Quasi-invariant properties and 3-D shape recovery of non-straight, non-constant generalized cylinders

The geometric protective properties of the contours of right generalized cylinders with a planar, but not necessarily straight, axis and circular, but possibly varying in size, cross-sections (called circular PRGCs) are addressed. Important rigourous quasi-invariant properties of circular PRGCs and invariant properties for their subclasses are derived. Their application for 2-D descriptions and for recovery of complete 3-D object-centered descriptions from the 2-D contours is shown