[Radiance-general] Testing -B -R in gensky

[Nick Devlin]

Giulio & Peter, 

Many thanks for the prompt responses. 

I followed Giulio's advice regarding testing the resultant illuminance
values. I am responding purely so that other newbies can find the answers
more quickly next time. 

To test the sky output I produced just one sky description with +s and -B &
-R defined. Created octree with a simple horizontal surface (not sure this
was necessary) and sky. Then: 

Rview -i -vf viewfile.vf test.oct

>From this I derived the direct illuminance on the surface using TRACE
command. 

Then restart rview with same parameters but include -ab 1 to include the
diffuse component from the skydome. Easy. Trace again, and check the values
against my assumptions. 

In short, specifying -R & -B explicitly define. Had just managed to confuse
myself by thinking too hard! 

Many thanks

Nick  


------------------------------

Message: 5
Date: Wed, 22 Nov 2006 10:24:34 -0000
From: "Giulio Antonutto" <Giulio.Antonutto at arup.com>
Subject: RE: [Radiance-general] FW: Gensky Question
To: "Radiance general discussion"
	<radiance-general at radiance-online.org>
Message-ID:
	<CC0B19F4C6132F4D9FDDEBF194200FB501E7E6E3 at ldcexc02.global.arup.com>
Content-Type: text/plain; charset="us-ascii"

Nick,

-R -B are supposed to specify direct and diffuse contribute.
a quick and easy check is to create a -s (diffuse only) and a +s
(global) sky with the same -R -B and check illuminances at a point (0 0
0, 0 0 1)
Now try without the sky dome and +s (direct only) and see...
you should get diffuse and global and direct values.
Please try it.


About the source primitive, you need it all the time.
Coefficients can be just (1 1 1) for the sky 
and a reduction like (0.1 0.1 0.1) or (0.2 0.2 0.2) for the ground
depending to the model you are working on.
If you use your coefficients you will be working with colour but you
need to check that the photopic average is correct.


Hope this is +s,
i.e. 'clear' 
:-)

Ciao
G>




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