ASE, 5-phases, and `Trans` material

Hello all, it has been a while! I am glad to be back.

I am reaching out because I need to run some ASE calculations and I have noticed that the models I am getting include some trans materials. So, I am now wondering what to do with them! I assume I cannot just transform them into a black plastic because they would not be allowing any light to go through (dah!)

Should I handle their specific parameters individually? Is there a better trick?



Hi German,

Could you be more specific about your issue with the ‘trans’ type? It sounds like you are questioning what to do in a particular part of the 5-phase calculation, but it’s not clear.


Oh, I M very sorry!!

So, when using the 5-phase method, I need to produce a scene with only black objects, except for the windows and shading devices. Now, I wonder if I should leave Trans untouched, or if I need to modify it in order to make the opaque component of it black. As in, how do I allow direct light to go through while avoiding reflection

Is this clearer?


Yes, it is clearer. Unfortunately, I don’t know the answer. Maybe @Taoning_Wang or someone else more familiar with the steps of 5-phase can venture an opinion?

Hi German,
I am not sure I know the answer to this either.
If ‘trans’ is part of your fenestration, then you’d probably want to include it in your system BSDF, using something like genBSDF.
If it’s part of something like a cubical partition, then I think you can leave it as it is.

Hi German,

As I remember it (I actually can’t find a copy of the IES LM-83 specification, hint hint to anyone out there with a pdf they want to send me), the specification for ASE only accounts for direct transmission, so unless your trans material has a direct component greater than 10% or so (to get to 1000 lux) turning the material black is perfectly valid, but to be safe, you can leaving it unchanged (since wth -ab 0 you will not get any indirect contribution through the trans anyways.

If you are also doing 5-phase runs, then as Taoning says, any surface transmitting light from outside will need to be included as one of your receivers and you will need a klems bsdf representation for the matrix multiplication step, but you would use the trans material for the direct view part.


Hi Stephen,

The issue is that not al shading elements will be less than 10% transparent. Also, they are not necessarily part of the Fenestration System, as they can also be semi-transparent overhangs and stuff like that.

I’ll follow Taoning’s advice: I’ll leave them be.