network render artefacts

[georglorenz]

Hello,

I am posting an issue with netweork rendering at the render farm that might be of interest:

I sent a very dark nighttime scene to the Ranch render farm and the combined image from their I believe 8 nodes does not get rid of the artefacts in the same way that my single node PC both reaching approximately the same spp.

Attached are two images. One is the image from the farm reaching 10000spp done in 8 minutes, the second is the image from my PC 12000spp which rendered over the weekend.

I am running Indigo RT v3.2.7, Windows 64-bit build.

Is there any way to avoid this problem in the future?

Thanky you /gxl

[Voytech]

As far as I know, the farm is now working on 3.2.8.

[georglorenz]

As far as I know, the farm is now working on 3.2.8.

could this be the problem?

[galinette]

Not fully answering the question, but here is an advice : the noise is very colored and this may come from the use of dispersive specular materials (materials with cauchy B coef non-zero). Setting all cauchy coefs in materials to 0 would probably reduce noise a lot, without causing any loss of realism. Cauchy dispersion is useless for window flat glass rendering. It is used mostly for jems and glassware whose shape emphasizes chromatic dispersion.

If the noise stays colored while all cauchy B set to zero, there is definitely something weird.

Etienne

[galinette]

The noise issue in the net renders could be a correlation problem between the numerous threads. That's quite typical when using low-discrepancy samplers in QMC with a too large number of threads. Using MLT might solve the problem, although this is not the primary purpose of MLT

Etienne