Using an animated person as a mask

[m4rtyn]

Hi all,
I've been a long term lurker of these forums but never posted so go easy if this has been asked before! I've had a search and its quite hard to find an answer to my problem..

I have a scene with animated people walking all over it, but the client has asked to remove some of the people from the renders. Is it possible to use the animated people as a "render selected" sort of mask - allowing me to region render whats behind the people walking?

Apologies if this is really simple I just can't find the answer!

Thanks in advance

[AlexP]

You could render a pass that gives you the person as a mask.
Then use that pass as a render mask with the person hidden, to then render the frames again.

An easier way may be to use Vrayspherefade though

[joconnell]

You can, but the shadow effects that the people caused in direct light and GI will be in the original render so you'll get a weird halo around where they used to be.

[m4rtyn]

You could render a pass that gives you the person as a mask.
Then use that pass as a render mask with the person hidden, to then render the frames again.

An easier way may be to use Vrayspherefade though

Ill give this a go, thankyou

[^Lele^]

You could also try rendering yourself some multimattes, post process those to get a grayscale mask (say, expand and blur a bit, so to avoid what John pointed out, like shadows and halos on the ground) and then use that as a render mask for what is behind the silhouette.
I'm not sure this would work (it's likely dependant on the scene, camera angle, people's size, and so on), but perhaps it's worht a try (multimattes without any lighting will go pretty darn quick.).

[m4rtyn]

You could also try rendering yourself some multimattes, post process those to get a grayscale mask (say, expand and blur a bit, so to avoid what John pointed out, like shadows and halos on the ground) and then use that as a render mask for what is behind the silhouette.
I'm not sure this would work (it's likely dependant on the scene, camera angle, people's size, and so on), but perhaps it's worht a try (multimattes without any lighting will go pretty darn quick.).

that sounds well above my skill level ha. Is that a render element? Only problem is that I dont really want to go through 500 frames to make them grey and blur them...

but thanks for the input!

[AlexP]

You would just do it in what ever post software you are using, you wouldnt have to manually edit all 500 frames.

[m4rtyn]

You would just do it in what ever post software you are using, you wouldnt have to manually edit all 500 frames.

gotcha, after effects of course

ill have a play with multimattes cheers