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There are a couple of more tracking cases here I wanted to show you and I am again using the Motion Demo clip from the Lesson_2_Media folder. This surface down here, when I play the clip, it's rotating kind of like a turntable. This is the kind of tracking target you would get if you had a camera orbiting something. So let's see how we might track this. I am going to go back to frame 1, draw an X spline around the perimeter and I am going to pull the corners nice and sharp, oops! Let's turn off the Planer Surface, we don't need that and tuck it in kind of tight.
Okay, I am going to turn off the Shear, so we're only tracking the Motion for Translate, Scale and Rotation. Let's see how that works, tracking forward. Yikes! I am getting divergence almost immediately. All right, that's not working. We'll push that back. Now I'll turn on the Shear and the Perspective and try it again, see if that's better. Okay, that's looking better, but I'm still getting some divergence over here and over there. What's happening is the planer tracker is becoming confused by the background mixed with the edges of my target.
So let's try that again back to the beginning. Now I am going to move all of the control points to set the spline just inside the surface, so the tracker will no longer see any of the edges out here. Okay, let's try tracking it now. The tracking spline no longer incorporates pieces of the background into the edges of the target.
So the planer tracker has a much better time of it. Well that actually looks pretty good. We'll scrub though the shot, and say that's seems to be sticking, but the proof of the pudding is the Planar Surface. So let's turn our Spline off and the Planer Surface on. Remember, you can be on any frame when you line up the Planer Surface. So watching our zoom windows in the upper-left hand corner, we'll line this up real tight with our target. There! Okay, now let's see how well it sticks.
Well, that's looking pretty darn good. We'll stop that. Okay! For these rotating surfaces kind of shots, you can see that moving the tracking spline to the interior helps quite a bit. We're done with that, so we'll delete that spline and take a look at another case, the globe. The globe of course is a spherical object. it's not a planer surface. The problem is-- let me zoom in on that -- we have a lot of surfaces we would like to track that are like this, most notably the human head.
The human head is more like a globe than a plane and people are always rotating there heads. So this is a real common tracking problem and it's not a planar surface. It's a round surface. So let's see what we can do. I'll select the X spline. draw a nice shape around here. Oops! Let's turn off the Planer Surface again, relax the tension, so we get a nice smooth curve all the way around, to adjust my points.
Okay, now let's track it forward using the default motions and of course the planer tracker seized this surface as a single flat plane and attempts to keep the tracking spline locked on to it. Of course, that's wrong because it's a curved surface. But it did a very nice job and locking onto it even then. Okay so what are we going to do? Well, we go back to frame 1 and try a new tag. What we are going to do is keyframe the shape on the globe. This way the rotation of the globe will not throw the shape off, but before we do that we have to get rid of all the tracking data.
Of course, we have tracking data, this movie and this spline, so to get rid of it I'll select Manual Track. We'll click in the Viewer and now we can see the keyframes for all the tracking data. So we'll select Delete all keyframes and we will get this confirmation because when you click Yes, you are going to delete all your tracking data. So I'll click Yes. The tracking data is gone. Make sure you select the Large Motion when you're done. Now to prove the tracking data is gone, I scrub the clip and the spline no longer moves.
All right! So, let's keyframe the spline, I'll slide down here and click on the Keyframe button to establish a keyframe there, come down here, add another keyframe here, another keyframe and at the end one more keyframe. Okay, we'll go back to the beginning and track it again with the exact same motion settings we have before, track forward. Now the tracker is trying to move the spline, but the spline has keyframes.
So you're seeing the spline kind of like torn between the tracker and its keyframes. However, once it finishes, the tracker is now locked onto our target. This is what we saw earlier when we did the keyframe on that brown wall. All right, we will stop that, jump back to the beginning of the shot, rehome the viewer and we'll delete this layer. So the moral of the story is this even when the planer tracker is asked to track on a non-planar surface, it can still collect useful tracking data that will speed up your rotoscoping work.
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