[OSM-talk] Topology (was: OSM the mediocre alternative)

[Artem Pavlenko]

On 26 Apr 2007, at 16:27, Martijn van Oosterhout wrote:

> On 4/26/07, Artem Pavlenko <artem at mapnik.org> wrote:
>> OK, I was hoping you have something to play with. I think  
>> investigating
>> PostGIS topology or even fixing MySQL is a good plan. I'm not so  
>> sure about
>> Oracle.
>
> Is there a particular reason why we need PostGIS topology?

Collecting and storing topological structure would be very useful.  
But, do we need PostGIS topology?  I'm not sure.

> If we store
> ways as arrays of node IDs and index them (which can be done in
> standard postgres) you get almost all the way. Add a trigger to
> automatically regenerate the polyline wherever the array changes and
> it should work just fine.

I don't believe that storing every single node as a separate record 
(object) would be a good idea. Some geometries can have lots of  
vertices and gathering them by id won't efficient. Only 'interesting'  
nodes e.g intersections need to be stored, IMHO.

Cheers,

>
> Have a nice day,
> -- 
> Martijn van Oosterhout <kleptog at gmail.com> http://svana.org/kleptog/
>

Artem Pavlenko
http://mapnik.org



-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/talk/attachments/20070426/dce20cc9/attachment.html>