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nD generalized map pyramids:: Definition, representations and basic operations

PATTERN RECOGNITION 2006年第4期39卷 527-538页

作者： Grasset-Simon, C Damiand, G Lienhardt, P CNRS SIC FRE 2731 F-86962 Chasseneuil France

Graph pyramids are often used for representing irregular image pyramids. For the 2D case, combinatorial pyramids have been recently defined in order to explicitly represent more topological information than graph pyramids. The main contribution of this work is the definition of pyramids of n-dimensional (nD) generalized maps. This extends the previous works to any dimension, and generalizes them in order to represent any type of pyramid constructed by using any removal and/or contraction operations. We give basic algorithms that allow to build an nD generalized pyramid that describes a multi-level segmented image. A pyramid of nD generalized maps can be implemented in several ways. We propose three possible representations and give conversion algorithms. (c) 2005 Pattern Recognition Society. Published by Elsevier Ltd. All rights reserved.

关键词： irregular pyramid hierarchical data structure pyramid of generalized maps multi-level segmented image

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data structures and algorithms for high-dimensional structured adaptive mesh refinement

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ADVANCES IN ENGINEERING SOFTWARE 2015年 82卷 75-86页

作者： Grandin, Magnus Uppsala Univ Div Comp Sci Dept Informat Technol SE-75105 Uppsala Sweden

Spatial discretization of high-dimensional partial differential equations requires data representations that are of low overhead in terms of memory and complexity. Uniform discretization of computational domains quickly grows out of reach due to an exponential increase in problem size with dimensionality. Even with spatial adaptivity, the number of mesh data points can be unnecessarily large if care is not taken as to where refinement is done. This paper proposes an adaptive scheme that generates the mesh by recursive bisection, allowing mesh blocks to be arbitrarily anisotropic to allow for fine structures in some directions without over-refining in those directions that suffice with less refinement. Within this framework, the mesh blocks are organized in a linear kd-tree with an explicit node index map corresponding to the hierarchical splitting of internal nodes. Algorithms for refinement, coarsening and 2:1 balancing of a mesh hierarchy are derived. To demonstrate the capabilities of the framework, examples of generated meshes are presented and the algorithmic scalability is evaluated on a suite of test problems. In conclusion, although the worst-case complexity of sorting the nodes and building the node map index is n(2), the average runtime scaling in the studied examples is no worse than n log n. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： structured adaptive mesh refinement Anisotropic mesh High-dimensional hierarchical data structure kd-tree Morton order 2:1 balancing

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AN ENCODING SCHEME FOR THE EFFICIENT REPRESENTATION OF hierarchical IMAGE structureS

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INFORMATION PROCESSING LETTERS 1987年第3期25卷 199-206页

作者： ALEXANDRIDIS, NA TSANAKAS, PD NATL TECH UNIV ATHENS DEPT ELECT ENGNDIV COMP SCIGR-15773 ATHENSGREECE

Attention is focused on a new scheme for encoding structured images. The method aims at minimizing the storage requirements while ensuring a rather short access time. For each picture to be represented in various resolution levels, the information for the finest resolution available is stored in an appropriately constructured array as a reference object for the calculation of coarser image representations via function calls. First, the problems associated with storing and accessing the picture's contents are presented, along with some of the most efficient solutions proposed in the literature. The virtual pyramid structure is described in detail; then, some algorithms for identifying the picture's quadrants are presented. An indexing scheme for the structure also is proposed along with the associative algorithms. The structure exhibits all of the attractive properties of the hierarchical structures, while avoiding the considerable storage overhead normally involved.

关键词： Image processing hierarchical data structure image encoding

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A Randomized Incremental Algorithm for the Hausdorff Voronoi Diagram of Non-crossing Clusters

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ALGORITHMICA 2016年第4期76卷 935-960页

作者： Cheilaris, Panagiotis Khramtcova, Elena Langerman, Stefan Papadopoulou, Evanthia Univ Svizzera Italiana Fac Informat Lugano Switzerland Univ Libre Bruxelles Dept Informat Brussels Belgium

In the Hausdorff Voronoi diagram of a family of clusters of points in the plane, the distance between a point t and a cluster P is measured as the maximum distance between t and any point in P, and the diagram is defined in a nearest-neighbor sense for the input clusters. In this paper we consider non-crossing clusters in the plane, for which the combinatorial complexity of the Hausdorff Voronoi diagram is linear in the total number of points, n, on the convex hulls of all clusters. We present a randomized incremental construction, based on point location, that computes this diagram in expected time and expected O(n) space. Our techniques efficiently handle non-standard characteristics of generalized Voronoi diagrams, such as sites of non-constant complexity, sites that are not enclosed in their Voronoi regions, and empty Voronoi regions. The diagram finds direct applications in VLSI computer-aided design.

关键词： Voronoi diagram Hausdorff distance Randomized incremental construction Point location hierarchical data structure

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NEW METHOD FOR REPRESENTING LINEAR QUADTREE

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ELECTRONICS LETTERS 1989年第2期25卷 137-139页

作者： KIM, YM PARK, SB Korea Adv. Inst. of Sci. & Technol. Seoul South Korea

A new pointerless quadtree representation is proposed, which encodes black nodes and white nodes complementarily. The proposed method is advantageous over Gargantini's linear quadtree in space saving and other res... 详细信息

关键词： black nodes computer graphics computer graphics data structures encoding encoding hierarchical data structure image processing linear quadtree picture processing pointerless quadtree representation trees (mathematics) white nodes

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The analysis-hierarchical models: Past, present and future

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PREVENTIVE VETERINARY MEDICINE 2014年第3期113卷 304-312页

作者： Stryhn, Henrik Christensen, Jette Univ Prince Edward Isl Atlantic Vet Coll Ctr Vet Epidemiol Res Charlottetown PE C1A 4P3 Canada Canadian Food Inspect Agcy Epidemiol & Surveillance Sect Atlantic Vet Coll Dept Hlth Management Charlottetown PE C1A 4P3 Canada

This paper discusses statistical modelling for data with a hierarchical structure, and distinguishes in this context between three different meanings of the term hierarchical model: to account for clustering, to investigate variability and separate predictive equations at different hierarchical levels (multi-level analysis), and in a Bayesian framework to involve multiple layers of data or prior information. Within each of these areas, the paper reviews both past developments and the present state, and offers indications of future directions. In a worked example, previously reported data on piglet lameness are reanalyzed with multilevel methodology for survival analysis, leading to new insights into the data structure and predictor effects. In our view, hierarchical models of all three types discussed have much to offer for data analysis in veterinary epidemiology and other disciplines. (C) 2013 Elsevier B.V. All rights reserved.

关键词： hierarchical data structure Random-effects model Survival analysis Non-proportional hazards Multi-level Bayesian modelling

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A generic structure for plant trait databases

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METHODS IN ECOLOGY AND EVOLUTION 2011年第2期2卷 202-213页

作者： Kattge, Jens Ogle, Kiona Boenisch, Gerhard Diaz, Sandra Lavorel, Sandra Madin, Joshua Nadrowski, Karin Noellert, Stephanie Sartor, Karla Wirth, Christian Max Planck Inst Biogeochem D-07745 Jena Germany Univ Wyoming Dept Bot Laramie WY 82071 USA Univ Nacl Cordoba Inst Multidisciplinario Biol Vegetal CONICET UNC RA-5000 Cordoba Argentina Univ Nacl Cordoba FCEFyN RA-5000 Cordoba Argentina Univ Grenoble 1 Lab Ecol Alpine CNRS UMR 5553 F-38041 Grenoble 9 France Macquarie Univ Dept Biol Sci Sydney NSW 2109 Australia Univ Leipzig Dept Special Bot & Funct Biodivers Res D-04103 Leipzig Germany Harvard Univ Dept Organism & Evolutionary Biol Biol Labs Cambridge MA 02138 USA

P>1. Plant traits are fundamental for understanding and predicting vegetation responses to global changes, and they provide a promising basis towards a more quantitative and predictive approach to ecology. As a consequence, information on plant traits is rapidly accumulating, and there is a growing need for efficient database tools that enable the assembly and synthesis of trait data. 2. Plant traits are highly heterogeneous, exhibit a low degree of standardization and are linked and interdependent at various levels of biological organization: tissue, organ, plant and population. Therefore, they often require ancillary data for interpretation, including descriptors of the biotic and abiotic environment, methods and taxonomic relationships. 3. We introduce a generic database structure that is tailored to accommodate plant trait complexity and is consistent with current theoretical approaches to characterize the structure of observational data. The over-arching utility of the proposed database structure is illustrated based on two independent plant trait database projects. 4. The generic database structure proposed here is meant to serve as a flexible blueprint for future plant trait databases, improving data discovery, and ensuring compatibility among them.

关键词： ancillary data bio-informatics covariates dimensional data model eco-informatics functional biodiversity hierarchical data structure relational database star-scheme

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SEGMENTATION OF PICTURES INTO REGIONS WITH A TILE-BY-TILE METHOD

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PATTERN RECOGNITION 1982年第1期15卷 1-10页

作者： BROWNING, JD TANIMOTO, SL UNIV WASHINGTON DEPT COMP SCISEATTLEWA 98195

A method is presented for segmenting a digital picture into regions of uniform value. Unlike most other methods, this method considers the image a piece at a time. Based upon the split-and-merge approach, the method is time-efficient. An important advantage over previous methods, however, is this method"s space-efficiency. Large pictures are easily handled, since main memory need only accommodate a relatively small portion of the picture, together with the accumulated segmentation, which in practice can be easily represented much more compactly than the picture array can. Moreover, this ‘tile’-based approach organizes the computation of a segmentation in such a way that parallel processors can readily be applied to cut the time required. Also presented are ways to incorporate edge information into segmentation decisions when the primary local feature of interest is brightness. An implementation of the method and the results it produced are discussed.

关键词： Picture processing Segmentation Region analysis Minicomputer Tile-oriented Split-and-merge Region linking Split-and-group-with-linking Pyramid hierarchical data structure

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DomLock: A New Multi-Granularity Locking Technique for Hierarchies

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ACM TRANSACTIONS ON PARALLEL COMPUTING 2017年第2期4卷 1–29页

作者： Kalikar, Saurabh Nasre, Rupesh IIT Madras CSE Dept Madras 600036 Tamil Nadu India

We present efficient locking mechanisms for hierarchical data structures. Several applications work on an abstract hierarchy of objects, and a parallel execution on this hierarchy necessitates synchronization across workers operating on different parts of the hierarchy. Existing synchronization mechanisms are too coarse, too inefficient, or too ad hoc, resulting in reduced or unpredictable amount of concurrency. We propose a new locking approach based on the structural properties of the underlying hierarchy. We show that the developed techniques are efficient evenwhen the hierarchy is an arbitrary graph. Theoretically, we present our approach as a locking-cost-minimizing instance of a generic algebraic model of synchronization for hierarchies. Using STMBench7, we illustrate considerable reduction in the locking cost, resulting in an average throughput improvement of 42%.

关键词： hierarchical data structure trees graphs object graphs locking synchronization dominators

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A simple statistical guide for the analysis of behaviour when data are constrained due to practical or ethical reasons

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ANIMAL BEHAVIOUR 2016年第0期120卷 223-234页

作者： Zsolt Garamszegi, Laszlo CSIC Estn Biol Donana Dept Evolutionary Ecol C Amer Vespucio S-N Seville 41092 Spain

Here, I provide a practical overview on some statistical approaches that are able to handle the constraints that frequently emerge in the study of animal behaviour. When collecting or analysing behavioural data, several sources of limitations, which can raise either uncertainties or biases in the parameter estimates, need to be considered. In particular, these can be issues about (1) limited sample size and missing data, (2) uncertainties about the identity of subjects and the dangers posed by pseudoreplication, (3) large measurement errors resulting from the use of indicator variables with nonperfect reliability or variables with low repeatability, (4) the confounding effect of the within-individual variation of behaviour and (5) phylogenetic nonindependence of data (e.g. when substitute species are used). I suggest some simple analytical solutions to these problems based on existing methodologies and on a consumable language to practitioners. I highlight how randomization and simulation routines, generalized linear mixed models, autocorrelation models, phylogenetic comparative methods and Bayesian statistics can be exploited to overcome the inefficient performance of some conventional statistical approaches with typical behavioural data. To enhance the accessibility of these methodologies, I demonstrate how they can be brought into practice in the R statistical environment, which offers flexible statistical designs. Although the primary motivation behind this discussion was to help animal behaviourists who address questions in relation to conservation, I also hope that researchers working on the evolutionary ecology of behaviour will also find some material useful. (C) 2015 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

关键词： bias bootstrap confidence interval effect size hierarchical data structure nonparametric statistics null hypothesis testing precision statistical power study design

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