I'm experiencing an odd behavior with deformation blur in Cycles with an specific model of an elephant even in a new scene.

When rendering with Motion Blur enabled I've got this render with only blur in its hair strands: enter image description here

Here you have a render without Motion Blur for comparison: enter image description here

The weird thing here is that if I add a new object and deform it with an armature, I do have the motion blur. But that's not all: if I render without MB, the geometry is missing from the Vector Pass!!! Only the strands are visible: enter image description here

I've checked if I have a full Vector Pass in the Internal engine and I do: enter image description here

The object have Motion Blur and Deformation enabled... I would like to share the file but I cannot as it is a Turbosquid model although I can share any screenshot. But normals are right, it doesn't work without the modifiers either or if I erase everything an apply an armature from the ground...

Do I missing something?

  • $\begingroup$ I found a "solution". If I join the elefant to a new object (then removing the object in edit mode) and re-apply the modifiers everything works. But I then need to comb again all the particle systems. So there's a difference between this model and a new one which causes this. $\endgroup$ Jun 19, 2016 at 13:34
  • $\begingroup$ If you upload a blend file that demonstrates the problem, someone will find it much easier to help you. $\endgroup$
    – Greg Zaal
    Jun 19, 2016 at 20:07
  • $\begingroup$ Yeah, but I can't share it. Finally I found the problem, will post it tomorrow I need to finish this job today! $\endgroup$ Jun 19, 2016 at 20:32
  • $\begingroup$ @GregZaal I suppose that it took me more than one day to post my answer, hehehe. Sorry, too much work :P $\endgroup$ Dec 5, 2016 at 20:19

1 Answer 1


The model has active Auto Smooth Normals. Disabling it fix the problem.

enter image description here

It was a purchased model and it appears that Blender activated Auto Smooth when importing the FBX model.


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