Rotation error in Foundry Tracker

JawsMan
JawsMan Website User Posts: 9 Just Starting Out*

When I set the plane of my tracker, the ground plane occasionally flips upside down for a frame when I let it play through. Is there a way to stop that from happening?

Comments

  • Triem23
    Triem23 Moderator Moderator, Website User, Ambassador, Imerge Beta Tester, HitFilm Beta Tester Posts: 19,930 Ambassador
    edited August 19

    Nope.

    Without going into detail, there are infinite mathematical solutions to a Camera Solve, whether in Mocha, Foundry or other solvers like the Ae camera tracker. The solve software picks one and alignment can just be off.

    @FilmSensei has a video on correcting Foundry tracks to "Normalize" your scene. His is based on a tutorial by Action Movie Dad on Normalizing an Ae track, while Imagineer/BorisFX have tutorials on doing this in Mocha.

    Having to correct orientation/scale of a Camera Solve is a typical part of the process.

    EDIT - reread your post. Maybe delete the tracking data for the single frame and let Hitfilm interpolate? I've never had a track with a single frame flip, but deleting the key for a single frame "stutter" has worked for me.

  • FilmSensei
    FilmSensei Moderator, Website User, Ambassador, HitFilm Beta Tester Posts: 3,100 Ambassador

    @JawsMan I have never had that happen. However, if it did, what @Triem23 says to do is what I would do as well... Delete the tracking data for the single frame that is glitched out and let HitFilm interpolate the position. That should work!

  • spydurhank
    spydurhank Website User, Imerge Beta Tester, HitFilm Beta Tester Posts: 3,169 Expert

    @JawsMan,

    First, I've been performing professional camera track/matchmoves for over thirteen years. I only mention because I know these techniques intimately because I created several of them so I tend to see the stuff that everyone else misses. All the linked videos below show my techniques. Check them out.

    Listen, what you're experiencing is called Gimbal Lock so deleting the single Keyframe as suggested, is probably gonna cause you more problems that you may not even notice after the fact. Explanation below.

    Gimbal Lock is flipping one of your axis the wrong way at -90 degrees, most times it will be your "X axis". This means that the preceding keyframes of you camera animation are also flipped so deleting a single keyframe does nothing but cause more problems. If you want to go the manual route... then you'd have to flip all of your preceding keyframes to +90 degrees one by one at the point in which the Gimbal Lock occurs. This will take you a nice long while if doing it by hand.

    The easiest thing for you to do is re-track the footage with a much higher tracking marker count in your Foundry tracking settings than you have now, so hopefully, you'll get a better track and without the Gimbal Lock.

    Here's a few camera tracking videos that I've done over the years. This is on Hitfilm's Foundry Camera tracker. It's the simplest you'll find out there. This is the newest video that I have on Camera tracking.


    The following videos are much older going back to 2012 which is when I first started teaching people. I really recommend you watching and digesting the videos below. You won't ever get better undiluted knowledge than when you go to the source. It's the fastest way to get to the core of your problem and find the correct solution... everything else is nothing but a guess.

    This is on Camera tracking in Blender and exporting to Hitfilm. It showcases my World Matrix Orientation Technique, or WMOT, which everyone else likes to re-name or re-brand for some very, very, strange reason. You'll notice that I used the same technique in the newer Foundry video above.

    And here is another video of me using my World Matrix Orientation Technique with Mocha Hitfilm.

    And another one except this one has a camera conversion equation that I came up with specifically for working with Blender and Hitfilm.

    The next two videos are on exporting Curves paths from Blender to Hitfilm.

    Yeah, so just crank up the number of tracking markers in you Hitfilm Foundry camera tracker Settings. 😀

  • Triem23
    Triem23 Moderator Moderator, Website User, Ambassador, Imerge Beta Tester, HitFilm Beta Tester Posts: 19,930 Ambassador

    @spydurhank Gah! Gimbal lock! You're probably right.

    Oddly I've never had a track that gimbal locked. Guess I never had an axis land on a "true 90!"

  • spydurhank
    spydurhank Website User, Imerge Beta Tester, HitFilm Beta Tester Posts: 3,169 Expert

    @Triem23, You are a laugh riot. 😀😂🤣

    You actually have had Gimbal lock before but you didn't know what you were looking at. Your Gimbal lock starts at around the 47:30 mark in the livestream video blow... you play a matchmove of tracked phone footage.

    Your tracked camera flips in the X axis at least 6 times which is Gimbal Lock but you didn't know what you were looking at so you made a wild guess and called it a Render Glitch. By the way... your reaction to me pointing out the Gimbal Lock in your tracked footage is classic. 😀


  • Triem23
    Triem23 Moderator Moderator, Website User, Ambassador, Imerge Beta Tester, HitFilm Beta Tester Posts: 19,930 Ambassador

    @spydurhank I obviously forgot to write that one down in my every growing reference file of troubleshooting, which was dumb of me, so thanks again! I'll go back over this livestream a bit later today.

  • spydurhank
    spydurhank Website User, Imerge Beta Tester, HitFilm Beta Tester Posts: 3,169 Expert

    No worries.

    All you've got to remember is that if a camera flips... it's always gonna be gimbal lock no matter what... because there is no Earthly reason for it to be anything else because... it can't be anything else. This is matchmoving 101 dude... it's the basics of the basics. And it's why I always do at least eight manual track points in all of the footage that I track.

    Gimbal lock means you got a bad track so you need to do a re-track with "More" tracking points and if needed... a little manual guidance or manual tracking, by the person doing the matchmove.

    It's always like this... the pattern and the mathematics of how matchmovers track footage doesn't change so the fix is always the same, and it don't matter what Tracking software that you're using.