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Creating masks with Auto-trace

From: After Effects CS5 Essential Training

Video: Creating masks with Auto-trace

When I was preparing the Exercise Files for the last movie, I used a very important feature of After Effects that I want to share with you here. Now, you will notice that with the rear tire curls layer, if I press the letter M, there is no mask here. So, in other words, I can't use Mask Expansion. So, I need to make a mask out of these layers so that we can use the Mask Expansion feature. Now, there are two ways of doing this. One, we can go in manually and use a tool like the Pen tool and click, click and drag, and then manually go through, laboriously go through I should add, every single spot here and trace these curls, clicking and dragging, clicking and dragging.

Creating masks with Auto-trace

When I was preparing the Exercise Files for the last movie, I used a very important feature of After Effects that I want to share with you here. Now, you will notice that with the rear tire curls layer, if I press the letter M, there is no mask here. So, in other words, I can't use Mask Expansion. So, I need to make a mask out of these layers so that we can use the Mask Expansion feature. Now, there are two ways of doing this. One, we can go in manually and use a tool like the Pen tool and click, click and drag, and then manually go through, laboriously go through I should add, every single spot here and trace these curls, clicking and dragging, clicking and dragging.

But this is such a pain. So, what I am going to do is just delete that and show you what I really did. I selected this rear tire curls layer, then go to the Layer menu at the top of the screen and then choose from the bottom of the Layer menu, Auto-trace. This will go through and automatically trace and create a mask for your currently selected layer. I am going to check the Preview box here so we could see what's going on. This is kind of a preview of what's happening. I want to make sure this is set to Current Frame.

If I set this to Work Area, what's going to happen is that After Effects is going to trace every single frame and create new masks for every frame. We don't want that. So, I want this to be Current Frame only. Although I should point out, if I had a moving layer then you might want to set this to be the Work Area. I am also going to set this to be the Alpha. It's going to look at the transparency of the layer and draw masks around the transparency. And we could adjust these values, such as Tolerance. I could increase that if I wanted to. And you could see the effect that's having on my mask here.

But I think default value of 1 is going to be just fine here. And actually, the mask doesn't look all that great right now. But when we actually click OK with these settings, it's going to look better than the preview is suggesting that it will. Although, if I was picky, I could come over here to some of the other values, Corner Roundness, Threshold, Minimum Area and play with these a little bit to get the value that I like. I am actually going to take this back down to 50 or so for right now. And again, I am just going to leave this pretty much at their defaults. But if you wanted to tweak this, you could.

So, I am going to go ahead and click OK here. And basically, what that did is it made a new layer. See the curls look much better than they did in the preview. So, it created a new solid layer and applied the mask to that solid. So, what I need to do and what I did is to select the rear tire curls, the original one, and go to the Ramp effect on the original rear tire curls. Hit Command+C to copy or Ctrl+C to copy on the PC. Select the new solid layer, the Auto- trace Solid, and hit Command+V or Ctrl+V to paste the Ramp effect so that our swirls look similar to what we had.

I will select the Selection tool here, click away to deselect, and I will turn off the visibility of the rear tire curls original layer. Now, you will notice that, and this is the way it is with Auto-trace a lot of times. There are some weird little glitches. So, what I had to do in the last movie was to go in and select certain points and maybe delete them. And in this case, there is a kind of a little bump right here. I could just click and drag these points up to get back the original curvature of the curls. It's just kind of the nature of the beast, but what's easier for me, in my own opinion, is to go through and tweak this rather than to fiddle with those Auto-trace settings and just try to guess the right thing to do.

So, it's easier for me, again, because I like playing with these Bezier curves. It's easier for me just to do that than to get the settings right, right out of the gate. And actually, I need to drag this down below the Bike layer, so it's in the back now. So, the movie would be there. That's the Auto-trace feature. But I want to show you some other benefits of having a mask. Not only do we get access to cool features like the Mask Expansion and Mask Opacity and all that kind of stuff, where we could selectively choose the opacity of these different curls. But one of the other benefits is there are a lot of effects that use masks.

One of the most basic ones is Stroke. So, if I were to apply this, then what we could do is you will see that the Stroke effect applies a stroke to one of our masks. And we can't apply the stroke to just our regular tire curls. At least we don't have this much flexibility. So, Stroke works with masks. And I could choose selectively which mask I want to apply this to. So, there's that. Or as I am going to do in this case, I could check All Masks.

And so now all masks have a stroke. Now, you will notice that it's a little bit pixilated because I am zoomed into 200%. This is the regular zoom ratio. And as you zoom in above 200%, you are going to get that pixilation, even though these are Illustrator files. If we were to scale these up to above 200%, then it'd be fine. It would look great. But because we are zooming in above 200%, that's what is making this not look so great. Now, what's cool about this is that I can animate the Start and End values. It's kind of like we saw with Paint. So, I could take End down.

And so basically what its doing is it's tracing on this paint or this stroke, in other words. So, what I am going to do is I am going to set End to 0%, beginning of the composition or 7 frames in as in the case here, some time towards the beginning of the comp. Move out in time a little bit and then we will take the End value to 100%. And so now, if I click away to deselect this, zoom out to 100%, then preview this, we get a really cool animation of our curls being drawn on, at least the Stroke being drawn on.

But what we can do is we can go back to our effect here, and just like with painting, we can increase the spacing so we have a series of dots. So, now when it is being painted on, it's a series of cool little dots. And we can go down to the Paint Style parameter at the bottom of the Stroke effect and change this from On Original Image, so it is basically making the Stroke on the original image to On Transparent. So, now we just have a series of dotted curls and look how cool that is. Also, it looks like some marquee or something that you might find at a Broadway show or something.

Take Paint Style to Reveal Original Image. And what this is going to do, it's going to be just like On Transparent except it is going to take the original color from the original layer. So, now we have this really cool effect of these dots being animated on with the original color of the curls. Very cool effect with again minimal work. And this was done for us by the Stroke effect, and there are several other effects as well that use masks like this. So, this Auto-trace feature does become much more powerful when we realize all that masks bring to the table.

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This video is part of

Image for After Effects CS5 Essential Training
After Effects CS5 Essential Training

111 video lessons · 68525 viewers

Chad Perkins
Author

 
Expand all | Collapse all
  1. 5m 40s
    1. Introduction
      1m 30s
    2. What is After Effects?
      3m 12s
    3. How to use the exercise files
      58s
  2. 28m 14s
    1. After Effects workflow overview
      2m 18s
    2. Bringing elements into After Effects
      2m 23s
    3. Adding elements to the Timeline
      1m 57s
    4. Working with layers
      3m 45s
    5. Creating animation with presets
      3m 24s
    6. Applying effects
      3m 34s
    7. Creating animation without presets
      5m 38s
    8. Previewing your work
      2m 46s
    9. Exporting content as a movie file
      2m 29s
  3. 27m 20s
    1. Touring the interface
      6m 2s
    2. How After Effects projects work
      4m 47s
    3. What is a composition?
      4m 52s
    4. Tips for adding content to compositions
      2m 49s
    5. Understanding the properties of video
      8m 50s
  4. 57m 8s
    1. Importing an Illustrator file
      4m 57s
    2. Animation basics
      7m 12s
    3. Animating opacity
      6m 40s
    4. Understanding anchor points
      4m 57s
    5. Animating position
      6m 8s
    6. Animating rotation
      4m 41s
    7. Animating scale
      7m 19s
    8. Using the Puppet tool
      7m 13s
    9. Copying and pasting keyframes
      3m 4s
    10. Animation shortcuts
      4m 57s
  5. 9m 42s
    1. Understanding precomposing
      6m 51s
    2. Navigating through compositions quickly
      2m 51s
  6. 1h 12m
    1. A showcase of effects
      2m 34s
    2. Creating a layer for effects
      3m 1s
    3. Applying effects
      4m 54s
    4. Animating effect properties
      4m 29s
    5. Using Glow
      5m 34s
    6. Creating patterns and textures
      6m 57s
    7. Creating a fireball
      7m 9s
    8. Using the Cycore effects
      5m 58s
    9. Adding blur
      5m 45s
    10. Creating a galaxy scene from scratch
      8m 38s
    11. Distorting objects with effects
      4m 7s
    12. Creating and using lens flares
      4m 21s
    13. Creating lightning bolts
      4m 3s
    14. Viewing random variations with Brainstorm
      4m 39s
  7. 30m 52s
    1. Shortening the duration of layers
      4m 23s
    2. Trimming in the Footage panel
      4m 14s
    3. Slowing and accelerating video speed
      7m 9s
    4. Applying video transitions between clips
      6m 7s
    5. Working with image sequences
      4m 47s
    6. Importing footage with an alpha channel
      4m 12s
  8. 36m 11s
    1. Brightening dark footage
      9m 12s
    2. Changing colors in footage
      6m 34s
    3. Creating cinematic color treatments
      8m 17s
    4. Creating a quick vignette
      3m 42s
    5. Colorizing black-and-white objects
      4m 50s
    6. Using adjustment layers
      3m 36s
  9. 21m 9s
    1. Creating and editing text
      7m 39s
    2. Applying text animation presets
      4m 41s
    3. Animating text manually
      4m 43s
    4. Applying layer styles to text
      4m 6s
  10. 28m 58s
    1. Let's get better
      37s
    2. Using work areas
      3m 37s
    3. Creating markers
      6m 17s
    4. Replacing layers
      2m 35s
    5. Mastering Timeline navigation
      3m 18s
    6. Aligning and distributing layers
      3m 4s
    7. Selecting layers quickly
      1m 56s
    8. Cropping layers
      3m 43s
    9. Adjusting comp resolution
      3m 51s
  11. 23m 53s
    1. Using the paint tools
      9m 35s
    2. Using the Roto Brush tool
      9m 25s
    3. Animating growing vines
      4m 53s
  12. 40m 29s
    1. Creating and using masks
      6m 42s
    2. Exploring mask options
      7m 57s
    3. Creating masks with Auto-trace
      6m 51s
    4. Masking objects with other objects
      5m 33s
    5. Making shape layers
      3m 43s
    6. Modifying shape layers
      9m 43s
  13. 30m 44s
    1. Turning 2D layers into 3D layers
      9m 22s
    2. Creating lights and cameras
      6m 14s
    3. Creating shadows
      4m 23s
    4. Using depth of field
      4m 42s
    5. Working with 3D effects
      6m 3s
  14. 18m 10s
    1. Removing a green screen background
      4m 37s
    2. Refining the matte
      4m 48s
    3. Compositing with color adjustments
      4m 50s
    4. Compositing with blend modes
      3m 55s
  15. 25m 44s
    1. Understanding spatial interpolation
      2m 5s
    2. Creating and adjusting motion paths
      3m 55s
    3. Orienting moving objects along a path
      1m 29s
    4. Drawing motion with Motion Sketch
      2m 51s
    5. Creating pauses in animation
      3m 6s
    6. Understanding temporal interpolation
      1m 56s
    7. Easing keyframes
      5m 57s
    8. About the Graph Editor
      4m 25s
  16. 12m 13s
    1. Stabilizing shaky footage
      7m 46s
    2. Tracking the motion in footage
      4m 27s
  17. 24m 58s
    1. Setting up parent layers
      5m 49s
    2. Working with null objects
      2m 31s
    3. What are expressions?
      7m 17s
    4. Modifying simple expressions
      2m 20s
    5. Using the wiggle expression
      7m 1s
  18. 6m 52s
    1. Understanding audio in motion graphics
      1m 22s
    2. Previewing and mixing audio
      3m 55s
    3. Enhancing audio tracks with effects
      1m 35s
  19. 11m 36s
    1. Adding comps to the Render Queue
      2m 30s
    2. Exploring key Render Queue settings
      4m 11s
    3. How should I export my video?
      4m 55s
  20. 7m 16s
    1. Using Photoshop with After Effects
      2m 10s
    2. Using Illustrator with After Effects
      3m 2s
    3. Using Flash with After Effects
      2m 4s
  21. 11s
    1. Goodbye
      11s

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