AE Masking/roto Questions

[Trevor Ward]

I have a similar qustion regarding masks and trakers. I’ve got 3 layers. Bottom layer is a video clip with a moving billboard. next layer is a motion graphics that is corner pinned to follow the tracking points of the billboard. So far so good. Here’s the catch. In front of the billboard are two parked cars the partially obstruct the billboard. So, I have created a 3rd layer, on top of the others, that is a duplicate of the bottom layer. I create a mask around the cars so that the cars now are in front of the billboard. Awesome. Ok, but as the images moves, the masks have to move (because the cars and the billboard have all moved.

Is there a way to have the MASK move with the tracking points? I can make the top layer move with the tracking points no problem. But that move the whole clip, not JUST THE MASK. Is there a way to do this?

-trevor ward
http://www.redeyevideoproductions.com
orlando, fl

[Mike Clasby]

You might look at this earlier post from thehardmanpast:

Here’s a script: Rotoscoping tool for AE 6.5 by thehardmenpath on 2005-12-18 07:22:15
You can also get it here (the jsx file), just drop the jsx file into the Scripts folder in the AE Support Files folder. And File>Run Script

https://del.icio.us/escruz/Rotoscope

Click on the ae enhancers view topic link.

I haven’t used it for roto, but have used the script to manipulate trackers that controlled mask vertices. It did get some good comments for roto(see below).

Here’s another explaination of the script by the author.

https://forums.creativecow.net/cgi-bin/new_read_post.cgi?forumid=2&postid=866624

Here is an earlier post from a guy that used it:

Name: glennser
Date: Jan 19, 2006 at 11:10:56 am
Subject: Re: Motion Tracking and Masks?

I don’t know how the script works exactly but it’s not necessary to use it. Save it to your hard drive then go File/Run Script/Choose File and navigate to where you saved it. (you have to enable scripts in your preferences first or else it’s greyed out). When you run the script it will create a dialogue box, with the mask selected hit the “Apply Tracker” button, it will create a motion tracker with a point set at each of the mask vertices, now run the tracker as usual (take your time, if it loses the track go back and fix it, I think you can do a point at a time if necessary) when you have finished tracking select the mask and the tracker in the timeline and hit the apply mask button.
I’ve only tried it with relatively simple stuff but it’s an amazing script, all credit to the guy who wrote and posted it, I had nothing to do with it at all unfortunately, scripting kind of freaks me out and I was hoping they would convert it to actions like photoshop.
Glenn Stewart
1-k Studios

[Espnetboy3]

Thanks yikes I have heard of this script before. Im sold im gonna have to give it a try. I know other compositing packages let you add track data to masks so I figured AE might.

[Mike Clasby]

I just did a test run on a roto with the script, it was better than I thought it would be.

Just draw a mask, File>Run Script>RotAE.jsx then with the mask selected click the Apply Tracker Button. Now double click the Tracker 1 and up pops the Motion Tracker,
and when you get a good track select the tracker and the mask and click the Apply Mask button. Getting a good track is the hard part, especially when the mask has many points. Then I went back and adjusted the mask points/beziers as needed. Not bad.

[Espnetboy3]

Thanks again for your help yikes. I have never painted in AE its one thing I want to really learn to do. Should I try painting this person out? Is that what vector paint is all about?

[Mike Clasby]

There are a few tuts on that, but I think the newer versions of Vector Paint might be even more adapted to roto, I dunno, but here’s a place to start.

Turning Paint Into Masks in After Effects by Timothy Kurkoski
https://forums.creativecow.net/cgi-bin/new_page_wrapper.cgi?forumid=2&page=https://www.creativecow.net/articles/kurkoski_tim/paint_to_mask/index.html

Rotoscoping with Vector Paint by Bill O’Neil
https://forums.creativecow.net/cgi-bin/new_page_wrapper.cgi?forumid=2&page=https://www.creativecow.net/articles/oneil_bill/as_matte/index.html

As you can tell I’ve avoided roto, maybe someone else has some real world input on Vector Paint roto (another todo).

It sounds like a lot of folks like Silhoutte roto.

[Espnetboy3]

I just finished reading the Bill Oneil Tutorial and Im giving it a whirl right now. Vector paints seems very useful. The only thing is unlike masks with paint I dont bellieve it interpolates keyframes. For instance when you create a mask you can make one 10 frames later and it stays on the footage. When I paint the subject and move one frame over I have to repaint. Is this true to paint?

[Andrew Shanks]

The other way to go is to place a solid colour layer over the layer you wish to roto (make it a vibrant colour that will stand out), change the opacity to 50% (so you see your video layer underneath), create a mask shape on the solid layer that conforms to part (or all) of the object you wish to cut out in the lower video layer (when you complete the mask, only the object will appear to be tinted with the solid colour layer).
Create a null, track the scene, and apply the tracker to it.
Go back to the first frame (where you created the roto shape).
Parent the solid colour layer to the null, …the shape will now follow the object.
Turn on keyframing for your mask on the solid layer, …and tweak the mask where-ever necessary to make sure only the object (not any of the background) is tinted by the colour.
When done, change the opacity of solid layer back to 100%, change the colour to white, create a new black solid (placing it under the white solid layer. You now have a moving black and white matte. Precomp the null, white layer and black layer. Now you can use that as a matte for your lower layer.

I know it sounds like a long-winded way of doing things, but its actually quite quick to do, and if you need to track a rotoshape its one of the better ways to do it to lessen the likelihood of chatter in your rotoshape edges. The other thing to remember is with complex objects (like people), break them down into simpler shapes, animating them individually. Far better to have a few simple shapes than one complex one (for chatter and ease of change reasons). Check out these great roto articles by Scott (fx god) Squires:
https://effectscorner.blogspot.com/2006/01/rotoscoping-part-1.html
https://effectscorner.blogspot.com/2006/01/rotoscoping-part-2.html

[Espnetboy3]

Wow Andrew that sounds like a pretty damn good idea. Im gonna give it a shot. Instead of doing the precomping and making the black layer and such, couldn’t I just bring the opacity of the first layer I made on top to zero? Then it just has the mask and you will see the layer im roto’ing under it.

[Andrew Shanks]

yeah, totally, good plan (its actually a technique I was shown in Shake that I adapted for AE). Give it a whirl and see how it works for you. Tracking basic roto shapes then tweaking the shape where needed ends up giving a lot smoother roto than lots of manual tweaking I find. If you do a lot of roto I recommend Silhouette, it does a sweet job (allowing you to track whole shapes or points on a rotospline, plus it has transforms on mask shapes that interpolate correctly over time, …i.e. no silly work arounds like the one I described).
Goodluck!

andrew