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BSDF layered over OS window?

asked 2017-01-26 19:05:39 -0500

Determinant's avatar

So I've got a working version of user-defined BSDFs in OpenStudio. I do this by simply re-writing mapping.rad Are the BSDFs in mapping.rad combined with the window specifications in OpenStudio? In other words, let's say I have a 40% VT window in OpenStudio, is that somehow layered with whatever BSDF I have in mapping.rad?

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answered 2017-01-27 14:26:50 -0500

updated 2017-01-27 14:32:51 -0500

The Radiance BSDFs in OpenStudio were computed for the shading devices themselves (e.g. Venetian blind), and do not include any glazing. The BSDF is "applied" to a proxy surface that is automatically generated by the Radiance forward translator at runtime, and the proxy surface is fully enclosed about the edges with polygons projected from the window. The depth of the enclosing polygons is user-adjustable, as these can be used to crudely simulate wall thickness in an otherwise infinitely-thin wall construction model.

So yeah, the shade BSDF sits just inboard of the window you add to the model. You can assign whatever construction you want to the window; there is no need to 'blend' the window constructions performance into the BSDF.

This probably should be better documented... =)

P.S. The 'blended glazing + shading system as BSDF' approach was how we initially implemented this support, but we changed tactics because the other way required nearly a hundred BSDFs just to support generic clear single pane glass.

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This implementation works well for general users. Unfortunately I would like to run just my BSDFs. Anyway I could skip the window being added onto the BSDF? Is there a step in measure.rb that I can skip/modify?

Determinant's avatar Determinant  ( 2017-01-27 17:41:57 -0500 )edit

Ah, gotcha. OK well, this will require a little more work, then. First question is how are you producing the BSDFs (genBSDF, or???), what are the BSDFs representing, what are the dimensions of the 'thing', and did you include enclosing geometry in the model that was sampled for the BSDF?

rpg777's avatar rpg777  ( 2017-01-30 12:07:10 -0500 )edit

I'm generating the BSDFs in WINDOW 7.4. It allows me a lot of flexibility and the ability to be dynamic. The default WINDOW 39.37" X 39.37. I don't know if enclosing geometry was included. Anyway to measure.rb or is it a ForwardTranslator thing? ...Does the ForwardTranslator vary VT by incident angle?

Determinant's avatar Determinant  ( 2017-02-02 13:56:45 -0500 )edit

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Asked: 2017-01-26 19:05:39 -0500

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Last updated: Jan 27 '17