Rotoscoping for Mattes, Paint, Clean-up and Plate Preparation
Domain focus
This domain covers rotoscoping for mattes, paint, clean-up, and plate preparation. The exam tests garbage versus core mattes, holdouts, clone and offset painting, wire and rig removal, and preparing plates before roto.
Core rules and concepts
- A garbage matte removes large unwanted areas quickly; a core matte isolates the subject more precisely. A holdout matte protects an area from a colour correction or effect.
- Paint tools include clone, offset, smear, and frame-by-frame repair. Clone from a clean frame or clean plate; track the patch if the camera moves.
- Remove wires, rigs, tracking markers, dust, and logos with clean plates. Match grain, motion blur, and edge softness after painting.
- Plate preparation includes stabilisation, denoise, retime, colour space conversion, and checking frame ranges before roto begins.
- Work in a duplicate layer or version; never paint destructively on the original plate.
Worked example
A safety wire crosses an actor during a jump. Find a clean frame where the wire is absent or can be rebuilt; clone a patch over the wire on each frame; track the patch through the jump; add grain and motion blur to match. Reasoning: a static patch will slide because the actor and camera move, so the repair must follow the plate. Matching grain prevents a smooth patch that stands out in the composite.
Traps that cost marks
- Painting on the original plate without versioning.
- Cloning repeated texture, such as brick or fabric, which creates a visible pattern.
- Leaving a hard edge where the patch meets the plate.
- Forgetting to restore grain after denoising.
- Using a garbage matte as a final core matte when a precise edge is required.