Also if you pick up a mouse and place it at a different spot on a surface, the mouse won't be able to register what happened.
Whereas this research project actually accomplishes that, you place your camera anywhere on a previously scanned/mapped surface, the software will instantaneously tell where you are.
So the difference: a mouse only tracks movement by relative changes. This project maps a texture onto a globally known map and calculates an absolute location.
FAA was investing heavily into this iirc, https://en.wikipedia.org/wiki/Local-area_augmentation_system
Here they used an optical flow sensor for obstacle avoidance in a canyon. The closer to one side you got the faster the terrain would pass by the sensor. Allowing the UAV to self correct.
See the last two pages: https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=...