[postgis] GEOMETRY_COLUMNS table

Nicolas Ribot nicol at ribot.com
Tue Mar 19 00:54:15 PST 2002

Hi all,

To give an opinion concerning this subject, we (at SCOT, a french company for
Earth Observation) have decided to separate the storage of data from the storage
of graphical/layout information.

As we mainly (well, exclusively !) use MapServer to render our geographic data,
we implemented a DB schema representing a MapServer mapfile.

A php-based tool allows us to load a mapfile into the DB, modify it graphically
(adding layers, choosing layers representation, layer order, symbols, etc.) and
then dump it as a file to be accessed by our applications.

By separating the data from the display, we can reuse display information (layer
representation, symbols) from one application to another. (kind of library of
reusable components...).
This development is not finished yet, we try to take some time to work on it.

Another solution I used some times ago was to add some extra columns to the
OpenGIS metadata tables (geometry_columns, spatial_ref_sys, etc...): we put in
these columns information that was relevant to our applications, (without
changing the ogis-defined columns, of course).
Our databases were still OpenGIS compliant (that is, queriable by everyone), but
also contains useful information for us (for example, we had developed a
file-based r-tree index, and each indexed geographic table had an entry in a
column of the geometry_column table)


> I would be interested in people's opinions. Once you start down this
> road, the complexities never end. Prefered fill and outline colors,
> scale preferences, full descriptive names. Is the storage of this
> information necessarily a part of the backend data store, or should it
> be part of the rendering application solely? The only benefit to pushing
> it back into the database is that applications can then share rendering
> specifications: to make my roads blue on both desktop and web apps, I
> change it once in the database.

------------------------ Yahoo! Groups Sponsor ---------------------~-->
Tiny Wireless Camera under $80!
Order Now! FREE VCR Commander!
Click Here - Only 1 Day Left!

To unsubscribe from this group, send an email to:
postgis-unsubscribe at yahoogroups.com


Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 

More information about the postgis-users mailing list