3D: frame matching
Registering the images of an event in a 3D model of its setting: finding the exact position of each camera lets us measure, in real space, what the image alone shows only in appearance.
The method involves matching a photograph or a video frame to the 3D reconstruction of the location, adjusting the position, orientation, and focal length of the virtual camera until the fixed points of the setting line up. Once the registration holds, everything in the image can be located and measured: distances, trajectories, firing angles, the positions of bodies.
It was this technique that established, in the Gaye Camara case, that the shooter was standing more than five metres from the vehicle and to its left, the bullet’s trajectory forming a 38° angle with the vehicle’s axis.