Tips to create a metal perforated venetian blinds with BSDF function

Dear Ladybug community,

I hope to find someone who can help me to understand a new theme.
I ran into a Project how having to calculate the glare through a perforated metal venetian blinds, when they are completely closed.
Initially I wanted to create only a surface on which to attach a perforated material directly in Radiance, but after going deeper into the theme and discovered that to be more detailed I should take into account the Bidirectional scattering distribution function.

Can someone with experience point me in the right direction?

What is a XML file that the component _HBBSDFmod needs? I have seen that I need an extra program (LBNL WIndows) to create this type of file, is right?
Through LBNL is possible to create a perforated metal venetian blind material with the BSDF in Radiance? (My Venetian is not together with the window, but it is a body in its own right).
For a full closed venetian blind, which value in the _up_vector Input, should be used?


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Hi @LaFleur ,

Some of the other Radiance gurus here may be more helpful than I am but you can definitely use LBNL WINDOW to generate the BSDF XML files that the honeybee components need. In particular, the “Shading Layer Library” can be used to create custom blind materials that can be exported to BSDF:

You can also use the native Radiance genbsdf utility to create BSDF XML files if you are comfortable with command line interfaces. But my guess is that using the nice graphical user interface of LBNL WINDOW will have the shallower learning curve.

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Maybe the “Glare” Maestro, @mikkel can help you.
Good luck


Hello @mikkel,
sorry if I bring you into question, I saw that you participated in other posts on the subject, maybe you can clarify my doubts.
I spent the weekend studying the LBNL WINDOWS software but unfortunately I have not solved my problem.
Starting from the fact that this is exactly the Venetian that I should replicate
I realized that even to create even a single Shading Layer (in this case perforated), I need to create a glazing system, which also contains the glazing, is that right?
After creating and calculate a Test Glazing System, no BSDF folder has been created, as the tutorial says Generating BSDF XML Files | Windows and Daylighting
for this I was stuck and I could not test a possible xml file. I don’t understand where I’m wrong, because the calculation is successful.
I wanted to ask, is this the correct procedure, even if I only want to create a perforated material containing BSDF information?
One last question, in case I would like to be even more detailed, through WINDOWS, could I insert the perforation inside a closed Venetian blind?

Hope you can help me solve this problem

Unfortunately I cannot help with the questions regarding LBNL WINDOWS. I have only generated BSDFs once some years ago, otherwise I have used genBSDF as Chris linked to above.

I guess you do not need the glazing, necessarily. If you have a BSDF of just the perforated material, you can model the venetian blind slats in Rhino/Grasshopper and add the BSDF modifier to that geometry. But I am not sure how well this will work if the slats are in any way curved. This way your BSDF is not dependent on the glazing (visual transmittance) or the slat angle of the venetian blinds. So you can simulate different glazings and slat angles using just one BSDF.

Or you can model the exact venetian blind geometry in a closed state with perforation and create a BSDF material for that. For this you will probably need genBSDF. You can then create a face (the incident side of the venetian blinds) in Rhino/Grasshopper and add the BSDF modifier, and probably set a thickness to the modifier.

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Hallo @mikkel, thanks for the reply,
I can’t figure out how to export a single perforated material in xml format out from WINDOWS, despite having read the manual.
I create in rhino a perforated blind directly via Grasshopper, but having a very small and dense perforation (d=1mm), the geometry is so detailed that the Honeybee component struggles to load.
Unfortunately the genBSDF world seemed too complex to be able to learn it in a short time.
Thank you, you have been very kind

you can check out this example of genBSDF in grasshopper.

you would need to change the materials etc.,0

Remember orientation as per below

All the best,
Mathias Sønderskov Schaltz

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Dear @Mathiassn,
thank you so much for forwarding this script to me.

I have some questions:

  • first of all I entered my geometries and materials, updated your “genBSDF” component so that it recognizes the OS v3.0.1 version and not the v2.4.0, but at the end, the generated XML file is empty. Am I wrong something?;
  • I don’t understand if in this case, it is also necessary to create the union boxes between the Glas and the Shades;
  • how can I check in your script the sense of direction you write about above? (495.9 KB)

Thanks and best regards

Hello @Mathiassn, honored to converse with you
I am lucky to have found this topic.

For a research, I would need to calculate the influence of the BSDF when screening methods such as Venetian blinds, are considered.
The LBNL program is not very intuitive and easy to manage and is affected by several bugs, from what I read, so being able to use your script would be really fantastic.

I edit the geometry and materials, but I run into this error…any advice?

Are you planning to converted the GenBSDF also for the LBT version?

Thanks and Greetings