[Radiance-general] Measuring red, green and blue light component in certain space

[Gregory J. Ward]

Hi Adriana,

To my knowledge, there is no standard metric for radiance independent  
of incoming direction.  You either need to define a particular  
direction, or in your case you probably want the irradiance value,  
which is the integral of radiance over the projected hemisphere.   
This also requires you to define a facing direction.

Phil Dutre has a nice compendium that explains lighting units, which  
may be found at:

	http://www.cs.kuleuven.ac.be/~phil/GI/

Section VI, starting page 25  is probably where you want to look.

-Greg

> From: alira at gsd.harvard.edu
> Date: May 29, 2006 8:49:03 PM PDT
>
> Hi all,
>
> I have modeled a cubical room (4 x 4 meters) with no windows or any  
> type
> of apertures; the room is completely closed and empty, without any  
> kind of
> objects inside. There is only a diffusive light source located in the
> middle of the ceiling. My intention is to change the color and  
> texture of
> the walls, and then measure the resulting light reaching the  
> geometrical
> center of the room: 1)INTENSITY (in radiance units) and 2)the  
> amount of
> RED, GREEN and BLUE of the resulting light spectrum also in radiance
> units.  How can I do these measurements?
>
> Adriana Lira
> Master in Design Studies, 2003
> Candidate for Doctor in Design Studies
> Harvard Graduate School of Design