Difference between 2D and 3D motion tracking ?

[surferadi96]

Whats the difference between 2D and 3D motion tracking ?

How do we know when to use which type of tracking ?

(I know its a pretty silly question)

[poisondeathray]

3D motion tracking (also called "matchmoving") is used when you need to composite elements into a 3D scene. For example , you shoot some footage, and you want to put something in afterwards, in post production. 2D tracking only looks at x,y translation coordinates, +/- other stuff like rotation, sheer, perspective. But 3D tracking adds z-space (depth) , by tracking objects and re-constructing a 3d scene with 3d coordinates (so everything "lives" in 3D space, in a 3D model, instead of a 2D layer).

Here is an example in blender, where the roller coaster was put into the mall
https://forum.videohelp.com/threads/336283-Blender-Tutorials-for-the-Video-People?p=209...=1#post2091736

[budwzr]

How do we know when to use which type of tracking ?

You'll know because you won't be able to match perspective.