This book presents the mathematics relevant to image understanding by computer vision and gives examples of actual applications. Group representation theory, Lie groups and Lie algebras, the theory of invariance, tensor calculus, differential geometry and projective geometry are used for three-dimensional shape and motion analysis from images, making use of techniques such as shape from motion, shape from texture, shape from angle and shape from surface. Although the mathematics itself may be well known to mathematicians, people working in areas related to computer science, image understanding, computer vision and image processing have usually never studied such mathematics, and so may be surprised to learn that abstract mathematical concepts can be of enormous help in building intelligent computer vision systems.