[Radiance-general] Tracing specular reflections using rtrace

[Antoine Bugeat]

Hello,

An other thing to try is to set the -dr parameter to at least 1. As Robert
Shakespeare said, Mirror is doing a virtual light source (or secondary
light source) and with -dr 0 this virtual light source are not simulated.
I think with -dr 1 you should get the result you expect (even with -dr 1
and -ab 0 I think).
An other thing to check is maybe to enlarge the window to be sure that the
relfection of the sun from the window arrive to your sensor, but you
certainly already did it!

I hope I helped you.

Antoine

Le mar. 30 oct. 2018 à 11:48, Shakespeare, Robert A. <shakespe at indiana.edu>
a écrit :

> Mirror is a virtual light source and to see its reflection effect, I think
> you require a minimum of –ab 2.
> Rob
>
> From: Clarence Wang <wangjuncwz at hotmail.com>
> Reply-To: Radiance discussion <radiance-general at radiance-online.org>
> Date: Tuesday, October 30, 2018 at 6:39 AM
> To: Radiance discussion <radiance-general at radiance-online.org>
> Subject: [Radiance-general] Tracing specular reflections using rtrace
>
> 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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