[GRASS-user] grass topography and postgis

[Markus Neteler]

Matt,

On Tue, Dec 2, 2008 at 4:31 AM, Matt B <mattslists at gmail.com> wrote:
> Hi Group,
> I'd like to set up grass to edit / work with data in a postgis database. So
> far I've figured out (and been informed, thanks Richard) that grass stores
> the topologoly data in it's own database and the external database is just
> used for attributes.

GRASS stores per default all data (geometry + attributes) in its own format
(i.e., attributes in a DBF file in GRASS 6 and in SQLite in GRASS 7).

Optionally attributes can be stored in PostgreSQL (not PostGIS), Mysql,
SQLite, and ODBC.

> Is there a way to have grass store the topology data in
> postgis so I can easily work with the data in different applications?

Yes, using v.external. But note that this is a read-only connection.
We hope that in future this will be read-write.

The issue behind this is that GRASS is a topological GIS while
PostGIS is Simple Features (no topology per default). So there
is a "conversion" needed between these two worlds.

Markus