An active contour model to surface approximation is presented. It adapts to the model shape to be approximated with help of local quadratic approximants of the squared distance function. The approach completely avoids the parametrization problem. The concept is open for inclusion of smoothing operators and shape constraints.

This paper deals with the numerical analysis of the focalization of a beam of particles. In particular, this model can be useful to check whether or not the cut-off Boltzmann equation leads to some kind of smoothing effect as for the Fokker-Planck-Landau equation.

PIC is an interpretative command language which can be applied to digitized images. l t includes the major operations in the field of image processing. Today it is a collection of more than 90 commands for dataset management, Storage, simple image manipulation, histogram modification, gradient Operators, smoothing algorithms, fourier functions, arithmetic and Boolean operations and display

Two procedures to compute the output distribution φS of certain stack filters S (so called erosion-dilation cascades) are given. One rests on the disjunctive normal form of S and also yields the rank selection probabilities. The other is based on inclusion-exclusion and e.g. yields φS for some important LULU -operators S. Properties of φS can be used to characterize smoothing properties.

on utilizing the spectral representation of selfadjoint operators in hilbert spaces, some error bounds in approximating $n$-time differentiable functions of selfadjoint operators in hilbert spaces via a taylor's type expansion are given.

For a smooth manifold X with boundary we construct a semigroupoid T −X and a continuous field C∗ r (T −X) of C∗-algebras which extend Connes’ construction of the tangent groupoid. We show the asymptotic multiplicativity of ~-scaled truncated pseudodifferential operators with smoothing symbols and compute the K-theory of the associated symbol algebra. Math. Subject Classification 58J32, 58H05, 3...

A complete mesh generation or mesh adaptation process usually requires a large number of operators : Delaunay insertion, edge-face-element point insertion, edge collapse, point smoothing, face/edge swaps, etc. Independently of the complexity of the geometry, the more operators are involved in a remeshing process, the less robust the process may become. In addition, deriving a parallel version o...

We present a set of interactive, free-form editing operators for direct manipulation of level-set models. The mathematics, algorithms and techniques needed to implement numerous level-set modeling capabilities have been developed. The operators have been combined with an OpenGL interface and the VISPACK level-set library to create a preliminary interactive level-set modeling system. VISPACK’s n...

We propose two improvements to the Reitzinger and Schöberl algebraic multigrid (AMG) method for solving the eddy current approximations to Maxwell’s equations. The main focus in the Reitzinger/Schöberl method is to maintain null space properties of the weak ∇×∇× operator on coarse grids. While these null space properties are critical, they are not enough to guarantee hindependent convergence of...

One component in Additive Schwarz Method (ASM) Domain Decomposition (DD) preconditioners BPS89, SBG96] using inexact subdomain solvers Boe89, HLM91] consists in an operator extending the boundary data into the interior of each subdomain, i.e. a homogeneous extension with respect to the diierential operator given in that subdomain. This paper is concerned with the construction of cheap extension...