[postgis-users] About OGC SFS Specification, PostGIS and topology information of features

[Paul Ramsey]

If by "plans" you mean "wild eyed dreaming on the part of Paul", then 
yes. The SQL/MM spec draft includes sections on topology which would be 
an excellent basis for an implementation.  Functions to build topology 
from raw linework would be needed too (I think) as well as functions to 
build topology into simple features. All in all a very fun project. Who 
wants to fund it? :)

Paul

On Friday, June 24, 2005, at 01:13 AM, Sergey Karin wrote:

> Hi.
>
> first of all sorry for my english. :(
>
> As we know, PostGIS based on Open Geospatial Consortium's Simple
> Features for SQL specification. So, geometry attribute of a feature is
> presented as separate entity. And if we have two touched geometries,
> we must store duplicate information about they coordinates.
> That is right. But...
>
> There are some topological vector formats (arc-node topology). S57,
> E00, for example. In that formats feature is not the owner of its
> geometry. So, if we want to convert data from that formats to postgis
> format we must "construct" geometry of a feature from arcs and nodes
> on which the feature have links. The method is used, for example, in
> OGR library. And ALL topology information is lost. OGR is based on OGC
> SFS too.
>
> So, my question is: are there any plans to store and work with
> topology information of features if it have that? I understand, OGC
> SFS not supported that... But I think it will be good idea...
>
> Sergey Karin
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      Paul Ramsey
      Refractions Research
      Email: pramsey at refractions.net
      Phone: (250) 885-0632