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Andreas Zerr
mocha and AE
on Nov 28, 2013 at 3:39:16 pm

Hi there,

I have a quick question regarding mocha AE: As I am pretty new to the software, I do not know if mocha is the right tool, and I do not want to spend hours and hours trying. So you may can help me.

The task: The are shooting a talent in our green screen studio. The camera is held freely in the hand, not on a tripod (on purpose). Afterwards we'd like to shoot some backplate outside (steady, from tripod) to match with the movement of the camera in the foreground.

The question: Does it work to track the the foreground-movement, to key it and to match it on the background in AE with mocha?

We tried it with the standard AE-tracker, but it does not work properly (the person shifts slightly on the ground).

We've seen some tutorials of mocha, but they do not answer the question, because in all cases there are only some objects being tracked onto a background, not vise versa.

Thanks for reading, and for helpful tips!
Andreas

PIXELGALAXIE
Hamburg, Germany


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Roland R. Kahlenberg
Re: mocha and AE
on Nov 28, 2013 at 6:01:38 pm

What you want to do is to match the movement of a hand-held footage to a static shot. To do this, you track the background of the hand-held footage and then apply the tracking data to the static shot.

mocha will do this nicely. You will of course need to ensure that there are track-able areas on your green screen for mocha to track.

You will also need to be mindful that the backing plate is a static shot and will not have parallax for the objects within the footage. Thus, shooting the talent requires a knowledge of this fact and will impinge on the type of camera movements you can use to create an effective composite.

I suggest that you hire a VizFX Supervisor to ensure that production footage gets into post in good shape.

HTH
RoRK

Intensive mocha & AE Training in Singapore and Other Dangerous Locations

Imagineer Systems (mocha) Certified Instructor
& Adobe After Effects CS6 ACE/ACI


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Andreas Zerr
Re: mocha and AE
on Nov 29, 2013 at 4:54:06 pm

Hi there,

Thanks for the reply.

We've literally shot hundreds of green screen scenes in our studio, but never with a handheld cam. That's the reason we were asking initially.

For tracking purposes of the green - what's your suggestion of how to mark the background? We've done some tests with a couple x's (plain dark green crosses with a black spot in the middle), and they worked fine for the point-trackers in AE. Will those crosses also be sufficient for mocha, or shall we glue some other tracking-points (like square shapes) onto the background wall?

We're thankful for any hints. Unfortunately, there is no VFX-supervisor on this project, so we have to handle it ourselves.

Thanks again, and all the best,
Andreas

PIXELGALAXIE
Hamburg, Germany


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Roland R. Kahlenberg
Re: mocha and AE
on Nov 29, 2013 at 6:56:23 pm

[Andreas Zerr] "For tracking purposes of the green - what's your suggestion of how to mark the background? We've done some tests with a couple x's (plain dark green crosses with a black spot in the middle), and they worked fine for the point-trackers in AE. Will those crosses also be sufficient for mocha, or shall we glue some other tracking-points (like square shapes) onto the background wall?"

For tracking/keyable tapes, take a look at this thread - http://forums.creativecow.net/thread/2/1044615.

When tracking, use a high-contrast version of the footage to obtain your tracking data. Then use the 'normal' footage for your compositing workflow.

Having said that, you only really need keyable markers if your talent crosses over the markers. Otherwise, a garbage matte plus keying will be sufficient. Thus, you can use anything as a tracking marker if there is no cross over issue. A picture mounted on the wall or magazine pages will do fine - just ensure that there is sufficient detail around the edges of the marker and you get plus points if there is sufficient detail within the marker.

You will want to look at the following tutorial (http://www.imagineersystems.com/videos/steve-wright-basic-tracking-techniqu...)to appreciate various tracking techniques that you should want to apply for a task such as yours. Especially useful are the pointers on keyframing the tracking spline before and/or during tracking (to give the tracking engine as much information as possible) and possibly co-planar tracking, which explains a lot of how mocha thinks and solves planar tracking tasks.

I forsee possible issues with your insert being cutoff after applying the Corner Pin tracking data. If you can't solve the issue then look at purchasing Matthias' mochaImport+ tool which provides an elegant way to solve such issues as well as ensure for a more comfortable ride for prepping tracking data for use in AE.

HTH
RoRK

Intensive mocha & AE Training in Singapore and Other Dangerous Locations

Imagineer Systems (mocha) Certified Instructor
& Adobe After Effects CS6 ACE/ACI


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