[Radiance-general] Glazing transparency/reflectivity study

[Greg Ward]

Hi Galen,

I won't comment on the usefulness of your proposed study, other than  
to say it sounds interesting to me...  I do have a couple of  
suggestions, however.

The output of Optics5 should not be used directly, but should be  
passed through the "optics2rad" script to get the desired angular  
behavior from the selected glazing.  In the case of multi-layer  
glazing systems, you may be better off using the "glaze" script to  
define your material.  This script does a much better job modeling  
the multiple reflections that occur in a double-glazed system.

Best,
-Greg

> From: Galen Burrell <Galen.Burrell at arup.com.au>
> Date: January 14, 2009 2:39:40 PM PST
>
> I'm considering doing a study comparing the transparency (as viewed  
> from outside) of two glazing types on a building modeled in  
> radiance.  The study would render several viewpoints (and view  
> angles looking up the facade) for the multiple glass types under a  
> variety of sky conditions (sunny, cloudy, etc).  The primary goal  
> of the study would be to as follows:
>
> 1. Demonstrate how exterior transparency changes with different  
> glass types (with different coatings and exterior reflectances)
> 2. Demonstrate how exterior transparency changes with angle of  
> incidence
> 3. Demonstrate how exterior transparency changes based on ratio of  
> interior to exterior illuminance (or more accurately, luminances).
>
> I'm only interested in this as a comparative study: does glass type  
> A look clearer than glass type B when viewed at X angle and under Y  
> sky condition, and Z interior/exterior illuminance ratio.
>
> My question to the list is:
> 1. Comments on the usefulness of this study?
> 2. Advantage of using Optics 5 rad file (BRTDfunc) over glass  
> primitive?  My understanding is it more accurately captures the  
> color of the glass and reflectivity... anything else?
>
>
> Thanks,
> Galen