Re: [Geotools-devel] GML topology from Geotools through to Geoserver

[Jody G. <jod...@gm...>]

 Hi Rob:  

Okay so more like graph data structures; edge graphics; network analysis fun and games and so forth. (Not GML's take on ISO 19107 Point, Curve, Surface etc...).  

You can look at the gt-graph package but it is more about isolating the concepts so algorithms can be written; a persistence mechanism has not been provided (GML or otherwise) - instead the graph is built from the feature relationships as needed). Adding a GML import/export to this would be a very welcome direction.

If you have any references (even just to the basics they would be a welcome addition to the conversation).

Given that this is a devel list I went straight to the source:
- http://schemas.opengis.net/gml/3.1.1/base/topology.xsd

It actually looks pretty much as expected:

<complexType name="DirectedEdgePropertyType"> <sequence minOccurs="0"> <element ref="gml:Edge"/> </sequence> <attribute name="orientation" type="gml:SignType" default="+"/> <attributeGroup ref="gml:AssociationAttributeGroup"/> </complexType>
And then gets into the fun/exotic (the gt-graph does support creating graphs based on polygon relationships but it is fun to see it in GML):
<complexType name="TopoSurfacePropertyType"> <sequence> <element ref="gml:TopoSurface"/> </sequence> </complexType>
Justin did have some ideas on how to persist this stuff; and there is at least one opengeo project that covers fun with graphs; and pgRouting based things.
--  
Jody Garnett


On Thursday, 28 July 2011 at 5:31 PM, Rob...@cs... wrote:

> Hi,
>  
> I’ve a new activity starting up that would like topology to be delivered through GML Topology. Given we use Geoserver WFS, Geotools will ultimately play an important role. We will eventually want query’s as well but suspect that will be a WPS issue.
>  
> It is worth noting that in this case the Geometry data product is not the same as the Topology data product – we don’t need to know the rivers shape in order to calculate interesting things about inflows and outflows. The topology is thus not directly constructed from the geometry and is, and can be, delivered all by itself. A Feature with only Topology information is likely.
>  
> I’d be interested in hearing experience from anyone who has taken a stab at or considered implementing GML topology delivery through Geotools and Geoserver WFS (or any other WFS server for that matter). Any pointers to any papers and trials would also be welcomed – I have trolled the OGS interoperability test beds and only found two references to this issue one in OWS3 and one in OWS4 (the latter being less relevant to my use-case).
>  
> Cheers,
>  
> Rob
>  
> Dr Robert Woodcock
> CSIRO – Canberra, Australia
> Mobile: 0412 298 696
> Ph: 08 6436.8780 | E: Rob...@cs... (mailto:Rob...@cs...) | W: www.csiro.au (http://www.csiro.au/)
>  
> Please note on Monday's and Tuesday's I will normally be found at Geoscience Australia as part of the CSIRO/GA e-Research Collaboration project.
>  
>  
>  
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