[Radiance-general] Can this be done with pcomb?

[Autif Sayyed]

Thanks Greg,
Window is the only source of light in the room. I do want to get the
luminance values from the modified pic file, so it seems adjusting
exposure will not be the right approach. I was thinking pcomb could be
used for this, but have not been able to figure out how to do it yet.
Any suggestions or guidance would be great..


Autif

-----Original Message-----
From: radiance-general-bounces at radiance-online.org
[mailto:radiance-general-bounces at radiance-online.org] On Behalf Of Greg
Ward
Sent: Thursday, June 10, 2010 11:42 AM
To: Radiance general discussion
Subject: Re: [Radiance-general] Can this be done with pcomb?

The short answer is 'yes.'  Light is linear, so you can always scale
according to window transmittance for light coming through the window.
There may be some (very) slight inaccuracies due to the varying angular
transmittance, but the results should be roughly correct.

If the window is the only source of light in the room, and you are
adjusting the picture exposure rather than looking at the luminance/
radiance values, then you will see no change at all, because one will
compensate for the other.

-Greg

> From: "Autif Sayyed" <AutifS at TWGI.com>
> Date: June 10, 2010 9:23:36 AM PDT
>
> Hello All,
> I have a pic file of an indoor scene with windows that I want to test 
> with varying visible transmittance of the glass. Without having to run

> rpict again, is there a way of dropping down the sky luminance using a

> multiplier OR to uniformly drop down the light in the scene by 
> combining the pic (using pcomb) with pic file of a screen of a 
> specific transmittance? In other words, can I just filter down the 
> light levels uniformly in the scene without having to run rpict again.
> Thanks.
> Autif

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