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gbXML - RectangularGeometry and PlanarGeometry

asked 2023-01-24 12:34:42 -0500

AdamsoSa's avatar

updated 2023-01-24 13:24:57 -0500

I am working with gbXML files generated by CAD, and I notice that all Surface elements seem to have their geometry described both by a PlanarGeometry child element and a RectangularGeometry child element. In the docs I see that RectangularGeometry is described as 'Geometry in a form typically used by Simulation engines'.

In some circumstances I have observed that RectangularGeometry describes a shape that differs from that which is described by PlanarGeometry for the same surface. For example the RectangularGeometry only provides a height and width (rectangular shape), while PlanarGeometry describes a non-rectangular polygon using a PolyLoop. There are some examples of this in the sample files listed on gbXML's sample files git repo.

Does the schema allow for surfaces to only be described by RectangularGeometry (not very clear in the documentation) without PlanarGeometry? What is the intended use case for RectangularGeometry?

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answered 2023-01-27 02:06:59 -0500

The OpenStudio gbxml forward translator at least writes both.

  • The RectangularGeometry defines a kind of an area-equivalent bounding surface: this represents the overall geometry of the surface, by defining an equivalent rectangular surface with the same area, a starting point, and a tilt,
  • The PlanarGeometry element has a PolyLoop element with all points / vertices describing the surface as it is actually in 3D space.

Couple of other sources that discuss this:

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Asked: 2023-01-24 12:34:42 -0500

Seen: 103 times

Last updated: Jan 27 '23