[Radiance-general] Understanding illum correctly?

[Mark Shewfelt]

Hello All,

I hoping someone can help me with my understanding of illum sources.
I've read RwR, done the tutorials, etc., and I think I'm OK with the
concept of secondary sources. All of the examples I've seen make illums
around windows and skylights. My situation is slightly different - I
have a skylight that is not flush with the interior of the space (i.e.
there is a well, the insides of which are painted white).


  -----------   <-- skylight glass
  |         |
  |         |   <-- well
  |         |
  |         |
--	 __    ---------------  <-- ceiling of room
        \
         \
	    -------------------- illum

   <- room ->


My intention is to make an illum at the ceiling of the room, which
incorporates the bounces that the light takes to get into the room.
Using the files below I've been able to simulate the skylight and the
results look pretty reasonable. However, when I run the simulation using
rad, I get the error message 'warning - no light sources found'. From
reading Axel Jacobs' excellent tutorials I was imagining that this
message would go away with the illums. 

Any comments/tips/pointers would be great.

Cheers,

Mark Shewfelt
Enermodal Engineering Ltd.
Kitchener Ontario Canada


skylight.rif:
------------------------------
scene = sky.rad 
scene = material.mat
scene = room3.rad
illum = skylight.rad
# The file in which to store indirect values
AMB= simple.amb
INDIRECT = 2
mkillum= -ab 2


material.mat:
------------------------------
skyfunc brightfunc window_dist
2 winxmit winxmit.cal
0
0

window_dist glass skylight_glass
0
0
3	0.8	0.8	0.8

# light is emitted from this but is invisible.
void illum skylight_illum
0
0
3	0	0	0

skylight.rad
------------------------------
# light enters skylight well from here
skylight_glass polygon skylight_window
0
0
12
 	5.491076	 6.503552	 3.400000

	 4.201076	 6.503552	 3.400000

	 4.201076	 5.213552	 3.400000

	 5.491076	 5.213552	 3.400000

# light is emitted from this "surface" into the room
skylight_illum polygon face.65
0 
0 
12
	 5.491076	 6.503552	 3.00000

	 4.201076	 6.503552	 3.00000

	 4.201076	 5.213552	 3.00000

	 5.491076	 5.213552	 3.00000