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Layer Scale in Apple Motion 2

Using fixed resolution with filters and behaviors By Dave Nagel
In Apple Motion, by default, the size of a layer is determined by its contents. So its dimensions can change based on what's happening to the objects it contains. If you blur an object, for example, this will cause the layer to grow. And this can lead to some unpredictable results in your composition, such as jittery movement or improper alignment of elements.

The problem
In general, where you're going to encounter this problem is when you're using behaviors or filters based on the relative position or scale of a particular element. One (of many) examples that illustrates this phenomenon pretty well is the Displace filter. Displace uses one element to offset the contents of another element, and, unlike Displace filters in other programs, it scales the displacing object to the dimensions of the displaced object. In the example below, we have a background image with some text over it.

Now we want to use this text to displace the pixels of the background image. So we apply a Displace filter and set the text as the source. Here's the result.

Definitely not what we wanted. The text has been scaled up in the displacement effect to match the scale of the background image. And this has two consequences. First, the obvious: The text in the displacement is the wrong size. But also, no matter how we animate the text within the bounds of the canvas--scale it or move it--we're not going to see any animation in the displacement itself, as the text is continually being scaled and positioned to match the dimensions and position of the background image.

Here, for example, I'm scaling the text over the course of the animation so that it grows to fill the screen. But what you see, instead of this, is just some jitter in the displacement effect.

And here you see the original text with a text behavior applied to it. The displacement effect clearly is not matching the text. It's giving us unpredictable results.

The solution
The fix for this, and most other is to apply a fixed resolution to the layer of the object that's the source of the displacement. This essentially expands the bounding box of the object so that it appears in correct proportion with the other element (the background image, for example) that's being affected by it.

In this example, we'll use fixed layer resolution to displace our background image so that the displacement takes on the actual dimensions of the displacement text, rather than the scaled dimensions.

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Related Keywords:apple motion 2, layer scale, fixed resolution, displacement, displace filter, scale


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