Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 21 for “"quadtree"”.
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Table-driven quadtree traversal algorithms
Two quadtree algorithms are presented that use table driven traversals to reduce the time complexity required to achieve their respective goals. The first algorithm is a two step process that converts a boundary representation of a polygon into a corresponding region representation of the same …
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A quadtree approach to parallel image processing
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.
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Representation Of Dam-Breach Geometry Using Quadtree Local Mesh Refinement
… done to facilitate the implementation of quadtree local mesh refinement to represent dam breach geometry in an existing two-dimensional flood model and to test the model's results and performance with several test cases. Results using local refinement agree with the results of global …
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A paging scheme for pointer-based quadtrees
The quadtree is a family of data structures that organize spatial data using recursive subdivision. A pointer-based quadtree uses an explicit tree structure to represent the subdivision, while a linear quadtree holds a sorted list of records corresponding to the leaves of the tree structure. Small …
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A Family of Hierarchical Encoding Techniques for Image and Video Communications
… by building our encoding techniques based on the quadtree and octree representation methods.</p> <p>First we developed an image encoding technique using the quadtree representation of images and vector quantization. We use a mean-removal technique to separate the means image and the difference …
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An Object-oriented design for hierarchical B-spline surfaces
… This design uses a spatial data structure, the quadtree, to achieve this goal. The quadtree, itself a hierarchical data structure, is very suitable in this application because of its ability to focus on the interesting subsets of the data. This focusing results in an efficient representation. …
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Adaptive Learning Terrain Estimation for Unmanned Aerial Vehicle Applications
… and tree-like data structures, like Octomap and Quadtrees. Since flight vehicles have different constraints, ground-based terrain mapping research may not be directly applicable to the aerospace industry. To address this issue, Adaptive Learning Terrain Estimation algorithms have been developed …
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Automated Adaptive Data Center Generation For Meshless Methods
… locally cartesian point distribution a recursive quadtree scheme is herein proposed. The quadtree method allows modeling of irregular geometries and refinement of regions of interest and it lends itself for full automation, thus, reducing problem setup efforts. Furthermore, the construction of the …
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Using simulations to predict the genetic connectivity of the Mojave desert tortoise
… desert tortoise. In Chapter 1, I describe the quadtree R package, which implements the region quadtree data structure in C++ and makes it available to the R programming environment - using this data structure increases the speed of the agent-based model. In Chapter 2, I calibrate and validate …
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Estendendo quadtress para suporte ao armazenamento e recuperação de dados espaço-temporais
… trabalho é estender estruturas de dados do tipo quadtree para suporte ao armazenamento e à recuperação de dados espaço-temporais.
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An Adaptive Mesh Refinement Scheme for Solidification Problems
Methods for adaptive mesh refinement, based on a quadtree data structure, have been developed with the specific objective of tracking a solid/liquid front in a two-dimensional solidification problem. These methods include mesh refinement and unrefinement algorithms for the finite element method …
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Mesh generation using a correspondence distance field
… to discrete surface points embedded within a quadtree data structure. The theory, development, and implementation of the distance field tool are described, and two main applications to two-dimensional mesh generation are presented with extension to three-dimensional capabilities in mind. First …
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Optimizations to a massively parallel database and support of a shared scan architecture
… means of an indexing framework. We implement a QuadTree spatial partitioning scheme and demonstrate how it improves the latencies of many queries when using the index as opposed to not using any. Moreover, we tackle the challenge of processing many queries (perhaps issued concurrently) where …
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The elevation pyramid: a method for compressing elevation data
A quadtree-like representation for storing gridded elevation data is described. In its simplest form, the data structure is a pyramid with each node containing a two bit code. The root of the pyramid has associated with it the minimum elevation for the grid and the range (the greatest power of 2 …
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A z-ordering cartesian grid method and its application in flow simulation
… structure. By deploying this ordering to quadtree/octree, a robust grid navigation algorithm is developed. The algorithm simplifies the grid's navigation procedure, which is usually the most time consuming part in both the grid generation and flow simulation. A binary coding system is …
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Digital image compression.
… plane image coding system based on a hierarchic quadtree structure in a transmission domain, using the Hadamard transform as a kernel. Good compression has been achieved from this scheme, particularly for images with low detail. The second scheme uses a learning automata to predict the …
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Using Visual Analytics to Discover Bot Traffic
… represent legitimate and bot traffic by adopting Quadtree data structure and Voronoi diagrams. The main contribution of this thesis is a novel visual analytics system that is capable of discovering bot traffic.This research conducted a literature review in order to gain systematic understanding of …
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Three-Dimensional Numerical Modeling Of Multiple-Sized Sediment Transport Modeling Under Current And Waves
… grid. The computational mesh is composed of quadtree rectangular grid on the horizontal plane and sigma coordinate in the vertical direction. The SIMPLEC algorithm with Rhie and Chow's momentum interpolation is used to couple the flow velocity and water level. A coupled solution procedure is …
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High-fidelity simulation and data-driven modeling of drop aerobreakup.
… The computaitonal domain is discretized using a quadtree/octree mesh to allow local refinement of mesh in user defined region. We have started from simulations of water drops at millimeter size and moderate We. The simulation results for drop shape evolution are validated against experiment and …
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