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Jittery motion tracking woes.

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Stuart SamuelsJittery motion tracking woes.
by on Oct 30, 2011 at 1:58:38 pm

Hi.

I've been having problems with motion tracking since my very first attempt a few years ago and despite searching and searching for an answer I'm still no closer to finding a solution.

Im trying to track a very simple handheld shot. The footage isn't particularly shaky, just what you'd expect from your average 'still' handheld shot. All I want to do is place some text within the shot and have it sit in the scene convincingly.

With the built in tracker I manage to get what looks like a good track but the text always ends up looking jittery which obviously ruins the effect.

From searching the net for answers I've found that many other people have the same problem and I've tried every suggestion I could find with no luck. I've watched tutorial after tutorial and followed their guidance to the letter and still end up with jittery text. I've even tried tracking with Boujou but infuriatingly still have the same problem!I tried with Mocha but for some reason I can't paste the data in to AE (but that's for another post!)

It's driving me absolutely crazy, I really hope someone can help!

P.S. Could it be something to do with my graphic card?


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Tudor "Ted" JelescuRe: Jittery motion tracking woes.
by on Oct 30, 2011 at 4:30:25 pm

No issue with the graphic card.
One good way to approach a shot like this is to stabilize the footage, comp the text in it, render and then de-stabilize it.
It would be helpful though to post a before and after of your clip- it will give us more insight and hopefully get you better answers.

Tudor "Ted" Jelescu
Senior VFX Artist


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Stuart SamuelsRe: Jittery motion tracking woes.
by on Oct 30, 2011 at 7:09:35 pm

Thanks for your help. How would I destabilize the footage after the render? Just add a wiggle to the position or to a camera?

Do you have any ideas why I'm coming up against this problem? I'm only shooting on a Kodak Zi8 so the quality is far from the best, could this have something to do with it? I'm guessing so, but I've had the same problem with HD footage so there must be something else going on too.


Thanks again for your help.


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Tudor "Ted" JelescuRe: Jittery motion tracking woes.
by on Oct 30, 2011 at 9:46:35 pm

Here's a tutorial that can help:
http://www.cgsutra.com/adobe_after_effects_tutorials/a0010_stabilization/fo...
Also if you have CS5.5 the Warp Stabilizer is great:
http://tv.adobe.com/watch/cs-55-production-premium-feature-tour-/stabilize-...

Tudor "Ted" Jelescu
Senior VFX Artist


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Roland R. KahlenbergRe: Jittery motion tracking woes.
by on Oct 31, 2011 at 2:47:30 am

If you can
1) embed the clip that you tracked with Mocha and
2) delineate the steps you took and
3) state where/when your issues occurred

then we may be able to help you sort out the issues you have with Mocha. It's an amazing piece of software and you shouldn't be left behind by not being able to leverage its awesomeness.

Cheers
RoRK

Intensive AE & Mocha Training in Singapore and Malaysia
Adobe ACE/ACI (version 7) & Imagineer Systems Inc Approved Mocha Trainer


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Stuart SamuelsRe: Jittery motion tracking woes.
by on Oct 31, 2011 at 10:29:48 pm

I managed to get the Mocha tracking info into AE by using the Mocha Impport script from mamoworld.com but the results were the same as ever.
Here's a clip that I just ran out and shot. I dropped it into Mocha, tracked it and then imported into AE to add the text.





As you can see the tracking is very shaky and not convincing at all. I obviously haven't spent a long time on this clip but even when I have put time and effort in to previous tracking attempts the results aren't much better.
Here's what I did....

  • Rendered out the clip in AE as JPEG sequence
  • Imported the JPEG sequence into Mocha ensuring the FPS matched
  • Using the X-Spline tool drew around the area to track (the road surface and the blue car)
  • Tracked the footage
  • Clicked "Align to Surface" button
  • Clicked "Export Tracking Data"
  • I saved the data as a text file
  • In AE I created a new comp with my original footage
  • Using the mamoworld script I applied the tracking data to a new solid layer (using the "corner pin layer" option)
  • I pre-composed the solid layer
  • Opened the pre-composed solid layer, added the text, hid the solid, closed the pre-comp.


Can you see anything I'm missing or doing wrong?

Thanks again for your help, it's genuinely appreciated.

Stuart.


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Roland R. KahlenbergRe: Jittery motion tracking woes.
by on Nov 1, 2011 at 2:48:10 am

Hi Stuart, my reply below is in italics -

[Stuart Samuels] "Here's what I did....
Rendered out the clip in AE as JPEG sequence


this isn't necessary unless the source format isn't compatible with Mocha. Do take note that the latest version of MOcha supports a variety of formats.


Imported the JPEG sequence into Mocha ensuring the FPS matched

This is good and important.

Using the X-Spline tool drew around the area to track (the road surface and the blue car)

This doesn't give me much confidence cos, the road and the car are on two different planes. The resulting tracked data will be neither useful should you want to insert an object onto either the car or the road.

It's important that you re-track with a new Mocha spline that defines just the road - something similar to the image below BUT to also include the area of the road where your text now resides.





Tracked the footage
Clicked "Align to Surface" button
Clicked "Export Tracking Data"
I saved the data as a text file


It sounds like you're tracking perspective. This isn't necessary. There is no perspective change nor shearing - just position and rotation require tracking. While perspective tracking may still work, it will actually make it harder to work with the results as opposed with tracking transforms. IOW, only conduct perspective (corner pin) tracking when it is required.

Align Surface isn't required for tracking transforms.




In AE I created a new comp with my original footage
Using the mamoworld script I applied the tracking data to a new solid layer (using the "corner pin layer" option)
I pre-composed the solid layer
Opened the pre-composed solid layer, added the text, hid the solid, closed the pre-comp.
"


What you've done with MochaImport sounds good although as I've mentioned earlier, corner pin data isn't required for this task.

Therefore, head back to Mocha and redo your spline as per the instructions earlier. When tracking is complete, apply the Surface to the define an area where you tracking data to be exported to AE. In your case, this will be where the bottom of your text will be.

Keep in mind that the Surface acts differently when exporting either Corner Pin or Transform data. In a Corner Pin export, the corners of the Surface correspond to the Corner Pin effect that is applied in AE. However, for a Transform export from Mocha, the Surface defines the Transform properties that you will be exporting with the center of the Surface defining the Position property.

In AE, paste the tracked data either onto a Null or directly onto the Text Layer (no precomposing required). If you apply the Mocha tracked data onto a Null, then remove the Anchor Point KFs and reset the Anchor Point to its default of [0,0]. This will align the Anchor Point of the Null to the center of the Surface that you earlier defined in Mocha. This makes everything more intuitive.

Lots of folks do not reset the Null's Anchor Point. While this also works, it is not intuitive cos the Null will be off in its position relative to any reference points that you had while in Mocha or even in AE.

Now parent the Text Layer to the Null and make adjustments to the Text Layer if necessary.

Should you paste the tracked data directly onto the Text Layer, then again, remove the Anchor Point KFs and reset the Anchor Point. And as expected, the Text Layer's Anchor Point will be aligned to the center of the Surface.

From here onwards, if you had a good track in Mocha, things should be fine here as well. You can even turn your text layer into a 3D layer and adjust its rotation values to add a perspective to your Text Layer - much easier this way than if you had used Corner Pin data for this job.


HTH
RoRK

Intensive AE & Mocha Training in Singapore and Malaysia
Adobe ACE/ACI (version 7) & Imagineer Systems Inc Approved Mocha Trainer


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Stuart SamuelsRe: Jittery motion tracking woes.
by on Nov 1, 2011 at 10:24:00 pm

Thank you for all that, it's really great advice.

The ony bit I'm not to sure about is this section;

When tracking is complete, apply the Surface to the define an area where you tracking data to be exported to AE. In your case, this will be where the bottom of your text will be.

Could you please try and explain how I "apply the surface" etc? I'm really not sure of my way round Mocha yet and am still trying to figure out the basics.

I tried redoing the spline excluding the car this time.
Then exported the data as transform data.
Imported the data into AE as transform data and applied it to a null
I then went to delete the anchor point key frames but there weren't any to delete. Just KF for position, scale and rotation.
Finally I parented my text to the null.
The resut was as jittery and shaky as ever.

I'm assuming I missed a stage in Mocha that would have generated the anchor point data?

Sorry if I'm being a little slow on the uptake!


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Roland R. KahlenbergRe: Jittery motion tracking woes.
by on Nov 2, 2011 at 1:03:05 am

[Stuart Samuels] "The ony bit I'm not to sure about is this section;

When tracking is complete, apply the Surface to the define an area where you tracking data to be exported to AE. In your case, this will be where the bottom of your text will be. "


Hmmm, I'm stumped too! :-D
What I meant to write was - "when tracking is complete, apply the Surface to define an area where your tracking data is to be exported to AE. In your case, this will be where the bottom of your text will be."

I suggest that you take a look at Steve Wright's Mocha tutorials here - http://www.imagineersystems.com/videos?tagFilter=%25learnmocha&sortBy=Newes...

Watch them in their proper order, from 1 to 6. Parts 7 & 8 aren't really necessary. I would also like to suggest that you refrain from using Mocha Import until you have a much better grasp of Mocha and how tracking is generally conducted in Mocha and how the different types of data work within AE. Mocha Import is an excellent tool BUT it does a lot of its goodness 'behind the scene' such that if you do not already have a good understanding of tracking, then chances are that you never will!

BTW, the COW has a few Mocha tutorials that are also worth a look.

HTH
RoRK


[Stuart Samuels] "Could you please try and explain how I "apply the surface" etc? I'm really not sure of my way round Mocha yet and am still trying to figure out the basics."

Intensive AE & Mocha Training in Singapore and Malaysia
Adobe ACE/ACI (version 7) & Imagineer Systems Inc Approved Mocha Trainer


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Stuart SamuelsRe: Jittery motion tracking woes.
by on Nov 2, 2011 at 4:59:04 pm

Thanks. Those tutorials are just what I need. I think I'm guilty of trying to run before I can walk.

Thanks for your time and patience!

Stuart


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Roland R. KahlenbergRe: Jittery motion tracking woes.
by on Nov 2, 2011 at 6:55:57 pm

You're most welcome Stuart. We've all been guilty at one time or more, of succumbing to our desires by trying to reach our goals faster than we should.

Structured learning is extremely crucial to learning anything new that is complex and actually more so when the new stuff we learn involves or interacts with that which we already know.

Cheers
RoRK

Intensive AE & Mocha Training in Singapore and Malaysia
Adobe ACE/ACI (version 7) & Imagineer Systems Inc Approved Mocha Trainer


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Bud JillettRe: Jittery motion tracking woes.
by on Dec 5, 2011 at 3:40:00 pm

This "problem" was driving me crazy, too, so I went back to the basics. I found that I was working in a 30p comp, but the 7D footage was actually 29.97.

I changed the comp frame rate to 29.97 and -- voila! -- the tracking was spot-on despite horribly shaky footage taken with a zoom lens ;-)

Incidentally, I changed the comp frame rate *after* I did the tracking and it still worked.

Peace,
Bud


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Shawn MacAlpineRe: Jittery motion tracking woes.
by on Feb 15, 2012 at 10:37:05 am

Yes! Thank you guys so much! I was having the same problem.


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