[Radiance-general] rtrace for luminance values

[John An]

I have run into a problem that I think Mehlika Nur Inanici had a couple 
of year's back.

I am trying to use rtrace to get luminance values on top of a desk 
surface.  The command I'm using is:

cnt 6 12 1 | rcalc -e '$1=51+((72/6)*$1+6);$2=96+((144/12)*$2+6);$3=30' 
\
-e '$4=0;$5=0;$6=1' | rtrace -h -ov @../options_aa08_ab5 -af 
b_b_m_2_bare_aa08_ad1024_ab5.amb -e 
b_b_m_2_bare_illumgrid_task_08_l.out b_b_m.oct \
| rcalc -e '$1=179*(.265*$1+.670*$2+.065*$3)' > 
b_b_m_2_bare_illumgrid_task_08_l.dat

The values reported by rtrace are in the range of 0.1 to 0.2 
candela/meter squared.  However, in an image, I am getting values in 
the range of 1.5 to 2.5 candela/meter squared (which is much more 
reasonable).

In response to Mehlika's question, Schorsch had mentioned that the 
header to the pic file would give an exposure value, and that luminance 
= 179*(.265*R+.670*G+.065*B) / e.  But I can't seem to find the 
exposure.

What am I missing?  Where am I not looking?

Thanks.