COVID Film: Alpha Matte Fire Solution

Last night I had a major breakthrough when I found out how t use track mattes in After Effects. I already had the candle flame working with hand drawn animation, and I had hand animated the flames fairing up the edges of the Constitution. However I didn’t like how the Constitution flames were painted.

I had imported every frame as a PNG into Callipeg and hand painted each in that program. However I didn’t have any way to see what the previous frame’s painting looked like, so I had to guess how to paint the next frame. Despite spending a solid day painting and repainting each frame, I wasn’t satisfied.

I decided to try and redo the animation using a displacement map to control the shape of the flames. However that shape had too many separate tendrils that animated straight upward. The shape didn’t look natural. So I used the animation I had already drawn and used it as a tracking matte. I created a fractal noise layer below it and worked out how the flame interior texture should look and move. Then I turned on the track matte on the animation layer I had drawn above it. This offered the best of both worlds. I had full control over the shape and movement of the flames and a fractal noise pattern animated upward inside offering texture and complexity, color and glow.

I suspect this solution will be used throughout the film to animate the flames. It offers control and chaos which is exactly what I need.