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"Tracking" on top of Tracking

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Patrick Reagan"Tracking" on top of Tracking
by on Jun 19, 2013 at 1:53:32 am

I'm doing a golf video of my girlfriend's brother where the ball has a light trail coming off it. The video provided is showing a simplified version of everything so it'll be easier to follow.

I have an emitter in Particular keyframed to follow the golf ball frame by frame and emit particles. Now of course, I want the light trail to remain for a few seconds, but during that few seconds, the light trail isn't tracked to the camera's jittery movements, yet it already has position keyframes.

I was thinking I could keyframe the emitter's position like normal, then precompose the layer. After that I would track the source footage, create a null, then parent the precomped emitter layer to the null's subsequent tracking data. However, when I do that, it makes the particle's position in relation to the emitter wildly off. It sooort of tracks correctly with the source footage, but does not follow the emitter (and as a result, where the golf ball is going).

BONUS PROBLEM: As you can see in the video, I have some strange problem that occurs rarely where the particles at the very beginning of the emitter trail refuse to render, even though they seem to flash in and out of existence under certain conditions. The emitter is actually starting where the ball is resting on the tee, and it's supposed to start from the second the ball leaves the tee, not a few "feet" after the ball leaves the tee as is shown in the video.

Trail Problem



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Roland R. KahlenbergRe: "Tracking" on top of Tracking
by on Jun 19, 2013 at 2:22:23 am

Stabilize the shot with Warp Stabilizer. This single step will solve two issues for you (1) shaky footage (2) lock down your particles.

To get Particular to emit its particles earlier, set the Pre-run property (Emitter section) to a positive value - start with a value of two seconds and adjust to taste.

HTH
RoRK

Intensive mocha & AE Training in Singapore and Other Dangerous Locations

Imagineer Systems (mocha) Certified Instructor
& Adobe After Effects CS6 ACE


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Patrick ReaganRe: "Tracking" on top of Tracking
by on Jun 19, 2013 at 2:26:35 am

Thing is though, the shot you see has already had warp stabilizer used on it. The shot has an upward tilt, so even with the stabilizer, the movement is still there.


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Roland R. KahlenbergRe: "Tracking" on top of Tracking
by on Jun 19, 2013 at 3:35:56 am

Try the following steps:

1) Track the ground area using either mocha or AE's Motion Tracker or even AE's 3D Camera Tracker.

2) Apply the results to a Null Layer.

3) Create a Solid and apply Particular

4) Parent the Solid to the Null

5) Keyframe (or track) Particular's Emitter position to follow the ball.

For an alternative take, take a look-see at this COW Tutorial from Carl Larsen - http://library.creativecow.net/articles/larsen_carl/analyzing_motion/video-...

HTH
RoRK

Intensive mocha & AE Training in Singapore and Other Dangerous Locations

Imagineer Systems (mocha) Certified Instructor
& Adobe After Effects CS6 ACE


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Patrick ReaganRe: "Tracking" on top of Tracking
by on Jun 19, 2013 at 4:07:15 am

Ahhhhhhhh yes, what you suggested is exactly what did the trick. Thank you so much!


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Roland R. KahlenbergRe: "Tracking" on top of Tracking
by on Jun 19, 2013 at 11:33:43 am

You're most welcome Patrick.

Cheers
RoRK

Intensive mocha & AE Training in Singapore and Other Dangerous Locations

Imagineer Systems (mocha) Certified Instructor
& Adobe After Effects CS6 ACE


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