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I've only come up with limited information on what the final statistics
shown after a render really mean. Am I missing an obvious portion of the
documentation? I have found a few previous messages posted in regards to
this, yet I am still a bit puzzled.
After an eighteen-hour render of my image at 320x240 resolution, I am
interested in trying to determine where my inefficiency lies. My scene is
mostly full of cylinders... along with a small object made of
smooth_triangles that happens to be copied... er, a lot. I suspect this
could be the error of my ways, and perhaps I should replace them with some
more efficient primitives. However, I thought I was being responsible by
placing my triangles inside a union, and then simply referring to this
object repeatedly. Have I misunderstood previous discussions about
efficient triangle mesh handling?
I thought, perhaps, I could use the histogram output option to determine
where my image was slowing down. Unfortunately, the only information I
really got from the histogram was that the glass objects in my scene take
more time to render than the other objects. Alas, by removing the glass
objects, I do not see a huge increase of speed (as one might expect from
having a scene full of only cylinders... er, and some of those
aforementioned pesky smooth_triangles).
So, would someone be so kind as to give me a thorough explanation of my
statistics (as follow), or else point me to the right location so I might
read up on what they mean? Not a usual exciting question for the group, but
I'm at a loss of where to go to learn this. Blush.
Here's what I see:
Statistics for experimental_setup3.pov, Resolution 320 x 240
----------------------------------------------------------------------------
Pixels: 77120 Samples: 693400 Smpls/Pxl: 8.99
Rays: 719773 Saved: 3052 Max Level: 6/10
----------------------------------------------------------------------------
Ray->Shape Intersection Tests Succeeded Percentage
----------------------------------------------------------------------------
Box 407629001 9601576 2.36
Cone/Cylinder 1302284200 9226351 0.71
CSG Intersection 208771746 4865007 2.33
CSG Merge 919798 256294 27.86
CSG Union 3239336206 8895934 0.27
Plane 11367768 675690 5.94
Sphere 7357978 17042 0.23
Torus 294219586 1801162 0.61
Torus Bound 294219586 2160324 0.73
Triangle 157988919600 148549 0.00
Bounding Box 187611431 69542575 37.07
Light Buffer 8242761 3898242 47.29
Vista Buffer 5779806 4141312 71.65
----------------------------------------------------------------------------
Roots tested: 2160324 eliminated: 1003830
Calls to Noise: 23584421 Calls to DNoise: 24259518
----------------------------------------------------------------------------
Shadow Ray Tests: 23171879 Succeeded: 2160378
Reflected Rays: 14639 Total Internal: 208
Refracted Rays: 11734
----------------------------------------------------------------------------
Smallest Alloc: 25 bytes Largest: 24600
Peak memory used: 39956520 bytes
----------------------------------------------------------------------------
Time For Parse: 0 hours 0 minutes 1.0 seconds (1 seconds)
Time For Trace: 15 hours 8 minutes 27.0 seconds (54503 seconds)
Total Time: 15 hours 8 minutes 24.0 seconds (54504 seconds)
----------------------------------------------------------------------------
CPU time used: kernel 1.77 seconds, user 50408.08 seconds, total 50409.84
seconds
Render averaged 1.52 PPS over 76800 pixels
Alright, now, I understand what the first section seems to be telling me,
except for the 'Saved' value. Are we referring to saved rays? What did I
save them from doing?
Forgive me for being dense, but in the second section I see that some shapes
have much lower percentages than others. This is a ... Bad Thing? I
naively envision my scene only testing (and succeeding with) rays it really
'needs' to calculate, so the better the percentages, the fewer 'wasted' rays
were used? Thus, the better the percentages, the more efficient my scene
is? If this is true, then I appear to be horribly inefficient with my
Triangles.
The third category is even more puzzling. Is this simply for my
information, or can I somehow glean useful knowledge about whether my
objects are calling Noise vs. DNoise, and which should be a better thing.
The docs only mention DNoise in one place (6.7.12.6.4) and from my reading,
it's not that DNoise is any better/worse than Noise calls... just different.
Does the fact that DNoise returns a direction instead of just a value
somehow indicate that those calls were slower? Perhaps they really are
shown just for my information.
The fourth section seems to make more sense to me. If I have a lot of
reflected/refracted rays, my scene will take longer to render. What about
shadow ray tests vs. success? Again, just information, or can I use this to
my advantage?
I'm also puzzled by the Smallest and Largest memory allocation (the next
section). Er, call me obtuse, but if my largest memory allocation is 24KB,
how can my peak memory used be 40MB? Obviously I am woefully
misinterpreting these values. Blush.
Well, at least I understand the last few lines - I know it takes me a really
long time to render a scene that (I think) should be relatively simple.
Anyone care to take a stab at enlightening me? I would greatly appreciate
it.
- How
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