[Radiance-general] visual transmittance

[Reinhart, Christoph]

Hi Karsten,

> Under what circumstances did you perform the calculation ? 
> Direct light

I actually carried out an annual daylight simulation using daylight
coefficients (http://www.nrc.ca/irc/ie/light/daysim.html) so I actually
looked at results for thousands of sky conditions. 

> "trick" the internal random generators, otherwise you simply would get
> the same result again. From my answer so far you can imagine where my
> thoughts are heading at: Within the algorithms, a lot of random
> fluctuation, ray direction jittering etc. is performed. This leads to
> noticeable deviations of results. (In a comparison experiment, I once
> observed relative brightness differences between 0 and 8% 
> throughout the

This is actually an excellent idea Karsten. I will try this and report.

Christoph