“In order to automate the rotoscoping process, a program would somehow have to know magically what it's supposed to do with each new frame in an animation. That's what Studio Artist does.”

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TUTORIAL JUNE 19, 2001
P
ost Processing in Studio Artist
Using autorotoscoping tools on 3D animations

by David Nagel
Executive Producer
[email protected]

We've spent a lot of time of the painting tools in Synthetik Studio Artist. There's still a lot more to cover in that area, but I thought we'd take a detour this week to look at one of Studio Artist's major features—its rotoscoping capabilities.

If you don't have Studio Artist and would like to follow along, visit http://www.synthetik.com.

How rotoscoping works in Studio Artist
When you think of rotoscoping, you probably think of labor-intensive techniques used to remove wires from movie scenes or to clean up mattes or to perform some other technical clean-up job. Or maybe you think of Max Fleischer and his original rotoscope device, wherein an "artist" would trace over the individual frames of a live-action sequence to produce cartoons like Gulliver's Travels or Popeye the Sailor or Superman.

The rotoscoping tools in Studio Artist don't resemble either one of these, although the result is more akin to the Fleischer model.

Studio Artist uses a unique process called "autorotoscoping." Essentially what it allows you to do is to paint over a frame of an animation, and then apply those strokes—uniquely—to every other frame in the animation.

The key word here is "uniquely." If you think about the problem of automating rotoscoping, you realize that to apply one frame's worth of paint strokes over an entire animation results in a very lengthy still frame. In other words, in order to automate the rotoscoping process, a program would somehow have to know magically what it's supposed to do with each new frame in an animation.

That's what Studio Artist does.

In this first installment of our look at Studio Artist's autorotoscoping tools, we're going to postprocess a small piece of animation that I output from a 3D program. You could do this with any piece of video though, since Studio Artist supports any CODEC you have installed on your system that can be recognized by QuickTime.

This particular installment will focus entirely on the automated rotoscoping process. You can also combine manual and automatic rotoscoping or do it all manually, both of which we'll examine in the future.

DEFINITION: We'll be referring to something called "PASeq" in this tutorial. PASeq stands for "Paint Action Sequence." This is simply the list of effects and parameters that Studio Artist will be recording for you as we go along. I'll show you how below.

The goal
For this one, I'm going to take an animation of a skater and make it look as if each frame had been individually painted. In my prep work for this piece, I wound up with two results that I liked, but we'll just take a look at the first one, as I think it's more of a crowd pleaser than the second. Each one started off as a render from Curious Labs Poser 4. I didn't pay any special attention to the quality of the render because I knew I'd be making significant changes in the end, and Studio Artist is both resolution-independent and very forgiving when it comes to the quality of your source material.

NOTE: If you'd like to see these effects in action for yourself, you can download my own Paint Action Sequences (PASeqs) and apply them to your own footage. You can download them here. To use these, just unstuff them and then go into Studio Artist and select Action > Import Paint Action Sequence. In the last part of this article, we discuss how to apply these actions to a movie.

So let's take a look at what we're going to do here. The first two examples below were rotoscoped from the third example below. You can click on the two processed images to see the animations, bearing in mind that compression for the Web has reduced the quality of the output.


Click image to see the animation (640 x 480, 2.7 MB).

Click image to see the animation (640 x 480, 3.7 MB).

 

I'm a fan of both of these. The first one looks something like colored pencil with acrylics, while the second looks like a bad photocopy that's been drawn over with a marker or watercolor pen. These in no way represent the limits of Studio Artist, but let's see how these particular pieces were made.

TIP: In Studio Artist, every stroke of every frame is unique, which requires special considerations. If you use a "normal" frame rate of 24 or 30 FPS, your background will look more like noise than art. So lower the frame rate to 8 or 10 FPS, at the most. You can then remap your footage in a compositing application, such as Adobe After Effects, to run at your desired frame rate.

Incidentally, if you'd like to take the easy way out and download the actual (tiny, 18 KB) actions that created these movies, just click here. You can load these up one at a time in Studio Artist by opening your Paint Action window, erasing the current sequence and then choosing Action > Import Paint Action Sequence.

The rotoscoping process
The first step in rotoscoping in Studio Artist is to open up your source footage and start playing around with some settings. So launch Studio Artist, and, when the program asks you for a source image, choose your QuickTime movie. Set the canvas to whatever you want your output size to be in the end. If you plan to output in multiple formats, set your canvas size to the largest output size you plan to use.

Now, up in the upper left-hand corner of your interface, you'll see a little window showing you the first frame of your QuickTime. The first frame might not be the ideal frame to work with. Choose a frame that's typical of your footage in terms of the scale of the subject, or work on the last frame, since that's where you're movie will stop and freeze, unless you're going to set it to loop for presentation on the Web.


The source window

Once you find a frame you're comfortable working with, it's time to start experimenting with the Paint Synthesizer to find the look you want. For both of mine, I worked mostly with presets that I modified to work better on my image.

As soon as you're done experimenting and are pretty sure how you want this to look, open up your Paint Action window (Action > Paint Action Window) and erase whatever's there.

Click on the check box labeled "Record," and start applying your settings. Studio Artist will record everything you do that affects your canvas. So, if you want to do something that you don't want recorded, make sure you temporarily deselect that Record check box. If you undo an action, it will automatically be removed from the Paint Action command list.

IMPORTANT: These painting steps all involve Studio Artist's automated painting actions. To use the automated painting, just click "Action" in the preset palette. When Studio Artist records your actions, it also records the amount of time spent applying the action, and will use the exact same amount of time for all future frames. This means that the longer each action takes to apply, the longer your final render time will be.

I did the first example (the lighter one with the red dress) in nine steps. Here are the settings I used to achieve my effects.

1. I first applied a background based on the source image's threshold. To do this, just go up to the background pull-down menu right above your canvas and select "Image B/W Threshold."

The benefit of applying a threshold to the background is that, no matter how abstract your composition gets, there's still a hint of the referential in there; there's still something recognizable as an object that's being animated.

2. Next I wanted to apply a Paint Patch that would pretty much destroy the threshold image, while just leaving enough to hint at it.

For this I chose the present called "Color Flower Scatter" under the Edge Autodraw category. But I made a slight modification by going into the Paint Synthesizer in the Path Application palette. I changed the "Prob" to "WhiteCanvasProbErr." This ensures that the pencil strokes avoid the while areas of my canvas while conforming themselves to my non-white curves. (You could also use an alpha channel, but my technique will help you avoid any hard edges.)

3. Next I applied some crayon to the image—not too much, but just enough to rough up the background a bit and bring in a little more color to my subject.

This preset can be found under "Crayon > Crackle 1" in the Presets menu.

4. The next step is probably unnecessary, but I wanted to add a little edge. So I used an outlining pencil, let it run for about a second, and then stopped it. In the end, the outline will not be visible, but this addition of a dark gray will provide almost an edge shadow to the image.

This is the "Edge Autodraw" preset in the Pencils category. I applied it for a little less than a second.

5. The next step just involves bringing in a little more color and texture to my image. I'm applying a rough style (download here) just to the subject using, as before, the WhiteCanvasProbErr setting under Path Application. I let it run about four seconds.

6. Next I'm using the same Paint Patch, but I'm applying it across the entire canvas. While my primary concern is the final appearance of my subject, I also didn't want to neglect the background. In this case, my background is white, so I just wanted to add a little texture. Since you're using the same preset as in the previous step, make sure you set the Prob back to Pressure.

7. Now, here's the part that I think makes this particular example less sophisticated than the other example. I was losing too much definition in my image, and I wanted to bring some back. So I used a modified version of the "A Thin Colored Pencil" in the Pencils category. I modified it by changing the Path Type (found in the Path Shape palette) from "Curved" to "Spiral Ellipse."

This obviously brings in a lot more definition to the image, and it also muddies it up.

8. So I want to get rid of some of that definition. The next step is not a Paint Patch but an Image Operation. Image Operations are basically effects, such as those you might find in a Photoshop plugin. To get rid of some of the definition and lighten things up a bit, I'm applying the Colored Edge operation with a Mix value of 74 and a composite mode of Soft Overlay White.

9. Finally I applied my last and favorite Image Operation: Watershed. I just used the default settings here to add a little wetness to the image. I think it helps get rid of some of the strokes and colors that look out of place and gives the image more of a painted, rather than sketched, look.

Applying your settings to a movie
So now we have the effect we want for one of our frames, and we want to apply it to our entire movie. At this point, you'll want to uncheck the record button in the Paint Action window. If you've followed along, your command list should look like the window below.

If you've accidentally stuck in some unwanted commands, it's easy enough to get rid of them from your sequence. Just uncheck the commands you don't want. If you get tired of looking at them in your list, just select Action > Paint Action Commands > Delete Muted Paint Action Commands. This will delete all commands that are unchecked.

Now, before we apply our PASeq (Paint Action Sequence) to our movie, make sure you save your command sequence. If you crash, you'll lose all of this and will have to start over, so it's always good to keep a few backups. To save a sequence, just select Action > Export Paint Action Sequence. I always put a .paseq extension on the end of mine, just so I can keep them straight, but it's unnecessary.

So here we go. To apply your PASeq, select the menu item Movie > Process Movie File with PASeq > To Movie.

You will first be asked whether you want to save your current canvas. Don't. Then you'll be asked to select the movie to process and the output size. Finally, you'll be asked for a movie name. Don't give it the same name as your original movie, or you might have problems.

TIP: Earlier I said you should output no more than eight or 10 frames per second. By default, Studio Artist will output at the same frame rate as your source movie. So, if your source was created at 30 frames per second, your output will be at 30 frames per second. You can change this by selecting Movie > Process File Settings. Here you can set the frame rate (based on your timeline settings) and the number of source frames to skip. Your timeline frame rate, by default, is 10. You can lower this by going into the Timeline palette and entering a value of 8.

So now you see your movie being rendered, each stroke being repainted right before your eyes. Here's where you begin to understand the value of economy. If you apply a large number of paint strokes and effects to an image, your render will take forever. As it is, my PASeqs for these examples take about one or two hours to process 176 frames.

But, in the end, I wound up with some pretty nice pieces of footage.

This week we looked at the very basics of rotoscoping in Studio Artist. Next time we'll look at a few more things you can do. For example, you can vary your paint strokes over time, manually paint onto a movie and do a whole host of other things. So stay tuned for pieces on these features. In the meantime, make sure you visit the Creative Mac tutorials section and the Digital Media Designer tutorial section for more indepth looks at the tools of Studio Artist.

If you have any further questions, be sure to visit me in the Synthetik Studio Artist user forum.

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Dave Nagel is the producer of Creative Mac and Digital Media Designer; host of several World Wide User Groups, including Synthetik Studio Artist, Adobe Photoshop, Adobe InDesign, Adobe LiveMotion, Creative Mac and Digital Media Designer; and executive producer of the Digital Media Net family of publications.