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The planar tracker is only available with Nuke X, and is based on completely different principles than a 2D point tracker, or a 3D camera tracker. It can, therefore, solve classes of tracking problems that the other two cannot, providing with a powerful third alternative for your tracking problems. To start off with, let's take a look at the overall planar tracker workflow. For that, we will need a Read node. We will select our Project Media folder, our Lesson_06_Media > Training Clip folder, and trainingClip_01.
Open; connect to Viewer. A little more screen space, please; type H to fill the Viewer. This is a little training clip that I developed to make it easier to tell the story of the planar tracker. We will stop that, jump the playhead to frame 1, and add the planar tracker node. So make sure we have the Read node selected, the Transform tab > PlanarTracker.
Notice, we get two nodes: we get a Roto node, hooked up to the PlanarTracker node. They work together. In the Roto node, we are going to draw the shapes that tell the PlanarTracker the area we want to track. So up here on the left, we get the standard Roto controls that you are already used to. Up above are the Planar Tracker controls. They are ghosted out right now, because we haven't opened up the PlanarTracker Properties panel, so let's double-click on the PlanarTracker node, and now they wake up. Now, the controls above the Viewer are duplicated over here in the Properties panel.
The nice thing about these is, they are not only easier to get to, but they are in the order of the workflow. So let's get a little more screen space, so we can see our labels better. First on the left, this pop-up controls the kind of motion the tracker is looking for. We will come back to look at this in more detail later. Next, these are the tracking controls: track forward, track backward, and like that. These buttons delete the tracking data. These buttons over here control the Planar Surface and the Planar Grid; two very important tools we will be looking at more closely in just a minute.
This, of course, is the previous key frame, and the next key frame, and add a key frame, and delete a key frame. This pop-up allows you to select which Planar Tracker layer in the Roto node you want to use for tracking. This pop-up allows you to choose the format for the tracking data when you export it. So let's say we want to track this surface here. I will make sure my play head is on Frame 1, my Roto is all ready to draw, so we will just go click, click, click, click, and close.
You will notice, when I scrub the playhead, the shape is not at all attached to it, because it has no tracking data. So now we will track forward. The Planar Tracker works by locking on to a large flat area of texture, such as a wall, or a door, rather than a few small points, like a point tracker. It essentially calculates the four corner pin that's required to move the texture from frame to frame. Because it grabs large areas, it's immune to grain, motion blur, and lighting fluctuations that would spoof a point tracker.
We are all done, and now the shape is attached to my surface with the tracking data. Now it's time to look at the planar surface, and the planar grid. To do that, I am going to jump the playhead to Frame 1. In order to turn on the Planar Surface, you must have the layer, or the Roto shape selected. Otherwise it won't turn on. So we will select it, and now it does. The planar surface actually defines the four corners of the four corner pin, and now, when I turn on the Planar Grid, you can see that the grid is not parallel to the face.
That's another thing that we use the planar surface for, is to align the surface to match or target. To do that, we have to turn on the Planar Surface adjustment right here. It doesn't turn on, because again, we don't have our layer selected. So once the Roto is selected, I can enable the Planar Surface adjustment tools. Notice that you get all the tracking points out here. So what we do is we line up the planar surface, so that the grid is parallel to the surface we are tracking.
So something like this. I can push in a little bit here, and I will fine-tune these positions. Tell you what; I don't like seeing the tracking points on the screen, so cursor in the Viewer type O, and the tracking points disappear. Now it unclutters my screen; that's better. Alright, so I am just refining these guys here, and now you can see that the planar grid is now parallel with this face, which is what I want. And now, when I play the clip, the planar grid, and the planar surface move with my target.
Stop that, and jump to Frame 1. Notice that on Frame 1, the planar surface turn yellow. That's because Frame 1, in this case, is the reference frame. The reference frame is whatever frame you drew your Roto shape. That's a very important frame, because all of the motion is relative to that frame. Notice, if I move the playhead off one frame, it turns blue. The reference frame is so important that the planar surface is marked yellow when you get to it.
We are done with the tracking, so now we want to inspect our tracking data to see how well it locks on to the target. To do that, we come up to the center viewer button here, and this will center our Planar Tracker in the middle of the viewer, no matter how much it moves. We will zoom in a little bit, and now we will play that. Okay, with the Viewer Stabilizer turned on, we can now see our track locks pretty darn well. We do have a little bit of drift, you will notice, at the end of the shot.
That's because point trackers compare Frame 1 to Frame 2, then Frame 1 to Frame 3, and then 1 to 4, and so on, always comparing Frame 1 to the current frame. The Planar Tracker, however, compares Frame 1 to Frame 2, then 2 to 3, then 3 to 4, and so on, always comparing adjacent frames. While this explains it's immunity to interference by grain, and other things, it also means that there can be an inherent drift in the tracking data. So next, we will see how to deal with that.
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