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4D Embryogenesis image analysis using PDE methods of image processing

Paul Bourgine, Róbert Čunderlík, Olga Drblíková-Stašová, Karol Mikula, Mariana Remešíková, Nadine Peyriéras, Barbara Rizzi, Alessandro Sarti (2010)

Kybernetika

In this paper, we introduce a set of methods for processing and analyzing long time series of 3D images representing embryo evolution. The images are obtained by in vivo scanning using a confocal microscope where one of the channels represents the cell nuclei and the other one the cell membranes. Our image processing chain consists of three steps: image filtering, object counting (center detection) and segmentation. The corresponding methods are based on numerical solution of nonlinear PDEs, namely...

A topological asymptotic analysis for the regularized grey-level image classification problem

Didier Auroux, Lamia Jaafar Belaid, Mohamed Masmoudi (2007)

ESAIM: Mathematical Modelling and Numerical Analysis

The aim of this article is to propose a new method for the grey-level image classification problem. We first present the classical variational approach without and with a regularization term in order to smooth the contours of the classified image. Then we present the general topological asymptotic analysis, and we finally introduce its application to the grey-level image classification problem.

Application of the partitioning method to specific Toeplitz matrices

Predrag Stanimirović, Marko Miladinović, Igor Stojanović, Sladjana Miljković (2013)

International Journal of Applied Mathematics and Computer Science

We propose an adaptation of the partitioning method for determination of the Moore-Penrose inverse of a matrix augmented by a block-column matrix. A simplified implementation of the partitioning method on specific Toeplitz matrices is obtained. The idea for observing this type of Toeplitz matrices lies in the fact that they appear in the linear motion blur models in which blurring matrices (representing the convolution kernels) are known in advance. The advantage of the introduced method is a significant...

Approximating the MaxMin and MinMax Area Triangulations using Angular Constraints

Mark Keil, J, Vassilev, Tzvetalin (2010)

Serdica Journal of Computing

* A preliminary version of this paper was presented at XI Encuentros de Geometr´ia Computacional, Santander, Spain, June 2005.We consider sets of points in the two-dimensional Euclidean plane. For a planar point set in general position, i.e. no three points collinear, a triangulation is a maximal set of non-intersecting straight line segments with vertices in the given points. These segments, called edges, subdivide the convex hull of the set into triangular regions called faces or simply triangles. We...

Approximation in the space of planes: applications to geometric modeling and reverse engineering.

Martin Peternell, Helmut Pottmann (2002)

RACSAM

Se estudia la aproximación en el espacio de planos. Se introduce una medida de la distancia en este espacio, con la que pueden resolverse problemas de modelado con superficies desarrollables mediante algoritmos de aproximación de curvas. Además, el reconocimiento y reconstrucción de caras planas en nubes de puntos aparecen como un problema "clustering" en el espacio de planos. La aplicabilidad práctica de estos resultados se muestra en varios ejemplos.

Cauchy problems for discrete affine minimal surfaces

Marcos Craizer, Thomas Lewiner, Ralph Teixeira (2012)

Archivum Mathematicum

In this paper we discuss planar quadrilateral (PQ) nets as discrete models for convex affine surfaces. As a main result, we prove a necessary and sufficient condition for a PQ net to admit a Lelieuvre co-normal vector field. Particular attention is given to the class of surfaces with discrete harmonic co-normals, which we call discrete affine minimal surfaces, and the subclass of surfaces with co-planar discrete harmonic co-normals, which we call discrete improper affine spheres. Within this classes,...

Close-to-optimal algorithm for rectangular decomposition of 3D shapes

Cyril Höschl IV, Jan Flusser (2019)

Kybernetika

In this paper, we propose a novel algorithm for a decomposition of 3D binary shapes to rectangular blocks. The aim is to minimize the number of blocks. Theoretically optimal brute-force algorithm is known to be NP-hard and practically infeasible. We introduce its sub-optimal polynomial heuristic approximation, which transforms the decomposition problem onto a graph-theoretical problem. We compare its performance with the state of the art Octree and Delta methods. We show by extensive experiments...

Courbure discrète ponctuelle

Vincent Borrelli (2006/2007)

Séminaire de théorie spectrale et géométrie

Soient S une surface de l’espace euclidien 𝔼 3 et M un ensemble de triangles euclidiens formant une approximation linéaire par morceaux de S autour d’un point P ∈ S , la courbure discrète ponctuelle K d ( P ) au sommet P de M est, par définition, le quotient du défaut angulaire par la somme des aires des triangles ayant P comme sommet. Un problème naturel est d’estimer la différence entre cette courbure discrète K d ( S ) et la courbure lisse K ( P ) de S en P . Nous présentons dans cet article des résultats obtenus dans [4], [5],...

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