Join Ian Robinson for an in-depth discussion in this video Point tracking, part of Mograph Techniques: Retiming and Tracking Footage.
If you've worked in motion graphics for any amount of time, I'm sure you've come to the realization that not all projects are created with a beautiful pristine seamless workflow. Many times you have to massage the results of the different tools you have access to, to create the exact look you're going for. And that's what we're going to do in this specific example. We're going to track the motion of our jumper's feet as he jumps through the scene using a simple Point Tracker inside of After Effects. Rather than jumping into a true 3D environment and trying to create 3D point clouds and all kinds of other advanced tools, we're going to go ahead and create similar results using an old school technique.
So I want to start by moving my current time indicator to around frame 10. This is where we'll start our track. Now in order to apply a point tracker, all you have to do is just double-click on the layer to open up your Layer panel. Now with a Layer panel active, we can go up under Animation > Track Motion. With our track point in the scene let's reposition our view. I'm going to press the Spacebar to grab my Hand tool and just move down in the scene. Now a point tracker has two main squares. The outer square allows you to define the search region. And the inner square allows you to define the precise shape that you're going to be tracking.
I want to position my little crosshairs here on the back part of our jumper's heel. So let's go ahead and position our mouse over top of the inner square here and just reposition our point tracker down into the scene until it's right about the midpoint of our jumper's heel. Now, I'll refer to his feet as left and right. And I'll refer to the exact feet of our runner. So this is, literally, his left foot and, literally, his right foot. Now, in order to track this scene, we need to go down to the Tracker panel.
Let's make our Tracker panel a little larger and go down to the Analyze section. In here, I want to click this Analyze 1 frame forward button. Let's analyze frame by frame, so we can massage the track as it's tracking through the scene. Each time you click, a new key frame is going to be added to the point tracker. And on occasion, you may want to go back up over your center square and just reposition your track, so it stays in the center of our jumper's heel. Now it doesn't have to be extraordinarily precise, because we are going to be generating particles from this point track. So it is okay, when you have these different jumps as you reposition the scene.
So I'm going to keep analyzing one frame forward, clicking through my projects. Just, again, on occasion, you want to go ahead and reposition your tracker, just to make sure that it's not drifting too far off your object. In many scenes, the point tracker will work perfectly well tracking frame by frame. Whenever you feel like you're having a successful track, you can go ahead and click this next button to the left to have the tracker automatically load up all the frames and track through the scene. Before I click that button, I'm going to go ahead and reposition my view here a little bit. So, when the runner gets close to the sand, I can stop the trackpoint. So let's go ahead and click that Analyze forward button, and it's going to switch to a Stop button.
So you can leave your mouse hovered over that area and just click it again to stop the track. Now, I'll click through the last few frames here. And then, since I tracked an extra frame, I'll just Command+Z or Control+Z on Windows to undo. Now in order to apply this tracking data to another layer, I need to create that other layer. So I'm going to go up under Layer > New > Null Object. Let's rename this Null. Make sure Layer 1 is selected in your time line by clicking on it and press Return.
Let's call this XY LF for left foot. Now, in order to apply this track data to our new null object we need to edit the target. So, click on Edit Target and make sure the layer that's chosen is XY LF when we click OK. Now, let's specify the target for the tracker. We need to actually click the Apply button to apply those key frames. Notice we'll get one more menu that pops up that allows us to choose whether want to apply each individual dimension or both together. So let's choose X and Y and click OK.
Now, if we press and U key, we can see that we have all of our position keyframes set up for our null object. Now as we scrub through the scene, you can see our null is tracked right along the bottom of our jumper's foot. With the tracking process fresh in our brain, I want you to go ahead and track the jumper's right foot using the same techniques that we've just learned. We'll use both of these tracks to create particle animations later on in the course
- Analyzing a rough cut
- Tracking with mocha
- Adding and animating spheres
- Creating an animated logo with particles
- Adding dynamic motion
- Color correcting the back plate
- Blending particles emitters
- Retiming layers with prerenders
- Adjusting speed with Timewarp