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25 Dec 2024 21:22:20 EST (-0500)
  HDR brightness (Message 1 to 4 of 4)  
From: Mark
Subject: HDR brightness
Date: 14 Jun 2006 13:05:00
Message: <web.44904122b24f9eec7a062e590@news.povray.org>
I've been using various lightprobes and all of them seem to be too dark in
my scenes. A temporary solution has been to increase the brightness value
in the radiosity block, however, it can give odd results. Are there perhaps
ideal radiosity settings for HDR or is there a different mindset needed
altogether? Any insight or general help/tips would be greatly appreciated.

Thanks,

Mark


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From: Trevor G Quayle
Subject: Re: HDR brightness
Date: 14 Jun 2006 14:20:01
Message: <web.449052e29f30154ec150d4c10@news.povray.org>
"Mark" <nomail@nomail> wrote:
> I've been using various lightprobes and all of them seem to be too dark in
> my scenes. A temporary solution has been to increase the brightness value
> in the radiosity block, however, it can give odd results. Are there perhaps
> ideal radiosity settings for HDR or is there a different mindset needed
> altogether? Any insight or general help/tips would be greatly appreciated.
>
> Thanks,
>
> Mark

I usually use the following finish for HDRs:

finish {ambient pow(2,FStops) diffuse 0}

where FStops is the number of FStops to adjust the HDR brightness by (i.e. 0
gives no adjustment, each +1 doubles the brightness, each -1 halves the
brightness)

-tgq


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From: Trevor G Quayle
Subject: Re: HDR brightness
Date: 14 Jun 2006 14:25:01
Message: <web.4490546e9f30154ec150d4c10@news.povray.org>
"Trevor G Quayle" <Tin### [at] hotmailcom> wrote:
> "Mark" <nomail@nomail> wrote:
> > I've been using various lightprobes and all of them seem to be too dark in
> > my scenes. A temporary solution has been to increase the brightness value
> > in the radiosity block, however, it can give odd results. Are there perhaps
> > ideal radiosity settings for HDR or is there a different mindset needed
> > altogether? Any insight or general help/tips would be greatly appreciated.
> >
> > Thanks,
> >
> > Mark
>
> I usually use the following finish for HDRs:
>
> finish {ambient pow(2,FStops) diffuse 0}
>
> where FStops is the number of FStops to adjust the HDR brightness by (i.e. 0
> gives no adjustment, each +1 doubles the brightness, each -1 halves the
> brightness)
>
> -tgq

I should also mention, that for use with radiosity, you need to find a way
to match the effect of the HDR to the visible brightness of the HDR.  This
is best done by either adjusting the rad brightness as you are already
doing, or bringing the HDR closer to the scene so it has less distance to
travel, and less attenuation (i.e., use a smaller sphere, assuming you are
using a physical sphere rather than sky_sphere)

-tgq


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From: Bill Pragnell
Subject: Re: HDR brightness
Date: 15 Jun 2006 05:45:01
Message: <web.44912ba29f30154e731f01d10@news.povray.org>
If you haven't already done so, try setting assumed_gamma = 1 in
global_settings (which, according to the docs, you should anyway). That can
brighten an image considerably if there's lots of dark areas.

Bill


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