How to track an object if it disappears from view at some point

Hi.

 

I have this footage: at first the ground is shown and then camera’s point of view pans along Y axis all the way to the top of church tower. I want to replace the towers with a wine bottle.

 

I chose to track the plane in the middle of the church building. However, this plane at some point disappears from the view ant the tracking process stops. How do I fix this?

 

Thanks

 

 

Hi there,

Simply track a similarly moving object and you should be fine. You may need to turn off perspective and shear and just grab the translation, scale, and rotation data as the track goes offscreen. You can move your shape to any new place during the track as long as you move it to a similarly moving plane.

Please let me know if you have any more questions and I will be happy to help you.
Cheers,
Mary

Hi Mary,

Thanks for the tips. I’ve managed to track the footage by simply increasing tracking area.

However, when I paste transform data on a jpg layer in After Effects, the layer moves to the right by some 1000 pixels, i.e. it disappears from the Composition window. The timeline indicator was at 00:00 when I pasted, and I also tried to adjust the jpg layer’s anchor point position, but it still keeps moving out off the composition window as soon as I paste Transform data from mocha. Why is that?

By the way, I forgot to mention that the camera location doesn’t change throughout the footage, it stays on the ground, but it’s point of interest (i guess i’m using correct term here) moves along Y axis, i.e. I begin to filming the ground and then gradually turn camera up to film the top of the tower. So I guess in this case I have to turn on Perspective and Shear?

 

Thank you!

So without seeing your footage I can make a few best guesses as to the issue… Yes, if you’re tilting, shear and perspective will help you. Also, if your data isn’t lining up you probably have a setting mismatch. Or your track is not correct. Turn your surface tool on and look at it, if it’s following along correctly in mocha, then your track is good. If not, then the track is not going to work in AE.

When you paste or import your mocha data into the final composite or edit, make sure you are pasting or loading your data in at the first frame of the clip, otherwise your data will not line up.

Project settings such as frame rate, dimensions and pixel aspect ratio must be match between your mocha project and your destination software. Make sure these values match the settings in your compositor or editor and inside of mocha, otherwise your tracking data will not match when you export it.

If your are using Adobe After Effects, the target layer you are pasting data to should also be the same size as your AE composition. A good After Effects troubleshooting tip: create a new solid that is the same size as your composition. Paste your track or roto shape data to this layer. If it does not line up, the issue is mostly likely a project mismatch.

If your jPEG in AE is smaller than the comp, you can use this technique to fix it: http://www.imagineersystems.com/videos/align-surface-and-mismatched/

Maybe I paste tracking data to the wrong layer or do some other mistake - when I preview the video in mocha after tracking is done (inserting a mocha logo), everything is fine, the logo sticks firmly to the church wall throughout the footage. But when I go to After Effects and paste the tracking data to a Null object, the Null object doesn’t stick to the wall but moves around the composition window. Here is the raw footage first and then the tracking result afterwards:

My aim is to get that skull to stick to the church wall. I tracked a large perpendicular area at the mid-section of the tower and used all tracking parameters (translation, scale, rotation, shear, perspective). After Effects project settings match the source footage parameters (pixel aspect, frame rate).

 

Try using the corner pin instead of transform, you need the corner pin to stick it to the wall properly. Also, I think you’re probably pasting the data in off the timeline. Check your keyframes and make sure they line up in your timeline.