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Mocha tracking limitation?

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Greg JacksonMocha tracking limitation?
by on May 19, 2012 at 6:37:11 am

I need to add a vertical element in post (AE CS5) to a video.

The video is of a flat sheet of white paper lying on a brown table. The camera tracks around the table with plenty of perspective. There are not vertical planar surfaces/features to track, only horizontal ones.

In mocha (2.5.2) I can easily get a solid track so that the planar grid and surface stick well to the flat paper.

The vertical element to add is another sheet of paper standing on its edge on or near the flat paper on the table. This needs to be added in AE (otherwise I would have simply tracked all this in Matchmover and rendered off the element in 3D max)

In AE, my vertical paper layer is linked to a null loaded with the corner pin or transform data from Mocha. The result is close but there is something very wrong with the scale. As I play the video in AE the vertical paper gets much smaller than it should. I can counter this scale issue with another null but it would be rather tricky as it’s not a linear scale change.

Note: using the exact same tracking data from mocha in AE I can place a graphic on the flat paper on the table and it sticks well with no noticeable scaling problems.

Thanks in advance for any ideas on getting this track to work, or if perhaps it’s simply not possible with mocha!


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Perry KrollRe: Mocha tracking limitation?
by on May 19, 2012 at 5:24:47 pm

I would take a look at Video Copilot's magic tracking tutorial/ which creates 3d tracked objects from planar tracking (i.e, mocha's kind of tracking.)

But you may have the best luck using a 3d camera tracker like Camera Tracker by The Foundry, the new tracker in AE CS6 (not that good...) or SynthEyes.

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Greg JacksonRe: Mocha tracking limitation?
by on May 20, 2012 at 7:20:07 pm

Thanks Perry for your help!
Just found out how to get Matchmover data into AE so I can bypass mocha entirely!
The VC tutorial was quite interesting too. I will certainly keep that method in mind for the future!

Note on Matchmover (MM) to AE in case anyone needs to know:
* MM track, export as .ma file from MM (I prefer to choose animate camera instead of scene)
* Import .ma into AE. This creates two comps. The one with square in the name contains the camera with tracking info.
* Every track point in MM you want brought into AE needs to have the text:
at the start of the name, (use the parameters window to change name). I have no idea if it’s possible to change many track names at once (suggestions welcome!) but thankfully I really only need one track point in AE to line things up fast.

Hope that helps!

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Ross ShainRe: Mocha tracking limitation?
by on May 21, 2012 at 9:04:02 pm

mocha AE v3 or mocha Pro v3 will now allow you to solve the 3D camera, so if I understand you correctly, it would be easy to rotate your solved track on 3D axis.


Ross Shain
Imagineer Systems

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