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Maniphest T40647

Longer render times
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Description

System Information
Win7/64, AMD HD 6850, Phenom II X4 965 BE

Blender Version
blender-2.71-6443bfd-win64

Short description of error
Don't know if it's a bug or due to fixing a bug, but the CPU render times for the BMW increased considerably:

blender-2.71-29e8c46-win64: 4:03
blender-2.71-6443bfd-win64: 4:29

Double-checked the results.

Could you please have a look at it? Thanks.

Event Timeline

Willi (willi) created this task.Jun 16 2014, 4:05 AM
Willi (willi) raised the priority of this task from to 90.
Willi (willi) updated the task description. (Show Details)
Willi (willi) added projects: BF Blender, Cycles.
Willi (willi) edited a custom field.
Willi (willi) added a subscriber: Willi (willi).
Adam Friesen (ace_dragon) added a subscriber: Adam Friesen (ace_dragon).Jun 16 2014, 4:46 AM

If you're using master, this should be due to an improved importance sampling algorithm for glossy shaders that has been implemented just a couple of days ago.

Do a side by side comparison, do you see a reduction in noise?

Thomas Dinges (dingto) changed the task status from Unknown Status to Archived.Jun 16 2014, 7:34 AM
Thomas Dinges (dingto) claimed this task.

The new Beckmann importance sampling makes rendering a bit slower, but improves noise. That is not considered a bug. See also here: http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.72/Cycles

Willi (willi) added a comment.EditedJun 16 2014, 1:15 PM

Ok. After reducing the number of samples to get the same render times as in the previous version, I compared the two images. They are different, but subjectively I'm unable to say clearly what has more or less noise. I've been looking for a part that shows it best, and to me it looks the left picture has a little less noise:


Left: old version, 200 samples, 4:04 minutes
Right: new version, 182 samples, 4:04 minutes

Anyway, for this bug tracker, it's solved (as it's not a bug). Thank you.

EDIT: FWIW, this is the difference of the two pictures, but it mainly shows that noise has a different pattern and makes no real statement about quality: