Applying identical keyframes to identical objects w/variation

Question

I have the following animation, in which a ball goes from the flashlight to the end of the frame. However, how do I create multiple iterations of this animation, except with the ball following the same path, except with some variation? I'm using Adobe After Effects V15.1.1.

Answer 1

I would use a particle engine of some kind to do this.

You set up the Emitter to start from the same position as your torch (in a layer behind it).

You set your particles to look like the ball.

You emit them at an appropriate rate, and use air or wind adjustments to "blow" them across the screen.

After Effects has a built in particle engine called Particle World

https://helpx.adobe.com/after-effects/using/simulation-effects.html

Or you could use Particular from Trapcode

Screen shots below showing roughly how you could do it in Particle World:

Answer 2

An alternative to using particles is to make copies of the layer with an expression that adds some variability to their motion. For example you could add some wiggle by adding this expression to the position property:

wiggle(1, 10);

This will randomly wiggle the layer around its keyframed position with a frequency of about 1 wiggle / second. If you want them all to start in the same position and get increasingly wiggly you could use this:

var wigglyness = 100; //how wiggly
var wiggleFreq = 1;  //how quickly to wiggle
var wiggleStartTime = inPoint; //you could also use a marker etc.
var timeWhenFullyWiggly = inPoint + 2; //seconds until full wiggliness

wiggle(wiggleFreq, linear(time, wiggleStartTime, timeWhenFullyWiggly, 0 wigglyness));

This will ramp up the wiggle from the inPoint of the layer for 2 seconds.