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

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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