I'm making an animation where a camera orbits a number of objects. Each object is on it's own render layer and has it's own blur effect.

So here is the setup for the visual effect i want.

Alpha Over

However the problem with this is that when the camera rotates around the objects, Alpha Over in the compositor does not render the objects depth according to their distance from the camera but just as ordered by order of the Alpha Overs in Node Editor.

When I switch to Z Combine the order of the objects as rendered is working but there is no longer a blur effect on each object.

Z Combine

Can anyone help me get the blur effect I want please?

  • $\begingroup$ If I understand your process correctly, to use the alpha over node I believe you want to mask the other layers. $\endgroup$ – PGmath Jul 27 '15 at 23:39
  • $\begingroup$ The Z-combine is happening after the Blur node, effectively masking out your blur. You want to Z-combine first, then blur. $\endgroup$ – Mike Pan Jul 28 '15 at 0:51
  • $\begingroup$ @mike I tried using Blur node after z combine. I z combine the cube and sphere render layers then blurring, then z combining with the floor but no difference. I tried z combine cube+sphere then floor then blurring but no difference. The blur is always behind the geometry.@pg math - not sure i can use masking as the camera is orbiting around a number of objects. Depending on where the camera is the same object can either be masked or the mask?! $\endgroup$ – wamballa Jul 28 '15 at 6:32

I got it working. As PG Math proposed I used Alpha Overs and Mask. I didn't use Z transform.

For each object layer ( except background ) i set all other object layers as a mask. The camera can now freely move around the scene and the objects are blurred nicely and the objects render correctly.


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