Mocha

Hi everyone,

I recently watched some tutorials on tracking, because I 'm new to it. However, I'm still bit confused about this: why would you use a point tracker, and why would you use a camera solve, and what is the use of having a mocha track?

Comments

  • @Triem23 knows everything. I would give my 2 cents, but Triem always has the best responses haha.

  • I tend to use 1 point 2D tracking for small objects when it's positions the only thing I'm after, 2 points 2D tracking for stabilizing the footage or catch a solid object rotation data too, and Mocha for background tracking, and 3D camera solving. The later is useful when you want to integrate 3D objects to your project. 

    Essentially the integrated Mocha is the big cannon of the tracking solutions in Hitfilm 4 :)

  • Triem23Triem23 Moderator

    Long story short-ish. Any time you want to lock an overlaid element, whether a picture, text object, particle system, 3D model to existing video, you'll probably have to track. Otherwise you would have to manually rescale, reposition and rotate the added elements by hand for every frame. 

    In Hitfilm you have a one or two-point track. A single point can track X-Y position (left/right, up/down) while a two point tracker can track x-y movement, z-rotation and scaling. Often this is enough to fake 3D data. But, basically the tracker is used to stick elements to existing footage. 

    A "Camera Solve"  is trying to extrapolate the position and movement of the camera used to shoot a scene by analyzing the footage. Now, Blender, AE, PfHoe, etc. can do a "Camera Solve" by point tracking, but instead of 1 or 2 points the solver tries to track hundreds of points. It compares the relative movement of all these points then calculates a camera that fits the movement. However, Hitfilm doesn't have 3D camera solving via "point clouds." To do a full 3D camera solve, you'll need mocha. 

    Mocha is a planar tracker. Rather than trying to identify and track hundreds of points, you tell mocha that certain areas are flat rectangles. Mocha attempt to track these rectangles movement relative to each other then create a camera that fits. 

    Camera solving is a fantastic cheat! Remember the computer doesn't know what anything in the footage is. The software is just looking at how a bunch of colored dots (pixels) are moving, then picks one of many mathematical models that fit. It's amazing it works! 

    Tracking is now an essential tool for many many VFX needs. Whether to use a 1 or 2 point track or do a full camera solve is going to depend on the shot and effect. Trying for glowing eyes? Probably two-point tracks for each eye. Doing a handheld shot running towards a house that needs to be on fire? That's gonna need a camera solve. 

    Tracking is a first step in tons of shots from muzzle flashes to glowing eyes to blood hits, set extensions, compositing fire and explosions, doing Iron Man style HUDs, etc. 

  • I hardly need to break out mocha as the two point tracking in Hitfilm works for a lot more cases than you'd think.

    The Position, Scale and Rotate you get from it works for the vast majority of the things I've needed to track and allows placement of items floating in 3D space, or attached to surfaces fairly convincingly.

    Like this quick test shows:
    https://www.youtube.com/watch?v=frCvyuaMnEc

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