How to Change a Mask Shape in After Effects
Introduction
Masks in After Effects allow you to control which parts of a layer are visible. By changing a mask’s shape over time, you can create unique animations and transitions. This guide will show you how to modify a mask shape using keyframes.
Step 1: Create a New Composition
Go to Composition > New Composition, set the desired resolution and duration, and select a background color. This color will be visible in areas where the mask does not apply.
Step 2: Import and Add Your Media
Go to File > Import > File and select the image or video you want to use. Drag it onto the Timeline Panel. If needed, use the Selection Tool (V) to adjust the layer’s position and scale.
Step 3: Create a Mask with the Shape Tool
Select the layer you want to mask, then choose the Shape Tool (Q). Click and drag on the layer to create a mask. For example, using the Ellipse Tool will create a circular mask. The masked area remains visible, while the rest of the layer is hidden.
Step 4: Animate the Mask Shape
In the Timeline Panel, expand the layer properties and find the Masks section. Click the dropdown arrow to reveal Mask Path. Move the Current Time Indicator (CTI) to the beginning of the composition and click the stopwatch next to Mask Path to create a keyframe. Move the CTI forward and adjust the mask by selecting individual points with the Selection Tool (V) and dragging them into a new shape. Repeat this process to create smooth transitions.
Step 5: Refine Mask Properties
You can further customize the mask by adjusting Mask Feather (softens the mask edges) and Mask Expansion (increases or decreases the mask size). These options help blend the mask seamlessly into the composition.
Step 6: Smooth Keyframes with Easy Ease
Press “U” on your keyboard to reveal all keyframes on the layer. Select the Mask Path keyframes, right-click, and choose Keyframe Assistant > Easy Ease. Open the Graph Editor and adjust the curves to create a more natural animation flow.
Step 7: Preview the Animation
Press the Spacebar to preview the animation. Check if the mask changes shape smoothly and make adjustments if needed.
Step 8: Render the Final Video
Once satisfied with the animation, go to Composition > Add to Render Queue, set your preferred format and settings, then click Render to export the final video.
Conclusion
Changing a mask shape in After Effects allows for creative animations and transitions. By keyframing the mask path and refining properties, you can achieve smooth and professional-looking effects.
