[Radiance-general] FW: Gensky Question
Gregory J. Ward
gregoryjward at gmail.com
Wed Nov 22 18:02:23 CET 2006
The glow computed for the ground includes whatever sunlight should be
falling on it. An intermediate sky has some sun, so the solar
irradiance (-R) setting has an effect. (Even if you use -i or -s,
gensky still computes the ground radiance based on the sun being out
-- it just leaves off the solar source.)
> From: "Phillip Greenup" <Phillip.Greenup at arup.com>
> Date: November 22, 2006 4:08:25 AM PST
> Well this is a funny little thing... Giulio has found something
> Having followed his test below, both sky definitions provided a global
> irrad of 55.7 W/m2. The reflected ground glow was 5.27 W/m2/sr for
> former model and 3.57 W/m2/sr for the latter. These correspond to
> ground reflectances of ~30 and 20% resp...
> Like Giulio, I have never noticed this as I prefer to use a local
> plane, particularly where sunlight is involved...
> What's going on here?
> -----Original Message-----
> From: On Behalf Of Giulio Antonutto
> Sent: 22 November 2006 11:27
> Indeed Phil is right!
> oops :-)
> but be careful when you use the options -i and -s, without the sun you
> need also to say -R 0.
> If not the 20% ratio will not work, because the ground will include
> reflected sun component anyway...
> Try to compare:
> gensky 12 12 12 -i -B 56
> gensky 12 12 12 -i -B 56 -R 0
> The ground is different.... why is it?
> Phil, what do you think? Can we call this a bug?
> I never noticed it before because I do not model the ground with a
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