Using the Smear effect, you define an area within an image and then move that area to a new location, stretching, or smearing, the surrounding part of the image with it. Use masks to define the area you want to distort.

This effect works with 8-bpc and 16-bpc color.

To use Smear, first create or import two masks: the source mask and the boundary mask. You can create masks on the layer in After Effects or use masks created in Adobe Illustrator. To use a mask created in Illustrator, copy the mask and paste it into a layer in After Effects. Masks must be closed to work with Smear; if a mask is an open trace, After Effects closes it when you select it. Both masks must be on the same layer as the footage to which you apply the Smear effect, although you can copy masks from another layer.

When you move the source mask within the image, Smear stretches the portion of the image inside the boundary mask to follow the edges of the source mask. The boundary mask tries to protect the image outside it from being stretched. Both the original position of the source mask (set in the Layer panel) and the offset position of the source mask are displayed in the Composition panel. The first position of the source mask is indicated by a light red outline, and the new position is indicated by a dark outline.

You can animate the position, size, and rotation of the source mask as it moves to its offset position. You can also animate the original position of the source mask in the Layer panel.

Processing can take up to several minutes with certain settings. Computation time increases as the source mask gets closer to the boundary mask. Processing is interrupted when you click a control.

Source Mask

Specifies a mask as the source mask. By default, After Effects selects the second mask you create or import for the layer as the source mask.

Note: You must specify both a boundary mask and a source mask to create a distortion.

Boundary Mask

Specifies a mask as the boundary mask. By default, After Effects selects the first mask you create or import as the boundary mask.

Mask Offset

Specifies a destination position for the source mask. The offset is a position specified by x and y coordinates, which appear to the right of the Offset button. To set an offset location, click the Offset button, and then click the image in the desired location. To set the offset position numerically, type a new value for each axis. When you don’t need the precision provided by Mask Offset, you can simply drag the source mask offset in the Composition panel.

Note: Unwanted undulations may occur if the source mask is close to the boundary mask during animation.

Mask Rotation

Rotates the source mask around its center point, between 0° and 360°.

Mask Scale

Scales the source mask (at its offset position) larger or smaller, in relation to its original position.

Percent

Specifies what percentage of the smear is actually performed. For example, when Percent is set to 50%, Smear performs half of the smear you have specified by moving, scaling, and rotating the source mask. This value doesn’t affect the location of the original and offset positions of the source mask; it affects only the percentage of the effect that is performed.

Elasticity

Specifies how closely the image follows the shape defined by the curve. Stiff distorts the least, while Super Fluid distorts the most. In general, use the stiffest setting possible that doesn’t create polygonal images.

Interpolation Method

Specifies a method for the interpolation that Smear performs between keyframes. Linear requires two or more keyframes and performs a straight-line interpolation between the keyframes. Discrete produces animations in which the distortions change at keyframes. Smooth requires three or more keyframes and approximates the distortion using cubic curves, producing distortions with graceful motion. If you need further precision in the animation between keyframes, add more keyframes. For example, a distortion representing a 90-degree rotation between two keyframes appears as a folding of the image. To make this distortion more fluid, add a keyframe for every 10°.