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Preprocessing for motion track?

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Peter Jay GouldPreprocessing for motion track?
by on Jun 23, 2011 at 2:28:04 pm

I'm trying to motion track a small blemish on an on-camera subject's face so I can fix it. The trouble is the coloration difference between the blemish and the rest of the person's skin tone is too small for the analyzer to reliably follow it. None of the options within the motion tracking system (enhance, RGB versus monochrome, etc.) are enough to help.

I believe that if I could enhance the image (start with just the green channel, for instance, then tweak levels or contrast) I could make it stand out enough for the tracker to work. But since the motion tracker only works on the source, I can't see how to do that. Doesn't look as though I can precomp it to add those effects either since it wants a source.

Short of rendering it out and reimporting it as a separate layer, is there a way to preprocess the footage in AE?

Thanks,

Pete


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Dave LaRondeRe: Preprocessing for motion track?
by on Jun 23, 2011 at 2:51:13 pm

If there's some other, more defined feature on the subject's face that moves consistently with the blemish, you could track it, then offset the point for the repair.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Peter Jay GouldRe: Preprocessing for motion track?
by on Jun 23, 2011 at 5:23:00 pm

Sadly no; it's a zit midway between lower lip and chin, so fairly constant motion during speech and independent of all other facial features.

Pete



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Chris ButtacoliRe: Preprocessing for motion track?
by on Jun 23, 2011 at 3:26:54 pm

I'm almost certain if you pre-comp the footage, you can add levels or sharpening or channel effects etc., and then track the pre-comp. Of course, save the data to a null as usual.


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Peter Jay GouldRe: Preprocessing for motion track?
by on Jun 23, 2011 at 5:24:23 pm

I can't seem to find a way to do that; the tracking function only appears when you have directly opened a source layer. Unless I'm missing something.

Pete



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Dave LaRondeRe: Preprocessing for motion track?
by on Jun 23, 2011 at 5:44:06 pm

[Peter Jay Gould] "Unless I'm missing something."

You might have:
  • Duplicate the layer in question.
  • Precompose the duplicated layer.
  • In the precomp, make the adjustments and play with the effects recommended by Chris.
  • In the main comp, motion track the precomp layer.
  • Use the track from the precomp as data for the unaffected, original layer.

Is that what you're doing?

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Steve RenardRe: Preprocessing for motion track?
by on Jun 23, 2011 at 6:38:52 pm

I think the key thing is to make sure you've got your comps and layers organized the way AE wants you to.

You should have two comps.
Comp 1 is your main comp where you'll do the tracking.
Comp 2 has your footage in it, with the curves, etc. applied to the footage layer.
Comp 2 sits in Comp 1 as a layer.
In Comp 1, right-click on the Comp 2 layer and select "Open Layer" and you should be able to do your tracking as you would if you had rendered the footage out with FX and brought it back in. Double-clicking on it will just open the comp, which is not what you want.

Hopefully whatever it was you were missing is contained in the above.

Good luck,
Steve

------------
Steve Renard
Media Director, Cicada Design Inc.
and Freelance Know-it-all
647-406-7991
srenard@cicadadesign.ca
http://www.cicadadesign.ca


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Peter Jay GouldRe: Preprocessing for motion track?
by on Jun 23, 2011 at 7:25:13 pm

Hi Steve,

It's still a mystery, but I got it to work. Whatever I was doing wrong before, AE simply would not offer motion tracking as a choice when I had the precomp selected.

Once it worked it worked perfectly.

Thanks everyone for the help. Wish I knew what ultimately made the difference but getting it to work was worth a million bucks!

Pete



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Mark SprakerRe: Preprocessing for motion track?
by on Jun 24, 2011 at 5:38:52 am

If you want to open a pre-comp as a footage layer for motion tracking (For example), you can right click on it and select "Open Layer" as mentioned before. Another option is to simply Alt + Double click on it.


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Brian CharlesRe: Preprocessing for motion track?
by on Jun 23, 2011 at 5:46:41 pm

If you have Mocha it may be easier.

Here are links to 2 face tracking tutorials, albeit for replacing features or adding scars, but they should point you in the right direction.

http://aeioweyou.blogspot.com/2009/04/face-replacement-part-1-basic.html

http://ae.tutsplus.com/tutorials/vfx/creating-a-tracked-head-wound/



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