检索结果-内蒙古大学图书馆

19th iapr international conference on discrete geometry for computer imagery, dgci 2016

ISBN: (纸本)9783319323596

the proceedings contain 34 papers. the special focus in this conference is on Combinatorial Tools, Discretization, discrete Tomography and Combinatorial Topology. the topics include: Convergent geometric estimators with digital volume and surface integrals;discrete calculus, optimisation and inverse problems in imaging;number of words characterizing digital balls on the triangular tiling;generation of digital planes using generalized continued-fractions algorithms;a tomographical interpretation of a sufficient condition on H-graphical sequences;geometrical characterization of the uniqueness regions under special sets of three directions in discrete tomography;a comparison of some methods for direct 2d reconstruction from discrete projected views;homotopic thinning in 2d and 3d cubical complexes based on critical kernels;p-simple points and general-simple deletion rules;two measures for the homology groups of binary volumes;shape classification according to LBP persistence of critical points;signature of a shape based on its pixel coverage representation;computation of the normal vector to a digital plane by sampling significant points;finding shortest triangular path in a digital object;digital surfaces of revolution made simple;on functionality of quadraginta octants of naive sphere with application to circle drawing;encoding specific 3d polyhedral complexes using 3d binary images;interactive curvature tensor visualization on digital surfaces;construction of digital ellipse by recursive integer intervals;digitization of partitions and tessellations;bijective rigid motions of the 2D Cartesian grid and adaptive tangential cover for noisy digital contours.

关键词：

来源：评论

学校读者我要写书评

暂无评论

discrete geometry for computer imagery: 19th iapr international conference, dgci 2016 Nantes, France, April 18-20, 2016 proceedings 19th

Discrete geometry for computer imagery: 19th IAPR internatio...

引用

19th iapr international conference on discrete geometry for computer imagery, dgci 2016

作者： Normand, Nicolas Guédon, Jeanpierre Autrusseau, Florent IRCCyN University of Nantes Nantes France

来源：评论

学校读者我要写书评

暂无评论

Reconstruction of the Crossing Type of a Point Set from the Compatible Exchange Graph of Noncrossing Spanning Trees 1

引用

21st iapr international conference on discrete geometry for computer imagery (dgci)

作者： Oropeza, Marcos Toth, Csaba D. Calif State Univ Northridge Los Angeles CA 91330 USA Tufts Univ Medford MA 02155 USA

ISBN: (数字)9783030140854

ISBN: (纸本)9783030140854;9783030140847

Let P be a set of n points in the plane in general position. the order type of P specifies, for every ordered triple, a positive or negative orientation;and the x-type (a.k.a. crossing type) of P specifies, for every unordered 4-tuple, whether they are in convex position. Geometric algorithms on P typically rely on primitives involving the order type or x-type (i.e., triples or 4-tuples). In this paper, we show that the x-type of P can be reconstructed from the compatible exchange graph G(1)(P) of noncrossing spanning trees on P. this extends a recent result by Keller and Perles (2016), who proved that the x-type of P can be reconstructed from the exchange graph G(0)(P) of noncrossing spanning trees, where G(1)(P) is a subgraph of G(0)(P). A crucial ingredient of our proof is a structure theorem on the maximal sets of pairwise noncrossing edges (msnes) between two components of a planar straight-line graph on the point set P.

关键词： geometry

来源：评论

学校读者我要写书评

暂无评论

Two Plane-Probing Algorithms for the Computation of the Normal Vector to a Digital Plane

引用

JOURNAL OF MAthEMATICAL IMAGING AND VISION 2017年第1期59卷 23-39页

作者： Lachaud, Jacques-Olivier Provencal, Xavier Roussillon, Tristan Univ Savoie Mt Blanc LAMA UMR5127 F-73376 Chambery France Univ Lyon CNRS INSA Lyon LIRISUMR5205 F-69622 Villeurbanne France

Digital planes are sets of integer points located between two parallel planes. We present a new algorithm that computes the normal vector of a digital plane given only a predicate "is a point x in the digital plane or not". In opposition to classical recognition algorithm, this algorithm decides on-the-fly which points to test in order to output at the end the exact surface characteristics of the plane. We present two variants: the H-algorithm, which is purely local, and the R-algorithm which probes further along rays coming out from the local neighborhood tested by the H-algorithm. Both algorithms are shown to output the correct normal to the digital planes if the starting point is a lower leaning point. the worst-case time complexity is in for the H-algorithm and for the R-algorithm, where is the arithmetic thickness of the digital plane. In practice, the H-algorithm often outputs a reduced basis of the digital plane while the R-algorithm always returns a reduced basis. Both variants perform much better than the theoretical bound, with an average behavior close to . Finally, we show how this algorithm can be used to analyze the geometry of arbitrary digital surfaces, by computing normals and identifying convex, concave or saddle parts of the surface. this paper is an extension of Lachaud et al. (Proceedings of 19th iapr international conference discrete geometry for computer imagery (dgci'2016), Nantes, France. Springer, Cham, 2016).

关键词： Digital geometry Digital plane Recognition Normal vector estimation Lattice reduction

来源：评论

学校读者我要写书评

暂无评论

Well-Composedness in Alexandrov Spaces Implies Digital Well-Composedness in Zⁿ 1

引用

20th iapr international conference on discrete geometry for computer imagery (dgci)

作者： Boutry, Nicolas Najman, Laurent Geraud, thierry EPITA Res & Dev Lab LRDE Le Kremlin Bicetre France Univ Paris Est LIGM Equipe A3SI ESIEE Champs Sur Marne France

ISBN: (数字)9783319662725

ISBN: (纸本)9783319662725;9783319662718

In digital topology, it is well-known that, in 2D and in 3D, a digital set X subset of Z(n) is digitally well-composed (DWC), i.e., does not contain any critical configuration, if its immersion in the Khalimsky grids H-n is well-composed in the sense of Alexandrov (AWC), i.e., its boundary is a disjoint union of discrete (n - 1)-surfaces. We show that this is still true in n-D, n >= 2, which is of prime importance since today 4D signals are more and more frequent.

关键词： Well-composed discrete surfaces Alexandrov spaces Critical configurations Digital topology

来源：评论

学校读者我要写书评

暂无评论

Ambiguity Results in the Characterization of hv-convex Polyominoes from Projections 20th

Ambiguity Results in the Characterization of <i>hv</i>-conve...

引用

20th iapr international conference on discrete geometry for computer imagery (dgci)

作者： Barcucci, Elena Dulio, Paolo Frosini, Andrea Rinaldi, Simone Univ Firenze Dipartimento Matemat & Informat U Dini Viale Morgagni 65 I-50134 Florence Italy Politecn Milan Dipartimento Matemat F Brioschi Piazza Leonardo da Vinci 32 I-20133 Milan Italy Univ Siena Dipartimento Ingn Informaz & Sci Matemat I-53100 Siena Italy

ISBN: (纸本)9783319662725;9783319662718

In 1997 R. Gardner and P. Gritzmann proved a milestone result for uniqueness in discrete Tomography: a finite convex discrete set can be uniquely determined by projections taken in any set of seven planar directions. the number of required directions can be reduced to 4, providing their cross-ratio, arranged in order of increasing angle with the positive x-axis, does not belong to the set {4/3, 3/2, 2, 3, 4}. Later studies, supported by experimental evidence, allow us to conjecture that a similar result may also hold for the wider class of hv-convex polyominoes. In this paper we shed some light on the differences between these two classes, providing new 4-tuples of discrete directions that do not lead to a unique reconstruction of hv-convex polyominoes. We reach our main result by a constructive process. this generates switching components along four directions by a recursive composition of only three of them, and then by shifting the obtained structure along the fourth one. Furthermore, we stress the role that the horizontal and the vertical directions have in preserving the hv-convexity property. this is pointed out by showing that these often appear in the 4-tuples of directions that allow uniqueness. A final characterization theorem for hv-convex polyominoes is still left as open question.

关键词： discrete geometry discrete tomography hv-convex set Uniqueness problem Switching component

来源：评论

学校读者我要写书评

暂无评论

An Introduction to Gamma-Convergence for Spectral Clustering 1

引用

20th iapr international conference on discrete geometry for computer imagery (dgci)

作者： Challa, Aditya Danda, Sravan Sagar, B. S. Daya Najman, Laurent Indian Stat Inst Syst Sci & Informat Unit 8th MileMysore Rd Bangalore 560059 Karnataka India Univ Paris Est LIGM Equipe A3SI ESIEE Paris France

ISBN: (数字)9783319662725

ISBN: (纸本)9783319662725;9783319662718

the problem of clustering is to partition the dataset into groups such that elements belonging to the same group are similar and elements belonging to the different groups are dissimilar. the unsupervised nature of the problem makes it widely applicable and also tough to solve objectively. Clustering in the context of image data is referred to as image segmentation. Distance based methods such as K-means fail to detect the non-globular clusters and hence spectral clustering was proposed to overcome this problem. this method detects the non globular structures by projecting the data set into a subspace, in which the usual clustering methods work well. Gamma convergence is the study of asymptotic behavior of minimizers of a family of minimization problems. Such a limit of minimizers is referred to as the gamma limit. Calculating the gamma limit for various variational problems has been proved useful - giving a different algorithm and insights into why existing methods work. In this article, we calculate the gamma limit of the spectral clustering methods, analyze its properties, and compare them with minimum spanning tree based clustering methods and spectral clustering methods.

关键词： Image segmentation

来源：评论

学校读者我要写书评

暂无评论

Digital disks by weighted distances in the triangular grid 19th

Digital disks by weighted distances in the triangular grid

引用

19th iapr international conference on discrete geometry for computer imagery, dgci 2016

作者： Nagy, Benedek Mir-Mohammad-Sadeghi, Hamid Department of Computer Science University of Debrecen Debrecen Hungary Department of Mathematics Eastern Mediterranean University Mersin-10 Famagusta North Cyprus Turkey

ISBN: (纸本)9783319323596

Weighted (or with other name, chamfer) distances on the triangular grid was introduced recently based on the three possible neighborhood. In this paper, digital disks are defined and analyzed based on these weighted distances: geometric and combinatorial properties are studied. Approximation of the Euclidean circles and distances are shown. the obtained disks are usually dodecagons, enneagons (nonagons) or hexagons. they are proven to be digitally convex. © Springer international Publishing Switzerland 2016.

关键词： Artificial intelligence

来源：评论

学校读者我要写书评

暂无评论

discrete calculus, optimisation and inverse problems in imaging 19th

Discrete calculus, optimisation and inverse problems in imag...

引用

19th iapr international conference on discrete geometry for computer imagery, dgci 2016

作者： Talbot, Hugues Université Paris-Est ESIEE Paris France

ISBN: (纸本)9783319323596

Inverse problems in science are the process of estimating the causal factors that produced a set of observations. Many image processing tasks can be cast as inverse problems: image restoration: noise reduction, deconvolution;segmentation, tomography, demosaicing, inpaiting, and many others, are examples of such tasks. Typically, inverse problems are ill-posed, and solving these problems efficiently and effectively is a major, ongoing topic of research. While imaging is often thought of as occurring on regular grids, it is also useful to be able to solve these problems on arbitrary graphs. the combined frameworks of discrete calculus and modern optimisation allow us to formulate and provide solutions to many of these problems in an elegant way. this tutorial article summarizes and illustrates some of the research results of the last decade from this point of view. We provide illustrations and major references. © Springer international Publishing Switzerland 2016.

关键词： Inverse problems

来源：评论

学校读者我要写书评

暂无评论

Adaptive tangential cover for noisy digital contours 19th

Adaptive tangential cover for noisy digital contours

引用

19th iapr international conference on discrete geometry for computer imagery, dgci 2016

作者： Ngo, Phuc Nasser, Hayat Debled-Rennesson, Isabelle Kerautret, Bertrand Université de Lorraine LORIA UMR 7503 Vandœuvre-lés-Nancy54506 France CNRS LORIA UMR 7503 Vandœuvre-lés-Nancy54506 France

ISBN: (纸本)9783319323596

the notion of tangential cover, based on maximal segments, is a well-known tool to study the geometrical characteristics of a discrete curve. However, it is not adapted to noisy digital contours. In this paper, we propose a new notion, named Adaptive Tangential Cover, to study noisy digital contours. It relies on the meaningful thickness, calculated at each point of the contour, which permits to locally estimate the noise level. the Adaptive Tangential Cover is then composed of maximal blurred segments with appropriate widths, deduced from the noise level estimation. We present a parameter-free algorithm for computing the Adaptive Tangential Cover. Moreover an application to dominant point detection is proposed. the experimental results demonstrate the efficiency of this new notion. © Springer international Publishing Switzerland 2016.

关键词： geometry

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：