[Radiance-general] Strange halo artifact in rendering

[Guglielmetti, Robert]

>I learned this morning that the halo is coming from the array of ceiling
>lights and not the spotlight.

That was pretty clear to me, in looking at the rendering. The multiple
edges evident particularly from the bottom of the frame are the giveaway.
You are using Radiance light objects, and these always give these
exceedingly (unbelievably) sharp edges to the pools of light that they
cast. Radiance lights based on a photometry file tend to have softer
edges, even those based on directional lamps.

Jack's trick worked because even tho you have -aa at zero, you have -ab 2
which will still cause the ambient calculation to be run; the increased
-ar has the effect of softening the halo, I think. -aa 0 simply turns off
interpolation, not the ambient calculation altogether.

I think. 

- Rob