Creating trails with an animation

[stevesideas]

I have an animation of footsteps from below so you can only see the bottom of the shoes. I need to kind of paint with this animation so that the shoes leave trails. I've tried in aftereffects using various time effects but it doesn't really paint, it just copies the frames. I need the subframe intervals to be solid too.

Does anyone know how I might accomplish this ? I need to basically paint with the animation so that it leaves a trail that sits there for a while.

[stevesideas]

I may have found a way to do it using fusion and the trails node.