[postgis-users] PostGIS Raster for Met Data

[Pierre Racine]

Hi Michael,

> - If I understand correctly, a Raster object in a table functions much like PostGIS
> Geometry object - including the limitation that one can only have one SRID per
> column. That's an issue for us, because we almost never deal with a single type
> of raster; we often have to deal with 10+ different data grids when doing data
> retrieval.

You can easily remove this limitation (this is true for geometry also) by removing the proper constraint. You could also decide to store different grid in different tables. Normally you want to store data with the same semantic (or theme) in the same table making sure they are all in the same srid.

> Does anyone have any experience with generating sub-tables to handle this
> problem? I'm particularly interested in performance, of course.

I don't.

> - Is there an easy (and efficient) way to run a query to get all of the coordinate
> points (x,y index) from within a raster that are contained in a polygon? That
> would be quite interesting for us if we still need to build our own solution on top
> of the existing functionality for performance purposes. Haven't looked at the
> source code yet.

You mean the raster values at those points? The points are contained in a polygon, the rasters are contained in the polygon or you speak about the vertexes of a polygon?

Pierre