Date Fri 11 May 2012 Tags Postgres / PostGIS

PostGIS 2.0 is out and the awesomness continues! You can install PostGIS 2.0 on Ubuntu using packages which is exactly what I am going to show you here. Read on for details on how to get up and running and do your first simple raster analysis!

Note: You should make good backups first!

Before we begin, you should uninstall your existing postgis packages:

sudo dpkg --purge postgis postgresql-9.1-postgis

Then add a new repository and install PostGIS from there (based on this post):

sudo apt-add-repository ppa:sharpie/for-science  # To get GEOS 3.3.2
sudo apt-add-repository ppa:sharpie/postgis-nightly
sudo apt-get update
sudo apt-get install postgresql-9.1-postgis

Next we should create a new template database (optional but recommended).

createdb -E UTF8 template_postgis2
createlang -d template_postgis2 plpgsql
psql -d postgres -c "UPDATE pg_database SET datistemplate='true' WHERE datname='template_postgis2'"
psql -d template_postgis2 -f /usr/share/postgresql/9.1/contrib/postgis-2.0/postgis.sql
psql -d template_postgis2 -f /usr/share/postgresql/9.1/contrib/postgis-2.0/spatial_ref_sys.sql
psql -d template_postgis2 -f /usr/share/postgresql/9.1/contrib/postgis-2.0/rtpostgis.sql
psql -d template_postgis2 -c "GRANT ALL ON geometry_columns TO PUBLIC;"
psql -d template_postgis2 -c "GRANT ALL ON geography_columns TO PUBLIC;"
psql -d template_postgis2 -c "GRANT ALL ON spatial_ref_sys TO PUBLIC;"
createdb training -T template_postgis2

Ok now we can load a raster (see sample data download below):

raster2pgsql -s 4326 srtm_4326.tif | psql training
shp2pgsql -s 4326 -d -g geom -I places.shp places| psql training

Good - now our spatial database is ready to use - and has raster support! Here is a nice example of what you can do. The query looks up the altitude from the SRTM raster for each place listed using the ST_Value function:

select ST_Value(rast, geom, true) from places, srtm_4326;

It should produce something like this:

Doing a 'point on raster' query on our raster in QGIS

Further reading: A really good place to start is the Boston GIS cheatsheets - I am really looking forward to exploring all the new features that are available in PostGIS 2.0, thanks to all those involved in building it!

Sample data for the example listed


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