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Electronic Theses and Dissertations

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Articles 31 - 50 of 50

Full-Text Articles in Databases and Information Systems

Yellow Tree: A Distributed Main-Memory Spatial Index Structure For Moving Objects, Hariharan Gowrisankar Dec 2006

Yellow Tree: A Distributed Main-Memory Spatial Index Structure For Moving Objects, Hariharan Gowrisankar

Electronic Theses and Dissertations

Mobile devices equipped with wireless technologies to communicate and positioning systems to locate objects of interest are common place today, providing the impetus to develop location-aware applications. At the heart of location-aware applications are moving objects or objects that continuously change location over time, such as cars in transportation networks or pedestrians or postal packages. Location-aware applications tend to support the tracking of very large numbers of such moving objects as well as many users that are interested in finding out about the locations of other moving objects. Such location-aware applications rely on support from database management systems to model, …

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Personal Privacy Protection Within Pervasive Rfid Environments, Eeva Kaarina Hedefine Aug 2006

Personal Privacy Protection Within Pervasive Rfid Environments, Eeva Kaarina Hedefine

Electronic Theses and Dissertations

Recent advancements in location tracking technologies have increased the threat to an individual's personal privacy. Radio frequency identification (RFID) technology allows for the identification and potentially continuous tracking of an object or individual, without obtaining the individual's consent or even awareness that the tracking is taking place. Although many positive applications for RFID technology exist, for example in the commercial sector and law enforcement, the potential for abuse in the collection and use of personal information through this technology also exists. Location data linked to other types of personal information allows not only the detection of past spatial travel and …

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Semantic Similarity Of Spatial Scenes, Konstantinos A. Nedas Aug 2006

Semantic Similarity Of Spatial Scenes, Konstantinos A. Nedas

Electronic Theses and Dissertations

The formalization of similarity in spatial information systems can unleash their functionality and contribute technology not only useful, but also desirable by broad groups of users. As a paradigm for information retrieval, similarity supersedes tedious querying techniques and unveils novel ways for user-system interaction by naturally supporting modalities such as speech and sketching. As a tool within the scope of a broader objective, it can facilitate such diverse tasks as data integration, landmark determination, and prediction making. This potential motivated the development of several similarity models within the geospatial and computer science communities. Despite the merit of these studies, their …

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Generating Linear Orders Of Events For Geospatial Domains, Suzannah Hall Dec 2004

Generating Linear Orders Of Events For Geospatial Domains, Suzannah Hall

Electronic Theses and Dissertations

Events in the world do not occur in neat chronological order, but may take place, for example, during or overlapping each other, or as simultaneous events. Efficient summaries of real-world events are important in many disciplines and require events to be modeled in a linear fashion. This thesis focuses on modeling events as intervals and using relations between the events to derive linear orders from more complex partially ordered sets. A method is developed for mapping Allen's thirteen temporal relations to only two relations, before and equals, which allow a linear ordering of all events present in the set. This …

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Using Linear Features For Aerial Image Sequence Mosaiking, Caixia Wang Dec 2004

Using Linear Features For Aerial Image Sequence Mosaiking, Caixia Wang

Electronic Theses and Dissertations

With recent advances in sensor technology and digital image processing techniques, automatic image mosaicking has received increased attention in a variety of geospatial applications, ranging from panorama generation and video surveillance to image based rendering. The geometric transformation used to link images in a mosaic is the subject of image orientation, a fundamental photogrammetric task that represents a major research area in digital image analysis. It involves the determination of the parameters that express the location and pose of a camera at the time it captured an image. In aerial applications the typical parameters comprise two translations (along the x …

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Context-Specific Preference Learning Of One Dimensional Quantitative Geospatial Attributes Using A Neuro-Fuzzy Approach, Georgios Mountrakis Dec 2004

Context-Specific Preference Learning Of One Dimensional Quantitative Geospatial Attributes Using A Neuro-Fuzzy Approach, Georgios Mountrakis

Electronic Theses and Dissertations

Change detection is a topic of great importance for modern geospatial information systems. Digital aerial imagery provides an excellent medium to capture geospatial information. Rapidly evolving environments, and the availability of increasing amounts of diverse, multiresolutional imagery bring forward the need for frequent updates of these datasets. Analysis and query of spatial data using potentially outdated data may yield results that are sometimes invalid. Due to measurement errors (systematic, random) and incomplete knowledge of information (uncertainty) it is ambiguous if a change in a spatial dataset has really occurred. Therefore we need to develop reliable, fast, and automated procedures that …

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Structuring A Wayfinder's Dynamic And Uncertain Environment, Michael D. Hendricks May 2004

Structuring A Wayfinder's Dynamic And Uncertain Environment, Michael D. Hendricks

Electronic Theses and Dissertations

Wayfinders typically travel in dynamic environments where barriers and requirements change over time. In many cases, uncertainty exists about the future state of this changing environment. Current geographic information systems lack tools to assist wayfinders in understanding the travel possibilities and path selection options in these dynamic and uncertain settings. The goal of this research is a better understanding of the impact of dynamic and uncertain environments on wayfinding travel possibilities. An integrated spatio-temporal framework, populated with barriers and requirements, models wayfinding scenarios by generating four travel possibility partitions based on the wayfinder's maximum travel speed. Using these partitions, wayfinders …

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Query-By-Pointing: Algorithms And Pointing Error Compensation, Farhan Faisal Dec 2003

Query-By-Pointing: Algorithms And Pointing Error Compensation, Farhan Faisal

Electronic Theses and Dissertations

People typically communicate by pointing, talking, sketching, writing, and typing. Pointing can be used to visualize or exchange information about an object when there is no other mutually understood way of communication. Despite its proven expressiveness, however, it has not yet become a frequently used modality to interact with computer systems. With the rapid move towards the adoption of mobile technologies, geographic information systems (GISs) have a particular need for advanced forms of interaction that enable users to query the geographic world directly. To enable pointing-based query system on a handheld device, a number of fundamental technical challenges have to …

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Public Commons For Geospatial Data: A Conceptual Model, Chakravarthy Namindi Sharad Aug 2003

Public Commons For Geospatial Data: A Conceptual Model, Chakravarthy Namindi Sharad

Electronic Theses and Dissertations

A wide variety of spatial data collection efforts are ongoing throughout local, state and federal agencies, private firms and non-profit organizations. Each effort is established for a different purpose but organizations and individuals often collect and maintain the same or similar information. The United States federal government has undertaken many initiatives such as the National Spatial Data Infrastructure, the National Map and Geospatial One-Stop to reduce duplicative spatial data collection and promote the coordinated use, sharing, and dissemination of spatial data nationwide. A key premise in most of these initiatives is that no national government will be able to gather …

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The Integration Of Cadastral Base Mapping With Cadastral Parcel Attribution, Kurt B. Wurm May 2003

The Integration Of Cadastral Base Mapping With Cadastral Parcel Attribution, Kurt B. Wurm

Electronic Theses and Dissertations

A cadastre is a parcel-based, up-to-date land information system containing a record of interests in land. Creation and maintenance of a cadastre usually involves coordination between different public and private organizations that are responsible for the various data. The U.S. Bureau of Land Management (BLM) has built a Geographic Coordinate Data Base (GCDB) that currently provides cadastral base map data for more than 38,000 townships across the country, with many of the western states nearly complete. The GCDB strategy is that the coordinates can and do change as more recent and accurate information becomes available. The locational reliability of the …

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A Mathematical Model For Simplifying Representations Of Objects In A Geographic Information System, Gabriel Perrow Jan 2003

A Mathematical Model For Simplifying Representations Of Objects In A Geographic Information System, Gabriel Perrow

Electronic Theses and Dissertations

The study of operations on representations of objects is well documented in the realm of spatial engineering. However, the mathematical structure and formal proof of these operational phenomena are not thoroughly explored. Other works have often focused on query-based models that seek to order classes and instances of objects in the form of semantic hierarchies or graphs. In some models, nodes of graphs represent objects and are connected by edges that represent different types of coarsening operators. This work, however, studies how the coarsening operator "simplification" can manipulate partitions of finite sets, independent from objects and their attributes. Partitions that …

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Detection And Generalization Of Spatio-Temporal Trajectories For Motion Imagery, Panayotis Partsinevelos Dec 2002

Detection And Generalization Of Spatio-Temporal Trajectories For Motion Imagery, Panayotis Partsinevelos

Electronic Theses and Dissertations

In today's world of vast information availability users often confront large unorganized amounts of data with limited tools for managing them. Motion imagery datasets have become increasingly popular means for exposing and disseminating information. Commonly, moving objects are of primary interest in modeling such datasets. Users may require different levels of detail mainly for visualization and further processing purposes according to the application at hand. In this thesis we exploit the geometric attributes of objects for dataset summarization by using a series of image processing and neural network tools. In order to form data summaries we select representative time instances …

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Evaluating Conflicts In The Use And Development Of Geographic Information Systems, Amber Bethell Dec 2002

Evaluating Conflicts In The Use And Development Of Geographic Information Systems, Amber Bethell

Electronic Theses and Dissertations

Use of geographic information systems is increasing in governments, commercial companies, and by individual users. With such pervasive use of GIs there has been surprisingly little investigation of the values that various parties would support in the development of geographic technologies. There are many parties involved in the use of GIs each with opinions of what are good goals for developing and using such systems. This research seeks to determine differences and similarities among parties in the importance placed on supporting specific societal goals germane to the use of geographic technologies and databases. Previous research determined six areas where the …

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Modeling Boundaries Of Influence Among Positional Uncertainty Fields, Joshua P. King Dec 2002

Modeling Boundaries Of Influence Among Positional Uncertainty Fields, Joshua P. King

Electronic Theses and Dissertations

Within a CIS environment, the proper use of information requires the identification of the uncertainty associated with it. As such, there has been a substantial amount of research dedicated to describing and quantifying spatial data uncertainty. Recent advances in sensor technology and image analysis techniques are making image-derived geospatial data increasingly popular. Along with development in sensor and image analysis technologies have come departures from conventional point-by-point measurements. Current advancements support the transition from traditional point measures to novel techniques that allow the extraction of complex objects as single entities (e.g., road outlines, buildings). As the methods of data extraction …

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Sketch-Based Queries In Mobile Gis-Environments, David Caduff Dec 2002

Sketch-Based Queries In Mobile Gis-Environments, David Caduff

Electronic Theses and Dissertations

Recent achievements in the field of mobile computing and wireless communication promise data retrieval anywhere and anytime. This development provided the basis to expand GIs technology to handheld devices, such as personal digital assistants (PDAs). Although traditional GIs technology is well suited for desktop workstations, it needs to be adapted in order to satisfy the requirements of users using handheld computing devices. This adaptation is necessary because the usability of traditional GISs depends on characteristics of desktop computers, such as their relatively large user interfaces (e.g., displays, keyboards, pointing devices), considerable computing resources (i.e., CPU, memory, storage, operating systems), and …

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Modeling Multiple Granularities Of Spatial Objects, Chitra Ramalingam Dec 2002

Modeling Multiple Granularities Of Spatial Objects, Chitra Ramalingam

Electronic Theses and Dissertations

People conceptualize objects in an information space over different levels of details or granularities and shift among these granularities as necessary for the task at hand. Shifting among granularities is fundamental for understanding and reasoning about an information space. In general, shifting to a coarser granularity can improve one's understanding of a complex information space, whereas shifting to a more detailed granularity reveals information that is otherwise unknown. To arrive at a coarser granularity. objects must be generalized. There are multiple ways to perform generalization. Several generalization methods have been adopted from the abstraction processes that are intuitively carried out …

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Modeling Intersections Of Geospatial Lifelines, Ramaswam Hariharan Dec 2001

Modeling Intersections Of Geospatial Lifelines, Ramaswam Hariharan

Electronic Theses and Dissertations

Modeling moving objects involves spatio-temporal reasoning. The continuous movements of objects in space-time captured as discrete samples form geospatial lifelines. Existing lifeline models can represent the movement of objects between samples from most likely location to all possible locations. This thesis builds on a model called lifeline bead and necklace that captures all the possible locations of moving objects. Beads are 3-dimensional representations of an object's movements and a series of beads form a necklace. The extent of finding the possible locations is constrained by the speed of movement of the objects. Intersections of lifelines occur when two or more …

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Access To Geographic Scientific And Technical Data In An Academic Setting, Bastiaan Van Loenen May 2001

Access To Geographic Scientific And Technical Data In An Academic Setting, Bastiaan Van Loenen

Electronic Theses and Dissertations

Data availability is a key issue affecting society's social well being. Information technology has increased the availability of and improved access to data. The academic community that uses spatial data is one of the groups that has taken advantage of fast and inexpensive opportunities to share data and knowledge in a relatively unfettered fashion across digital networks. However, pressure by the private sector to increase protection for databases through database legislation, self-help measures (contracts, licensing and technological methods for limiting access) and movement by some local governments towards revenue generation from sales of data are decreasing or threatening to decrease …

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Ontology-Driven Geographic Information Systems, Frederico Torres Fonseca May 2001

Ontology-Driven Geographic Information Systems, Frederico Torres Fonseca

Electronic Theses and Dissertations

Information integration is the combination of different types of information in a framework so that it can be queried, retrieved, and manipulated. Integration of geographic data has gained in importance because of the new possibilities arising from the interconnected world and the increasing availability of geographic information. Many times the need for information is so pressing that it does not matter if some details are lost, as long as integration is achieved. To integrate information across computerized information systems it is necessary first to have explicit formalizations of the mental concepts that people have about the real world. Furthermore, these …

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Using Raster Sketches For Digital Image Retrieval, James Carswell May 2000

Using Raster Sketches For Digital Image Retrieval, James Carswell

Electronic Theses and Dissertations

This research addresses the problem of content-based image retrieval using queries on image-object shape, completely in the raster domain. It focuses on the particularities of image databases encountered in typical topographic applications and presents the development of an environment for visual information management that enables such queries. The query consists of a user-provided raster sketch of the shape of an imaged object. The objective of the search is to retrieve images that contain an object sufficiently similar to the one specified in the query. The new contribution of this work combines the design of a comprehensive digital image database on-line …

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