A General Construction Scheme for Unit Quaternion Curves with Simple High Order Derivatives1

This paper proposesa new class of unit quaternion curves in SO(3). A general method is developed that transforms a curve in R3 (defined as a weighted sum of basis functions) into its unit quaternion analogue in SO(3). Applying the method to well-known spline curves (such as Bézier, Hermite, and B-spline curves), we are able to construct various unit quaternion curves which share many important differential properties with their original curves. Many of our naive common beliefs in geometry break down even in the simple non-Euclidean space S3 or SO(3). For example, the de Casteljau type construction of cubic B-spline quaternion curves does not preserve C2-continuity [10]. Through the use of decomposition into simple primitive quaternion curves, our quaternion curves preserve most of the algebraic and differential properties of the original spline curves. CR Descriptors: I.3.5 [Computer Graphics]: Computational Geometry and Object Modeling – Curve, surface, solid, and object representation, – Geometric algorithms.