Jim Henderson wrote:
> Ah, so you've decided Darren and I were right after all, then? ;-)

I've come to the conclusion that I would be terribly disappointed if the 
universe and/or life actually were designed by an intelligence. All the 
awe and wonder would just turn into "oh, he meant it that way."

Kind of like watching an amazing speed-run, only to find out they did it 
on God mode or something.  What would be the point of living in such a 
place?

-- 
   Darren New / San Diego, CA, USA (PST)
     On what day did God create the body thetans?

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On Thu, 21 Feb 2008 11:17:00 -0800, Darren New wrote:

> Jim Henderson wrote:
>> Ah, so you've decided Darren and I were right after all, then? ;-)
> 
> I've come to the conclusion that I would be terribly disappointed if the
> universe and/or life actually were designed by an intelligence. All the
> awe and wonder would just turn into "oh, he meant it that way."
> 
> Kind of like watching an amazing speed-run, only to find out they did it
> on God mode or something.  What would be the point of living in such a
> place?

:-)

Jim

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Invisible wrote:

>> Now have a look at the images below for some state-of-the-art rendering.
>> http://thirdseventh.cgsociety.org/gallery/573528/
> 
> Sorry - due to my extremely lame monitor at work, most of these come out 
> nearly black... :-(

OK, now I can view these on a decent monitor... Mmm, yes, that's pretty 
damn impressive. I'm not too keen on the slightly fuzzy "I'm using a 
real camera lense" effect. But other than a few dark areas which seem a 
tad noisy, these all look pretty damn real to me...

[Oh, and the bark on that tree.]

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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Darren New wrote:

> I've come to the conclusion that I would be terribly disappointed if the 
> universe and/or life actually were designed by an intelligence. All the 
> awe and wonder would just turn into "oh, he meant it that way."
> 
> Kind of like watching an amazing speed-run, only to find out they did it 
> on God mode or something.  What would be the point of living in such a 
> place?

Mmm. I'll have to remember that one...

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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Warp wrote:

>   A BRDF is a function between incoming light (from all possible directions)
> and outcoming light (to all possible directions).
> 
>   In other words (in an ideal case), at each point light coming from all
> possible directions are taken into account, and this light can be reflected
> to all possible directions, with a factor given by the BRDF function.
> 
>   Naturally in order to calculate this you would have to shoot an infinite
> number of rays from each point, and when those rays intersect other surfaces,
> again an infinite amount of rays would have to be sent from those points,
> ad infinitum.
> 
>   In practice this is, of course, impossible. However, brute force renderers
> try to approximate this by simply sending rays at random directions, lots
> and lots of them. The more rays are sent, the more the final results
> approaches the optimal. This results in a very grainy image at first,
> because the amount of samples is not even nearly enough. However, as more
> and more rays are traced, the result starts slowly approaching the ideal.
> 
>   When the BRDFs are properly designed to simulate the behavior of
> real-world materials, the results can be quite realistic.
> 
>   Or this is how I have understood it.

OK. Thanks.

>   POV-Ray's stochastic global illumination resembles this, although it's
> quite limited (and doesn't use BRDFs).

Also doesn't recompute irridescence at each point, but reuses samples 
from nearby points [in an effort to reduce the insane number of ray 
intesection tests required]. Hence all that parameter-fiddling business.

As best I can tell, the algorithm described just sounds like POV-Ray's 
radiosity with an infinitely low error_bound. (I.e., always resample.) 
But applied to *all* terms, not just diffuse illumination...

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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Jim Henderson wrote:
> Ah, so you've decided Darren and I were right after all, then? ;-)

yes, now I'm a satanist. :P </sarcasm>

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Orchid XP v7 wrote:
> As best I can tell, the algorithm described just sounds like POV-Ray's 
> radiosity with an infinitely low error_bound. (I.e., always resample.) 
> But applied to *all* terms, not just diffuse illumination...
> 

That's the key. I'm not too sure POVRay's radiosity gives an unbiased 
result even with all settings turned up to the best quality. If there is 
just one reflective surface in the mix I'm downright sure it does not...

Even throwing photons in I believe there are situations POV will not 
handle correctly. Can we do a wall lighting one side of a room because 
it is itself lit by a light reflecting in a mirror?

Yeah, I should try myself :-)

-- 
Vincent

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> Orchid XP v7 wrote:
>> As best I can tell, the algorithm described just sounds like POV-Ray's 
>> radiosity with an infinitely low error_bound. (I.e., always resample.) 
>> But applied to *all* terms, not just diffuse illumination...
>>
> 
> That's the key. I'm not too sure POVRay's radiosity gives an unbiased 
> result even with all settings turned up to the best quality. If there is 
> just one reflective surface in the mix I'm downright sure it does not...
> 
> Even throwing photons in I believe there are situations POV will not 
> handle correctly. Can we do a wall lighting one side of a room because 
> it is itself lit by a light reflecting in a mirror?

"Light shines onto a white diffuse wall. Reflected light from the wall 
creates caustics through a glass sphere. That is diffuse -> Specular 
(caustics). I got the idea for this scene from a document by Henrik Wann 
Jensen describing some difficult test scenes."

http://www.winosi.onlinehome.de/Gallery_t15.htm

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Nicolas Alvarez wrote:

>> Even throwing photons in I believe there are situations POV will not 
>> handle correctly. Can we do a wall lighting one side of a room because 
>> it is itself lit by a light reflecting in a mirror?
> 
> "Light shines onto a white diffuse wall. Reflected light from the wall 
> creates caustics through a glass sphere. That is diffuse -> Specular 
> (caustics). I got the idea for this scene from a document by Henrik Wann 
> Jensen describing some difficult test scenes."
> 
> http://www.winosi.onlinehome.de/Gallery_t15.htm

Ah yes now I remember seeing this one... Well it is expected that 
unbiased renderer are able to tackle this, of course...

-- 
Vincent

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Vincent Le Chevalier wrote:

> That's the key. I'm not too sure POVRay's radiosity gives an unbiased 
> result even with all settings turned up to the best quality. If there is 
> just one reflective surface in the mix I'm downright sure it does not...

I do recall somebody rendered a radiosity scene with no photon maps at 
all, and yet a large curved mirror still produced correct caustics. (It 
was a damn long time ago now though, so I'd never be able to find the 
image...)

> Even throwing photons in I believe there are situations POV will not 
> handle correctly. Can we do a wall lighting one side of a room because 
> it is itself lit by a light reflecting in a mirror?
> 
> Yeah, I should try myself :-)

Radiosity ought to do it - although it may or may not require some 
fairly crazy settings...

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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