Apply glow to image that bleeds off screen

[Celull0yd]

I'm trying to apply a glow to a person in a clip. I used the roto brush to determine the edges but part of the person is off-screen (from the waist down). The roto brush seems to end at the edge of the image so it looks like the glow goes across the person's waist but I need it to not show at the bottom of the screen (does that make sense?) because the peron is supposed to be glowing, so the glow wouldn't show at their waist (see attachment). Should I be creating this with the roto brush or should I be using a different tool to roto?

I'm using the newest version of AE on an M1 iMac.

Thanks for your help.

Lloyd

[Mylenium]

Pre-compose the roto work. Duplicate the resulting layer and slightly push down the position behind the person to extend the bottom. Change the composition size to accommodate the trickery. Apply the glow and pre-compose once more into a comp with the original size to crop everything away.

Mylenium 

[Celull0yd]

Mylenium,

Was that English...LOL. I'm still learning the intracacies of After Effects, so I'll give this a shot. Is there any other way to roto, maybe with a path?

Lloyd

[Celull0yd]

Mylenium,

Thanks, that worked.

Lloyd

[Celull0yd]

OK, one more easy question...is there a way to change the tolerance of the roto brush like in Photoshop? There's not a lot of contrast in the clip...

[Mylenium]

No. Rotobrush has no "tolerance" because it isn't a selection tool like the ones in PS. All that matters to RB is the differences in motion across frames and the underlying synthesized vector field. If it doesn't produce good results you will need to complement or replace it with conventional masking.

Mylenium