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Track in mocha AE - problem with tracking past the shot's edges

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Lori Waite
Track in mocha AE - problem with tracking past the shot's edges
on Feb 1, 2018 at 4:57:21 pm

I'm working in After Effects, using the 'Track in mocha AE' function in the Animation menu. The shot I'm tracking is a moving car door. I need to paste a logo onto it. The car makes a clean entrance and clean exit in the shot, but MOCHA will not track beyond the edges of the shot. The tracker gets bunched up against the edge, making weird shapes, etc. Is there some trick to get MOCHA to track beyond the edges? To compensate for this, I've manually set key frames but not very well so that the tracking is not smooth and seamless. (I've also edited the tracking keyframes in the AE timeline, and I still cant' get it to look good.). It seems such a basic thing to ask - for MOCHA to keep tracking past the shot's edges on objects with clean entrances and exits. Any one know of a trick of how to do this?


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Mark Whitney
Re: Track in mocha AE - problem with tracking past the shot's edges
on Feb 2, 2018 at 3:29:08 am

Hey again Lori. Hopefully Martin B. will chime in here as he'd be able to give you a lot more info. This issue was a bit of a known problem with the Pro version (waiting for the next release myself) but can't say for certain if thats the case with the AE version too.

W/O knowing your shot, in some cases it's possible to keep your spline as it is but actually track a different area and accomplish what your after. I've done this with a test shot I did some time ago, but it's "fiddly" process to verbally describe as to how to go about it. See if you can search through the various Mocha tutorials on Vimeo. Seems it had something to do with tracking lights on a playground, but there may be others. I recently had a system restore go awry and over-wrote all of my archived tutorial saves so can't give you any sort of clue as to title or presenter. Other than that, perhaps simple register with the Mocha forum at Boris FX:

https://forum.borisfx.com/c/mochaae


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Lori Waite
Re: Track in mocha AE - problem with tracking past the shot's edges
on Feb 6, 2018 at 5:49:48 pm

Thank you again, Mark, for you help. I've joined the BorisFX forum and will put this to good use!


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Roei Tzoref
Re: Track in mocha AE - problem with tracking past the shot's edges
on Feb 2, 2018 at 7:27:05 pm

can we see the shot? there are ways to overcome a feature exiting the frame in many ways. one of Mocha's trademark abilities is the way it can track a feature even if a lot of it is not there.

Roei Tzoref
2D/VFX Generalist & Instructor
♫ AeBlues Tutorials ♫
http://www.tzoref.com


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Lori Waite
Re: Track in mocha AE - problem with tracking past the shot's edges
on Feb 6, 2018 at 5:42:36 pm

Thank you, Roei, for your input. I've attached the uncolor-corrected shot. I've watched some BorisFX tutorials (as recommended by Ross of BorisFX on this thread) which have helped me in general with understanding how the software works, butI'm still have diffulty tracking this shot, as you can see. I could not get MOCHA to track the van's exit screen right, so you can see how the logo speeds up and also the corner pins change shape. THe resulsts of my trying to get MOCHA to track smoothly past the edge of the shot. And, I've tried to fix this problem in AE, but end up making things worse.

THere's also the issue of the logo getting pushed to the right when the door opens. Another thing I've tried to correct in AE by deleting the tracking keyframes at this spot, but, weirdly, it affects the logo's positioning when the van is moving before it stops. It drifts to the left so that its ends up right by the keyhole. Frustrating.


12136_vandoortrackingfxprojectreturnlinkedcomp05.mp4.zip


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Ross Shain
Re: Track in mocha AE - problem with tracking past the shot's edges
on Feb 5, 2018 at 9:06:33 pm

A very common technique is to stop your track before the object goes off-screen and position the search area (the spline shape) on something that is moving relative to the motion of the object that goes off-screen.

Understanding the relationship between the spline layer (the search area) and the Surface (the tracking data) in Mocha is essential to solving difficult tracks. This is a quick way to do offset tracking.

This video might be useful:
https://borisfx.com/videos/mocha-tips-with-mary-poplin-explore-shape-based-...

Ross Shain
Boris FX / Imagineer Systems
https://borisfx.com/products/mocha/


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Lori Waite
Re: Track in mocha AE - problem with tracking past the shot's edges
on Feb 6, 2018 at 5:44:39 pm

Thank you, Ross, for the tuturials. They have helped me in general with understanding how MOCHA 'thinks.'


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Ross Shain
Re: Track in mocha AE - problem with tracking past the shot's edges
on Feb 6, 2018 at 5:51:50 pm

Lori,
Looking at your video it seems to me that your search area must be too large as when the door opens, you are getting bad track. You will need to edit your search area to avoid the door opening. When the car moves offscreen at the end, you will then need to move the search area to an offset part of the car.

Ross Shain
Boris FX / Imagineer Systems
https://borisfx.com/products/mocha/


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Lori Waite
Re: Track in mocha AE - problem with tracking past the shot's edges
on Feb 6, 2018 at 6:41:29 pm

Thanks for your response, Ross. The two videos you recommended were good and illuminating, thanks, but do you have a video to share that shows the offset tracking technique you refer to that is step-by-step and in detail?


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Ross Shain
Re: Track in mocha AE - problem with tracking past the shot's edges
on Feb 6, 2018 at 9:29:19 pm

This is a 50 min long webinar that I presented last year:


If you jump to 30 min mark, i covered the concept of moving your search area for offset tracking.

Ross Shain
Boris FX / Imagineer Systems
https://borisfx.com/products/mocha/


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Lori Waite
Re: Track in mocha AE - problem with tracking past the shot's edges
on Feb 6, 2018 at 10:01:10 pm

Great, thank you!


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Roei Tzoref
Re: Track in mocha AE - problem with tracking past the shot's edges
on Feb 6, 2018 at 11:16:58 pm

Lori, it took me a while with this shot. first I was picky on what I should choose as my area, after A LOT of trial and error I realized that a big area would do it even if there are some reflections. so I tracked a big area of the van, then used a separate tracker as a track matte to hold out of the door.

here's a walkthrough at double speed:
https://drive.google.com/file/d/16dm7n8dslrVZwKHgh3ywkRIbxXWOlJNl/view?usp=...

Roei Tzoref
2D/VFX Generalist & Instructor
♫ AeBlues Tutorials ♫
http://www.tzoref.com


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Lori Waite
Re: Track in mocha AE - problem with tracking past the shot's edges
on Feb 7, 2018 at 9:41:36 pm

Thank you, Roei - I could not have done this in a million years without your help! The demo you posted was invaluable. I was able to do the tracking effect successfully with only a little bit of movement when the van door is opened. Even though the track matte does not move when the man opens the door, the tracking of the logo gets bumped ever so slightly even though I tried many adjustments to fix this. If you have any thoughts, please pass them along. Otherwise, because the movement is so slight, I think I can get away with it.

Again, thank you for your expert help!
12141_vandoortrackingfxprojectreturnlinkedcomp05forcreativecow.mp4.zip


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Roei Tzoref
Re: Track in mocha AE - problem with tracking past the shot's edges
on Feb 8, 2018 at 9:57:33 am

make sure your track matte in mocha contains all the guy and the door. this information will be subtracted from the area which is tracked and therefor there won't be any drift.


Roei Tzoref
2D/VFX Generalist & Instructor
♫ AeBlues Tutorials ♫
http://www.tzoref.com


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Lori Waite
Re: Track in mocha AE - problem with tracking past the shot's edges
on Feb 9, 2018 at 3:59:12 pm

That was the ticket - thank you again, Roei! This was my first time using MOCHA and your demo explained so much to me of how it works. The next time I have a tricky tracking shot on a project that actually has a budget, I can look you up?


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Roei Tzoref
Re: Track in mocha AE - problem with tracking past the shot's edges
on Feb 9, 2018 at 5:37:09 pm

Sure. you can contact me through my website. this shot was not that easy so for a first time, so you not giving up means you are alright. ☺

for your training I would recommend absorbing all the professional tutorials in the Imagineer Systems vimeo page:
https://vimeo.com/mochapro

and taking a full course here:
https://www.lynda.com/mocha-training-tutorials/1038-0.html

Roei Tzoref
2D/VFX Generalist & Instructor
♫ AeBlues Tutorials ♫
http://www.tzoref.com


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Lori Waite
Re: Track in mocha AE - problem with tracking past the shot's edges
on Feb 12, 2018 at 5:17:53 pm

Thanks again, Roei, for your help and for the words of encouragement and links!


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