267 same-object problem is solved for many different boundary representations in time U( F log F + D log D + V) and space O(F + D), where F, D, and V are the numbers of faces, directed edges, and vertices, respectively, in the two boundary representations. In addition, the problem of converting from
Image segmentation with a Sobolev gradient method
β Scribed by R.J. Renka
- Publisher
- Elsevier Science
- Year
- 2009
- Tongue
- English
- Weight
- 492 KB
- Volume
- 71
- Category
- Article
- ISSN
- 0362-546X
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β¦ Synopsis
The most effective methods for finding object boundaries in a digital image involve minimizing a functional over a set of curves or surfaces, where the functional includes internal energy terms for regularization and external energy terms that align the curves or surfaces with object boundaries. Current practice is to seek critical points of the energy functional by what amounts to a steepest descent iteration with the discretized L 2 gradient. Since the functional involves derivatives, a descent method with a discretized Sobolev gradient is likely to be much more efficient. We demonstrate this with test results for an implementation of a variational level set method for edge-based segmentation with active contours in two dimensions.
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We have devised a new method for constructing discrete approximations to fair curves and surfaces by directly minimizing an arbitrarily selected fairness functional subject to geometric constraints. The nonlinear optimization problem is solved efficiently by a Sobolev gradient method. We first descr