Foundry Tracker Drifting

edited October 2019 in HitFilm Pro Support

Sometimes on shots when I've tracked, solved, and created a new scene for them, when I put in the 3D model the track ends up drifting a ways. For example, a track of a canyon drone shot, where I try to make a 3D spaceship landed in the canyon, the spaceship doesn't stay still on the ground and drifts across it as the shot goes on. Am I missing a step? Or what am I doing wrong...

Is it possible that small things like trees waving in the wind interfere with the track and I need to make a matte for all of those?

This is the shot I tried tracking.


  • @HeySiri I may be wrong, but that shot seems to be primarily rotation around a point, and not standard translation. There may be alterations you need to make to your track to improve the quality, but I will pass this on to our tracking expert to get their input.

  • Triem23Triem23 Moderator
    edited October 2019

    @HeySiri @TheBenNorris I'm pretty certain I've successfully tracked this shot. It's rendering now. (My machine isn't quite suitable for 4k)

    Now, I did generate a matte using a copy of the footage and some effects to isolate the rocks.

    HeySiri the tracker does assume things in frame are still. I didn't see THAT much movement in the background, but I do, as a rule, always suggest matting away areas that are outside what you want to track, anyway. In this case I used a Channel Mixer to pretty much pull all the blue and red from the image. This left me green, which was mostly on the rocks. After that, a Custom Grey to further isolate the rocks, then a Threshold and Blur to finish it off.

    EDIT: Yup, rock solid track, first try. We'll have to figure out what HeySiri is missing in the workflow.

    But what's that flicker?

  •  @Triem23 You definitely have a flicker there on the model. It seems to be a constant oscillation. I noticed that on the last frame your camera disappears also. When the Foundry Tracker creates something, whether its a point, a camera, etc... it always leaves it off the last frame. You have to drag it over on the timeline to make it complete. Nice track though! I have been playing with using sharpening tools to help the application get a better track. I got a great track of my seamless jiu-jitsu mat which has no discernible features doing that.

  • @Triem23 ; The Eagle!  Looks good except for that elusive flicker...   I always had a fondness for that ship. I just recently bought a physical model of the eagle from Auto World.

  • Triem23Triem23 Moderator

    @FilmSensei yeah, Jay, I didn't bother to stretch out the last frame. I really just plopped the Eagle in to check for tracking drift, and a last-minute second Eagle, figuring if the Eagle was farther away from the tracked/created point any jitter would magnify.

    No clue what that rhythmic flicker is! Also, my shadow catcher plane wasn't taking shadows. The cast shadow on the grounded Eagle is actually another model duplicate with its Y-scale set to - 0.5%, a fill color and a blur. 

    @tddavis the Eagle is one of my all-time favs! 

  • @Triem23 Would you be able to send that project file to us? I had an issue with a similar flicker and we're trying to pin it down.

  • @Triem23 The shadow catcher wasn't working? Strange! I recently had a shadow catcher not work because I was sourcing a Grade Layer with a Clone Stamp Effect in the Comp. Apparently this is a bug. Nice fake shadow... I would have never noticed!

  • Triem23Triem23 Moderator

    @JavertValbarr sure! Should I send it to you, Oli or Ady?

    @FilmSensei interesting. I sourced a grade layer as the matte for the tracker. Since it's tracked, already I wonder if I delete tracker plug in and grade layer if the Shadow catcher would work again. If so, then it's the same issue you found. 

    Yeah, the fake shadow works pretty well, even though it's not stretching in the same direction as the rest of the shadows. 

  • @Triem23 Me please, thank you.

  • Triem23Triem23 Moderator

    @JavertValbarr Sent.

    @FilmSensei I'm not going to re-render the shot (this was really only to test that the shot could be solidly tracked), but eliminating reading a Grade Layer as a Matte Source in the Tracker also had the Shadow Catcher kick in. Seems that whatever glitch you found with the Clone Stamp might apply to any Grade Layer being referenced as a Source LAyer in an effect?

  • @Triem23 Interesting. Here is the discussion regarding the Grade Layer issue. It was confirmed by @Ady as a bug that the Devs are working on.

    I ran this shot through the tracker with no changes and it tracked perfectly. I was even able to select a few points and create a perfect ground plane on the first try. In fact, I don't think I've ever had a more perfect track! Here it is. Notice the shadow catcher is good to go also!

  • @FilmSensei as good as that track is I can actually detect a tiny amount of drifting, mainly by looking at the AT-AT feet position at the start and end relative to the little greenish patch next to it. If this is the drift OP is referring to then it is pretty negligible.

  • edited October 2019

    @TheBenNorris I see what you mean, if you catch my drift! 

    Seriously, you are right though. It's so small, I didn't even notice! I slapped this together pretty quickly (about 15 minutes), so it maybe my fault. I may have the anchor point of the ATAT off by a few pixels or something like that.

    Edit: Since the Falcon doesn't seem to move at all, it is most probably my placing of the ATAT and not the track itself. The Foundry Camera Tracker is truly amazing, that's for sure..

  • @FilmSensei how did you do the shadows in your test shot?

  • edited October 2019
  • @HeySiri Yup... what Greg Said ^^^

  • Aah… Camera tracks... sigh. :)

    Uneven and unlevel surfaces guys... Uneven and unlevel surfaces. :)

  • edited October 2019

    @HeySiri ,

    The chosen floor plane is not a level surface so you will see drift. @FilmSensei did a live chat episode where he and I talked about camera tracking issues and things that fool you into thinking that you have a bad track. It wasn't too long ago so I'm surprised everyone already forgot it.

    Your camera track is actually pretty good but the floor plane is at  slight angle which gives you drift.

    Take a look at @FilmSensei video above... the AT AT Walker is leaning awkwardly to the viewer left. Same thing for @Triem23 video above, the ship is also at an angle.

    The shot used above is a very bad example to use for the Foundry camera tracker because it shines a bad light on it where there is none. The scene above that you guys are using is full of uneven surface points and uneven planar surfaces which you cannot take into account for with simple 2D planes. You shouldn't use nature shots unless you can reconstruct them in 3D or at least get many, many good tracking points as reference. 

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