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BMW Render difference
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Windows 7 Pro 64-bit Service Pack 1
Intel I7-4770K 3.5ghz - 8gig RAM
Nvidia GeForce GTX 760 - driver 334.89

Broken: 2.71 official - hash 9337574

The BMW test file gives different results in Blender 2.71 as compared to Blender 2.70 or 2.69

The difference(s) can be seen in the detail of the wheels. In particular, the wheel bolts, the disc brake rotor and/or shadowing are different in the latest render.

Note that I do not know if these differences represent an actual performance bug or simply a result due to changes in other Blender functions.

Please investigate. Thank you.



Event Timeline

Ignatz (ignatz) added a project: Add-ons.
Ignatz (ignatz) set Type to Bug.
Ignatz (ignatz) added a subscriber: Ignatz (ignatz).
Ignatz (ignatz) created this task.
Ignatz (ignatz) raised the priority of this task from to Needs Triage by Developer.

I think that is a pretty subtle difference, which can happen when features change. I would not consider this a bug. @Sergey Sharybin (sergey)?

Will have a loot a bit later, in the middle of other changes.

I had similar problems. It came down to "Beckmann" with roughness=0 does not work in latest cycles. If you change it to "Sharp" it works again. Maybe it's that?
BTW the break-disk is also pretty dark compared to the old render indicating a reflection problem, not a shadow problem.

EDIT: I experienced problems not with IOR=0, but roughness=0 (fixed above text)

Sergey Sharybin (sergey) closed this task as Archived.Jul 10 2014, 9:36 PM

That's nothing to do with the reflections or shadows, this is auto-smooth option which wasn't implemented in Cycles for until 2.71 and which was enabled for the break disk and the bolts.

There's no reliable way to disable this option for old files in order to preserve 100% compatibility, so the only way is to disable autosmooth for those objects.

Wouldn't consider this is a bug, but thanks for the report and replies anyway!

Thanks for looking into this one guys! :-)