I'm using Barnes Surface to compute a set of points from my PostgreSQL db. The problem is that my whole table is processed for each tile. I added a geospatial index on my points, how can I tell ...
I have a grid of points, each with a value to it as shown in the image below. The data was retrieved from PostGIS and rendered in Quantum GIS. The final result should be a polygons of a choropleth map ...