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Rotoscoping a 2nd Set of Arms

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Max Jackson
Rotoscoping a 2nd Set of Arms
on Jun 8, 2011 at 4:28:02 am

Hi CC,

I'm shooting a dolly-tracked roto shot where I move in on a subject with a vest on. She turns to the camera. As she does, she reveals a 2nd set of arms from inside her vest.

I've been over and over in my head about how I'm going to roto this. I can't seem to determine what a better approach might be. I've been told to just do two passes and roto/time re-map the other set of arms.

In terms of paint, that'd be great if she was wearing a tanktop or t-shirt, but because her arms are coming out of her vest I'm thinking I should string her vest open with the top arms shot or something. That way her her vest will open appropriately with the bottom arms opening up. Otherwise, they'd cut through and would look fake.

In fact, I'm thinking shoot both set of arms without any jacket. Then re-map/position/roto the lower set of arms inside the fishing lined jacket.

I hope that makes sense. Am I approaching this the right way? I've never done this before and won't be able to do it again. I have plenty of time to work on it at home after work. But one day for the shot.

If anybody has any input I'd really really appreciate it.

Thanks,
-maX


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Dave LaRonde
Re: Rotoscoping a 2nd Set of Arms
on Jun 8, 2011 at 3:01:18 pm

[Max Jackson] "I'm shooting a dolly-tracked roto shot where I move in on a subject with a vest on."

Oooooh, this sounds like you're entering dangerous waters. How do you propose to match the movements of camera, dolly and subject with the precision necessary to pull this off? You can rent a motion control rig for several thousand dollars to get the camera movement right, but you can't control the subject by computer.



[Max Jackson] "She turns to the camera. As she does, she reveals a 2nd set of arms from inside her vest."

I also hope you've planned PRECISELY HOW this is going to look, and that the images appear on a storyboard.

Right now this whole shot appears to be too much wishful thinking to even attempt it.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Max Jackson
Re: Rotoscoping a 2nd Set of Arms
on Jun 8, 2011 at 6:44:08 pm

CAMERA MOTION - That's a great question about shot matching. The dolly track is on decline. Some form of heavy weight and release so the gravity and ramp up easing is the same every time would be awesome. Right now I'm still trying to figure out whatever I can to make every shot as uniform as possible.

PRECISION - I know, I'm nervous believe me. But the shoot's become backed into this scenario unless I have some major script change last minute. I've done storyboards and gone over and over the shot in my head. In all the challenge of the roto is the arms coming out from underneath the jacket. The rest is a basic dolly shot. The challenge is re-pasting/rotoscoping the arms from underneath. Aside from very accurate tracking a few things have to happen.

1) The second set of arms have to be isolated, most preferably with a green screen. Then re-mapped, re-located, and re-sized in conjugation with the rig.
2) The jacket of the previous shot has to open
3) The arms can't overlap

1 and 2 are the most difficult mostly because they need to happen at the same time.


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Dave LaRonde
Re: Rotoscoping a 2nd Set of Arms
on Jun 8, 2011 at 7:20:30 pm

Well, I wish you luck. You're going to need a whole bunch of it. Boatloads of it.

Personally, I wouldn't even dream of taking it on myself without the resources of an effects house behind me with the experience necessary to create and motion track complete 3D characters, like WETA's work on The lord Of The Rings. Think Gollum. That's what you're up against with this shot.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Walter Soyka
Re: Rotoscoping a 2nd Set of Arms
on Jun 9, 2011 at 6:33:49 pm

I don't think the challenge is just roto here -- I think the tracking is going to be a lot more complicated than it may seem. At a minimum, you need a 3D tracker to solve for the camera, you need to track the sites where the arms meet the body, you need to track and stabilize the second set of arms, and you will almost certainly need to warp them a bit to make them look like they're sticking properly.


[Max Jackson] "But the shoot's become backed into this scenario unless I have some major script change last minute."

I'd investigate that last-minute script change -- or at least simplify the shot. Is there any way you can cut around the reveal moment to minimize the amount of tracking you have to do to get this to comp cleanly?

However you ultimately approach this effect, I think you'll want to do tests before shooting for real.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog - What I'm thinking when my workstation's thinking
Creative Cow Forum Host: Live & Stage Events


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Max Jackson
Re: Rotoscoping a 2nd Set of Arms
on Jun 10, 2011 at 4:10:47 am

We're doing some trial test before-hand but we're borrowing the dolly so I'm only going to have it the day before. We're going to do as much testing that evening before-hand, but it doesn't give us that much time for the next day. It will give us an amount of perspective in approach. I'm want to ramp pass after pass into this thing more and more like a stunt or something.

Also, we are going to do still takes as well as dolly. That's really our only CYA scenario. Do that and then just scale up if at all possible.

We're going to have art dept pull open the jacket. Even if it looks a bit contrived, it's better than having the arms fighting the jacket on the way open. The jacket will have to lead the arms even if "magically" doing so like ladybug wings.

There's a number of things I'm trying to prepare for. Tracking the 2nd set is a huge deal otherwise the revealing arms will look like they're floating. At some point I might have to track the roto'd elements frame by frame. It's rather Max Fleischer but I got myself into this mess. I am going to do everything at 15 fps though as the normal speed, so hopefully that will cut down on editing time.

For tracking, I'm going to have to marker track the actress on the takes with the 2nd set and use that take as the index, key out the arms and composite it with the master 1st arms (main) shot. Then do a ton of roto, shading, and grading to combine them.

I'm probably going to want a layer or node above the arms as well as below for depth.

All I have is Mocha in After Effects for any kind of faux 3D tracking. I'm not sure if I can afford renting Nuke though having something like that would be really nice.

Another concern I have is making sure there's a sense of depth between the arms and the jacket body, dolly or not.

Thanks Walter,
-m


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Mark Suszko
Re: Rotoscoping a 2nd Set of Arms
on Jun 14, 2011 at 4:01:20 pm

What occurs to me is more low-tech.
Instead of rotoing arms IN, roto a second actor OUT.

What I mean is, put a guy in one of those chromakey body stockings, with just their arms exposed, have him stand right behind your actor and work the arms thru holes or slits in the vest or jacket. Kind of like Bun-Raku puppetry. Then key and rotoscope-out the second actor.

The only other thing I can think of is, lock down the camera, stand the actor on an apple box, shoot a pass, remove the apple box, shoot the actor again, with jacket and vest off, but the chromakey body stocking on, leaving just arms exposed.

This gag of yours really demands a motion-controlled camera and/or a huge CGI budget to pull off realistically. If you did a CGI body and rotoed the live head onto it, that might be easier to pull off.


I might get more ideas if you could post some sketches or pre-vis for how this is supposed to work.


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Max Jackson
Re: Rotoscoping a 2nd Set of Arms
on Jun 14, 2011 at 5:51:39 pm

That's largely what I'm doing. I just purchased a full body green suit. My plan was to cut off it's arms and do two passes.

1st pass: no green, just tracking markers as guides that I can paint later and she opens her arms above. The jacket is rigged with fishing line. Her left leg to the table (hopefully a pulley system) the right side manually opened.

2nd pass: same subject in full green suit, GS background full set tracking markers. she open up her arms below. That's how we plan on isolating the arm elements.

3rd pass:

I really like your idea of a second set of arms coming out of her dress and doing one full pass. The keying out the person behind.

No doubt this shoot is not going to look polished and Hollywood. If it comes out like a CGI version of Evil Dead 2 or something I'll be feeling like I got something accomplished. But I've got to give this shot as much consideration and focus as possible.

My camera guys says there's no sense in dollying the second shot of the arms and that the tracking will largely depend on the primary image and what we're attaching it to.

I'm also speaking with a senior SFX guy today to ask him what more or how I should approach this on set w/o a motion rig for the camera.

I'll definitely add your perspective to my consultation with him.

Thanks Mark!


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Stewart Bourke
Re: Rotoscoping a 2nd Set of Arms
on Jun 15, 2011 at 1:44:32 pm

Max,

Please do post back and let us know the outcome - I for one would be very interested to know how you got on.. I am at the very early stages of pre-planning something similar (but not as adventurous) and I would really love to hear about progress (and the final outcome if appropriate...)

Thank you.


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Max Jackson
Re: Rotoscoping a 2nd Set of Arms
on Jun 15, 2011 at 4:21:20 pm

Most definitely, it might be a while though. :D I've got a lot of work to do in the can.

My meeting with the FX guy was worth it's weight in platinum. Saved my butt on a number of points. The three that stick out most in the final dolly-in roto shot that I'm doing are:

1) Take BG photos of EVERYTHING that involves compositing/keying.

2) Go green all the way. Don't partially greenscreen somethings and think you'll match them. Go all GS with the element(s) in question, or all material. Don't put one greenscreened object in the set (for my application) it won't work.

3) Don't shoot the floor! If the floor is in the shot and you're looking to combine foreground and background elements it's a dead giveaway to floating perspective. Your back wall will look fake unless you're using a motion control rig to sync the background with the camera.

There's a number of other things he mentioned as well, but it mostly pertains to my situation and is a bit too esoteric to make sense on a forum.

I was on the fence as to whether I was going to do a 1-person 2-pass approach or a 2-person 1-pass approach, and after a lot of thought I'm going to do the old school theatrical version where a 2nd person's arms in a GS suit come through the jacket. The jacket is going to need clasped shut at the beginning so we don't see the person come through. That and the whole motion of the subject turning to the camera and the arms coming out have to be in 2 stages not one. Otherwise, we'll see the greensuit interfere with the back part of the jacket upon entry.

Really, really, REALLY tedious stuff, but I'm feeling somewhat better about this shoot. I'm still leaning more though just in case. The details in this shot are like army ants.


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Mark Suszko
Re: Rotoscoping a 2nd Set of Arms
on Jun 16, 2011 at 2:45:02 pm

Please do come back and post at least some still frames from this when you do it.


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Max Jackson
Re: Rotoscoping a 2nd Set of Arms
on Jun 16, 2011 at 3:42:22 pm

That would be a lot easier. My actress's second set of arms is actually a man. He has the same skin type and is really small. He really wanted the job, and I know him as an actor so...How can you turn down an dude who'll shave and manicure himself for a job?

I should be able to post some picture a week or so from now. After shooting this thing I'm going to have to take a hiatus for a about a week.

Thanks everybody for all your help, it's been a definite aid in getting this video project in the right direction.

Best,
-maX


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Michael Szalapski
Re: Rotoscoping a 2nd Set of Arms
on Jun 22, 2011 at 9:13:16 pm

"How can you turn down an dude who'll shave and manicure himself for a job?"

I dunno. I know an awful lot of actors who do that sort of thing just for the weekend. ;)

- The Great Szalam
(The 'Great' stands for 'Not So Great, in fact, Extremely Humble')

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.


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