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opengeospatial / ogc-geosparql

Public Repository for the OGC GeoSPARQL Standards Working Group
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Use Case ONTO19: Flip XY Coordinates #576

Open ar-chad opened 3 weeks ago

ar-chad commented 3 weeks ago

Use Case ONTO19

Flip Coordinates

As a GeoSPARQL data user I would like to retrieve a given geometry with X and Y axis flipped.

For the 'POLYGON ((0 1 5, 2 3 5, 3 2 5, 2 1 5, 0 1 5))'the flipped geometry is POLYGON ((1 0 5, 3 2 5, 2 3 5, 1 2 5, 1 0 5))

Function signature:

flipXY(geometry: ogc:geomLiteral): ogc:geomLiteral

Actor: GeoSPARQL data user (human or software agent querying RDF dataset with GeoSPARQL)

Preconditions

Features and Geometries with 2D and 3D representations are present in a dataset to be queried. The flip XY function is discoverable.

Postconditions

A SPARQL query can be executed that includes a function to return geometry with X and Y axis flipped. The results of the query are known to be true or false in 2D and 3D.

Steps

Actor: discovers flip XY function implemented by the system Actor: executes a SPARQL query with flip XY function and a geometry argument. System: returns a SPARQL result with a value that is a geometry with X and Y axis flipped.

situx commented 3 weeks ago

Thanks for the ticket. Is there also demand for a function to flip other axis? X and Z axis for instance?

ar-chad commented 3 weeks ago

Yes, definitely it would be good to cover flipping on the other axes as well.

I can either add them separately or we could generalise this function. What do you think will be better?

aothms commented 2 weeks ago

I guess this could be rephrased as a 90d rotation around an axis followed by mirroring. Maybe that could also be a way to generalize this even further?

ar-chad commented 1 week ago

@aothms rotation with mirroring looks like a more general function, which could be added separately to the simpler ones (90 degree, specifically), or as a general replacement of them.