• Adobe After Effects

  3D layers intersection/clipping errors when Z-space is low but > 0

  Posted by Raza Ahmad on November 17, 2011 at 9:04 pm

  Hello friends,

  I’m having a hell of a time diagnosing this peculiarity and would really appreciate any help or advice you can offer.

  I am currently running AE CS5.5, but I have had a similar problem occur previously in CS5.

  Basically, when I place 3d layers close to each other, I’m getting clipping artifacts as if they are intersecting. I’ve seen this happen before when layers share the same z-depth, but in theory even a gap as little as 0.1 px is supposed to be able to remedy this, right?

  Previously I’ve used the ‘adjustment layer between 3d layers’ trick to solve this, but if I do so with this project, it breaks the look, so that’s not an option.

  Here’s an image that describes the problem:

  

  Here’s a link to the image as well: clippingproblem.png

  The clipping artifacts aren’t visible in the thumbnail that’s embedded in the post, but are very clear in the full-res.

  Thanks for your help in this matter…

  -raza

  Some additional details if required:

  This is an 8-bit 1920×1080 project with Square PAR.

  The layers are pre-comped solids with a Hue/Sat effects on them, but toggling the effect makes no difference. Just in case this was a strange Z-scale issue, both layers are z-scaled to 0.1%

  One camera, 4 shadow-casting point lights. In my actual comp, the z-depth is randomly generated by an expression but for the sake of the screenshots I put the numbers in manually instead, the expression being on or off does not change the artifacting.

  Raza Ahmad replied 14 years, 6 months ago 3 Members · 4 Replies
• 4 Replies

• 

  Ross Daly

  November 18, 2011 at 1:10 am

  Hi Raza,

  I’ve never run into that look when they weren’t actually on the same z depth. I’ve also never run into it when layers are perpendicular. Sorry to be of no help. At least you aren’t alone in being surprised by that behavior.
• 

  Raza Ahmad

  November 18, 2011 at 2:23 am

  Thanks for looking at this, Ross.

  To clarify, these layers are all parallel, sorry the perspective is a bit misleading on the screenshot.

  For now, I solved the problem by breaking the expression for z-depth and setting the layers roughly 5px apart.

  My guess is that this is a rendering issue related to shadow casting. There seems to be a minimum distance between layers required for the shadow to be cast, and if that distance is not met then the shadow itself becomes a layer that causes clipping errors.

  Strange, but the only logical explanation I can think of…

  -raza
• 

  Roland R. kahlenberg

  November 18, 2011 at 2:29 am

  That shadow problem has been around since version 5.5!!!

  Using Point Lights instead of Spot Lights may help to alleviate the problem. If you insist on a Spot Light then shifting the rotation values may also help.

  And you’re right, layers that are close together will exhibit this artefact. Moving them apart in Z-space is also a good solution – you’ll just have to tweak the Scale value to retain the original look of the layers.

  HTH
  RoRK

  Intensive AE & Mocha Training in Singapore and Malaysia
  Adobe ACE/ACI (version 7) & Imagineer Systems Inc Approved Mocha Trainer
• 

  Raza Ahmad

  November 18, 2011 at 2:31 am

  Hi Roland,

  Thanks for replying. Just FYI this comp was using only point lights as the source…

  -raza

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