[Radiance-general] modeling an insulating glass with an integrated capillary slab

[Andy McNeil]

It's really tough to say without knowing what they mean by direct and diffuse transmission.  From their website I understand that by "direct" they mean normal incidence direct-hemispherical transmission and by "diffuse" they mean hemispherical-hemispherical transmission.  I would suggest setting Td to 30% and know that for non-normal incidence angles you will over estimate overall transmission.

This product, with it's capillary tubes and diffusing papers, is a perfect example of a system that should be modeled with a BSDF.  Unfortunately your options for BSDF characterization are murky at best right now.

Andy




On Apr 27, 2012, at 2:47 PM, Valeria De Giuli wrote:

> Thank you Andy, this is a quick and useful widget, however in this case I have only direct and diffuse visible transmission, therefore I can only assign the diffuse transmission. Am I right?
> Thanks,
> Valeria
> 
> Il giorno 27/apr/2012, alle ore 23:31, Andy McNeil ha scritto:
> 
>> Hi Valeria,
>> Trans is a quick and easy way to model this type of glazing.  
>> You can use this widget to generate a trans material definition by entering your transmission and reflection parameters: http://gaia.lbl.gov/people/andy/public/transwidget/
>> 
>> However trans does not account for Fresnel effects that reduce transmission of glass at non-normal incidence angles (http://en.wikipedia.org/wiki/File:Amptitude_Ratios_air_to_glass.JPG).  So treat trans results with some degree of caution.
>> 
>> If you want to include fresnell effects and diffusion, you might consider use a glass surface and a trans surface one in front of the other.  Or you could generate a BSDF and use the new BSDF material.
>> 
>> Hope this helps,
>> Andy
>> 
>> 
>> 
>> 
>> 
>> On Apr 27, 2012, at 1:34 PM, Valeria De Giuli wrote:
>> 
>>> Dear all,
>>> I have to model a two-pane glass make up with a selective 6mm outer pane with an integrated capillary slab (it is called kapilux), white tinted. The obtained effect is a uniform and diffuse light transmittance. The only technical data that I have are: 30% of direct visible transmittance  and 15% of diffuse visible transmittance. I think I should model it with "trans" material, but I don't know which parameters I have to use. Does anybody has an idea?
>>> Thanks in advance. Best regards,
>>> Valeria
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>> 
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