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Tracking Bluescreen Footage

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David Smith
Tracking Bluescreen Footage
on Dec 2, 2012 at 12:30:02 am

Hi Guys,

I've got a dolly shot with a boy walking passed a window (left to right). Behind the window is a bluescreen with tracking marks. It's quite a long shot and the camera reveals the window with the blue screen.

My problem is that there are no tracking marks right at the beginning where the bluescreen first pops up. I've tried offsetting the tracking points as well as parenting tracks together, with no luck. I've also tried to track a plane in mocha but that didn't give me any better results.

The background plate tracks well about two seconds in after the window has been revealed, but it is pretty obvious that it's not before hand.

Any ideas or tips would be much appreciated.

Cheers,
David


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mathew fuller
Re: Tracking Bluescreen Footage
on Dec 2, 2012 at 3:57:04 am

Post the footage.

My Work:
http://www.morecompletefx.com


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David Smith
Re: Tracking Bluescreen Footage
on Dec 2, 2012 at 6:24:00 am

https://vimeo.com/54695726

pw: cow


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Tudor "Ted" Jelescu
Re: Tracking Bluescreen Footage
on Dec 2, 2012 at 7:48:44 am

You can use a 3d camera tracker (the Foundry plugin in CS 5.5 - CS6 comes with one). You just need to mask out the kid from the track.

Tudor "Ted" Jelescu
Senior VFX Artist


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David Smith
Re: Tracking Bluescreen Footage
on Dec 2, 2012 at 8:40:46 am

Thanks for your quick response!

Sadly, I tried that as well and it gave me strange results. The background plate is also not big enough to be scaled up that much. Maybe I'm doing something wrong.

I've basically just tracked the camera for the part that it need to be tracked. I before hand masked out the kid. After the analysing was done I've selected tracking points and created a camera. I changed the background plate to a 3d layer, precomped everything and used it as the background for the key in a previous comp.

It still seems to wobble quite a bit right when the window is revealed and I had to scale up the background plate a lot so that it won't leave the frame.

I've also tried a 2d motion track and expanding the feature with an expression. That looked way to 'automated' though.

As I said, not really sure if I'm doing something wrong or not.

Cheers,

David


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David Smith
Re: Tracking Bluescreen Footage
on Dec 2, 2012 at 9:07:08 am

Ok, figured it out. I think the track seems to work now. I forgot to parent it to the null.

It's still a bit wobbly every now and then but I'll give the warp stabiliser a try.

Thanks for your help!


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David Smith
Re: Tracking Bluescreen Footage
on Dec 2, 2012 at 11:00:50 am

Ok, me again.

I take back what I said. I'm completely lost now. I've tracked everything but the track is extremely jittery and I can't seem to find a way smoothen it out.

I've tried stabilizing the footage beforehand which didn't help either. I'm not sure if the camera tracker is the right solution for this or maybe I'm just doing something wrong.

Any tips or suggestions are more then welcome.

Cheers,
David


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Tudor "Ted" Jelescu
Re: Tracking Bluescreen Footage
on Dec 2, 2012 at 4:38:26 pm

Mocha Pro uses planar tracking but it can also create a clever 3d camera solve- if you have access to that you may want to give it a shot.

http://www.imagineersystems.com/products/mochapro

Tudor "Ted" Jelescu
Senior VFX Artist


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David Smith
Re: Tracking Bluescreen Footage
on Dec 4, 2012 at 10:40:14 am

Hey,

Thanks for that tip! The 3d solver is pretty awesome. It didn't solve my problem but I figured it out myself.

I used a loopIn and Out expression to continue the track and through some miracle it automated it perfectly. No idea how that happened because I tried it before but it always looked really bad. I'm mega happy now!

Thanks heaps for all your suggestions!


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