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From: Lieut Data
Subject: Reflected Illumination?
Date: 2 Mar 2002 10:42:51
Message: <3c80f2fb@news.povray.org>
Is it possible to have reflected illumination, that is a light source
bounces off a mirror, and lights up objects in that newly reflected path?

I experimented using a spotlight on a mirror pointing at the reflection of
an object, but no success -- I hope I am missing something, and this is not
a limitation of Pov-Ray --

But if it is, thats ok, since PovRay ROCKS anyway :-)

Thanx


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From: Zeger Knaepen
Subject: Re: Reflected Illumination?
Date: 2 Mar 2002 10:51:26
Message: <3c80f4fe$1@news.povray.org>
> Is it possible to have reflected illumination, that is a light source
> bounces off a mirror, and lights up objects in that newly reflected path?
>
> I experimented using a spotlight on a mirror pointing at the reflection of
> an object, but no success -- I hope I am missing something, and this is
not
> a limitation of Pov-Ray --
>
> But if it is, thats ok, since PovRay ROCKS anyway :-)
it indeed does, but it rocks even more, cause with photons you can get the
effect you want.

cu!
--
ZK AKA SaD
http://www.povplace.be.tf
"From beneath the floor, the man does control me! Yes!"


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From: Hugo
Subject: Re: Reflected Illumination?
Date: 2 Mar 2002 11:08:55
Message: <3c80f917$1@news.povray.org>
> Is it possible to have reflected illumination, that is a light source
> bounces off a mirror, and lights up objects in that newly reflected path?


Hi Data,

Yes it's possible. But it will slow down rendering, depending on how
accurate you want the light to reflect. In some cases it's awfully slow, but
usually not. The feature is called radiosity. This causes all objects to
reflect light, and not just the mirror. But you can adjust how many times
the light will reflect (once might be just enough).

If you're using Pov3.5 beta, it's very easy to activate radiosity because
there is an include file with ready-made setups for many situations. I'm not
sure if this include file is found in older Pov versions, and then you'll
have to experiment with quite a few settings.. Or, you can try the default,
of course.. Radiosity is cool.

MegaPOV and Pov3.5beta also have a feature called "photons" that makes
caustics on specific objects. It's not the same as radiosity. It's only for
glassy objects. I don't have much luck or experience with photons, but other
people have. Maybe they'll post here too.

- UFP, End Transmission -

Regards,
Hugo


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From: Christoph Hormann
Subject: Re: Reflected Illumination?
Date: 2 Mar 2002 11:16:03
Message: <3C80FABA.930F11A3@gmx.de>
Lieut_Data wrote:
> 
> Is it possible to have reflected illumination, that is a light source
> bounces off a mirror, and lights up objects in that newly reflected path?
> 
> I experimented using a spotlight on a mirror pointing at the reflection of
> an object, but no success -- I hope I am missing something, and this is not
> a limitation of Pov-Ray --
> 

It is not a limitation of POV-Ray, but a limitation of raytracing in
general.  In POV-Ray you can use photon mapping to get this effect though.

Christoph

-- 
POV-Ray tutorials, IsoWood include,                 
TransSkin and more: http://www.tu-bs.de/~y0013390/  
Last updated 21 Feb. 2002 _____./\/^>_*_<^\/\.______


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From: Christopher James Huff
Subject: Re: Reflected Illumination?
Date: 2 Mar 2002 15:22:07
Message: <chrishuff-FCB738.15221202032002@netplex.aussie.org>
In article <3c80f917$1@news.povray.org>, "Hugo" <hua### [at] post3teledk> 
wrote:

> Yes it's possible. But it will slow down rendering, depending on how
> accurate you want the light to reflect. In some cases it's awfully slow, but
> usually not. The feature is called radiosity. This causes all objects to
> reflect light, and not just the mirror. But you can adjust how many times
> the light will reflect (once might be just enough).

Radiosity is not what he wants. Radiosity simulates diffuse reflection, 
like light bouncing off a lampshade or white walls. You might get 
something vaguely like caustics with effort, but that's not what the 
algorithm is designed for, so it won't be very efficient.


> MegaPOV and Pov3.5beta also have a feature called "photons" that makes
> caustics on specific objects. It's not the same as radiosity. It's only for
> glassy objects. I don't have much luck or experience with photons, but other
> people have. Maybe they'll post here too.

Photons work on any reflective or refracting object, not just glassy 
ones, and are specifically designed for the situation he has in mind.

-- 
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/


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From: Florian Pesth
Subject: Re: Reflected Illumination?
Date: 2 Mar 2002 17:17:26
Message: <3c814f76@news.povray.org>
Hello!
I think it would be an interesting effect to use an complete reflective
ellipsoid and placing one light source into the first "burning point"
(correct
expression?) and the object in the second one. Should give some sort of
artificial "ambient light". I've tried this with no success because of the
explained reasons. I'm a newbie, so I'm not experimenting with photons at
the
moment... ;), so it could not work.
Best regards,
Florian


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From: Lieut Data
Subject: Re: Reflected Illumination?
Date: 2 Mar 2002 18:15:59
Message: <3c815d2f@news.povray.org>
Thankyou for all the replies!

I am using Pov 3.1, and never came across photons in the help file, so I am
presuming this must be a new feature in Pov 3.5 -- cant wait till it comes
out!

:-)



"Lieut_Data" <lIe### [at] yahOOcom> wrote in message
news:3c80f2fb@news.povray.org...
> Is it possible to have reflected illumination, that is a light source
> bounces off a mirror, and lights up objects in that newly reflected path?
>
> I experimented using a spotlight on a mirror pointing at the reflection of
> an object, but no success -- I hope I am missing something, and this is
not
> a limitation of Pov-Ray --
>
> But if it is, thats ok, since PovRay ROCKS anyway :-)
>
> Thanx
>
>
>


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From: Lieut Data
Subject: Re: Reflected Illumination?
Date: 2 Mar 2002 18:20:00
Message: <3c815e20$1@news.povray.org>
Lol, I also found photons in MegaPov

I am concerned about the "discliamer" of possibly crashing my system -- has
anyone had bad experiences with MegaPov?



"Lieut_Data" <lIe### [at] yahOOcom> wrote in message
news:3c815d2f@news.povray.org...
> Thankyou for all the replies!
>
> I am using Pov 3.1, and never came across photons in the help file, so I
am
> presuming this must be a new feature in Pov 3.5 -- cant wait till it comes
> out!
>
> :-)
>
>
>
> "Lieut_Data" <lIe### [at] yahOOcom> wrote in message
> news:3c80f2fb@news.povray.org...
> > Is it possible to have reflected illumination, that is a light source
> > bounces off a mirror, and lights up objects in that newly reflected
path?
> >
> > I experimented using a spotlight on a mirror pointing at the reflection
of
> > an object, but no success -- I hope I am missing something, and this is
> not
> > a limitation of Pov-Ray --
> >
> > But if it is, thats ok, since PovRay ROCKS anyway :-)
> >
> > Thanx
> >
> >
> >
>
>


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From: Hugo
Subject: Re: Reflected Illumination?
Date: 3 Mar 2002 05:28:21
Message: <3c81fac5@news.povray.org>
> Radiosity is not what he wants. Radiosity simulates diffuse reflection,

I thought he wanted exactly this ... a big area of light.. In all examples
I've seen, photons are used for small, highlighted caustics.

But alright.


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From: Hugo
Subject: Re: Reflected Illumination?
Date: 3 Mar 2002 05:33:45
Message: <3c81fc09$1@news.povray.org>
> I am concerned about the "discliamer" of possibly crashing my system

It's very unlikely to cause any harm to your system. MegaPOV is the same as
Pov3.1 but with some extra features. It shouldn't make any difference during
install.


Regards,
Hugo


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