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Masking and Rotoscoping The Easy WayThe more thought you put into your rotoscoping, the quicker and easier it will be for you to finish it
I always joke that there are two things that make motion graphic artists cringe. One is chromakeying, and the other is rotoscoping. Why do we dislike these tasks so much? Mainly because they can be extremely time consuming if you don't think through what you are doing first. Let's take a look at a good and simple way to wrap your head around rotoscoping, and this can apply in any compositing application.
First, we need a shot that could prove to be tricky, and I'm going to use a shot from my wedding video, as I know that my wife loves being a star (yeah, right!)! What we are going to do is mask her out, so that she is in full color, and the background is two-tone. Here is the before shot.
Most people new to compositing would look at this shot and say that it's really easy, and it will be no problem at all, and proceed to mask out my wife and her veil, and go frame by frame to achieve the look we want. Here's the problem. My wife's veil is going to make masking extremely difficult, as it is flapping back and forth in the wind, and going beside and behind her, which is going to make for a masking nightmare. Or is it? The most important thing to remember is that masking is 80% thought, 20% work. If you sit down and look at your shot a few times first before you start, your job will become much easier. Let's take a look at our shot and see what's going on.
There are two main things going on in this shot. First, is my wife, and second is her veil. My wife does not move very much in this shot, whereas her veil starts beside her, then moves outstretched behind her, and then moves back down towards her. I can already tell you that if we do this shot in one mask, we are going to be in for problems. So, the simple solution is don't use one mask! The biggest mistake that junior compositors, or experienced motion graphic artists with little rotoscoping experience make is trying to do these types of shots with one mask. For this particular shot, I would use two. One for my wife, and one for her veil. Let's take a look at this in After Effects!
First thing is first. I need to pick a point in the shot where my wife is the most visible, as that will require the most keyframes, so for that, we will go to the end of the shot, where I can see her from head to toe. Next, I will click on the Pen Tool (Shortcut - G), and mask out my wife, minus her veil. Now, what we have is my wife, standing on a totally black background which will make our lives complicated, as we need to see what is happening around her so we can adjust her mask accordingly. No problem, simply turn your mask off by selecting your layer, pressing the "M" key to reveal the mask , and instead of the "Add", we want "None", as we want to see the mask, but not have it effect our shot.
Now, we can see all of our shot, but it is very difficult to see the mask, as it is a bright yellow, and the shot is very bright, so double-click on the yellow box beside your mask to make it an easier color to see. We'll use red, and as you can see, the mask is now much easier to see.
Now, we are going to animate our mask in reverse starting at the end frame, and working our way forward to mask my wife out from the background. When I'm done, the mask should look a little something like this.
Now, we are ready to mask my wife's veil, and most people at this point would duplicate the layer, and mask it out, but there is no need. Simply select your Pen Tool again (Shortcut - G), and quickly mask around the veil. As before, it will create a new yellow mask around the veil, and you can simply double click on the yellow icon and change that color to any one of your choice. For a bit of contrast, we'll use blue. Now, we are only dealing with the veil, and we can overlap the masks, to make our job much easier.
When we are done masking the veil, we can add in our background with a bit of a sepia look to it, and render it out to get our final result.
Needless to say, that if I had attempted to rotoscope my wife and the veil at the same time, it would have been extremely time consuming, and frustrating. The best part about this method of rotoscoping is that it works the same across any compositing program. Remember, the more thought you put into your rotoscoping, the quicker and easier it will be for you to finish it, with good looking results.
|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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