Okay, so as I understand it, the grainier image is multiple media and
the smoother of the two is multiple containers (the images posted at
p.b.i.).


Peter Popov wrote:
> 
> Hi there.
> 
> Here're the results from the tests I promised. Sorry it took me so
> long, but it's media, you know...
> 
> Please see p.b.s-f for the code and p.b.i for example images.
> 
> Type 1 - multiple densities
> 
> type1_1.tga, Quality 2  -  7 minutes
> type1_2.tga, Quality 3  - 21 minutes
> type1_3.tga, Quality 4  - 29 minutes
> 
> Type 2 - multiple containers
> 
> type2_0.tga, Quality 1  -  4 minutes
> type2_1.tga, Quality 2  -  6 minutes
> type2_2.tga, Quality 3  - 17 minutes
> type2_3.tga, Quality 4  - n.a. sorry, dad played freecell :(
> type2_2.tga, Quality 5  - 37 minutes
> 
> Multiple containers are faster and with better quality. The examples
> posted in p.b.i. show a particle system of 50 particles. Using
> multiple containers, the result was much less grainy and was rendered
> in 6 minutes vs.29 for multiple media. The results differ slightly but
> that's due to the small accuracy of type 1.
> 
> I also did a 100 frames 100x100 anim. It started with a single
> particle and added a particle every frame (if anyone's interested I'll
> post it). Here're the stats:
> 
> Type 1 (multiple media) statistics:
> 
> Total time: 3:16:34, render 3:16:11, parse 0:0:23
> 
> Intersections:
> Shape           Tests           Succeeded       Percentage
> Sphere          419435          1708050 70.60
> Bounding Box    3831950         3830350 99.95
> Vista           1030320         1030320 100.00
> 
> Media:
> Intervals       4963140
> Samples         34746921        7.00 per interval
> Transmitted rays                1418040
> I-Stack overflows               7125
> 
> Memory:
> Smallest        26
> Largest         8216
> Peak            134132
> 
> command line:
> +w100 +h100 +mb0 +uv +kfi0 +kff99 -d +a0.4 +r2
> 
> Type 2 (multiple containers) statistics:
> 
> Total time: 2:59:18, render 2:58:39, parse 0:0:16
> 
> Intersections:
> Shape           Tests           Succeeded       Percentage
> Sphere          54614525        37059270        67.86
> Bounding Box    266093261       113576463       42.68
> Vista           19936209        12944728        64.93
> 
> Media:
> Intervals       45169600
> Samples         313641496       6.94 per interval
> Transmitted rays                7248496
> I-Stack overflows               989
> 
> Memory:
> Smallest        26
> Largest         8216
> Peak            198691
> 
> System: K6/233 96 RAM running POV-Ray for windows 3.1e on 98
> command line: +w100 +h100 +mb0 +uv +kfi0 +kff99 -d +a0.4 +r2
> 
> (These look fine using Lucida Console)
> 
> The main disadvantage of type 1 is that all densities are calculated
> for every interval and every sample. This leads to graininess and
> inaccuracy because small radius densities may not be hit at all.
> 
> The main disadvantage of type 2 and it is that max_trace_level and
> max_intersections should be really high. This could be really painful
> in scenes with reflective / refractive objects. I've put in a type 3
> which uses merge to avoid the problem, but preliminary tests show that
> it's slower than type 1 (though more accurate).
> 
> Well, that's it for now. Any comments?
> 
> Peter Popov
> ICQ: 15002700

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