Radiosity + Glass = Soft caustics.

I had no idea Radiosity lead to a photon-like effect. I remember someone 
a while back positing an image that had caustics caused by radiosity, 
but I thought it was a modification to POV-Ray.

-- 
~Mike

Things! Billions of them!

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Cool, isn't it?

radiosity is a bit like photons turned backwards...

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Eli wrote:
> Cool, isn't it?

Yep.

> 
> radiosity is a bit like photons turned backwards... 
> 

 From what I can tell, the radiosity algorithm basically takes a patch 
from a surface, traces out from it in a psuedo-random pattern ([[count]] 
points), averages it together and calls the illumination of that patch 
the result. So, it makes sense that caustics would happen.

I have not looked at the code to see if this is really what it does. 
There's more to it, I'm sure.


-- 
~Mike

Things! Billions of them!

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Mike Raiford wrote:

> Radiosity + Glass = Soft caustics.
> 
> I had no idea Radiosity lead to a photon-like effect. I remember someone 
> a while back positing an image that had caustics caused by radiosity, 
> but I thought it was a modification to POV-Ray.

I posted such an image a long time ago.. a room interior with a big 
reflective sphere in it. I doubt that's the one you mean, though.

-Xplo

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Xplo Eristotle <xpl### [at] infomagicnet> wrote:
> Mike Raiford wrote:
>
> > Radiosity + Glass = Soft caustics.
> >
> > I had no idea Radiosity lead to a photon-like effect. I remember someone
> > a while back positing an image that had caustics caused by radiosity,
> > but I thought it was a modification to POV-Ray.
>
> I posted such an image a long time ago.. a room interior with a big
> reflective sphere in it. I doubt that's the one you mean, though.
>
> -Xplo

Original post here:
http://news.povray.org/povray.binaries.images/thread/%3C418129b4%40news.povray.org%3E/?ttop=203630&toff=100

He means the image I posted, using one of Tim Nikias' scenes. For an
experiment I was doing, I modified POV-Ray so that it would calculate
radiosity for every pixel (first bounce), and then essentially do path
tracing for subsquent bounces.

Disabling the irradiance caching feature prevented fine details in the
"caustics" from getting smoothed out and lost, at the expense of longer
rendering times, and graininess. (However, It also made it much easier to
parallelize a radiosity render!)


George
http://www.gammaburst.net

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"George Pantazopoulos" <go### [at] tomyaboutpage> wrote in message
news:web.431f6b7923fcac0866e2d7a50@news.povray.org...
> Xplo Eristotle <xpl### [at] infomagicnet> wrote:
> > Mike Raiford wrote:
> >
> > > Radiosity + Glass = Soft caustics.
> > >
> > > I had no idea Radiosity lead to a photon-like effect. I remember someone
> > > a while back positing an image that had caustics caused by radiosity,
> > > but I thought it was a modification to POV-Ray.
> >
> > I posted such an image a long time ago.. a room interior with a big
> > reflective sphere in it. I doubt that's the one you mean, though.
> >
> > -Xplo
>
> Original post here:
>
http://news.povray.org/povray.binaries.images/thread/%3C418129b4%40news.povray.o
rg%3E/?ttop=203630&toff=100
>
> He means the image I posted, using one of Tim Nikias' scenes. For an
> experiment I was doing, I modified POV-Ray so that it would calculate
> radiosity for every pixel (first bounce), and then essentially do path
> tracing for subsquent bounces.

uhm, I posted a demonstration of radiosity-caustics a long time before that
actually :)

cu!
--
#macro G(b,e)b+(e-b)*C/50#end#macro _(b,e,k,l)#local C=0;#while(C<50)
sphere{G(b,e)+3*z.1pigment{rgb G(k,l)}finish{ambient 1}}#local C=C+1;
#end#end _(y-x,y,x,x+y)_(y,-x-y,x+y,y)_(-x-y,-y,y,y+z)_(-y,y,y+z,x+y)
_(0x+y.5+y/2x)_(0x-y.5+y/2x)            // ZK http://www.povplace.com

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Here is the image referred to by my above reply:
 http://news.povray.org/povray.binaries.images/thread/%3C418129b4%40news.povray.org%3E/?ttop=203630&toff=100
>
> He means the image I posted, using one of Tim Nikias' scenes. For an
> experiment I was doing, I modified POV-Ray so that it would calculate
> radiosity for every pixel (first bounce), and then essentially do path
> tracing for subsquent bounces.
>
> Disabling the irradiance caching feature prevented fine details in the
> "caustics" from getting smoothed out and lost, at the expense of longer
> rendering times, and graininess. (However, It also made it much easier to
> parallelize a radiosity render!)
>
>
> George
> http://www.gammaburst.net

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Attachments:
Download 'radcaustics.png' (505 KB)

Preview of image 'radcaustics.png'

George Pantazopoulos wrote:
> Here is the image referred to by my above reply:
> 
http://news.povray.org/povray.binaries.images/thread/%3C418129b4%40news.povray.org%3E/?ttop=203630&toff=100
> 
>>He means the image I posted, using one of Tim Nikias' scenes. For an
>>experiment I was doing, I modified POV-Ray so that it would calculate
>>radiosity for every pixel (first bounce), and then essentially do path
>>tracing for subsquent bounces.
>>
>>Disabling the irradiance caching feature prevented fine details in the
>>"caustics" from getting smoothed out and lost, at the expense of longer
>>rendering times, and graininess. (However, It also made it much easier to
>>parallelize a radiosity render!)
>>
>>
>>George
>>http://www.gammaburst.net
> 
> 
> 
> ------------------------------------------------------------------------
> 

That was the one!

I looked at the statistics in the original message, and 1 hour seems 
reasonable, given what you're doing.

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