Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] Bug Reporting => [Max] Resolved Bugs => Topic started by: maru on 2013-10-23, 18:13:59

Title: Light leaks
Post by: maru on 2013-10-23, 18:13:59
1. Create a box
2. Place camera inside it
3. Turn on environment light or add a light source outside the box
4. ???
5. Profit!

I remember his has already been mentioned. What is causing this and are there any ways of fixing this other than applying shell modifier? I'm sure this contributes to some fireflies when rendering interiors.

related: http://corona-renderer.com/bugs/view.php?id=133
Title: Re: Light leaks
Post by: Dom74 on 2013-10-23, 18:17:39
It remind me some problems with mental ray and photons passing throught thin geometry.
Title: Re: Light leaks
Post by: vkiuru on 2013-10-23, 20:45:57
Yeah isn't this the same p much with any renderer? In Vray it helps to make for example light cache samples smaller if I remember correctly.. apart from that there's the Shell modifier as you said.
Title: Re: Light leaks
Post by: Ondra on 2013-10-23, 20:55:10
It remind me some problems with mental ray and photons passing throught thin geometry.
that is different, photons leak consistently and it is a defficiency in the algorithm (bias). This is an implementation issue (although extremely difficult to get rid of)
Title: Re: Light leaks
Post by: Captain Obvious on 2013-10-23, 21:55:42
Does it leak if the box has thickness? I'm assuming this is just the ray skipping a small distance to avoid self-intersection.


Keymaster, as an aside... Does Embree do ray-primitive intersections in object space or world space? Just out of curiosity.
Title: Re: Light leaks
Post by: maru on 2013-10-23, 22:18:07
Does it leak if the box has thickness?

Quote
What is causing this and are there any ways of fixing this other than applying shell modifier?

Title: Re: Light leaks
Post by: Ondra on 2013-10-23, 22:24:48
Does it leak if the box has thickness?

Quote
What is causing this and are there any ways of fixing this other than applying shell modifier?
well his name IS captain obvious... :D

Keymaster, as an aside... Does Embree do ray-primitive intersections in object space or world space? Just out of curiosity.
Embree by itself has no notion of spaces, so it depends on how do you use it. For instances, you obviously need object space, other than that, world space is simpler. Embree has several different triangle intersection algorithms, but they all have this sort of problems.
Title: Re: Light leaks
Post by: Captain Obvious on 2013-10-24, 11:48:56
Does it leak if the box has thickness?

Quote
What is causing this and are there any ways of fixing this other than applying shell modifier?
Haha, ooops. :-)


But anyway, real-world objects have thickness, so I don't really see the problem.



Quote
Embree by itself has no notion of spaces, so it depends on how do you use it. For instances, you obviously need object space, other than that, world space is simpler. Embree has several different triangle intersection algorithms, but they all have this sort of problems.
Ah, ok. Thanks.
Title: Re: Light leaks
Post by: Ondra on 2014-05-20, 14:56:51
Improved