[Radiance-general] Calculating luminance of surface

[Andy McNeil]

Florian,
As a placeholder, until you have a BRDF, you could use data from table 1 of
Alson's paper I sent previously or possibly the angular reflectance and
roughness in Sandia's SGHAT technical reference (section 5.3 and 5.4):
https://share.sandia.gov/phlux/static/references/glint-glare/SGHAT_Technical_Reference-v6.pdf
Andy

On Mon, Mar 6, 2017 at 1:20 AM, Florian Wochele <emb15fwo at student.lu.se>
wrote:

> Hello Greg,
> unfortunately we don't have the BRDF (at least not yet). What kind of
> assumptions are you talking about? Maybe we can still use the solution in
> reference to those assumptions.
> /Florian
>
>
> Am 03.03.2017 um 19:21 schrieb 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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