Motion tracking and Plexus

[Roland R. kahlenberg]

On this video ->https://www.broadcastgems.com/showreel/RoRK_Tracking_Particles_Rotoscoping_Composite2.mp4, I used AE’s 2D Tracker and mochaPro for the different tracking tasks and of course Plexus2.

You can get 2D arrays (for position or effect points) to follow a 3D layer’s position or a 3D layer’s position or an effect’s XYZ array to follow a 2D layer’s position with the following scrip –

Track_MG = thisComp.layer("TrackPoint_Mudguard");
Track_MG.toComp([0,0,0])

In your specific case, you will apply the Expression script to an aptly named (for easy management of your layers) 3D Null’s position.
You will need four Nulls, one for each of the CP points.

The script for linking a 3D Null to a 2D layer’s CP’s Upper Right corner property, the script reads as such –

3DTrackPoint_UR=thisComp.layer("CP_Track_Mudguard");
3DTrackPoint_UR.toComp([thisComp.layer("CP_Track_Mudguard").effect("Corner Pin")("Upper Right")[0],thisComp.layer("CP_Track_Mudguard").effect("Corner Pin")("Upper Right")[1],0])

You will now have to repeat and rinse for each of the other three points – three more 3D Nulls and remember to change the name for the appropriate CP corner property in the script, ie Upper Left etc.

Take note that mochaPro is able to export 3D Nulls after a successful camera solve. Unfortunately, mochaAE does not offer 3D camera solves.

If you want to export Transform tracking data from mocha, take note that the center of the Planar Surface is where the position property is when you paste the data into an AE layer.

Further, once you have a successful track in mocha, you can move the Planar Surface within the tracked plane to gather other position properties. You can of course do these offsets in AE using the Anchor Point. Another important thing to remember once you’ve exported Transform tracking data to E is to delete all the Anchor Point KFs and to reset the Anchor Point value.

Lastly, whether you can or should use AE”s built-on 3D tracker depends on your footage. If you do want to post a video then upload it to the COW and embed the URL in your post.

HTH
RoRK

Intensive mocha & AE Training in Singapore and Other Dangerous Locations

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

[Ross Shain]

If using mocha AE for this, I would recommend tracking with transform only as you probably want just x,y for the Plexus part. After you track, display the Surface (blue box) and scale and position it exactly to where you want. When exporting transform tracking data to AE, it will use the center of the Surface.

This should allow you paste the transform track from mocha AE to your Null and get something very accurate,

There is a tutorial that covers some of this, but I believe there are lots more ways to link Plexus to track data: https://www.imagineersystems.com/videos/tracking-titles-with-mocha-ae-and-plexus

Hope this helps.

Ross Shain
Imagineer Systems
http://www.imagineersystems.com

[Scott Green]

Is it possible to use this technique for what I’m trying to achieve here?

I want to track some nulls (with graphics attached to those nulls) to specific points on my Plexus sea that I’m creating. The sea gets quite choppy towards the end and as indicated by my pink arrows it might be difficult to track the tiny points in the distance using the motion tracker as the point will overlap other point and get confusing, and in my head I don’t think it will work.

I’m wondering if there’s a way to pick the data from a particular point and link it to a null somehow or if you have any suggestions?

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