[Radiance-general] genBSDF error

[Rob Guglielmetti]

Yeah, we were gonna go a similar route with OpenStudio, including a simple library of "clear BSDFs" to be used with models, but in the end we are going to do what I described, doing a two pass daylight coefficient deal, once for the VMX with glazing, and once as a three phase pair of VMX/DMX. This was all thanks to Andy for plotting my stupid "clear BSDFs".

Which I guess means there is now technically a four phase method. =)

-Rob

> On Sep 30, 2013, at 4:21 PM, Greg Ward <gregoryjward at gmail.com> wrote:
> 
> You're right, Rob.  I remember I even wrote a script at some point for HMG to create clear glazing XML files, since it was faster than running genBSDF.  Faster still would be using WINDOW6 to create the appropriate XML files.
> 
> -Greg
> 
>> From: "Guglielmetti, Robert" <Robert.Guglielmetti at nrel.gov>
>> Date: September 30, 2013 11:28:24 AM PDT
>> 
>> One scenario I can think of would be using the 3- or 5-phase method to look at a window with clear glazing and a shade, and wanting to select the appropriate BSDF based on whether the shade is up or down (at runtime). But you’re right Greg, of course; given the difficulty of even a high resolution BSDF to represent purely specular transmittance or reflectance, the best way to handle these situations is to do simply calculate the view matrix with the whole model – including the glazing, modeled as glass or trans or whatever  -- and then do another round where you do the VMX to the glass and the DMX to the sky, and just have the one BSDF for the CFS. With gendaymtx, the generation of the matrices is so fast now it makes more sense to just do them both (for this scenario) and then at runtime just select the appropriate result.
>>  
>> - Rob
>>  
>> From: Greg Ward [mailto:gregoryjward at gmail.com] 
>> Sent: Monday, September 30, 2013 10:29 AM
>> To: Radiance general discussion
>> Subject: Re: [Radiance-general] genBSDF error
>>  
>> Beyond that, I should point out that it is neither necessary nor recommended to create an XML file to describe a pane of clear glass.  Even the tensor tree format has difficulty representing perfectly specular systems such as this, and in fact all the default algorithms in WINDOW6 and Radiance work quite well with a more exact description.  Can you explain why you even think you need to do this?
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