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Motion Tracking and the Match Move Behavior in Motion 3By adding the Motion Tracking filters to Motion, Apple has added an indispensible set of tools
I've been an unhappy compositor since Apple's decision to discontinue Shake. But thankfully, some good things have come out of it. Apple is now starting to pull out some of Shake's great features, and give them to Final Cut Pro and Motion, and one of those great features is Match Move. Motion Tracking, like Chromakeying, is one of those tasks that always makes me cringe, but with Match Move, your tracking jobs will be quick and easy.
First, let's take a look at our footage. In my shot, I have a TV that I've turned on so that I have a nice blue screen that will help me with my tracking. I've turned the TV onto the blue screen for two reasons. One, I'm going to key that blue out, and put my footage "behind" it, and secondly, if you look at the corners of the TV, we have pretty good "contrasty" areas for us to use as a tracking reference. Now, let's set up our track.
Motion doesn't do its tracking in the conventional way that most programs (like After Effects) do, as it is a two "behavior" process. That's right, Motion considers its Match Move to be a behavior, so the first thing we need to do is to analyze our footage, so that we have a reference for our Match Move.
Select your footage, then navigate to ADD BEHAVIOR>MOTION TRACKING>ANALYZE MOTION.
You will notice a small (very small) yellow "bulls eye" appear in the center of the screen. This is your tracking point. You can use up to six track points, but for our purposes, you will only need one. Click on the tracker, and you will notice that you now have a zoomed in view of your footage. This is to let you be specific with the area you want to track. You can adjust the magnification of your tracker, by simply navigating to your Inspector, and changing the "Auto-Zoom" value to 8x. Now, we need to select a point of reference for our track. I always prefer to use areas of high contrast, and there is no better area of our footage for that than the corner of the picture tube, where it comes to a corner. Making sure I'm at the start of my clip, I can drag my tracking point over one of the corners (any one is fine), and I'm ready to analyze my footage. One thing that threw me for a curve is that when you click "Analyze", a new "yellow dot" appears, and that is your "current location", and your tracking "bulls eye" is the original start frame. It's a little confusing, and I think that Apple should look at fixing this to make it a little less confusing for future releases. Once our analyzing is complete, we're ready for our key.
This is the quickest and easiest part of the entire process. First, pick a shot that you want to put in the TV, and since I love my wedding video, that's what's going in there. Drag and drop your footage, so that it is the bottom most layer, and then scale and reposition your footage so that it appears behind your television more or less where you want it to be (on the first frame).
Next, navigate your way to ADD FILTER>KEYING>PRIMATTE RT.
Next, click the check box beside the Primatte filter, as we don't need to see it just yet. What we want to do first is to select our key color, so with the plug-in deactivated, and the Inspector open to the "Filters" tab, click on the color selector for the "Backing Color", and click on the blue of the television. The key looks alright, but not perfect, it needs a spill suppression. With your "television" clip selected, navigate to ADD FILTER>KEYING>SPILL SUPPRESSION, and just like magic, the "blue ring" around the image is gone! What I will normally do is play around with the "Matte Density" attribute in the Primatte RT filter to get my edges just the way I want them, but otherwise, our last step is to "attach" our "television show" to our TV, and this is quite easy to do. Select your "TV show" clip, and navigate to ADD BEHAVIOUR>MOTION TRACKING>MATCH MOVE, and you will see that the Match Move behavior has been added to your clip, but when you preview your clip, nothing happens. That is because we have to attach the "Analyze Motion" data to our Match Motion effect. That is done by first, making sure you have the Inspector open and the "Behaviors" tab selected so you can see your "Match Move" behavior, and now where it says "Source None", drag the "Analyze Motion" behavior from your "Layers" window over on top of the box beside "Source". Once you do that, you will see your data appear in the "Match Move" behavior. Now simply press the space bar to preview your final composited animation that is ready to render.
At this point, you can finesse your mattes, add glows, scan lines and other embellishments to your "TV footage" to give it more of a "TV image" feel to it, but the power of the Match Move filter is obvious, as our track took one pass to do, and produced great results.
By adding the Motion Tracking filters to Motion, Apple has added an indispensible set of tools that every editor will need, and the simplicity with which you can create your tracks, will WOW your clients every time.
|Kevin P McAuliffe is currently a Senior Video Editor working in HD post production in Toronto, Canada. He has been in the television industry for 12 years, and spends his days onlining on a Final Cut Pro HD. Kevin's high definition onlining credit list includes concerts for Coldplay, Sarah McLachlan, Barenaked Ladies, Snow Patrol, Sum41, Paul Anka, Il Divo and Pussycat Dolls, to name a few. Also, Kevin is an instructor of Advanced Final Cut Studio 2 at the Toronto Film College. If you have any questions or comments, you can drop him a line at firstname.lastname@example.org|
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