17 research outputs found
Representing Images Using the Quadtree Data Structure (Hebrew Consonants and Vowels)
Computing and Information Science
Diamond-based models for scientific visualization
Hierarchical spatial decompositions are a basic modeling tool in a variety of application domains including scientific visualization, finite element analysis and shape modeling and analysis. A popular class of such approaches is based on the regular simplex bisection operator, which bisects simplices (e.g. line segments, triangles, tetrahedra) along the midpoint of a predetermined edge. Regular simplex bisection produces adaptive simplicial meshes of high geometric quality, while simplifying the extraction of crack-free, or conforming, approximations to the original dataset. Efficient multiresolution representations for such models have been achieved in 2D and 3D by clustering sets of simplices sharing the same bisection edge into structures called diamonds. In this thesis, we introduce several diamond-based approaches for scientific visualization. We first formalize the notion of diamonds in arbitrary dimensions in terms of two related simplicial decompositions of hypercubes. This enables us to enumerate the vertices, simplices, parents and children of a diamond. In particular, we identify the number of simplices involved in conforming updates to be factorial in the dimension and group these into a linear number of subclusters of simplices that are generated simultaneously. The latter form the basis for a compact pointerless representation for conforming meshes generated by regular simplex bisection and for efficiently navigating the topological connectivity of these meshes. Secondly, we introduce the supercube as a high-level primitive on such nested meshes based on the atomic units within the underlying triangulation grid. We propose the use of supercubes to associate information with coherent subsets of the full hierarchy and demonstrate the effectiveness of such a representation for modeling multiresolution terrain and volumetric datasets. Next, we introduce Isodiamond Hierarchies, a general framework for spatial access structures on a hierarchy of diamonds that exploits the implicit hierarchical and geometric relationships of the diamond model. We use an isodiamond hierarchy to encode irregular updates to a multiresolution isosurface or interval volume in terms of regular updates to diamonds. Finally, we consider nested hypercubic meshes, such as quadtrees, octrees and their higher dimensional analogues, through the lens of diamond hierarchies. This allows us to determine the relationships involved in generating balanced hypercubic meshes and to propose a compact pointerless representation of such meshes. We also provide a local diamond-based triangulation algorithm to generate high-quality conforming simplicial meshes
New data structures and algorithms for the efficient management of large spatial datasets
[Resumen] En esta tesis estudiamos la representación eficiente de matrices multidimensionales,
presentando nuevas estructuras de datos compactas para almacenar y procesar
grids en distintos ámbitos de aplicación. Proponemos varias estructuras de datos
estáticas y dinámicas para la representación de matrices binarias o de enteros
y estudiamos aplicaciones a la representación de datos raster en Sistemas de
Información Geográfica, bases de datos RDF, etc.
En primer lugar proponemos una colección de estructuras de datos estáticas para
la representación de matrices binarias y de enteros: 1) una nueva representación
de matrices binarias con grandes grupos de valores uniformes, con aplicaciones
a la representación de datos raster binarios; 2) una nueva estructura de datos
para representar matrices multidimensionales; 3) una nueva estructura de datos
para representar matrices de enteros con soporte para consultas top-k de rango.
También proponemos una nueva representación dinámica de matrices binarias, una
nueva estructura de datos que proporciona las mismas funcionalidades que nuestras
propuestas estáticas pero también soporta cambios en la matriz.
Nuestras estructuras de datos pueden utilizarse en distintos dominios. Proponemos
variantes especÃficas y combinaciones de nuestras propuestas para representar
grafos temporales, bases de datos RDF, datos raster binarios o generales y
datos raster temporales. También proponemos un nuevo algoritmo para consultar
conjuntamente un conjuto de datos raster (almacenado usando nuestras propuestas)
y un conjunto de datos vectorial almacenado en una estructura de datos clásica,
mostrando que nuestra propuesta puede ser más rápida y usar menos espacio que
otras alternativas. Nuestras representaciones proporcionan interesantes trade-offs y
son competitivas en espacio y tiempos de consulta con representaciones habituales
en los diferentes dominios.[Resumo] Nesta tese estudiamos a representación eficiente de matrices multidimensionais,
presentando novas estruturas de datos compactas para almacenar e procesar grids
en distintos ámbitos de aplicación. Propoñemos varias estruturas de datos estáticas
e dinámicas para a representación de matrices binarias ou de enteiros e estudiamos
aplicacións á representación de datos raster en Sistemas de Información Xeográfica,
bases de datos RDF, etc.
En primeiro lugar propoñemos unha colección de estruturas de datos estáticas
para a representación de matrices binarias e de enteiros: 1) unha nova representación
de matrices binarias con grandes grupos de valores uniformes, con aplicacións
á representación de datos raster binarios; 2) unha nova estrutura de datos
para representar matrices multidimensionais; 3) unha nova estrutura de datos
para representar matrices de enteiros con soporte para consultas top-k. Tamén
propoñemos unha nova representación dinámica de matrices binarias, unha nova
estrutura de datos que proporciona as mesmas funcionalidades que as nosas
propostas estáticas pero tamén soporta cambios na matriz.
As nosas estruturas de datos poden utilizarse en distintos dominios. Propoñemos
variantes especÃficas e combinacións das nosas propostas para representar grafos temporais,
bases de datos RDF, datos raster binarios ou xerais e datos raster temporais.
Tamén propoñemos un novo algoritmo para consultar conxuntamente datos raster
(almacenados usando as nosas propostas) con datos vectoriais almacenados nunha
estrutura de datos clásica, amosando que a nosa proposta pode ser máis rápida e
usar menos espazo que outras alternativas. As nosas representacións proporcionan
interesantes trade-offs e son competitivas en espazo e tempos de consulta con
representacións habituais nos diferentes dominios.[Abstract] In this thesis we study the efficient representation of multidimensional grids,
presenting new compact data structures to store and query grids in different
application domains. We propose several static and dynamic data structures for the
representation of binary grids and grids of integers, and study applications to the
representation of raster data in Geographic Information Systems, RDF databases,
etc.
We first propose a collection of static data structures for the representation of
binary grids and grids of integers: 1) a new representation of bi-dimensional binary
grids with large clusters of uniform values, with applications to the representation
of binary raster data; 2) a new data structure to represent multidimensional binary
grids; 3) a new data structure to represent grids of integers with support for top-k
range queries. We also propose a new dynamic representation of binary grids, a new
data structure that provides the same functionalities that our static representations
of binary grids but also supports changes in the grid.
Our data structures can be used in several application domains. We propose
specific variants and combinations of our generic proposals to represent temporal
graphs, RDF databases, OLAP databases, binary or general raster data, and
temporal raster data. We also propose a new algorithm to jointly query a raster
dataset (stored using our representations) and a vectorial dataset stored in a classic
data structure, showing that our proposal can be faster and require less space than
the usual alternatives. Our representations provide interesting trade-offs and are
competitive in terms of space and query times with usual representations in the
different domains
Design and performance evaluation of indexing methods for dynamic attributes in mobile database management systems
Ankara : Department of Computer Engineering and Information Science and the Institute of Engineering and Science of Bilkent University, 1997.Thesis(Master's) -- Bilkent University, 1997.Includes bibliographical references leaves 99-104.Tayeb, JamelM.S
Data Structures & Algorithm Analysis in C++
This is the textbook for CSIS 215 at Liberty University.https://digitalcommons.liberty.edu/textbooks/1005/thumbnail.jp
Multiresolution Techniques for Real–Time Visualization of Urban Environments and Terrains
In recent times we are witnessing a steep increase in the availability of data coming from real–life environments.
Nowadays, virtually everyone connected to the Internet may have instant access to a tremendous amount of data coming from satellite elevation maps, airborne time-of-flight scanners and digital cameras, street–level photographs and even cadastral maps.
As for other, more traditional types of media such as pictures and videos, users of digital exploration softwares expect commodity hardware to exhibit good performance for interactive purposes, regardless of the dataset size.
In this thesis we propose novel solutions to the problem of rendering large terrain and urban models on commodity platforms, both for local and remote exploration.
Our solutions build on the concept of multiresolution representation, where alternative representations of the same data with different accuracy are used to selectively distribute the computational power, and consequently the visual accuracy, where it is more needed on the base of the user’s point of view.
In particular, we will introduce an efficient multiresolution data compression technique for planar and spherical surfaces applied to terrain datasets which is able to handle huge amount of information at a planetary scale.
We will also describe a novel data structure for compact storage and rendering of urban entities such as buildings to allow real–time exploration of cityscapes from a remote online repository.
Moreover, we will show how recent technologies can be exploited to transparently integrate virtual exploration and general computer graphics techniques with web applications