Light pass through solid object

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Sharlybg
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Light pass through solid object

Post by Sharlybg » Wed Nov 07, 2018 8:08 pm

Just encountered this behaviour sometimes while working and always thing of error from me. But just discover with a new project that it might be a bug.I also wonder if this don't affect performance as light passing through object are calculated. here are twos render of the camera inside the object :

Bidirectional
Bi.jpg


Path tracing
Pa.jpg

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Light pass object.blend
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kintuX
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Re: Light pass through solid object

Post by kintuX » Thu Nov 08, 2018 9:02 pm

i'd say it's precision issue mixed with bad values and inadequate scene construction

"one could make a bad scene for any and every engine devised, but what's the purpose in doing that" :twisted: ;)

some possible solutions
- enlarge objects and use Scene Unit Scale to your advantage
- give thickness to things, every matter/particle has it <<< almost every time fixes the leaking issue
- lower bump


PS
also worth to consider - render engines don't get the concept of solids (like CAD apps, which do double precision for watertight mathematical form) here, we are all dealing just with triangles which in certain conditions (dividum ad infinitum) as atoms, show space in between (ie. similar "falling apart" issue had Cycles with motion blur until recently, should be fixed now with the help of Intel's Embree),

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Sharlybg
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Re: Light pass through solid object

Post by Sharlybg » Fri Nov 09, 2018 8:48 am

i'd say it's precision issue mixed with bad values and inadequate scene construction
Thanks for your input Kintux ! if this didn't lead to performance (speed) issue i'm more than happy with that ;)
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FarbigeWelt
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Re: Light pass through solid object

Post by FarbigeWelt » Sat Nov 10, 2018 9:16 pm

Remembers me the ‚cuboid room effect‘. Camera placed inside a room with tight thick walls. Outside sky light creeped through the walls. Room size 2.5 m3, walls 30 cm.
Solution: avoid sun or sky light. Reason: I don’t know. Maybe Aborption is not 100% due to imprecision like kintuX mentioned. Switching bright sky lights off, decreased time for interior rendering dramatically. For stills and closed rooms its not a big issue.
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kintuX
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Re: Light pass through solid object

Post by kintuX » Sun Nov 11, 2018 4:13 pm

Sharlybg wrote:
Fri Nov 09, 2018 8:48 am
i'd say it's precision issue mixed with bad values and inadequate scene construction
Thanks for your input Kintux ! if this didn't lead to performance (speed) issue i'm more than happy with that ;)
If i understood correctly, issue was with light leakage - so i simply applied Solidify modifier to Sphere object, which prevented light coming through. No performance hit was observed (since interior became dark/black).
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Light pass objects.7z
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