Re: [Radiance-general] Glass & MTL file troubles... (or how to go from Revit to Radiance with little pain...)

[Lars Grobe]

Hi!

> That's what we've got going, it's a building with lots of glass and 
> skylights and such. So do you think just having the windows be glass 
> would be enough to get somewhat-close numbers? I fear that not making 
> the glass a secondary light source, and just having it be, well, glass 
> and only having the ray of sunlight bouncing around is going to give me 
> bad numbers.

I think you are worried too much here. The numbers should not change so much
because of mkillum, the image will look nicer in many cases. But the main
reason for mkillum is the following.

If you have a model where most of the indirect light enters the room through
small windows, the probability that the (random) indirect rays, which are
send from the surface to several (random) directions to find out its
indirect contribution hits the (small) light source is getting low. You can
increase the number of random rays, but that won't help sometimes and takes
a lot of rendering time. So, in these cases, it is better to bring the light
source closer. Bt as it sounds to me, your model is not the typical case
with shading devices etc, right? So, if you have simple, large windows, at
least your numbers should be fine.

Lars.