorial01
Pierre ________________________________________ From: postgis-users-boun...@postgis.refractions.net [postgis-users-boun...@postgis.refractions.net] On Behalf Of Louwrens du Toit [louwrence...@eva.mpg.de] Sent: Wednesday, February 02, 2011 5:24 AM To: postgis-users@postgis.refractions.net Subject: [postgis-users] Postgresql, postgis and PHP Dear Postgis-Users List, I'm an experienced web developer (mainly PHP, Javascript, MySQL) and have recently started a job where I need work with geographic information, mainly in a Postgresql database. So, I'm quite new to all this geographical data etc and have a few questions: So, I have a database (Postgresql) with geographical data (mainly polygons in format "geometry" - srid 4326). Now I can do some area (ST_Area) and intersection (ST_Intersection) queries but would like to know the following: 1. I have several tables with polygon data (layers) but need to do queries across them (what I need to do in the end is to create charts - bar,pie etc). I.e I would like to know for instance, what percentage area of layer 1 falls within the area in layer 2? or 2. I have raster data (in geotiff format), and would like to know... per polygon (in layer 1 above), what is the mean value of the raster data... Can someone point me in a direction of where to information like this. How should I go about this problem? I hope this makes sense. As I said, I'm very new to all this geographic stuff. Thank you, LJ du Toit -- __________________________________________________ LJ du Toit _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users