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So I have a single-frame project and want to send it to a renderfarm that does not support OpenEXR or compositing (SheepIt). Can I simply do a 1 sample pass on my computer and still get high accuracy compositing passes like Z-Buffer, Object ID and so on, to combine them later with the renderfarm result?

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    $\begingroup$ Yes, actually those passes only use 1 sample already. However some passes similar to those (such as mist) do use all the samples. Depending on the exact nature of your scene you may be able to get away with lower samples for mist (I would still use more like 50 or so), but in some cases (e.g. with motion blur or DoF, where multiple objects are visible in the same pixel) more may be needed. $\endgroup$ – gandalf3 Aug 20 '15 at 7:12
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    $\begingroup$ Related: blender.stackexchange.com/q/14925/599 and (somewhat) blender.stackexchange.com/q/7025/599 $\endgroup$ – gandalf3 Aug 20 '15 at 7:30
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No, Z pass, ObjectID and alike are not dependent on Cycles render samples. Their visual output will always be the same like rendered with 1 sample - so not nice.

It's better to obtain them in Cycles with a different method - Z pass with Mist pass or Ray-depth shaders, ID-masks with random-colored shadeless materials for example.

Or get them from Blender Internal (you want to use Full Sample there).

Here is a little table what is (green) and is not (red) dependent on render samples:

enter image description here

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  • $\begingroup$ Why and to which point are Emission, Environment, Mist, Normal and UV passes dependent of the samples amount? I always thought samples didn't change anything except anti-aliasing. $\endgroup$ – piegames Jan 27 '17 at 21:06
  • $\begingroup$ @piegames Why: because of the nature of unbiased rendering. More samples equal less noise for the pass. For each AA sample (in branched pathtracing) you can set the amount of emission samples, volume (mist) samples, AO, direct/indirect and so on. $\endgroup$ – Jaroslav Jerryno Novotny Jan 27 '17 at 21:33
  • $\begingroup$ The Mist pass is not a Volume pass. And what about Normal/UV and Environment pass? $\endgroup$ – piegames Jan 28 '17 at 16:59
  • $\begingroup$ Why is normal dependent on # samples??? I thought it is purely geometric, just like depth? Thanks for the clarification. $\endgroup$ – Sibbs Gambling Aug 25 '18 at 0:44
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    $\begingroup$ @SibbsGambling you need samples to clear alias on object edges. Without it the pass would be useless as the index and depth passes are. $\endgroup$ – Jaroslav Jerryno Novotny Aug 25 '18 at 11:47

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