Use Case ONTO2: Geometry Extrusion

[ar-chad]

Use Case ONTO2

Geometry Extrusion

As a GeoSPARQL data user I would like to extrude 2D geometries to 3D geometries in order to execute 3D functions when I have only 2D footprint data available.

There is plenty of building footprint data available on the internet, but not all building data corresponding to those footprints is available. This function could be useful for certain simulations and estimations. For instance one could take building footprints and average building height in the area to extrude building envelopes. Together with elevation data this could be useful for estimating solar irradiation for photovoltaics. Another example could be a simulation of drone flying in the area.

https://courses.washington.edu/arch481/1.Tapestry%20Reader/1.3D%20Data/4.Modeling/1.Extrusion.html

Function signature:

extrude(geometry: ogc:geomLiteral, line-segment: geomLiteral): geo:Feature

extrudeInTime(geometry: ogc:geomLiteral, line-segment: geomLiteral, start: xsd:dateTime, end: xsd:dateTime) geo:Feature

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

Preconditions

Features and Geometries with 2D representations are present in a dataset to be queried. The 2D extrusion functions are discoverable: bounding box, axis-aligned bounding box

Postconditions

A SPARQL query can be executed that includes a function to extrude 2D geometry to 3D given the linestring as argument. The results of the query consist of a 3D bounding box corresponding to the provided 2D footprint and a linestring argument.

Steps

Actor: discovers extrusion function implemented by the system
Actor: executes a SPARQL query containing an extrusion function with 2D geometry argument and linestring as argument.
System: returns a SPARQL result with extruded 3D geometry

[situx]

Two comments here:

1. Would it make sense to add a function signature with a LineString, for instance:
   extrudeToHeight(geometry: ogc:geomLiteral, height: geomLiteral): ogc:geomLiteral
   With that, one could also add differing heights/z values, e.g. a pattern of altitude differences.`
2. How about extrusion in the X dimension or a temporal dimension? Does it make sense?
   If so, could we add a third parameter in this function indicating the axis that should be used for extrusion?

[ar-chad]

Both make sense to me.

[situx]

Great! Would you like to add the suggested changes to the proposal?

[ar-chad]

Yes, I will work on this soon.

[ar-chad]

I left only the signature with the linestring because it is the most general of all. In this way extrusion is relative to the plane of 2D shape. It does not need to be perpendicular. Is there any existing example of including time dimension in GeoSPARQL?

[situx]

Not that I know of. Handling time has been out of scope for GeoSPARQL, so we never bothered to create an example I think. If you think it is useful feel free to create one with a pull request.

[ar-chad]

Not that I know of. Handling time has been out of scope for GeoSPARQL, so we never bothered to create an example I think. If you think it is useful feel free to create one with a pull request.

I created the pull request with spatial and spatio-temporal extrusion functions separately: #612

This pull request has been deleted. I'll create a new one with starting from geosparql-1.3 branch.

New pull request #613