[Radiance-general] Irradiance on tilted surfaces discarding downwards rays

[Greg Ward]

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

> From: Victor LRG <rioboo at 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
> 
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