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AE - Match Camera Zoom w/ Z Axis of Background?

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David Jensen
AE - Match Camera Zoom w/ Z Axis of Background?
on Jun 14, 2011 at 1:09:10 pm

Hi Everyone,

I’ve always learned a lot from the posts on here, now it looks like it’s time for my first post! I've run into a little situation nd I need some help! I'll get right to it...

I'm shooting a doc-style piece with green screened interviews. During some of the interviews, we zoomed in a little on the subjects to frame the shots and get a closer view of their expressions.

Now that I have keyed out the green screen in Premiere Pro (with Ultra Key), I would like to replace it with a background either designed in Photoshop or AE. Not a moving background, just a static texturized image. Here's the problem that I'm running into..

We're using CS5.5, and I was wondering if there is a way to match the zoom of the camera to the z-axis OR the scale properties of the background image, so when the camera zooms in on the interviewee's faces, the background zooms as well.. this way it won't look as obvious that they're green screened. Does this make sense?

I’ve tried matching a few tracking points – including scale, but I am having difficulty applying these keyframes to the scale or movements in the background. If there is a way to do this in either AE, Premiere Pro, or Mocha, please let me know!

I’m obviously not an AE expert, to say the least but I’m learning as I go. If this is something really basic, I apologize in advance. Any help would be greatly appreciated! Thank you!

Dave

Video Producer / Director
North Carolina Justice Academy


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Dave LaRonde
Re: AE - Match Camera Zoom w/ Z Axis of Background?
on Jun 14, 2011 at 3:19:13 pm

What's the resolution of the background? I hope it's bigger than your chroma key shot.

I'd apply the track to a null object, and then parent the background to the null.

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


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David Jensen
Re: AE - Match Camera Zoom w/ Z Axis of Background?
on Jun 14, 2011 at 3:35:22 pm

The background can be as high of a resolution as it needs to be.. I created a photoshop document to create a textured, lighting effect. Currently, it's 1920x1080 square pixels, but I could easily double that to avoid any artifacts when it zooms in.

Thanks for the help.. just to be clear, I will motion track the person being interviewed, for position and scale(?), and then apply that to a null object. The background will be parented to the null.. got it.

Any suggestions on the size of the motion tracker or locations? I am experimenting with different areas, like the person's face or from shoulder to shoulder, so it doesn't frame every single slight motion. I'm assuming that a larger sample area should me more effective than a smaller one. Does that sound right?

Thanks again for your help!

Dave

Video Producer / Director
North Carolina Justice Academy


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Dave LaRonde
Re: AE - Match Camera Zoom w/ Z Axis of Background?
on Jun 14, 2011 at 3:52:55 pm

I'd try tracking something static in the shot rather than the subject; this assumes that there actually IS something static. If you've got nothing, you might have little choice but to animate scale & position manually.

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


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David Jensen
Re: AE - Match Camera Zoom w/ Z Axis of Background?
on Jun 14, 2011 at 5:06:08 pm

Ok.. hence people using motion tracker marks on a green screen. I probably should have thought of that.

Thanks again!

Video Producer / Director
North Carolina Justice Academy


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Dave LaRonde
Re: AE - Match Camera Zoom w/ Z Axis of Background?
on Jun 14, 2011 at 5:29:52 pm

[David Jensen] "hence people using motion tracker marks on a green screen."

Yup. They would have made life a whole lot easier for you.

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


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David Jensen
Re: AE - Match Camera Zoom w/ Z Axis of Background?
on Jun 14, 2011 at 6:11:23 pm

No doubt! Live and learn, I guess..

I'm thinking red would be the best color for tracking tape on a green screen (for future projects), correct?

Thanks again for your help, Dave.

Dave

Video Producer / Director
North Carolina Justice Academy


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Dave LaRonde
Re: AE - Match Camera Zoom w/ Z Axis of Background?
on Jun 14, 2011 at 6:27:14 pm

[David Jensen] "I'm thinking red would be the best color for tracking tape on a green screen (for future projects), correct? "

Nope: a slightly different green.

I'm thinking you'd learn a TON about chroma key work by checking the freebies on this web site:
http://www.hollywoodcamerawork.us/vfx_index.html

And as always, pick the proper key color for the circumstances, e.g. don't use a green screen to key Kermit The Frog. Blue screen? Different story.

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


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David Jensen
Re: AE - Match Camera Zoom w/ Z Axis of Background?
on Jun 15, 2011 at 1:42:23 pm

Dave,

Thanks for that link.. those look like an amazing resource! Great stuff!

Video Producer / Director
North Carolina Justice Academy


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