Set Matte Not Working w/ AI Layers

[hannahs52316156]

I've imported an AI file with two different layers. One is the background (a city street) and the other is a car.

I've created an animation of a car moving down the street. I want it to disappear behind the certain buildings.

I've made a shape layer of of the building cut outs, hide the layer, "set matte" to the mask layer, selected alpha, and inverted the matte. The car recognizes the mask, but instead of the mask covering the background it appears to scale down to the car size (ref images below).

I made a simple rectangle in AE and didn't have the same problem.

[Roei Tzoref · Accepted solution]

Unfortunately the Set Matte effect has limitations that prevent it to be useful in some of the cases without a preparation.

the limitation is Ae's render order that renders the effect before the transform. for this type of an effect, when you use pixel layers that don't have a collapse switch (sunburst icon), you need to reverse the render order (by precomposing) for the effect to work properly. the effect works fine for shapes and text because they are collapsed by default so their render order is reversed.

Setup for the Set Matte Effect for pixel layers (no collapse switch available)

1. Precomp the matted layer and the matte layer (leave all attributes)

2. Set the collapse transformation switch for both.

another option - use a different matte operation: instead of Set Matte, like Alpha matte. here's an explanation about it: Luma and Alpha modes in track mattes | Adobe After Effects CC tutorials.

please submit a feature request to improve the set matte's effect functionality: Feature Request/Bug Report Form

[Sterphy]

I don't understand why Adobe can't address these issues of functionality. I mean there's no logical reason why this HAS to be the case with the set matte effect, it just IS. That's my biggest frustration with Adobe - that instead of just introducing little fixes they'd rather just say "well that's just how it is". That might have been acceptable on the old CS update cycle, but now we're all on the subscription method I'd just appreciate more thought going into releases... I feel like every CC release of Adobe software is beta testing us with buggy software that never *really* gets fixed.

[hannahs52316156]

I'm not sure if this is what you were saying, but I turned my car layer into a pre-comp and the Set Matte still didn't work.

I found a work around solution though. I made a duplicate of the just the building I wanted to use as my mask shape (in illustrator) and I just placed that layer (in AE) above my car layer, so it acted like a mask.

[Roei Tzoref]

I'm not sure if this is what you were saying, but I turned my car layer into a pre-comp and the Set Matte still didn't work.

thank you for the feedback.  I have revised my first response and the workaround to make it more clear and accurate. please see if this is working for you now.

made a duplicate of the just the building I wanted to use as my mask shape (in illustrator) and I just placed that layer (in AE) above my car layer, so it acted like a mask.

yes, That can work too . an obvious and simple solution that works fine for simple situations, and I probably should have mentioned it since it's an easy fix. guess I probably wanted to offer a complete breakdown of the set matte effect for all those who might join in too. the advantage of using a set matte effect is that many layers can use just one matte and if there are changes, like effects on the obscure image, you need to apply it only once on the original and not duplicate it to the copy.