On 9/25/19 3:24 PM, William F Pokorny wrote:
> On 9/25/19 1:38 PM, Norbert Kern wrote:
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> 
> Otherwise, not sure. If you do play with any of the options above beware 
> it might be you end up suddenly with many more photons deposited at your 
> current spacing.
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> 

As the day passed a few other thoughts popped into my head.

a) Might be worth it to try "split_union off" in all your unions. It 
sometimes makes for a significant difference though I find it hard 
myself to align results and the documented behavior.

b) You are using spotlights so might be worth checking they are lined up 
well on things you expect to "focus/disperse" light. If your photons 
shot to photons deposited ratio >>1 sometimes an indication and that 
might relate to (a) somewhat.

c) Quite a few photon scenes I've seen are relatively simple. Single 
water surface, lens, etc . In your scene you have quite a few lights and 
quite a few glassy / reflective objects. The more bounce/bend surfaces 
the higher your photon density needs to be because a lot of it spreads. 
Scenes like the one posted are also more sensitive max trace levels. The 
greater that depth the more accurate results, but also you tend to need 
to shoot more photons... Long winded way to say it might just be you 
need a lot of photons...

Aside: Since you have multiple lights... Christoph added some 
parallelism when shooting photons based upon each light source. Long 
wondered how much we might speed up photon generation on a large 
machines like yours by creating multiple, near duplicate light sources 
where each light source sits today. My bet is it would speed up the 
photon shooting step quite a bit if you have the cores - and slight 
offsets in the near duplicates might help the deposited distribution 
some. Would have to manage/adjust intensities for the multiples. If your 
interested in some experimentation, I'd be interested in what you find.

Bill P.

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