POV-Ray : Newsgroups : povray.binaries.images : radiosity caustics Server Time
10 Aug 2024 05:22:49 EDT (-0400)
  radiosity caustics (Message 1 to 6 of 6)  
From: George Pantazopoulos
Subject: radiosity caustics
Date: 28 Oct 2004 13:17:40
Message: <418129b4@news.povray.org>
http://www.gammaburst.net/cg/povray/radcaustics.png

I was surprised by the quality of caustics I got. Notice that the 
refracted images of the surroundings are projected onto the floor. AFAIK 
you can't get this effect with photons.

To get these good-quality caustics, I modified the megapov-1.1 
sourcecode to disable the irradiance caching feature. This causes the 
renderer to take diffuse samples at EVERY pixel. Since it does not even 
try to smooth the results, the familiar radiosity artifacts are 
completely absent. It was slower, but not as slow as I thought it would be.

I noticed that I needed a recursion level greater than 1 to get the 
caustics to appear.

Normally, the irradiance cache prevents an explosion of rays in higher 
recursion levels. Since my patched version does not have this cache, I 
instead took a path-tracing-like approach and only shot a single ray for 
each recursion level beyond the first. Suprisingly, the caustics still 
appeared, and this technique did not diminish their quality.

Megapov 1.1's randomize feature for radiosity rays was key to this 
experiment.

Key radiosity settings:
-----------------------
randomize on
recursion limit 3
count: 200

error_bound Not applicable
nearest_count Not applicable


Render stats on my P4 2.26GHz 512MB RAM - patched Megapov 1.1/gcc 
3.3.4/gentoo linux 2.6.7
-----------------------------------------------------------------------------------------
Render Statistics
Image Resolution 800 x 800
----------------------------------------------------------------------------
Pixels:           692500   Samples:          692500   Smpls/Pxl: 1.00
Rays:          568927171   Saved:              5357   Max Level: 6/6
----------------------------------------------------------------------------
Ray->Shape Intersection          Tests       Succeeded  Percentage
----------------------------------------------------------------------------
Box                          852686722       728326146     85.42
Sphere                       322495240       199954909     62.00
Torus                        625727955        77885961     12.45
Torus Bound                  625727955       104126456     16.64
Bounding Box               12622101025      3426467548     27.15
Vista Buffer                   4317793         2602349     60.27
----------------------------------------------------------------------------
Roots tested:             104126456   eliminated:             21331779
Calls to Noise:                   0   Calls to DNoise:              10
----------------------------------------------------------------------------
Shadow Ray Tests:        1146571186   Succeeded:             253716556
Reflected Rays:            61938611   Total Internal:         11737051
Refracted Rays:            50203138
----------------------------------------------------------------------------
Smallest Alloc:                   9 bytes
Largest  Alloc:             2560008 bytes
Peak memory used:         123312372 bytes
Total Scene Processing Times
   Parse Time:    0 hours  0 minutes  1 seconds (1 seconds)
   Photon Time:   0 hours  0 minutes  0 seconds (0 seconds)
   Cloth Time:    0 hours  0 minutes  0 seconds (0 seconds)
   Mechsim Time:  0 hours  0 minutes  0 seconds (0 seconds)
   Render Time:   1 hours  7 minutes 54 seconds (4074 seconds)
   Postpr. Time:  0 hours  0 minutes  0 seconds (0 seconds)
   Total Time:    1 hours  7 minutes 55 seconds (4075 seconds)



-- 
-------------------------
George Pantazopoulos
http://www.gammaburst.net


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From: Tim Nikias
Subject: Re: radiosity caustics
Date: 28 Oct 2004 15:30:16
Message: <418148c8$1@news.povray.org>
Hey, that looks awesome! The scene reminds me of something... ;-)
There still is some noise, so do you have the ability to do some smoothing
or such on the samples? Maybe a possibility to just blend the current sample
with samples within a certain radius would do. A small radius should be
sufficient to get rid of the noise.

Great work, keep it up!

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>


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From: George Pantazopoulos
Subject: Re: radiosity caustics
Date: 28 Oct 2004 21:27:43
Message: <41819c8f$1@news.povray.org>
Tim Nikias wrote:
> Hey, that looks awesome! The scene reminds me of something... ;-)
> There still is some noise, so do you have the ability to do some smoothing
> or such on the samples? Maybe a possibility to just blend the current sample
> with samples within a certain radius would do. A small radius should be
> sufficient to get rid of the noise.
> 
> Great work, keep it up!
> 

Hey thanks Tim! Yes, I found your page on radiosity very thorough and 
helpful. Thanks for releasing your scene source! Got any other 
interesting scenes I could try out? :)

As far as the smoothing, my simple patch can't do that. It just 
calculates each pixel independently (which, incidentally makes it 
perfectly usable with parallel rendering now). Other than re-enabling 
the irradiance caching/smoothing, maybe I could abuse the code in some 
other evil way that I haven't thought of yet...

-- 
-------------------------
George Pantazopoulos
http://www.gammaburst.net


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From: Samuel Benge
Subject: Re: radiosity caustics
Date: 28 Oct 2004 22:28:11
Message: <4181AA9B.5050907@hotmail.com>
George Pantazopoulos wrote:

<snip> 
> I was surprised by the quality of caustics I got. Notice that the 
> refracted images of the surroundings are projected onto the floor. AFAIK 
> you can't get this effect with photons.
> 
> To get these good-quality caustics, I modified the megapov-1.1 
> sourcecode to disable the irradiance caching feature.

<clip>

This looks good! I hope an option to use your 'patch' becomes available 
in MegaPov or the official release.

-Sam


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From: Christoph Hormann
Subject: Re: radiosity caustics
Date: 29 Oct 2004 04:50:02
Message: <clsvv3$24e$1@chho.imagico.de>
George Pantazopoulos wrote:
> 
> http://www.gammaburst.net/cg/povray/radcaustics.png
> 
> I was surprised by the quality of caustics I got. Notice that the 
> refracted images of the surroundings are projected onto the floor. AFAIK 
> you can't get this effect with photons.
> 
> To get these good-quality caustics, I modified the megapov-1.1 
> sourcecode to disable the irradiance caching feature. This causes the 
> renderer to take diffuse samples at EVERY pixel. Since it does not even 
> try to smooth the results, the familiar radiosity artifacts are 
> completely absent. It was slower, but not as slow as I thought it would be.

It will be very slow as soon as you use slightly more complex scenes 
because there you will need much more rays to avoid noise in the final 
image.  The reason why this scene renders fast is mostly because the 
light is fairly uniformly distributed in the scene.  If you try 
something like a dark room only illuminated through a window you will 
see this.

Christoph

-- 
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 23 Sep. 2004 _____./\/^>_*_<^\/\.______


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From: Eli
Subject: Re: radiosity caustics
Date: 29 Oct 2004 20:19:18
Message: <4182de06$1@news.povray.org>
aaahhhhh I've tried this so many times with the regular POV-Ray version!!!

At least one person (me) would be very happy if I could turn that irradiance 
caching off while rendering radiosity pictures..... :P


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