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ShotANVIL: Tracking Options (Tutorial)

ShotANVIL combines PaintX , SliceX and TrackX into one combined editor interface allowing you to do everything in one plugin, with powerful new tools for AI masking, paint, keying and enhanced shape masks.


For more information on Coremelt ShotANVIL: 

TRANSCRIPT

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Hi. In this tutorial I'm going to explain the settings for motion tracking,

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which are grouped into a pre tracking menu on the left and a post tracking menu

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on the right.

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These tracking settings are common across all of our moca based tracking

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products. We are reviewing them here in the Slice X editor,

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but they're the same for Paint X and others.

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Let's explain a few terms and concepts before we go over the individual

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parameters. When we're tracking,

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the movement is modeled in two different ways when we choose to track and

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translate scale rotate mode. The tracker is solving for the X and Y position,

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simple two d rotation in the Z axis and the overall scale,

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but ignores perspective distortion.

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The perspective mode adds perspective distortion to the mix and is the setting

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you will most commonly want to use.

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The benefit of tracking and perspective is that when you want to track an

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extreme rotation or movement,

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we'll better follow the motion of individual shapes and textures within the

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tracking area.

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If you were just to try and match that motion with a translate scale rotation

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mode,

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the shapes will most certainly lose their connection to the image due to the

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lack of distortion.

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Let's look at the apply track mode setting.

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Choosing position only means that the track layer will only move in X and Y and

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ignore rotation and distortion.

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This is good for call outs such as when we might want a text label to track an

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object's position,

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but stay flat in the same size on screen with no rotation or scaling setting

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apply track to perspective mode will treat the motion as if applied to a two D

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plane viewed in three D space.

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It will effectively warp the shape mask with four corner points to better map to

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three D surfaces. To reiterate,

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tracking model and apply track mode should be set to perspective in most cases

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with the exceptions being text callouts and some specific effects.

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So now let's track this sword using a detailed shape mask. As mentioned,

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we will use the perspective tracking model and set apply track as to

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prospective mode as well, and then we can track it.

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We can see after tracking that it's working quite well.

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There is a tiny bit of slipping,

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which we could fix by adding a couple of shape key frames to,

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to tweak the points in the mask over time,

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but we will save that for another tutorial.

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Let's have a look at some additional options to see other ways that we could

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have approached it. If you are tracking a very small shape,

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sometimes there simply isn't enough information to get a good track from the

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shape itself. In this case, we can change the track shape oversized property,

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which will expand the tracking area outside the shape mask.

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This ensures that the tracker will have more details to use for calculating the

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motion without affecting the way the clip is masked.

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We can also change the track shape overlay opacity to give us a clearer view of

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the underlying pixels.

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So while we tracked in perspective mode after tracking,

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we can switch the track apply setting to translation.

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We can see that it pins the shape to the center of the tracked area,

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but ignores changes in scaling rotation and perspective distortion,

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exactly what we need for tracked callouts.

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Let's make sure again that the track apply setting is in perspective mode, and

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then have a look at the track smoothing parameter.

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If the track motion has some jittery high frequency vibrations,

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we can turn on smoothing and choose how many seconds we want to smooth over.

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In this case, the results were already smooth.

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Copy track data and paste track data allow us to copy motion tracking to

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different layer groups such as two different groups of strokes and pan X or

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between instances of slice X. After choosing copy track data,

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we can immediately see that paste track data is available in the right side menu

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indicating that the track motion was copied successfully and is now available

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for pasting. The

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next settings here are for solving specific problems with bad tracking

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solutions. For example, if a track fails halfway through,

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generally you want to stop the track, move the playhead to the last good frame,

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and then use the delete track data forward function to clear the unusable

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tracked motion.

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We can then try other approaches to create the second part of the track by

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changing the shape somewhat or choosing a completely different area of the

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image. The details of this will be covered in a separate tutorial.

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We can also just delete track data at the current frame via the menu or using

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the hotkey queue.

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This is useful if we only have a couple of bad frames that we need to delete.

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Delete track data backwards, as we would expect,

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deletes the track motion before the current frame and delete all track data

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clears the entire track.

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The yellow tick mark here indicates that there is valid track data at that

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frame. If I delete the track data forward,

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you'll see that the yellow line here indicates that track data is on this part

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of the clip only,

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and that the track motion is clear where there is no line or tick mark.

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I can undo that using the menu or command Z and get the track data back again.

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So that's the basic overview of the tracking menu parameters.

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We will publish additional tutorials demonstrating in detail how to use these

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functions to solve difficult problems such as dealing with shots with a subject

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you're tracking, goes behind other objects or needs to be tracked out of frame.

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Please go to coremelt.com/downloads to get your free trials.