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A 7-TUPLE REPRESENTATION FOR hierarchical data-structures

INFORMATION SYSTEMS 1983年第3期8卷 151-157页

作者： NIEMI, T University of Tampere Department of Mathematical Sciences Computer Science P.O. Box 607 SF-33101 Tampere 10 Finland

Different kinds of data structure diagrams, especially Bachman's, and tabular representations are very often used to visualize hierarchical data structures. The popularity of these visual modes of representation is due to the possibility they afford of describing data structures clearly and regardless of any implementation. However, it has been observed in diverse contexts that instead of the visualization we need a general and exact representation containing the same structural components as these visual representations. In this paper we introduce a seven-tuple representation which can be used for exact description of any hierarchical data structure. We give both the explicit construction operations and the implicit rules which can be utilized in forming any hierarchical data structure. We show that the formal representation introduced contains the descriptive power of the visualization methods mentioned above. Furthermore we examine how, in the context of this representation, it is possible to define flexibly general analyzing functions for hierarchical data structures.

关键词： hierarchical data structures data structure diagrams tabular representation recursive data structures

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NPSNET: hierarchical data structures for real-time three-dimensional visual simulation.

NPSNET: hierarchical data structures for real-time three-dim...

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作者： Randall Lee Mackey NAVAL POSTGRADUATE SCHOOL

学位级别：硕士

NPSNET is a low-cost visual simulation system designed and constructed at the Naval Postgraduate School. 'SNET uses digital terrain data and renders scenes involving vehicles, aircraft, cultural features, and natural itures in real-time. The implementation of a terrain paging algorithm in NPSNET is discussed. Terrain paging pands the terrain area available for simulation and overcomes the limits of main memory size. hierarchical data uctures commonly used in visual simulation systems are surveyed. The generation of a multi-resolution terrain: aset and the implementation of a hierarchical data structure are explained. The multi-resolution dataset is created generating lower resolution descriptions of polygons from the original data. The hierarchical data structure used NPSNET, based on quadtrees, provides a means to attenuate the resolution of terrain over distance and cull those rtions of terrain outside of the user's field of view.

关键词： Computer Graphics Simulators hierarchical data structures Digital Terrain data

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THE QUADTREE AND RELATED hierarchical data-structures

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COMPUTING SURVEYS 1984年第2期16卷 187-260页

作者： SAMET, H Computer Science Department University of Maryland College Park Maryland

A tutorial survey is presented of the quadtree and related hierarchical data structures. They are based on the principle of recursive decomposition. The emphasis is on the representation of data used in applications in image processing, computer graphics, geographic information systems, and robotics. There is a greater emphasis on region data (i.e., two-dimensional shapes) and to a lesser extent on point, curvilinear, and three-dimensional data. A number of operations in which such data structures find use are examined in greater detail. [ABSTRACT FROM AUTHOR]

关键词： Geographic information systems hierarchical data structures image databases multiattribute data multidimensional data structures octrees pattern recognition point data quadtrees robotics.

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Cylindrical static and kinetic Binary Space Partitions

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COMPUTATIONAL GEOMETRY-THEORY AND APPLICATIONS 2000年第2期16卷 103-127页

作者： Agarwal, PK Guibas, LJ Murali, TM Vitter, JS Duke Univ Dept Comp Sci Ctr Geometr Comp Durham NC 27708 USA Stanford Univ Dept Comp Sci Stanford CA 94305 USA Compaq Comp Corp Cambridge Res Lab Cambridge MA 02139 USA

We describe the first known algorithm for efficiently maintaining a Binary Space Partition (BSP) for n continuously moving segments in the plane, whose interiors remain disjoint throughout the motion. Under reasonable assumptions on the motion, we show that the total number of times this BSP changes is O(n(2)), and that we can update the BSP in O(log n) expected time per change. Throughout the motion, the expected size of the BSP is O(n log n). We also consider the problem of constructing a BSP for n static triangles with pairwise-disjoint interiors in R-3. We present a randomized algorithm that constructs a BSP of size O(n(2)) in O(n(2) log(2) n) expected time. We also describe a deterministic algorithm that constructs a BSP of size O((n + k) log(2) n) and height O(log n) in O((n + k) log(3) n) time, where k is the number of intersection points between the edges of the projections of the triangles onto the xy-plane. This is the first known algorithm that constructs a BSP of O(log n) height for disjoint triangles in R-3. (C) 2000 Elsevier Science B.V. All rights reserved.

关键词： Binary Space Partitions hierarchical data structures kinetic data structures computational geometry computer graphics

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SMART SENSING WITHIN A PYRAMID VISION MACHINE

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PROCEEDINGS OF THE IEEE 1988年第8期76卷 1006-1015页

作者： BURT, PJ David Sarnoff Res. Center Princeton NJ USA

A machine is designed, based on a pyramid architecture, that supports smart sensing and related highly efficient processing. Key elements of the design are (a) hierarchical data structures for image representation, (b) fine-to-coarse algorithms for the fast generation of image measures, (c) coarse-to-fine search strategies that rapidly locate objects or events within a scene, and (d) high-level control mechanisms that guide data gathering even as visual information is being interpreted. This system, known as the Pyramid Vision Machine, achieves high performance at modest cost. Design considerations and several applications are described.<>

关键词： applications coarse-to-fine search strategies computer architecture computer vision design considerations fast generation of image measures fine-to-coarse algorithms guide data gathering hierarchical data structures high performance high-level control mechanisms highly efficient processing image representation modest cost pyramid architecture pyramid vision machine rapidly locate objects smart sensing

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External memory management and simplification of huge meshes

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IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2003年第4期9卷 525-537页

作者： Cignoni, P Montani, C Rocchini, C Scopigno, R CNR Ist Sci & Tecnol Informaz Area Ric I-56124 Pisa Italy

Very large triangle meshes, i.e., meshes composed of millions of faces, are becoming common in many applications. Obviously, processing, rendering, transmission, and archiving of these meshes are not simple tasks. Mesh simplification and LOD management are a rather mature technology that, in many cases, can efficiently manage complex data. But, only a few available systems can manage meshes characterized by a huge size: RAM size is often a severe bottleneck. In this paper, we present a data structure called Octree-based External Memory Mesh (OEMM). It supports external memory management of complex meshes, loading dynamically in main memory only the selected sections and preserving data consistency during local updates. The functionalities implemented on this data structure (simplification, detail preservation, mesh editing, visualization, and inspection) can be applied to huge triangles meshes on low-cost PC platforms. The time overhead due to the external memory management is affordable. Results of the test of our system on complex meshes are presented.

关键词： out-of-core algorithms hierarchical data structures mesh simplification level of detail 3D scanning texture synthesis

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Efficient collision detection for models deformed by morphing

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VISUAL COMPUTER 2003年第2-3期19卷 164-174页

作者： Larsson, T Akenine-Möller, T Malardalen Univ Dept Comp Sci & Engn Vasteras Sweden Chalmers Inst Technol Dept Comp Engn Gothenburg Sweden

We describe a fast and accurate collision-detection algorithm specialised for models deformed by morphing. The models considered are meshes where the vertex positions are convex combinations of sets of reference meshes. This new method is based on bounding-volume trees that are extended to support efficient tree-node updates by blending associated sets of reference bounding volumes. With our approach, it is possible to use either axis-aligned bounding boxes, discrete-orientation polytopes, or spheres as bounding volumes. The expected performance of our algorithm is of the same order as for rigid hierarchical collision detection. In our tested scenarios, the speed-up we achieved ranged from 1.5 to 58, compared to another more general algorithm for deforming bodies.

关键词： collision detection morphing deformable bodies hierarchical data structures virtual reality

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A hierarchical BOUNDARY MODEL FOR SOLID OBJECT REPRESENTATION

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ACM TRANSACTIONS ON GRAPHICS 1988年第1期7卷 42-60页

作者： DEFLORIANI, L FALCIDIENO, B CNR IST MATEMAT APPLVIA LB ALBERTI 4I-16132 GENOVAITALY

A new hierarchical model for solid object representation is described. This model, called a hierarchical face adjacency hypergraph (HFAH), is based on a relational description of the object boundary, called a face adjacency hypergraph (FAH), which considers faces as the primary topological entities defining the object boundary. The HFAH consists of a hierarchy of FAHs describing the decomposition of the boundary of an object into form features. In this paper the HFAH is described together with its internal encoding structure. Two basic transformations, called refinement and abstraction, are defined on the hierarchical model; these allow effective and efficient modifications of the hierarchical boundary model.

关键词： hierarchical data structures solid modeling boundary representations tree graphs

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COMPUTING GEOMETRIC-PROPERTIES OF IMAGES REPRESENTED BY LINEAR QUADTREES

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IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE 1985年第2期7卷 229-240页

作者： SAMET, H TAMMINEN, M HELSINKI UNIV TECHNOL INFORMAT PROC SCI LABSF-02150 ESPOO 15FINLAND

The region quadtree is a hierarchical data structure that finds use in applications such as image processing, computer graphics, pattern recognition, robotics, and cartography. In order to save space, a number of pointerless quadtree representations (termed linear quadtrees) have been proposed. One representation maintains the nodes in a list ordered according to a preorder traversal of the quadtree. Using such an image representation and a graph definition of a quadtree, a general algorithm to compute geometric image properties such as the perimeter, the Euler number, and the connected components of an image is developed and analyzed. The algorithm differs from the conventional approaches to images represented by quadtrees in that it does not make use of neighbor finding methods that require the location of a nearest common ancestor. Instead, it makes use of a staircase-like data structure to represent the blocks that have been already processed. The worst-case execution time of the algorithm, when used to compute the perimeter, is proportional to the number of leaf nodes in the quadtree, which is optimal. For an image of size 2n × 2n, the perimeter algorithm requires only four arrays of 2n positions each for working storage. This makes it well suited to processing linear quadtrees residing in secondary storage. Implementation experience has confirmed its superiority to existing approaches to computing geometric properties for images represented by quadtrees.","doi":"10.1109/TPAMI.1985.4767646","publicationTitle":"IEEE Transactions on Pattern Analysis and Machine Intelligence","startPage":"229","endPage":"240","rightsLink":"http://***/AppDispatchServlet?publisherName=ieee&publication=0162-8828&title=Computing+Geometric+Properties+of+Images+Represented+by+Linear+Quadtrees&isbn=&publicationDate=March+1985&author=Hanan+Samet&ContentID=10.1109/TPAMI.1985.4767646&orderBeanReset=true&startPage=229&endPage=240&volumeNum=PAMI-7&issueNum=2","displayPublicatio

关键词： data structures Image storage Application software Image processing Computer graphics Pattern recognition Orbital robotics Image representation Image analysis Algorithm design and analysis Author Keywords quadtrees Computer graphics connected component labeling DF-expressions Euler number hierarchical data structures image processing linear quadtrees pattern recognition perimeter

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A REAL-TIME ROBOT ARM COLLISION AVOIDANCE SYSTEM

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IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION 1992年第2期8卷 149-160页

作者： SHAFFER, CA HERB, GM Department of Computer Science Virginia Polytechnic Institute and State University Blacksburg VA USA

A data structure and update algorithm are presented for a prototype real-time collision avoidance safety system simulating a multirobot workspace. The data structure is a variant of the octree, which serves as a spatial index. An octree recursively decomposes three-dimensional space into eight equal cubic octants until each octant meets some decomposition criteria. We use the N-objects octree, which indexes a collection of 3-D primitive solids. These primitives make up the two seven-degrees-of-freedom robot arms and workspace modeled by the system. Octree nodes containing more than a predetermined number N of primitives are decomposed. This rule keeps the octree small, as the entire world model for our application can be implemented using a few dozen primitives. As robot arms move, the octree is updated to reflect their changed positions. During most update cycles, any given primitive does not change which octree nodes it is in. Thus, modification to the octree is rarely required. Incidents in which one robot arm comes too close to another arm or an object are reported. Cycle time for interpreting current arm joint angles, updating the octree to reflect new positions, and detecting/reporting imminent collisions averages 30 ms on an Intel 80386 processor running at 20 MHz.

关键词： COLLISION AVOIDANCE hierarchical data structures OCTREES TELEOPERATED ROBOTS

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