Keyframes & Pre-Comps in After Effects

November 25, 2013 § 1 Comment

Thinking & Practice Tutorial 25/11/13

Today we looked at keyframes and pre-comps in animation.

A new composition and a new solid were created and positioned with the timeline so that the object could be animated. By moving the timeline to different points and moving the shape, the shape will move to the path that has been made when the timeline is played. One thing to note is that the object will not travel in a straight line – this is because After Effects will try to smooth out the movement by default when it creates keyframes. This is called interpolation.

Screen Shot 2013-11-25 at 13.57.54 Screen Shot 2013-11-25 at 14.02.12

When the shape is selected at a specific point you can see the handles – these can be changed within the animation depending on which tangents are altered. If you right click on the position layer and click on ‘Keyframe Interpolation’, the interpolation can be changed to ‘linear’ so that the shape moves move in a straight line.

Screen Shot 2013-11-25 at 14.03.19 Screen Shot 2013-11-25 at 14.07.37

When the animation is played after this, it is clear that the shape moves slightly slower on the x axis than on the y axis. This is because the keys are evenly spaced, but the distances are different lengths – this alters the speed of the animation. A visual representation of this can be viewed in the graph editor. To change this, select the layer and go to ‘Rove Across Time’. This tries to even out the animation so that it is consistent no matter what the start and end times are set at. This saves you having to calculate even timed spaces yourself.

A new composition was then made as another thing we were shown today was how to  pre-compose. A new solid was created as a 500 x 500 square. By clicking on this layer and going into ‘Scale’, you can animate the shape by moving the timeline onward a couple of seconds, and then clicking animate – then, by moving the timeline back to 0 and making the scale of the square 0, when the timeline is played the shape will grow in size from 0 to 100%. To make the transition smoother, right click on the layer and go to ‘Keyframe Assistant > Easy Ease’ – the animation then plays quite differently. The shape scales up to 100% but in a slower and smoother way than previously.

Screen Shot 2013-11-25 at 14.18.13 Screen Shot 2013-11-25 at 14.19.43

If the layer is duplicated and made a different colour, once scaled you can create quite a nice animation where the two shapes scale in time with each other. By duplicating the layers and re-scaling them, you can create quite complex animations by making the shapes interact with each other – by duplicating the layers the shapes have the same animated properties as the originals, so will scale at the same rate as the initial square that was made. Using pre-comps is a useful and simple method for doing this.

Screen Shot 2013-11-25 at 14.23.02 Screen Shot 2013-11-25 at 14.26.39


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