2,680 research outputs found
Topology, homogeneity and scale factors for object detection: application of eCognition software for urban mapping using multispectral satellite image
The research scope of this paper is to apply spatial object based image
analysis (OBIA) method for processing panchromatic multispectral image covering
study area of Brussels for urban mapping. The aim is to map different land
cover types and more specifically, built-up areas from the very high resolution
(VHR) satellite image using OBIA approach. A case study covers urban landscapes
in the eastern areas of the city of Brussels, Belgium. Technically, this
research was performed in eCognition raster processing software demonstrating
excellent results of image segmentation and classification. The tools embedded
in eCognition enabled to perform image segmentation and objects classification
processes in a semi-automated regime, which is useful for the city planning,
spatial analysis and urban growth analysis. The combination of the OBIA method
together with technical tools of the eCognition demonstrated applicability of
this method for urban mapping in densely populated areas, e.g. in megapolis and
capital cities. The methodology included multiresolution segmentation and
classification of the created objects.Comment: 6 pages, 12 figures, INSO2015, Ed. by A. Girgvliani et al. Akaki
Tsereteli State University, Kutaisi (Imereti), Georgi
Astronomical Data Analysis and Sparsity: from Wavelets to Compressed Sensing
Wavelets have been used extensively for several years now in astronomy for
many purposes, ranging from data filtering and deconvolution, to star and
galaxy detection or cosmic ray removal. More recent sparse representations such
ridgelets or curvelets have also been proposed for the detection of anisotropic
features such cosmic strings in the cosmic microwave background.
We review in this paper a range of methods based on sparsity that have been
proposed for astronomical data analysis. We also discuss what is the impact of
Compressed Sensing, the new sampling theory, in astronomy for collecting the
data, transferring them to the earth or reconstructing an image from incomplete
measurements.Comment: Submitted. Full paper will figures available at
http://jstarck.free.fr/IEEE09_SparseAstro.pd
Topological Homogeneity for Electron Microscopy Images
In this paper, the concept of homogeneity is defined, from a
topological perspective, in order to analyze how uniform is the material
composition in 2D electron microscopy images. Topological multiresolution
parameters are taken into account to obtain better results than
classical techniques.Ministerio de EconomÃa y Competitividad MTM2016-81030-PMinisterio de EconomÃa y Competitividad TEC2012-37868-C04-0
Construction of Parseval wavelets from redundant filter systems
We consider wavelets in L^2(R^d) which have generalized multiresolutions.
This means that the initial resolution subspace V_0 in L^2(R^d) is not singly
generated. As a result, the representation of the integer lattice Z^d
restricted to V_0 has a nontrivial multiplicity function. We show how the
corresponding analysis and synthesis for these wavelets can be understood in
terms of unitary-matrix-valued functions on a torus acting on a certain vector
bundle. Specifically, we show how the wavelet functions on R^d can be
constructed directly from the generalized wavelet filters.Comment: 34 pages, AMS-LaTeX ("amsproc" document class) v2 changes minor typos
in Sections 1 and 4, v3 adds a number of references on GMRA theory and
wavelet multiplicity analysis; v4 adds material on pages 2, 3, 5 and 10, and
two more reference
Dynamical systems associated to separated graphs, graph algebras, and paradoxical decompositions
We attach to each finite bipartite separated graph (E,C) a partial dynamical
system (\Omega(E,C), F, \theta), where \Omega(E,C) is a zero-dimensional
metrizable compact space, F is a finitely generated free group, and {\theta} is
a continuous partial action of F on \Omega(E,C). The full crossed product
C*-algebra O(E,C) = C(\Omega(E,C)) \rtimes_{\theta} F is shown to be a
canonical quotient of the graph C*-algebra C^*(E,C) of the separated graph
(E,C). Similarly, we prove that, for any *-field K, the algebraic crossed
product L^{ab}_K(E,C) = C_K(\Omega(E,C)) \rtimes_\theta^{alg} F is a canonical
quotient of the Leavitt path algebra L_K(E,C) of (E,C). The monoid
V(L^{ab}_K(E,C)) of isomorphism classes of finitely generated projective
modules over L^{ab}_K(E,C) is explicitly computed in terms of monoids
associated to a canonical sequence of separated graphs. Using this, we are able
to construct an action of a finitely generated free group F on a
zero-dimensional metrizable compact space Z such that the type semigroup S(Z,
F, K) is not almost unperforated, where K denotes the algebra of clopen subsets
of Z. Finally we obtain a characterization of the separated graphs (E,C) such
that the canonical partial action of F on \Omega(E,C) is topologically free.Comment: Final version to appear in Advances in Mathematic
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