questions about rendering using Radiance

[famous_doraemon]

I am using Radiance for measuring the working plane illuminance, however, there are some problems and hence i cannot continue with my work.

a) I have constructed a room and wanna compare the result between normal situation and using a mirror redirecting the sunlight into the room. obviously, the illuminance level in the deeper area of the room must be higher than that without a mirror. however, the result obtained is so depressed. seems like the result is worse than without a mirror. I don't know if I have set something wrong or not.

the sky is:
!gensky 7 29 15 -a 22.18 -o 114.08 -m 114.28 +s
the room is 6m x 4m x 3.2m
window is 4m x 1.9m on one of the smaller size of the wall.
mirror is adjusted to reflect the sunlight onto the deepest area of the ceiling.
value of -ab is 2
normally, the deepest area of the ceiling will have a higher illuminance level, however, the result is only the small, even slightly lower than without a mirror.

b) actually, how can i measure the working plan illuminance by using the Radiance? because i have tried so many times, and also read through Greg Ward's "Rending with Radiance", but still cannot find out the method to estimate the required result, but only the illuminance level of the wall, ceiling and wall. could anyone tell me about the process of evaluating the illuminance level of working plane (0.8m above floor)?

Really thanks a lot for those who could help me to solve this problem/read this message.

[Kevin]

Great question - plz see thread at http://www.designcommunity.com/forums/topic-15690.html for discussion...