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Mocha AE Tracking Drifting Off when using Parented Layers

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Brandon DavidsMocha AE Tracking Drifting Off when using Parented Layers
by on Dec 17, 2015 at 6:03:21 pm

I've watched tons of tutorials and messed around with trial and error for a couple days now, but I'm missing a nuance of how the tracking data is working when I am parenting to a null object or solid. On a side note, I was able to do flawless corner pinning using Mocha AE on my first try. For this project, I'm just trying to track my kids power wheels police car lights so I can apply lens flares to them and make them look like police lights.

So, my tracking data is perfect in mocha and it's a really simple track with very smooth footage, so this is very easy. I'm confident this is done correctly. I'm also NOT copying the corner pin data from Mocha, I'm copying the Position, Scale and Rotation. My version of Mocha doesn't copy the Anchor point, like I've seen in demos. I must have a different version.

Here is my problem:

So, I have a layer with a lens flare on it and if I paste in the tracking data directly onto my lens flare solid, it works perfectly. The issue is if I want to create multiple solids as flares and then parent them to a null or other solid, the tracking seems to drift about 5-10 pixels over 5 seconds.

Can someone explain this to me? What am I missing. I can obviously paste all my tracking data into each solid (lens flare) but that's not optimal for keeping up with any adjustment if I end up having 10 lens flares. I just want to understand the nuance that I'm missing here.

Thanks


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Dave LaRondeRe: Mocha AE Tracking Drifting Off when using Parented Layers
by on Dec 18, 2015 at 12:10:29 am

The original solid with the flare works correctly, right?

Just parent subsequent solids to the original. It should work. This assumes you're NOT animating the flare's position in the effect.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Brandon DavidsRe: Mocha AE Tracking Drifting Off when using Parented Layers
by on Dec 18, 2015 at 12:38:36 am

No, what's weird is that it works fine if I paste the tracking info directly into the solid that my flare is on, but if I add a null object and then parent my flare/solid to it, it ends up drifting.

If I am basically tracking a point, and I want my flare on that point, should I zoom real tight and try to track a very small area or does it matter?

I'm a total NOOB at this, matter of fact this is my 2nd video ever with AE. I did figure out how to drag select large collections of keyframes to adjust them a few pixels to compensate but it's a lot of extra work.


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Dave LaRondeRe: Mocha AE Tracking Drifting Off when using Parented Layers
by on Dec 18, 2015 at 12:41:33 am

I'm not saying, "parent to a null". I'm saying, "parent it to the solid that WORKS and forget about the null".

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Brandon DavidsRe: Mocha AE Tracking Drifting Off when using Parented Layers
by on Dec 18, 2015 at 1:05:59 am

Yes, I did that and I still get a little drift but it wasn't as bad as the null object. That's when I figured out to just parent to the original flare/solid and then about 1/3 or 1/4 along the track, select all keyframes for position through the end and nudge them using the keyboard arrows and then go another 1/3 or 1/4 down and see if any corrections are needed. It can get messy quick though.

What's your opinion on tracking a point? Should I keep the tracked area as small as possible or does it matter? The build in AE motion tracker does a good job sometimes, but it's very erratic sometimes.


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Dave LaRondeRe: Mocha AE Tracking Drifting Off when using Parented Layers
by on Dec 18, 2015 at 1:14:58 am
Last Edited By Dave LaRonde on Dec 18, 2015 at 1:17:27 am

In AE's tracker there are two boxes. The inner box should contain the point (or the high-contrast area surrounding the point) you want to track. The outer point should contain the area in which that point will move over one frame.

And if you're parenting a new solid to a solid known to work, I don't get why there would be any drift AT ALL. There has to be something else going on you've overlooked.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Brandon DavidsRe: Mocha AE Tracking Drifting Off when using Parented Layers
by on Dec 18, 2015 at 1:49:03 am

I agree. I appreciate your feedback. I'm sure another 10-20 hours of trial and error and I'll figure it out. I'm a programmer, so I'm used to this type of stuff.

Part of the problem is that the lights are small and confined in a small area and I tracked a much larger area so the track is shrinking/expanding a few pixels here and there, even though I manually adjusted it some of the way through.

Is there an easy way to adjust a track over multiple frames? Any easier than what I was already doing?

I'll post a link of my video when it's done!


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Dave LaRondeRe: Mocha AE Tracking Drifting Off when using Parented Layers
by on Dec 18, 2015 at 3:56:24 pm
Last Edited By Dave LaRonde on Dec 18, 2015 at 5:47:11 pm

If AE's point tracker isn't maintaining an accurate track, you may want to use Mocha, which is bundled with AE.


EDIT: Well, duh--you've already tried Mocha, and didn't have rousing success.

Maybe just fool around with trackers more... and double check for errant keyframes in the effects

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Brandon DavidsRe: Mocha AE Tracking Drifting Off when using Parented Layers
by on Dec 20, 2015 at 1:47:35 am

OK, Here is my first track results. The screen replacement (in the beginning) was a breeze in mocha and only took minutes. I didn't really try to do any sort of glow around the edges or all that. This is a kids video but I'm happy with the results.

The first track is from the rear of the car and starts just after 1:55. I'm happy with the results, but it wasn't perfect and knowing what I know now, after doing the 2nd track, I could do it better.

The 2nd track, the 15 second clip after, was a huge undertaking for my first project. After screwing around the better part of 10-12 hours really learning how tracking works and reading and watching tutorials and starting from scratch, It took me about 6 hours to learn how to do everything. The light occlusion is a total hack with multiple masks but it serves it's purpose. I had to get 8 lights onto that car and easily spent 1-2 hours just screwing around with the flares. I ended up using 3 tracks due to the perspective changes etc... It was a very challenging job, but that's why I did it.

I can't say how important it is to read the adobe documentation. I was using the components of AE's tracker wrong and it costed me at least 2 hours of frustartion. This document was the biggest help.
https://helpx.adobe.com/after-effects/using/tracking-stabilizing-motion-cs5...

Here is my project! Power Wheels Police, Ep. 2!






I'm really having a blast doing these with my kids and wife and I'm learning a lot!


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Dave LaRondeRe: Mocha AE Tracking Drifting Off when using Parented Layers
by on Dec 21, 2015 at 5:18:12 pm

Glad you got it, glad you you're having fun and wow! That was a lot of effort.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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