I'm working on a project for a client in Motion 3.0.2 and I'm having an issue with the emitter I could really use help with. There are a variety of 'tracers' under a finger image which is animated using the Motion Path behavior (B-Spline). The emitter is Match Moved to the finger. They all use the same source image, and most movements look fine, but the problem is that one of the movements is significantly faster than the others and it's causing the trace to be very angular (aliased) on the curves. I've tried a LOT of thing to decrease this effect to no avail. The only thing that comes close is to Gaussian Blur the heck out of the source and that makes a line the client doesn't like. Changing the birth rate just makes the line darker or lighter. They want the clean edged line, but also no aliasing. It seems to be that the emitter follows a linear path from frame to frame and not the curve of the motion path. How can I smooth out this line?
(I've removed all client references from this image and left only the hand and emitter line)
I think you're always going to get issues when you're trying to move an emitter very fast.
The best way around this would be to slow your source footage right down in a new composition, track the slowed down footage, apply the emitter, render out the result, bring it back into your original comp and change the speed back up so it matches your original footage.