3D CAMERA TRACKING (match moving)
In cinematography, match moving is a cinematic technique that allows the insertion of computer graphics into live-action footage with correct position, scale, orientation, and motion relative to the photographed objects in the shot.
It analyses the source sequence and extracts the original camera’s lens and motion parameters, allowing you to composite 2D or 3D elements correctly with reference to the camera used to film the shot.The term is used loosely to describe several different methods of extracting camera motion information from a motion picture.
Sometimes referred to as motion tracking or camera solving, match moving is related to rotoscoping and photogrammetry.
Structure from motion (SfM) can be seen as the inverse process.
It refers to the process of estimating three-dimensional structures from two-dimensional image sequences which may be coupled with local motion signals. It is studied in the fields of computer vision and visual perception.
1° Identifying and tracking features
A feature is a specific point in the image that a tracking algorithm can lock onto and follow through multiple frames
2° Solving for 3D motion
This process attempts to derive the motion of the camera by solving the inverse-projection of the 2D paths for the position of the camera. This process is referred to as calibration
3° Ground-plane determination
The camera and point cloud need to be oriented in some kind of space. Therefore, once calibration is complete, it is necessary to define a ground plane. Normally, this is a unit plane that determines the scale, orientation and origin of the projected space. Some programs attempt to do this automatically, though more often the user defines this plane.
In after effect we have different solutions:
1° Tracker panel
– perspective corner pin
2° Mocha AE
– planar tracking
3° Camera tracker
The effect i chose is the 3d Camera tracker, that differs from other tecniques because is powerfull in rotational scenes and for better tracking points when the ground-plane determinated runs out of the scene.
Gruppo di lavoro: Onepersongroup
Autori: Enrico Giacalone