[Radiance-general] Radiance and lightshelves

[Nick Doylend]

> -----Original Message-----
> From: John Mardaljevic [mailto:jm at dmu.ac.uk]
> Sent: 20 June 2006 11:51
> To: radiance-general at radiance-online.org
> Subject: [Radiance-general] Radiance and lightshelves
> 
> 
> Nick,
> 
> Need a little bit more information: is the shelf specular 
> and are you modelling skies with sun?  If yes to both, are
> you modelling the shelf as material "mirror" and have you
> set the parameters for the "virtual light source" 
> calculation accordingly?  See section 11.3 of the Radiance
> book and have a look at the "virtual" office example in  
> the "obj" directory of the Radiance release.

I used a semi-specular 90% reflective plastic material for the shelf under
both cloudy and intermediate sunny skies.  I guess this explains why no
direct sunlight was being reflected.  I'll read up on the virtual light
source calculation and try using a mirror material later.  I'm still not
sure why I saw virtually no improvement in daylight distribution, even
without the direct reflection shouldn't there be some bouncing of diffuse
light deeper into the space.  I used quite a high ceiling reflectance and I
think I used sufficient ambient parameters, number of bounces etc.  

The test room was based on the one in chapter 6, with a 500mm clerestory
window, 500mm internal projection and 750mm external projection.  I used
skies for spring, summer and winter at midday, latitude 51 degrees north: a
CIE cloudy sky, and four intermediate sunny skies rotated to give N S E W
orientations.

Nick