how to make particular's emitter fit the shape of a roto?

I have a piece of footage where the client wants a person to 'appear' in a sudden burst of particles, i have trapcode particular & form, so i want to create a few second long burst of particles that match the shape of the guy in the frame. I have created a nice clean plate so all i really need to nail is how to get a really good apparition using particular.

so how would i go about having particular only emit where the body is, i tried masking it but that just limits visibility. i need a body shhaped emmiter.. do i have to build multiples for each body part? or is there a function im not aware, of,

thanks for any assistance, and sorry for the stupid questions.

Josh

you could also use CC Sphere to explode/implode the roto-ed shape into particles and mix with Particular.
For using Form, look for a tutorial that uses the plugin to replicate the look from a Radiohead music video.

Tudor "Ted" Jelescu
Senior VFX Artist