[Radiance-general] Illuminance Values

[Lars O. Grobe]

Hi!
> 1.        In the base case the slats have the same tilt angle at one
> point of time ("conventional control").
> 2.         In the prototype model, the blinds are divided into three
> sections: Top , Middle and Bottom Blinds, each of equal dimensions
> ("splitcontrol"). In each section blinds can have the different slat
> tilt angle.
(...)
> For pilot testing I tested  conventional control for  0, 45 and 90
> degrees and split control for 0, 45, and 90 degrees, too (i.e. I kept
> the same tilt angle in each section of the split blinds just for the
> pilot testing  and the result  comparison purpose).
>
> The results that I obtained show variation in the values of
> Illuminance obtained for these two models (results difference ranges
> from 10-150%) although the results should be the same.
(...)

So you mean, as the blind settings are the same for both models during
your current test runs, you actually have the same model set-up with
different geometry?
> genblinds whitealum main 0.0125 1.82 0.63 66 90 |xform -rz 90 -t 2.71
> 0.05 2.06>66-1-90.rad
Is the "whitealum" material specular or diffuse?
> rtrace -h -I -ab 1 -ad 4096 -as 128 -av .02 .02 .02
> hr.oct<mainsamples.inp|rcalc -e '$1=47.4*$1+120*$2+11.6*$3'>>$month.out

Are you sure that your ambient paramters are suiteable for that set-up?
As far as I understand it, you get illumination only for the light
"directly" hitting your surfaces from the sky you generated. So you have
a very non-uniform environment for your rtrace-call. Did you ever render
an image of the scene, with the same parameters, using a fisheye-view
for the same view as your rtrace measurement point is getting? Imagine
the rtrace-measurement-point being a sensor, or put yourself into its
place, what do you expect to see - and do your rendering settings
account for that? As I have not seen the result, these are only guesses
for now, but I am pretty sure that you will need higher -ab settings for
such a set-up (probably -ab 4 or higher), and using ar and aa settings
to get a uniform luminance over your rooms surfaces. I guess your
ceiling is more or less black now (except the -av-contribution, but what
is your aw than)?

Good luck!

CU Lars.