Geometric algebra provides a number of powerful tools for the treatment of rotations in three dimensions. Rotations are parameterised by *rotors*, which are normalised multivectors in a 4-d subalgebra of the 3-d geometric algebra. This parametrisation can be exploited to simplify both extrapolation and optimisation problems involving rotations. A number of these are considered in the context of computer vision.

C.J.L. Doran, **Bayesian inference and geometric algebra: an application to camera localization, **In: E. Bayro and G. Sobczyk eds. *Geometric algebra: a geometric approach to computer vision, neural and quantum computing, robotics and engineering*. Birkhauser, 172 (2000)