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Green Screen Motion Tracking
Hello Everyone,
I have a little problem (obviously, or I wouldn’t be posting 🙂 ) Anyway, I was called to a job to shoot a fair amount of greenscreen material with only a week of prep time. I have minimal greenscreen experience, but know enough to research before I shoot. I did, and came up with the great idea that I should, since the camera will be panning, tilting, and zooming, place yellow tracking markers upon the screen. Shot the material, all went well. Now my problem:I have absolutely no idea how to use and subsequently key out the yellow tracking markers. I’ve keyed straight green before using AE and an older version of Ultimatte with decent results. Question is, how do I use those tracking markers and then get rid of them? For reference, I do know that AE has tracking capibility, but not quite sure how it works in this situation, whereas I am tracking a greenscreen marker to allow the background to move as the camera does.
If anyone has any suggestions or possible workflows, please let me know. If anyone also has any plug-in or software solutions, I would be happy to consider purchasing. However, just so everyone knows, I am using a PC and not a Mac… So, the program that I have consistently read to use for this type of situation, Shake, is out of the question *(or at least I think). 🙂
Thank you all for your time,
Dustin -
4 Replies
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The order should not matter. In other words, if you key it out, when you go to track it, you should still see the unkeyed footage, since it opens a layer window for tracking.
However, if that makes you uncomfortable, track it first. Once tracked, you can just key it out. It won’t effect the track.
In the past I worked with Chroma Green BG’s and then Dark green + marks on the walls, and this all worked fine. tracking should be even easier with yellows on green, though keying may be harder since you now have 2 colors you’re excluding (possibly more holes in the footage than you want).
If you find that the extra keying is causing part of your desired footage to be keyed out, check out this tutorial:
https://library.creativecow.net/articles/rabinowitz_aharon/junk_mattes.php
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Aharon Rabinowitz
arabinowitz(AT)yahoo(DOT)com
http://www.allbetsareoff.com—————————————-
Click the link below to subscribe to the Creative Cow After Effects Podcast, and get free AE video tutorials:https://phobos.apple.com/WebObjects/MZStore.woa/wa/viewPodcast?id=111087911
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Aharon,
Thank you much for the fast reply and the tutorial. I will soon check that out. Once I track the marks, how can I link the background image to it. I always thought that it was through the parenting process, but after quickly experimenting, that did not seem to do it. Secondly, is it possible to track more than one mark? Is it necessary?Thank you,
Dustin -
When you open up tracker controlls you could select rotation and then could select two marks to track. I would track the footage then apply it to a null object then parent the bg to the null.
This tutorial may help with tracking.
https://library.creativecow.net/articles/kramer_andrew/Set_Extensions.php
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To Aharon:
First off I just wanted to praise you, enormously, for the tutorial you offered me on junk mattes. You are a saviour, no doubt. Thank you much.For Aharon and everyone else:
Everything works great now with the auto-traced junk matte eliminating bad areas on the green screen. Now another, but perhaps simple problem. How do I go about animating a mask to eliminate the areas shot that aren’t greenscreen? These areas do not have a foreground subject in front of them, but are rather just areas to the sides of the greenscreen that were included in frame. I can put down a mask to cover them for one frame, but with camera movement, how do I animate that mask and can I somehow automate it through auto-trace, perhaps?Thank you again,
Dustin
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