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Matching clean plate to a moving plate from a drone?

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Max Monty
Matching clean plate to a moving plate from a drone?
on Jun 6, 2018 at 11:06:19 pm

So I was just doing a test from a drone where I put the camera straight down over some cars at a 4-way stop. I want to try the difference matte effect and copy and paste cars driving by. The only problem is that during the 45 clip the drone shifts a little bit. I tried doing the warp stabilizer but it still didnt match the beginning frame to the end frame. Overall I think it can be manipulated so it is locked down like a tripod, but I'm not sure. I was thinking using Mocha to somehow align the layers would be best but I'm not sure the best way to do it. Anyone know how to do this?

https://vimeo.com/273785204/a55e3e89c9 - the clean plate frame is at 1:47

-Max


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Mark Whitney
Re: Matching clean plate to a moving plate from a drone?
on Jun 6, 2018 at 11:28:25 pm

That is r-e-a-l-l-y subtle. Had to d/l the clip & to a quick drag from head to tail to even see what movement you were talking about. Seems it's mostly a Z-axis roll with some x-y. I'd probably turn off Mocha's Perspective & Shear when tracking & definitely use the Small Motion setting.

You might wish to look at some of the tutorials here but in particular:

https://mamoworld.com/tutorials/mochaimport-ae-mini-tutorial-4-stabilize


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Max Monty
Re: Matching clean plate to a moving plate from a drone?
on Jun 6, 2018 at 11:38:00 pm

you are awesome, thanks for checking the clip out. Yes, it is VERY subtle. It was shot at 60fps and slowed down to 23.976 so its hard to tell. I will give that tutorial a watch and see what I come up with. Thanks again!


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Blaise Douros
Re: Matching clean plate to a moving plate from a drone?
on Jun 6, 2018 at 11:28:52 pm

You just need to use the right tracking tool. Use the point tracker to stabilize position, rotation, and scale with multiple track points. That will allow you to really lock the frame down in a fixed position. Then you can roto in your cars from earlier/later in the take, without the problem of Warp Stabilizer's uncontrollable movement.

BTW, a difference matte will NOT be effective. You will need to track each car, using the point tracker, and then attach some kind of mask to it, in order to reveal it.


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Max Monty
Re: Matching clean plate to a moving plate from a drone?
on Jun 6, 2018 at 11:38:48 pm

Thanks Blaise. I am new to AE so i'm still learning the ropes. I will try out the point tracker and see what that does. Thanks for your reply.


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Blaise Douros
Re: Matching clean plate to a moving plate from a drone?
on Jun 7, 2018 at 5:33:24 pm

Here, check out this AE comp I built with your Vimeo video file. It should give you a few ideas. The main comp scales up a pre-comp by 103% to hide the slight mismatch in edges. In the precomp, there are two layers: the lower layer is where I did tracking and stabilization, and the upper layer has three cars that I masked off to add into the lower scene.

12437_intersectioncomp.aep.zip


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Max Monty
Re: Matching clean plate to a moving plate from a drone?
on Jun 7, 2018 at 9:07:49 pm

yeah that is exactly what I was going for, i love where the cars almost collide at the beginning. That seems like a very simple matte. I will keep playing around with this. If I add in my original file, which is 4K, should I change the scale size to around ~25% and would the stabilization match that?


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Blaise Douros
Re: Matching clean plate to a moving plate from a drone?
on Jun 7, 2018 at 10:08:24 pm
Last Edited By Blaise Douros on Jun 7, 2018 at 10:10:29 pm

You'll have some scaling problems if you try to replace the footage, since the point tracker is animating position, scale, and rotation. There might be a way to do it, but for my money, you'd do just as well to duplicate the setup--since you've got the AEP, you can see the two locations I placed the point tracker to get position/scale/rotation data. It'll be a more detailed track anyway, because of the extra rez. You just let the tracker cook away (I had zero problems with it losing the track points, since it's very minimal drift), and then in the tracking panel, apply the results to the same footage layer.

After that, you duplicate the stabilized layer, offset the time a bit, and start keyframing your car masks. It only took me ten minutes to do that quick test, so you'll get good results if you spend some time on it.


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Cassius Marques
Re: Matching clean plate to a moving plate from a drone?
on Jun 8, 2018 at 12:08:17 pm

[Blaise Douros] "You'll have some scaling problems if you try to replace the footage, since the point tracker is animating position, scale, and rotation."

I'll guess he could just pre-compose and then replace and scale down. Then check collapse transformations on the pre-comp and all is well. Since all that's happening are transformations and no camera is involved.

Cassius Marques
http://www.zapfilmes.com


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Blaise Douros
Re: Matching clean plate to a moving plate from a drone?
on Jun 8, 2018 at 6:08:13 pm

Maybe, but I'd still bet he'll get even better tracking results than I did by re-tracking the camera-original 4K file; I tracked the downscaled, compressed HD file from Vimeo.


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