[Radiance-general] rtrace vs rcontrib

[Jack de Valpine]

Hi Mario,

The programs do things very differently from each other.

One source of difference is in the options, both programs require 
different settings for the same set of options. Rcontrib actually 
disables the ambient cache by setting -aa 0, so you will need to 
increase ambient divisions (-ad) parameter along with a few others. As 
quick experiment you could try 2x or 4x whatever is set for -ad in the 
rtrace run in your rcontrib run. Also it would be instructive to see 
what defaults rcontrib uses and perhaps work from those. To do this you 
can do rcontrib -defaults.

Axel Jacobs had a very instructive tutorial on rtcontrib (older version 
of rcontrib) that included a section that compared running rtrace and 
rtcontrib. I think unfortunately it is no longer available though.

Regards,

-Jack de Valpine

-- 
Jack de Valpine
President

Visarc Incorporated
www.visarc.com

channeling technology for superior design and construction

On 9/2/2014 6:43 AM, Mario Geiger wrote:
> Hello,
>
> I would like to understand why /rtrace/ and /rcontrib/ are so different.
>
> I ran the two programs as following.
>
> oconv window.rad office.rad > scene.oct
>
> echo "1.8 *y* 1 0 0 1" | rtrace   -w -h -I                option -n 4 
> scene.oct
> echo "1.8 *y* 1 0 0 1" | rcontrib -w -h -I+ -m windowglow option -n 4 
> scene.oct
>
> where option = -ab 5 -ad 1024 -as 256 -lw 1e-5 -dj 0 -ds .5 -dt .5 -dc 
> .25 -dr 3 -dp 64 -st .85 -aa .1 -ar 32 -lr 4
>
> My scene is a simple box 3.6 x 8.2 x 2.8 meters with a "window" as a 
> role of a light source. I put the *.rad files in attachment.
>
> By varying *y* the distance from the "window" in the box I get the 
> following results.
>
> Also it takes much longer to run /rtrace/ than /rcontrib/ :
>
> /rtrace/ : Elapsed time is 475.741 seconds.
> /rcontrib/ : Elapsed time is 1.10356 seconds.
>
> To compute all the 50 points.
>
> Why don't I get the same result in the same time ?
>
> Thanks for your time!
>
>
>
>
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