Irradiance on tilted surfaces discarding downwards rays

radiance-general
1

Dear all,

I was wondering if there is a simple way in Radiance to calculate
irradiance (rtrace -I) on a tilted surface, but discarding the rays that
are fired downwards, aiming below the horizon. I guess it can be done
manipulating the source code, but I cannot think of a simple way.

Perhaps it could be done inverting the initial ray, measuring the luminance
of the surface by using a lambertian white material with an altitude
modifier, and calculating then the illuminance, but it is a bit convoluted
and the white material may distort too much the real lighting levels in the
scene.

Any ideas?

Thanks,

Victor Lopez-Rioboo Gil

2

Could you place very small, horizontal black ring surfaces (void plastic black 0 0 5 0 0 0 0 0) at each measurement position? These would then block downward rays without giving any contribution. The surfaces themselves can be so small as to not affect the rest of the scene.

-Greg

ยทยทยท

From: Victor LRG <rioboo@gmail.com>
Date: March 31, 2017 3:32:55 PM PDT

Dear all,

I was wondering if there is a simple way in Radiance to calculate irradiance (rtrace -I) on a tilted surface, but discarding the rays that are fired downwards, aiming below the horizon. I guess it can be done manipulating the source code, but I cannot think of a simple way.

Perhaps it could be done inverting the initial ray, measuring the luminance of the surface by using a lambertian white material with an altitude modifier, and calculating then the illuminance, but it is a bit convoluted and the white material may distort too much the real lighting levels in the scene.

Any ideas?

Thanks,

Victor Lopez-Rioboo Gil