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

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Raza Ahmad3D layers intersection/clipping errors when Z-space is low but > 0
by on Nov 17, 2011 at 9:04:01 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 1920x1080 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.


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ross dalyRe: 3D layers intersection/clipping errors when Z-space is low but > 0
by on Nov 18, 2011 at 1:10:12 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.


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Raza AhmadRe: 3D layers intersection/clipping errors when Z-space is low but > 0
by on Nov 18, 2011 at 2:23:55 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


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Roland R. KahlenbergRe: 3D layers intersection/clipping errors when Z-space is low but > 0
by on Nov 18, 2011 at 2:29:02 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


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Raza AhmadRe: 3D layers intersection/clipping errors when Z-space is low but > 0
by on Nov 18, 2011 at 2:31:06 am

Hi Roland,

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

-raza


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