This is an issue (or feature?) I experience with the blender version 2.76b from the offical ubuntu 16.04 xenial xerus repository. I can't reproduce it with 2.78c or 2.76b build from the blender homepage.

This one is rendered with the xenial release. Almost no noise and fast render time. xenial gpu

This one is rendered with CPU and yields the same result as the same version build from the blender homepage. Both four times higher render time and much more noise. enter image description here

Is all this maybe due to some specific build options? Because i'd really like to keep the first result even in future blender releases.

It gets even stranger when I decrease the samples from 60 to 10. Xenial build GPU shows multiple sharp shadows around the object while the Xenial CPU and blender build CPU + GPU gets just noisier.

enter image description here

enter image description here

The file from the examples is unchanged between renders, you can try it yourself but the condition occured with every blend file I stumbled upon, therefore it shouldn't be file specific.


Here another example enter image description here

Thank you!

  • 3
    $\begingroup$ if you need to post more images, post them to imgur.com and then add the link as part of your question. $\endgroup$
    – user1853
    Jun 26, 2017 at 20:51
  • 1
    $\begingroup$ And i think title is wrong, in all images i see GPU $\endgroup$
    – Crantisz
    Jun 26, 2017 at 20:58
  • 1
    $\begingroup$ Wait, both of these are rendered with GPU, am I missing something? $\endgroup$
    – bertmoog
    Jun 26, 2017 at 20:58
  • 2
    $\begingroup$ See cegaton's comment above for posting more pictures. Are all settings identical? I.e. did you just open the exact same .blend file in two different versions with different noise results? $\endgroup$
    – bertmoog
    Jun 26, 2017 at 21:59
  • 1
    $\begingroup$ In the sampling panel, the cpu render uses the sobol pattern option. The sobol pattern is not offered with opencl rendering unless the experimental feature set is enabled. That points to the difference could be opencl related, which is known to not be 100% supported. $\endgroup$
    – sambler
    Jun 27, 2017 at 6:40


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