Interacting with camera

Camera orientation has 3 degrees of freedom (+ 3 dof in position)
How to handle a camera orientation using a mouse (2-dof) ?
- Assuming a freely oriented camera

Common approaches

"Spherical camera"/coordinates \((\theta,\phi)\)

- (+) Good to easily "turn around" oriented structure
- (-) Lacks a dof: No "twist": position on the unit sphere force the angle
- - Not adapted to turn around non-oriented/badly-oriented objects.

Spherical coordinates + twist (ex. roll, pitch, yawn)

- (+) Precise and complete control
- (-) Require an additional key/controler to the mouse to control the 3 dof

Example of "Spherical camera"

Correct orientation

Bad orientation of the shape
- spherical camera is "stuck" in this orientation