Odd camera track problem with mocha

Hi,

I've been trying to track a piece of drone footage which is admittedly a challenging track. I've got what looks like a fairly solid track but when I export the composite shot the camera is inverted. Here's the track in Mocha:


Full size @ https://ibb.co/k8Mr8F

And the Comp in Hitfilm:


https://ibb.co/dbBDNa

Any thoughts? I can't just rotate the camera 180 degrees as you can see the X orientation appears correct, it's just Y that's inverted.

 Also, anyone else notice their splines expanding and sliding more as you increase the % of pixels used?

Cheers,
Brian

 

Comments

  • Triem23Triem23 Moderator
    edited June 8

    Try putting in your overlay and insert objects in Hitfilm and see if they track correctly. Mocha never actually knows what it's tracking (it's just pixel patterns and guessing perspective based on the surfaces defined) so Mocha often spits out a track where everything is correct (in terms of relative positions), but at an arbitrary point in 3D space. If your surfaces are still in the same relative locations over your video your track is correct, just offset in space. 

    If the above is correct, then this video will help you realign your video to line up the ground plane of your video with Hitfilm's zero plane. 

    https://vimeo.com/54818695

    To TL/DW the video, create a "Master"  3D point, parent all the mocha points to the Master and drag Master up in Y-space to adjust. OR, try parenting all the other Mocha points to the center point of your floor surface, set position and rotation of the center-floor to 0, 0, 0 and adjust its Orientation until your floor lines up with Hitfilm 0-plane.

    No, I've not noticed more drift with higher percentage of pixels used. One thing that might be happening is the wide angle lens on the drone might have enough barrel distortion to throw off Mocha. I've found anything under a focal length (equivalent) of about 24mm requires lens correction before import into Mocha (or lens correction IN Mocha if you have Mocha Pro). 

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