Motion Tracking and Green Screen in AE CS3

[Brock Nordstrom]

Keylight is usually the best choice for Green Screen.
and 1 tracking point should do the trick. A simple cross made in black tape should work.

[Dan Oster]

Thanks.

I’m more or less familiar with keylight. It’s trying to parent the background to tracking points that I’m new at. I found a good tutorial that seems to apply:

https://library.creativecow.net/articles/kramer_andrew/Set_Extensions/video-tutorial.php

However, will motion tracking compensate for zooms?

– Dan

[Tom Scott]

“I want to “pin down” my digital background so that it appears to be fixed in place despite the camera movement. ”

I read the above line to mean that you want the background to remain static, “despite the camera movement”. If that’s the case, no tracking is needed at all.

[Dan Oster]

I’m sorry, let me rephrase. I want the background to move in order to compensate for camera movement so that it looks like the camera is panning around an actual set.

– Dan

[Jim Dodson]

Dan-

With respect to your question about motion tracking the camera’s “zooming”.

You will need to check “position” and “rotation” and “scale” in the motion tracker window, then when you shoot your greenscreen give yourself 2 separate tracking marks separated as far apart from each other as possible… but make sure that neither tracking mark ever leaves frame or is obscured by your foreground or your actors…

good luck!

Jim Dodson

8 Core Intel — Mac – OSX

[Chris Buttacoli]

You know what works great!? Post-Its! AE tracks squares nicely, and there’s no mess left on the expensive greenscreen. I typically use five around the actor. Any time the actor moves in front of a marker you will need to clean up in AE, but fairly simple roto work is worth the nice track. The only advice I can stress to you is to make sure you can ALWAYS see at least two markers at all times. This will ensure proper scale and rotation when tracking.

[Dan Oster]

Post-Its! That is some great advice. I bet if I get them in a wild color I can key that out no problem. Thanks!

– Dan

[Dan Oster]

I think the camera motion will be fairly restricted–mostly just the jitteriness of a “handheld” cam that’s mostly stationary, with the occasional quick zoom. So hopefully a background that’s a bit larger than the screen will suffice.

Thanks for the input! This will be fun…

– Dan

[Dan Oster]

Good point. I can keyframe in a blur at that point if I’m really worried. But my background is 720p so I should have some wiggle room.

– Dan

[Chris Buttacoli]

BTW, don’t try to “key out” the markers. Prior to keying, you should make a garbage matte around your subject, as tight as possible, which will eliminate the markers and allow Keylight to work faster.