[Radiance-general] Illuminance values

[Rob Guglielmetti]

Lars O. Grobe wrote:

> Mkillum has been written to precalculate the effect of compex
> fenestration such as blinds. You calculate a light source on the inside
> of the complex fenestration using mkillum, so that during your (rpict or
> rtrace) rendering, the light source for ambient calculations is not
> obstructed. The reasons for this are explained in detail in the book
> "Rendering with Radiance".

Lars is correct; as Greg Ward says, you want the virtual light source 
positioned just inside of "where it gets nasty".  You're basically 
taking the backwards ray tracing operation away from the view plane and 
placing it right up against the blinds to help guarantee that plenty of 
rays get through the "nastiness" and find those bright light sources out 
there.  The result of that calculation is then saved as a .dat file and 
used on that virtual light source plane in the regular calculation, 
giving much better results in less time (opposed to relying on brute 
force with the ambient calculation).  As Lars said, there is good 
information on this in the RwR text.

- Rob Guglielmetti