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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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