Exercise 9 · Roto & Occlude

Project 5 · Motion Reel + Brand Spot · Week 14 · Rotoscoping · ~45 min

Practice goal: Isolate a subject with Roto Brush 2 (refine, freeze, re-background), then hand-roto so an element passes behind the subject.

Set up: New project. A clip of a subject moving against a busy background, plus an element to place behind it.

Steps

New composition from a clip with a clear moving subject; name it Main.
Double-click the layer to open the Layer panel; select the Roto Brush tool and paint a stroke down the center of the subject.
Add/subtract strokes (Alt/Option to subtract) until the boundary hugs the subject on the current frame.
Propagate forward (Page Down / spacebar); fix drift with small corrective strokes where the edge slips.
Open Refine Edge; brush hair/soft edges and tune the matte (Feather / Shift Edge). (AE 2026: note the AI Object Matte for faster selection.)
Freeze the matte to lock the work; add a new background behind the cutout.
Now make an element pass behind the subject: duplicate the subject layer and draw a Pen mask around it on the top copy.
Animate the Mask Path every few frames to follow the subject — rough pass, then refine; add Feather / Shift Edge.
Place a new element (graphic/text/solid) on a layer BETWEEN the background and the masked subject copy.
Confirm the subject covers the element where they overlap — the element reads as behind; animate it passing behind.
Alternative: use Mocha AE to track a planar region and drive the roto more efficiently.
Clean up edge chatter; lower the element's opacity/grade to integrate, then save & render.

The subject is isolated with Roto Brush 2 (refined, frozen, re-backgrounded), and an element convincingly passes behind a hand-rotoscoped subject.

Pittman_Ex09_RotoAndOcclude.aep → render Pittman_Ex09_RotoAndOcclude.mov · versions Pittman_Ex09_RotoAndOcclude_001.aep

This drill is your in-class activity for the week; it ladders directly into the project.