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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Progressive Spatial Networks

Curren, Samuel 17 April 2009 (has links) (PDF)
Digital street and trail maps are typically represented by an interconnected network of path segments. These spatial networks are used in map creation, route planning, and geo-location. Consumer GPS devices have become popular as a method of collecting data for use in spatial networks. Existing methods for creating spatial networks either require extensive hand editing or use inefficient algorithms that require re-computation when adding new data to an existing network. I demonstrate a method for creating and maintaining spatial networks that allows for incremental updates without complete re-computation. I also demonstrate how spatial limits on data set growth allows networks to be updated in linear time after initial path discovery. This approach allows networks to be rapidly and accurately updated using data from consumer GPS devices.
2

An Edge-Based Algorithm for Spatial Query Processing in Real-Life Road Networks

Wu, Xu-Lun 14 July 2011 (has links)
Due to wireless communication technologies, positioning technologies, and mobile computing develop quickly, mobile services are becoming practical and important on big spatiotemporal databases management. Mobile service users move only inside a spatial network, e.g. a road network. They often issue the K Nearest Neighbor (KNN) query to obtain data objects reachable through the road network. The challenge problem of mobile services is how to efficiently answer the data objects which user interest to the corresponding mobile users. Therefore, how to effectively modeling road networks, effectively indexing, and querying on the road networks have become a popular topic. Lu et. al. have proposed a road network model that captures the real-life road networks better than previous models. Then, based on their model, they have proposed a RNG (Road Network Grid) index for speeding up the KNN query on real-life road networks. The RNG index structure is a quad-tree structure and a point-based structure. However, in their model, they divide the double track road which U-turn is allowed at some parts. This modeling does not capture the real-life road networks accurately. Since they divide the road, this makes the number of points of the graph increase. The number of times of partitioning the graph increases. It increases the execution time of constructing the index structure. The format of the leaf node of the RNG index makes the search time increase. Moreover, the query processing on the RNG index structure has to visit the root repeatedly. This condition makes the search time increase. Therefore, in this thesis, we propose a network model that captures the real-life road networks. We do not have to divide the real-life roads when we map the real-life roads into graph. We map the real-life road networks into graph directly. Then, based on our network model, we propose an EBNA (Edge-Based Nine-Area tree) index structure to make the search time of obtaining the interest edge information quickly. The EBNA index structure is an edge-based index structure. We store all of the edge information on the leaf node. We can obtain the edge information directly. Each edge information entry has a pointer point to link edges. Links of each edge entry consist a graph. This graph makes the KNN query processing visit the root only one time. From our simulation result, we show that the performance of constructing the EBNA index is better than constructing the RNG index and the performance of the KNN query processing by using EBNA index is better than the KNN query processing by using RNG index.
3

Valley of connections : Networks and spatiality in the archaeological landscape of the Morello Valley in central Sicily

Tegerdal Hune, Josefine January 2022 (has links)
This thesis uses GIS and spatial analysis to study connections in the archaeological landscape of the Morello Valley, in the Enna province in Sicily (Italy). To identify potential social relations, the idea of social networks is adapted into the spatial network analysis. The spatiality of 42 sites with archaeological layers from Mid-to Late Neolithic until Medieval times are explored by looking at intervisibility, movement and accessibility. A historical map is used to reconstruct hydrology, and spatial data is accessed to include ancient paths and sulphur resources. Phenomenological methods are also used to describe the landscape and applied in GIS and spatial analysis to explore how people may have related to their environment. Local and external contacts in Sicily throughout history are reflected upon through different time scales to give context to the spatial network analysis of the Morello Valley. Furthermore, links between people and landscape are also contemplated through the notion of affordances. Throughout the thesis, the methodology of spatial analyses is being assessed. The aim is to put emphasis on the practical process of analysing landscape and spatiality through networks, while at the same time analysing the connectedness of the Morello Valley.

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