Question-and-Answer Resource for the Building Energy Modeling Community
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Hi Chantal,
You are right to be concerned about the reflections of the original XML file. If your measurements do not include reflection on both sides as well as transmission, then there will be no interreflection between the slats in your subsequent genBSDF simulation. I think this will lead to an underestimate of the transmitted (as well as reflected) components.
You also need to be very careful with your xform command, which currently puts the genblinds output into the positive-Z domain you should avoid. Your maximum Z value, which you can check with getbbox, should be zero (within some tolerance). Based on my test, your transform should be "xform -rz -90 -rx -90 -t 0 0 -1.414" rather than what you have. You should also double-check that your slats are slanting in the desired direction. You can use objview to look at the Radiance scene file you are giving to genBSDF.
Finally, your BSDF specification should have its "up vector" set to "0 0 1" for any slat angle that is less than 90°, since that will orient the measured distribution into the room, which is the positive-Z direction.
