c © 2002 Kluwer Academic Publishers. Manufactured in The Netherlands. Orthonormal Vector Sets Regularization with PDE’s and Applications

Abstract. We are interested in regularizing fields of orthonormal vector sets, using constraint-preserving anisotropic diffusion PDE’s. Each point of such a field is defined by multiple orthogonal and unitary vectors and can indeed represent a lot of interesting orientation features such as direction vectors or orthogonal matrices (among other examples). We first develop a general variational framework that solves this regularization problem, thanks to a constrained minimization of φ-functionals. This leads to a set of coupled vector-valued PDE’s preserv-ing the orthonormal constraints. Then, we focus on particular applications of this general framework, including the restoration of noisy direction fields, noisy chromaticity color images, estimated camera motions and DT-MRI (Diffusion Tensor MRI) datasets