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Cycles - noise on dense meshes
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Description

System Information
Windows 7 x64, Geforce GTX 295 (CPU rendering)

Blender Version
Broken: Blender 2.69 a65ef6a, buildbot
Worked: never. Checked 3 past official releases.

Short description of error
There seems to be a significant amount of ray misses on dense geometry, causing a visible amount of noise that never clears up, and making the objects look somewhat transparent. This is not apparent on sparse geometry.

Exact steps for others to reproduce the error
Open attached blend, set the viewport to rendered mode.

Event Timeline

can confirm this.
some findings: as this seems to be some kind of precission error you dial against this by lowering focal length (orthographic seems to be worst), also narrowing camera clipping helped in my tests. not familiar with rayintersection code otherwise (hopefully will have time for this sometime in the future)...

Brecht Van Lommel (brecht) changed the task status from Unknown Status to Unknown Status.Nov 27 2013, 4:08 PM

I'm aware of these precision issues, it's on the todo list to solve. I'd like to rewrite triangle intersection code from scratch to make it more precise, but right now I don't consider this a bug. There is a performance vs. precision tradeoff here as well, adding more precision will make renders slower, it's not a simple fix but needs to be done very carefully as part of a bigger refactor.