On Friday, we setup six machines to act as our render farm for a short (3000 frame) animation. All machines were loaded from a single saved blend file on a network drive. Five were Windows machines running blender 2.78a/b and one was a Linux box running 2.74. The blend file is set to render at 100 samples. Output was set to .png files with 95% compression.

All machines rendered over the long weekend.

This morning I found that the frames written by the Linux box (2.74) were all significantly larger than the frames from the other machines (~5k vs ~3k). Looking at them, the reason was obvious: they are all much noisier than the others.

I might have expected that between 2.74 and 2.78, the time it took to render 100 samples might have improved, but I wasn't expecting the noise of 100 samples to change much.
My question is this: What is the source of the differences in noise between these two versions?

Thanks in advance!

  • $\begingroup$ Maybe your 2.78 scene is using a feature capable of reducing the noise that the 2.74 version can't take advantage of. I am referring to something like portals, that were introduced in 2.75 wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.75/Cycles. $\endgroup$
    – Carlo
    Feb 21, 2017 at 19:10
  • $\begingroup$ @Carlo I read the link. Thanks! Unfortunately, it seems not to be the solution, as no portals were used in the blend file. $\endgroup$ Feb 21, 2017 at 20:27
  • 2
    $\begingroup$ In general a lot of improvements have happened between 2.74 and 2.78 with some of that being the reduction of noise. Would need to know what you use in the scene that could make noise, like glass material and what settings you use to know what may make a difference. Also you shouldn't need to run an older version on one machine to have this issue. $\endgroup$
    – sambler
    Feb 22, 2017 at 1:02


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