Chromakey foreground moves, background doesn't

Just wondering if there is a good way to fix an annoying issue...

The situation is that the footage was shot against a green screen, and the camerman has decided that zooming and panning, just slightly, was a good idea. It is a medium shot, two people. Of course, in edit we are trying to put the backgrounds in place and the foreground image appears to float around unnaturally (and unnervingly).

The obvious answers would be to use cutaways (which we don't have) or to match the movement of the foreground with the background image, setting key frames and scaling or moving the image according to how the foreground moves, thus 'pinning' the background to the foreground.

However, this is turning in to a considerable nightmare of a job, and the best we can do is not good enough.

Re-shooting is not an option available to us, as the client will not suffer the additional cost for the 'talent' to do the work... we must therefore do what we can to make it look as good as possible.

What ways can you good folks suggest of trying to match the background image to the foreground movement?

> What ways can you good folks suggest of trying to match the background image to the
> foreground movement?

I know it's not that helpful, but you'd probably just have to match the movement of the background image to the foreground camera.

I had to do that using a "virtual set" a few years ago. And you can't really blame camera -- their job is to shoot the shots that best express the show. Unless he went hog-wild with handheld and jittery shots. The commercials I cut would've been awfully boring as well if they only had dead-static shots. Easy for keying, but bad for the spot overall.

Get an FX artist.


www.derekmok.com

You say you don't have cutaways, but how about a still image as a cutaway. You can animate it with an image pan to make it move a little and voila -- a cutaway.

Well, unless they put tracking markers on the green screen (that are also green), so that you could track the background with the foreground (motion does this), then you are left to having to try to do this by hand.

Doesn't seem like this was thought out or planned well.


www.shanerosseditor.com

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Yeah...I would manilpuate the background to match the background to the keyed image. Not a nightmare for folks that know how to do this (not for beginners)...but that's what Compositors get paid for.

...and never use that camera guy again. I disagree with D that it's not Camera's fault. If it wasn't in the pre-pro talks, lock the friggin' camera down on a greenscreen shoot. A professional cameraman should automatically know (unless specifically told otherwise) that by moving the camera on a greenscreen shoot it will require the Compositor to do a serious amount of work to straighten it out (me being a Compositor...speaking from experience).

I agree with Derek - get an FX Artist.

When life gives you dilemmas...make dilemmanade.

Camera tracking is actually pretty easy these days. If there's only side to side movement you can probably pull it off with a motion tracker in Motion and finesse with keyframes. But if the camera dollies in/out you might need to switch to a 3D tracker such as Syntheyes:

[www.ssontech.com]

also I don't know how the shoot was setup but I don't see how it's the operator's fault. Was the director not clear in the instructions or not watching the video feed? That's pretty much a failure of direction not camera op. Gotta give clear instructions.

-Noah

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> I disagree with D that it's not Camera's fault. If it wasn't in the pre-pro talks, lock the friggin'
> camera down on a greenscreen shoot.

It's all down to communication. Yes, if the producers and director didn't ask for it, the cameraman shouldn't have done it. But, that would also lead me to ask: Wasn't anybody watching the video tap? If they didn't like it, why didn't they tell the cameraman to stop moving?


www.derekmok.com

Because people don't think about stuff like this. There are a LOT of camera guys and directors and producers who just think it is all easy and just works. They don't think about needing tracking markers, unless have done visual effects shooting. I can count on my fingers and toes, and my wife and kids fingers and toes how many times people shoot green screen and mess it up. One time I insisted on going to the set after one bad shoot and they were trying to do a whole lot of stuff wrong. Needed me there to tell them what would work and what wouldn't.

I know several editors who insist on being on set, or visual effects artists who insist on being on set when they shoot green screen. This is a requirement, unless the crew has extensive Visual Effects shooting experience.

I have had red headed people...not green screened, not blue screened, but PURPLE screened. Purple contains red, so keying that out was a challenge for our effects artist.

I have had shoots with no markers.

I have seen shoots where they thought they could shoot WHITE SCREEN and just key out Luma. That was a wasted $50,000 shoot. Totally wasted.

I have seen green screen shots with 4 shades of green, shadows, bright sunlight...you name it.

I have seen people green screen half the shot, but the screen didn't cover the entire frame, but they though it would still be OK. WRONG!

People don't know. A VFX artist on set is crucial.


www.shanerosseditor.com

Listen to THE EDIT BAY Podcast on iTunes
[itunes.apple.com]

I agree with everyone.

Okay, that's probably not true. But it's been a long day, and I'm too tired to form coherent opinions.

I will say this: Don't underestimate the effectiveness of hand-tracking. If I remember right, "Twister" was entirely hand-tracked. Granted, that was fourteen years ago, before 3D tracking software was a widely available option, but still, it's possible.

Quote

A VFX artist on set is crucial

...yep

When life gives you dilemmas...make dilemmanade.

Thanks guys - all really useful stuff!

The shoot is a very short set of seven training scenarios for the health service here in the UK. The cameraman definitely didn't get asked for movement, and should have locked the camera down. It seems he was struggling to get the framing right - lots of minor side to side, quick zoms in and out for short distances. The communication was probably poor on the day too - last shots of a long day, no review of the shoot, yada, yada, yada... lots of poor excuses, but ultimately down to me on the day to have spotted and corrected as I was directing.

The six others are fine - very good in fact, right on script. Why this one, I have no idea! It's a two minute clip, with two sections of around 20 seconds each where this is an issue... not massive, but incredibly annoying!

I like the thought of using a still for a cutaway - hadn't thought of that and in fact might well work if I can get an external shot of the room, and use it to help establish the scene. It's in a secure unit inside a hospital, so tricky to just pop by... mind you, at the end of this I think I'll be checking myself in :-)

So, back to hand tracking then... but I'll have a look at how Motion can help, although I am not at all confident that it will. VFX... heh! With the health service paying we couldn't have afforded the cost of another person! Ah well, thanks for all your ideas and input.

I'll have a look at

> It seems he was struggling to get the framing right - lots of minor side to side, quick zoms in and
> out for short distances.

Ouch. Definitely the cameraman's fault, then. Those moves are also the worst -- indecisive "wobbles" and zooms. You'll be keyframing 'til the end of time.

Option #2 is to try to stabilize the keyed shot -- attempt to stabilize the foreground so that the background doesn't have to be quite so wobbly to match.

Next time, you should also tell the cameraman that when all else fails, frame slightly wide. Not only will that allow for movement, but you can zoom into a shot to some degree in post, and you would have avoided this nightmare. Whereas if you frame too tight, you'll have problems with the edges of frame if you tried to widen it out.


www.derekmok.com

Noah - SynthEyes looks awesome, and pretty much covers the issue - the demo of the green screen cat on the web site is pretty much the same situation we have got. We didn't have tracking points on the green screen, so I am not sure how close we can get, but I'll be looking at the demo version as of tomorrow morning! for $400 it seems very reasonably priced... although I may only use it once, it looks to be a bit of a life (or rather, reputation) saver... thanks for the heads up.

here is something to look into:

[www.imagineersystems.com]

Thanks Wayne - the Imagineer software is still in beta though, right? I don't mind using it if it will get me through the job in hand, but my spidey sense is tingling telling me to keep away from betas on a live production job! I am very interested in having a go with this kind of software though... just being cautious about using it on such a time pressured piece of work.

No...not in BETA...Mocha v1.2.3 for After Effects actually comes FREE with After Effect CS4.

When life gives you dilemmas...make dilemmanade.