[Radiance-general] Tracing specular reflections using rtrace

[Clarence Wang]

Hi list,

I'm trying to calculate daylight illuminance at a point where receives sunlight reflected from a specified 'mirror' material using rtrace. However, I get zero when executing the following command:

#oconv onepatch.rad sun.rad > mirror.oct
#cat point.txt | rtrace -I -ab 1 -dr 0 -lr 0 -h -oov mirror.oct | rcalc -e '$1=$2;$2=179*(.265*$4+.670*$5+.065*$6)' > results/rtrace/lux_mirror_ab1.csv

#The details of sun.rad (note: I only consider the impact of direct sunlight, so the sky contribution is not included)
void light solar
0
0
3 7.500e+06 7.500e+06 7.500e+06

solar source sun
0
0
4 0.341818 -0.579831 0.739565 0.533000

#The mirror type (onepatch.rad) is:
void mirror virtual
0
0
3 1 1 1

virtual polygon window
0
0
12
   0.5 6 8
  -0.5 6 8
  -0.5 6 7
   0.5 6 7

#The location and direction of measurement point are:
0 1.88 1.5 0 1 0

My questions are:

  1.  Are there any rtrace parameters needed to specify so that a reasonable result can be yielded?
  2.  Is it the limitation of rtrace to trace specular reflections to the "light source"? See the link below:

https://www.radiance-online.org:447/pipermail/radiance-general/2017-October/012294.html

In addition, I wonder if the expected daylight illuminance can be achieved using three-phase method. Since three-phase method consists of V,T,D, and s, is it logical to only use the "back reflection" and "back transmission" (genBSDF -f +b)  to calculate the daylight illuminance.

Any helps and advices will be greatly appreciated.

Thanks,

Clarence
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