What are masks, expresions, trakers?

[Chris Smith]

Masks are shapes you can draw with the pen tool or use the elipse and square shapes. Masks are used to confine your alpha (transparency) to specific areas. Masks can be difined to cut out holes or fill in holes in your image. For example if you want a red square, creat a red solid and draw a square mask on it. More advanced uses of masks is isolating moving images. It’s incredibly tedious work, but by animating masks you can isolate a person from an image and treat it separaetly or even move that person to another environment.

Trackers are a tool that allows you to grab a unique point in your image and the tracker will attempt to follow along. It generates position data that can be used on a layer. For example you want to put a sign on the side of a building in a moving shot. You could either try to keyframe it by hand, or have a tracker do the work for you by figuring out how the image moves.

Expressions are basically an equation that allows you to use math and certain functions to perform procederal tasks for you. There are limitless options so it’s hard to explain here. Click on Dan Ebberts head and go to his site to see the best examples of it.

Chris Smith
https://www.sugarfilmproduction.com

[Steve Roberts]

A mask is drawn on a layer using the pen tool or the rectangle/ellipse tool. One mask drawn on a layer can cut out a hole from that layer or cut out the area around the mask. You can also draw more than one mask on a layer to make multiple shapes or different combinations of shapes and holes.

Expressions are lines of text applied to an animatable property of a layer such as scale, opacity, position, etc. Basically, the expression acts like programming code, detyermining the value of that property. Expressions are useful when you want to make a lot of layers behave the same way, or create animations that are difficult to create using keyframes. Here is an expressions site, but it may be too advanced for you: https://www.motionscript.com/ .

Trackers are visible markers added to a scene which is to be filmed or videotaped. The markers could be tape, balls, circles, squares or triangles. When the scene is shot and imported into After Effects, the computer can use motion tracking to follow the markers and apply the position of those markers to a new computer-generated object such as a photograph.

For more information, please check the After Effects manual or the online After Effects help.

Steve