A finite element discretization for two-dimensional MHD is described. The elements are triangles with piecewise linear basis functions. The main computational difficulty is the accurate calculation of the current. The most effective solution is to employ a current-vorticity advection formulation of
An Adaptive Finite Element Method for Large Scale Image Processing
✍ Scribed by T. Preußer; M. Rumpf
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 596 KB
- Volume
- 11
- Category
- Article
- ISSN
- 1047-3203
No coin nor oath required. For personal study only.
✦ Synopsis
Nonlinear diffusion methods have proved to be powerful methods in the processing of 2D and 3D images. They allow a denoising and smoothing of image intensities while retaining and enhancing edges. As time evolves in the corresponding process, a scale of successively coarser image details is generated. Certain features, however, remain highly resolved and sharp. On the other hand, compression is an important topic in image processing as well. Here a method is presented which combines the two aspects in an efficient way. It is based on a semi-implicit finite element implementation of nonlinear diffusion. Error indicators guide a successive coarsening process. This leads to locally coarse grids in areas of resulting smooth image intensity, while enhanced edges are still resolved on fine grid levels. Special emphasis has been put on algorithmical aspects such as storage requirements and efficiency. Furthermore, a new nonlinear anisotropic diffusion method for vector field visualization is presented.
📜 SIMILAR VOLUMES
This paper presents an adaptive ®nite element method to solve forced convective heat transfer. Solutions are obtained in primitive variables using a high-order ®nite element approximation on unstructured grids. Two general-purpose error estimators are developed to analyse ®nite element solutions and
The image segmentation problem in computer vision is considered. Given a two-dimensional domain D and a function de®ned on it (the original image), the problem is to obtain a `cartoon' associated with this function, namely to ®nd a set of inner boundaries which divide D into subdomains (objects) in
An rh-method, which combines r-and h-methods, is proposed for cost-eective adaptive FE analysis in twodimensional linear elastic problems. Through various numerical test examples, the rh-method is compared with the h-method. From these examples it is concluded that the rh-method has the advantages o