Need advice about tracking drift in Mocha

I’m tracking containers on a freight train. I created a garbage matte, so the clip is clean. The track starts well, but as the train goes off screen, the track drifts. Any help would be appreciated. Here is a link to a screen capture of the clip: http://www.casanovaproductions.com/track.mov

track.mov
98 Mb

-JM

Hi JM,

I think the tracker is being confused by the substantial change in perspective on the front edge of the container as it gets closer to the camera. Your shape is perfect for the earlier part of the shot, but for the later part, try pulling the leading edge of the shape back so it is inside the side plane of the container.

Hope this helps,

J-P

Hi JM,
I think the tracker is being confused by the substantial change in perspective on the front edge of the container as it gets closer to the camera. Your shape is perfect for the earlier part of the shot, but for the later part, try pulling the leading edge of the shape back so it is inside the side plane of the container.
Hope this helps,
J-P

Hi JM,

I tried a few things on that shot and nothing got a stable result close to the camera. Maybe someone else has some ideas, but I’m thinking you might have to animate it by hand. I suspect most trackers based on points (like the AE tracker or all 3D trackers) will also fail due to the huge amount of motion blur.

If you do decide to hand animate this, a good technique might be to lock down camera motion using a track of the grass on the right-hand side or the tower in the background, use the After Effects 3D space to animate the surface on the side of the container, then add the camera motion back in.

Sorry I can’t be more help,

J-P

Hi JM,
I tried a few things on that shot and nothing got a stable result close to the camera. Maybe someone else has some ideas, but I’m thinking you might have to animate it by hand. I suspect most trackers based on points (like the AE tracker or all 3D trackers) will also fail due to the huge amount of motion blur.
If you do decide to hand animate this, a good technique might be to lock down camera motion using a track of the grass on the right-hand side or the tower in the background, use the After Effects 3D space to animate the surface on the side of the container, then add the camera motion back in.
Sorry I can’t be more help,
J-P

I’m tracking containers on a freight train. I created a garbage matte, so the clip is clean. The track starts well, but as the train goes off screen, the track drifts. Any help would be appreciated. Here is a link to a screen capture of the clip: http://www.casanovaproductions.com/track.mov
track.mov
98 Mb
-JM

John-Paul,

Thanks for the tip. I have used Mocha successfully in the past, mostly to track screen surfaces. But in that clip, there’s indeed a lot of perspective distortion. I did as you suggested without much luck. I have no problem tracking backward, but as the container gets closer, it all goes wrong. I spent a couple of hours and I was wondering if it is worth my time, without having to spend hours in AE fixing the corner pin. Without taking too much of your time, I would appreciate your input regarding the feasibility of such an endeavor, especially if I have to track several containers. Thanks a mil.

test: http://www.casanovaproductions.com/track2.mov.zip
raw video: http://www.casanovaproductions.com/video.mov.zip
http://www.casanovaproductions.com/tracking.mocha.zip

John-Paul,
Thanks for the tip. I have used Mocha successfully in the past, mostly to track screen surfaces. But in that clip, there’s indeed a lot of perspective distortion. I did as you suggested without much luck. I have no problem tracking backward, but as the container gets closer, it all goes wrong. I spent a couple of hours and I was wondering if it is worth my time, without having to spend hours in AE fixing the corner pin. Without taking too much of your time, I would appreciate your input regarding the feasibility of such an endeavor, especially if I have to track several containers. Thanks a mil.
test: http://www.casanovaproductions.com/track2.mov.zip
raw video: http://www.casanovaproductions.com/video.mov.zip
http://www.casanovaproductions.com/tracking.mocha.zip