Handling of Z-coordinates by geometry functions is underspecified

opengeospatial / ogc-geosparql

Public Repository for the OGC GeoSPARQL Standards Working Group

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Handling of Z-coordinates by geometry functions is underspecified #301

Open FransKnibbe opened 2 years ago

FransKnibbe commented 2 years ago

Geometry functions like geof:buffer and geo:convexHull ignore Z-coordinates (as per SFA-CA). but GeoSPARQL does not say how this influences generated output Geometry. Are Z-coordinates completely absent from output? Or are they all set to 0?

VladimirAlexiev commented 6 months ago

@FransKnibbe Since current GeoSPARQL is 2.5D, aren't there other functions with a similar concern?

Eg what do intersects, difference, symDifference do to Z?
You mention convexHull, surely the same applies to concaveHull?
And their 2 agg* variants: see https://github.com/opengeospatial/ogc-geosparql/issues/483
(On the other hand, I assume that union and aggUnion leave Z in place)