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Wierd behaviour with even/non-even samples in cycles
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Description

System Information
Operating system and graphics card
Windows 7 x64
Intel Core i7-2700k
Nvidia GTX460

Blender Version
Broken: (example: 2.69.7 4b206af, see splash screen)
2.70a
also 2.69

Short description of error
When using viewport rendering, it's more noisy when samples value set to non-even

Exact steps for others to reproduce the error
Based on a (as simple as possible) attached .blend file with minimum amount of steps

In this file i'm using Area lamp with multiple importance sampling turned on
Just set it to viewport rendering, and when rendering is done, add +1 to Samples Preview value and check for noise appears with non even and dissapears with even values

Details

Type
Bug

Event Timeline

Viktor Mukayev (vitos1k) set Type to Bug.
Viktor Mukayev (vitos1k) created this task.
Viktor Mukayev (vitos1k) claimed this task.
Viktor Mukayev (vitos1k) raised the priority of this task from to Needs Triage by Developer.

That's the correct behavior. It samples one of the two lamps at random (unless you use branched path tracing). So at even samples it can sample both of them the same number of times, on odd samples that is not possible so there is noise from that.