[Radiance-general] Illuminance values

[Rob Guglielmetti]

On Apr 22, 2005, at 4:32 AM, Marija wrote:
> My scene is simple:
> 1.Rectangular room, with ideally diffuse surfaces. Reflectances are 
> 0.8 0.8 0.8.
> 2.Room dimensions are 10x10x10 and the center is positioned in the 
> (0,0,0).
> 3.In the middle of the room is placed a luminaire, with indirect light 
> distribution. It is oriented toward ceiling, so workplane illuminance 
> has only indirect component.

> Which value is the most appropriate for -ab parameter? Should I also 
> use some other ambient parameters?
> I've tried with different -ab values and results are ascending, so I 
> don't know which result is the most accurate.

The answer to the first question is, whatever value you deem 
appropriate.  The answer to the second one is, probably.

The raw truth of using Radiance is that there is no single correct 
answer for parameterizing your simulations. The proper settings for the 
myriad options will differ with every single simulation you do, and 
depend on... pretty much everything.  The good news is that the rad 
utility can be put to good use as you get started with Radiance.  rad 
makes good guesses about proper parameters for your simulations based 
on a few basic assumptions about your scene.  You can even save those 
assumptions to a file and reuse them in subsequent rpict and rtrace 
runs.  Refer to the manpage of rpict for more onfo on that.  There are 
also some good discussions of this on this list's archives (I should 
know, since I learned about this from this very list).

=================
    Rob Guglielmetti
www.rumblestrip.org