[Radiance-general] Modeling glare from light fixtures

[Randolph M. Fritz]

On 2011-05-16 06:32:41 -0700, Christopher Rush said:

> If you model estimated geometry surrounded by the "impostor surfaces," 
> would this impact your results depending on how you are estimating 
> glare? If you use luminance for glare evaluation, do you get the 
> luminance value of the faux luminaire geometry behind the illum 
> "impostor surface" or do you get the luminance value of the IES illum?

Right.  Since what the rendering shows is the false luminaire geometry, 
that's what a direct view of the luminaire will show.  So you would 
have to use a straight "light," not an "illum," to get a calculation of 
glare looking into the luminaire.  This will not produce a realistic 
image, but I expect that, for a T5 fluorescent, it would produce a 
useful glare calcuation.  As Lars points out, it probably won't be as 
useful for LEDs fixture that allows for a direct view of many small 
points of light.

I wonder if HDR images of an LED fixture would provide a useful basis 
for glare calculation.  I suppose one could, if one had the resources, 
move the camera around the luminaire, the way a photometer does, and 
create multiple images which, if we had a way of getting those images 
into Radiance, might provide a fairly accurate basis for glare 
computation.

Randolph