[Radiance-general] Calculating luminance of surface

[Greg Ward]

The quantity you are asking for, luminance as a function of incident illuminance, is precisely what the BRDF (bidirectional reflectance distribution function) tells you.  If you have the BRDF of your panel, you can compute the luminance directly from illuminance and incident direction.  If you do not, you cannot compute the luminance without making some (likely wrong) assumptions.

-Greg

> From: Florian Wochele <emb15fwo at student.lu.se>
> Date: March 3, 2017 1:24:56 AM PST
> 
> Dear Sir or Madam,
> 
> We are working on our master thesis at Lund University about Glare from reflections on PV panels. To evaluate whether glare occurs or not, we need the luminance of the reflection on the surface the PV panel reflects light on. However we only get the illuminance of the sun (light source). How can we translate the illuminance from the sun to the luminance of the surface? There has to be a way since we can get the luminance via simulations, however we are interested in a way to calculate the luminance. We also have to take into account that PV panels are neither perfectly specular nor perfectly diffuse.
> 
> Best regards,
> 
> Erik Hjorth and Florian Wochele
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