Join Alan Demafiles for an in-depth discussion in this video Keyframing masks, part of After Effects CC 2018: VFX Essential Training.
- [Instructor] One aspect of visual effects involves creating masks to isolate areas of our footage. Of course, since what we want to cut out will often move over time in our shot, animating masks manually isn't always the first approach we want to tackle on our list; but sometimes manually animating masks is unavoidable. This work of rotoscoping is really the unsung hero of visual effects, a tedious task whose results are supposed to go unseen. In this movie we'll examine the pen tool and how we can use it to create animated masks and create transparency. In my shot I've got a long jumper whose foot contact there is going to be accentuated with a bit of ground shatter.
So as I introduce that top layer here, you'll see that ground shatter happens on top of the foot. Let's go ahead and zoom in here. I'm going to shorten the duration of our work area, so right here we can click and drag or hit B on the keyboard to begin that work area and N to create the outpoint. Now when we create a preview, it will only show us that duration. In order to sell this effect we need to introduce that foot layer on top. So let's go ahead and do that by selecting this background layer, going up to Edit, and duplicating that.
Then reorder that so it sits on top. We'll also rename this Foot Roto. Let's go ahead and trim the endpoint of this first layer by hitting Option+[ to match in with that ground shatter. I'm going to zoom in a little bit further and look for a point in the footage where the foot comes to kind of a nice resting place. Somewhere right there. And it's here that I'm going to switch over to my pen tool and start clicking onto this Roto Layer. Make sure that's selected. Once you start clicking and dragging, you'll create a brand new mask.
So as I click and drag you'll see that I'm making these little bezier handles that will smooth out the corners. Otherwise, you'll get a sharp, sharp corner; and I don't want that here. We definitely want that be smoothed out a little bit and rounded. When we come back to that first point again and click on it, you'll see that we have a bit of our ground shatter showing; and layer one now has a brand new mask. Now it's very important to create a keyframe for this mask path, because otherwise as you start to work and tweak and move these points around, you won't be creating animation.
Save yourself some time, and definitely keyframe that first mask path. So now as we scrub through, let's go ahead and look for these major changes right here as the foot starts to roll up somewhere in there. Let's go ahead and switch over to our selection tool; and with our Foot Roto selected, go ahead and click on any one of those points. Now you can individually move these points and their handles. But rather than doing individual points, let's go ahead and click and drag and select a bunch of these guys. We'll hit Command+T, and you'll get the Transformation box. Let's move this anchor point down here to where the ball of the foot is, and on the corner here you'll notice that our cursor changes to these arrows indicating that you can rotate them.
So let's go ahead and rotate that all together. Double-click, and you'll come out of that transformation; and you can freely move up these individual points again. By default, our mask tool gets added in as Add mode. We can select Subtract to do the opposite. That's just important to know that as you start to put in multiple masks, you can add or subtract or intersect based on these different modes here. So let's go ahead and disable this visibility of the mask; and you'll see that we have a bit of harsh edging around here, which doesn't really sit in well with the rest of the shot.
Let's go ahead and move to our mask feather tool and introduce a couple of pixels of feathering to kind of help it sit in the shot a little bit better. We needed to fine tune that a little bit. We'll turn this visibility back on again. Click and drag these guys, we'll Command+T, move these out just a little bit. You can start to see how this task of rotoscoping gets to be pretty tedious, and this is a task I like to tackle with a pair of headphones and a nice playlist just so that you can zone out and kind of just basically trace over this stuff. Okay, and as we come out let's go ahead and focus in there where the foot goes completely out of the ground shatter layer where it's completely cleared.
Somewhere in there. Looks like it's moving much, much faster than we have it animated. So fine tuning and scrubbing through and looking for where these major changes happen. Let's go ahead and turn this off and preview that. Okay. So in context let's watch it all together. And, of course, we can fine tune this all day long; but you get the point. So as you can see, creating transparency manually by way of the Pen tool isn't the most glamorous work, but it's vital for visual effects.
Often times if not other methods will work, hand rotoscoping can always come through.
- Creating transparency
- Tracking masks in Motion
- Utilizing the Roto Brush tool
- Camera and motion tracking
- Working with 3D layers
- Using effects
- Creating destruction with Shatter
- Creating fire with particles
- Distorting layers with the Puppet tool
- Compositing 3D renders
- Creating virtual reality experiences