Light leaks

[maru]

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

[Dom74]

It remind me some problems with mental ray and photons passing throught thin geometry.

[vkiuru]

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.

[Ondra]

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)

[Captain Obvious]

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.

[maru]

Does it leak if the box has thickness?

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

[Ondra]

Does it leak if the box has thickness?

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.

[Captain Obvious]

Does it leak if the box has thickness?

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.

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.

[Ondra]

Improved