Learn More
We prove optimal bounds for the discretization error of geodesic finite elements for variational partial differential equations for functions that map into a nonlinear space. For this we first generalize the well-known Cea lemma to nonlinear function spaces. In a second step we prove optimal interpolation error estimates for pointwise interpolation by(More)
Subdivision is a powerful way of approximating a continuous object f (x, y) by a sequence ((S l p i,j) i,j∈Z) l∈N of discrete data on finer and finer grids. The rule S, that maps an approximation on a coarse grid, S l p, to the approximation on the next finer grid, S l+1 p, is called subdivision scheme. If for a given scheme S every continuous object f (x,(More)
Linear stationary subdivision rules take a sequence of input data and produce ever denser sequences of subdivided data from it. They are employed in multiresolution modeling and have intimate connections with wavelet and more general pyramid transforms. Data which naturally do not live in a vector space, but in a nonlinear geometry like a surface, symmetric(More)
We study the following modification of a linear subdivision scheme S: Let M be a surface embedded in Euclidean space, and P a smooth projection mapping onto M. Then the P-projection analogue of S is defined as T := P • S. As it turns out, the smoothness of the scheme T is always at least as high as the smoothness of the underlying scheme S or the smoothness(More)
Linear interpolatory subdivision schemes of C r smoothness have approximation order at least r + 1. The present paper extends this result to nonlinear univariate schemes which are in proximity with linear schemes in a certain specific sense. The results apply to nonlinear subdivision schemes in Lie groups and in surfaces which are obtained from linear(More)
This paper proves approximation order properties of various nonlin-ear subdivision schemes. Building on some recent results on the stability of nonlinear multiscale transformations, we are able to give very short and concise proofs. In particular we point out an interesting connection between stability properties and approximation order of nonlinear(More)
The present paper is concerned with the study of manifold-valued multiscale transforms with a focus on the Stiefel manifold. For this specific geometry we derive several formulas and algorithms for the computation of geometric means which will later enable us to construct multiscale transforms of wavelet type. As an application we study compression of(More)