How do I create a certain rainbow trails effect?

[David Rickles]

The first link was a dud, but the rainbow in the second link (if I’m getting what your asking) is being generated by rotoscoped or keyed footage. Correct?

Here’s how i’d do that. Take the rotoed or keyed footage and pre comp it. Place it twice in a master comp and make one 3d. Name the 3d layer “Emitter” and the 2d layer “Particle”. Make a new solid and apply trapcode particular. Twirl down the emitter properties, and change the emitter type to a layer emitter. Selected the layer “Emitter” as your layer emitter. Change the emitter direction to “directional” and turn down all of your velocity parameters to 0. Likewise, I’d significantly shrink your emitter size options to very small if not 0. Then twirl down the particle properties. Change the particle type at “custom fill” particle, and select your “particle” layer as the custom particle. Generate your color variation off of the color gradient in the “color over life” parameter. You will need to resize the footage to the appropriate size. Finally, twirl down the physics properties, and the sub-properties for air, and the sub-properties for turbulence. Increase the effect position property to taste.

That should hopefully take care of a majority of it. You will need to tweak the particles/sec parameter to get the right amount of particles, and you will likely want to adjust that appropriately with the particle size.

Hope that helps!

–D

David Rickles
Motion Designer | Editor
David.Rickles@gmail.com
http://www.davidrickles.com