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Participant
January 25, 2017
Question

Delete everything except a moving object

  • January 25, 2017
  • 2 replies
  • 3878 views

For example say I have a stationary video of a butterfly flying around in front of the camera. How do I make it so that the butterfly is all we see and it never leaves the composition?

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2 replies

Roei Tzoref
Legend
January 28, 2017

tracing over a live video is called Rotoscoping. here's an old but still good article about it: https://www.fxguide.com/featured/the-art-of-roto-2011/

there are several ways to approach this:

1. Masks - Managing and animating shape paths and masks in After Effects

2. Rotobrush tool - After Effects Roto Brush, Refine Edge, and Refine Matte

3. Mocha Ae - it is bundled with your Ae release since CS4 - it's main use is for tracking, but also roto masking. after you roto your element, you can bring the information back to Ae as masks or mocha shape effect : Paste mocha roto shapes to After Effects masks on Vimeo

one cool technique to help better trace your moving object is to use Reverse Stabilization. you stabilize your object, trace it with as minimum keyframes as possible, then re-introduce the motion. here's an example by our community's guru Rick Gerard: Simple Roto - YouTube

you can also show us the footage so we can better assist you by giving specific instructions.

todalinaAuthor
Participant
January 29, 2017

I'm not trying to trace anything. I'm trying to crop out everything but a moving image. I don't want the cropping mask to move around, but rather the video behind it so that it focuses on the thing I choose.

Roei Tzoref
Legend
January 29, 2017

if you want to crop a moving image, you need to trace it. The mask will move same as your image thus isolating it from the background. If you could show us the video in question, we can demonstrate the possible techniques and it will probably clear things up,

todalinaAuthor
Participant
January 28, 2017

any ideas guys?