I'll second Keith's mention of mesh lights.  If you set the ambient of a computer monitor to 1, it may look too bright and washed out, and when you render, you'll find that it doesn't cast hardly any light.  If you crank up the ambient to 15, it will probably emit sufficient light, but then the monitor appears as a searing white silhouette.

     So, a "mesh light" property would tell Firefly to cast much more light from this object (or material zone) for a given value of ambience. Thus, your mesh light lamp could have a soft warm glow with an ambience of 0.67 and it would cast an effective amount of light in IDL.  Ideally, I would want this to be selectable on a per-material basis (rather than per-object), and adjustable for relative intensity.

Poser 12, in feet.  

OSes:  Win7Prox64, Win7Ultx64

Silo Pro 2.5.6 64bit, Vue Infinite 2014.7, Genetica 4.0 Studio, UV Mapper Pro, UV Layout Pro, PhotoImpact X3, GIF Animator 5