Hochschule für Architektur, Bau und Geomatik FHNW
Dauerhafte URI für den Bereichhttps://irf.fhnw.ch/handle/11654/6
Listen
6 Ergebnisse
Bereich: Suchergebnisse
Publikation Real-time generalization of point data in mobile and web mapping using quadtrees(Taylor & Francis, 29.04.2013) Bereuter, Pia; Weibel, RobertWith a focus on mobile and web mapping, we propose several algorithms for on-the-fly generalization of point data, such as points of interest (POIs) or large point collections. In order to achieve real-time performance, we use a quadtree data structure. With their hierarchical subdivision structure and progressive levels of detail, indices of the quadtree family lend themselves as auxiliary data structures to support algorithms for generalization operations, including selection, simplification, aggregation, and displacement of point data. The spatial index can further be used to generate several local and global measures that can then serve to make educated guesses on the density and proximity of points across map scales, and thus enable control of the operation of the generalization algorithms. An implementation of the proposed algorithms has shown that, and thanks to the quadtree index, real-time performance can be achieved even for large point sets. Furthermore, the quadtree data structure can be extended into a caching structure, which can be used to store pre-computed generalizations; thus, a desired level of detail (LOD) can simply be retrieved from cache.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Content zooming and information exploration for web and mobile maps. Adaptation of real-time map generalisation to the information seeking strategies of web and mobile users(Lovoisier, 2013) Bereuter, Pia; Weibel, Robert; Burchardt, DirkIn the context of the development of mobile map applications with capabilities for map generalisation and abstraction, we propose a methodology for content exploration that uses a technique that we term content zooming to change the degree of abstraction of map content independently of the map scale. Content zooming allows overriding the effects of ‘standard’ map generalisation, focusing on optimised content representation to aid the information seeking task of a mobile user. It is thus complementary to map generalisation. The paper defines content zooming operations and proposes technical solutions for each of these, illustrating them with examples from a research prototype.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Generalisation operators(Springer, 08.07.2014) Stanislawski, Lawrence V.; Buttenfield, Barbara P.; Bereuter, Pia; Savino, Sandro; Brewer, Cynthia A.; Burghardt, Dirk; Duchêne, Cécile; Mackaness, WilliamThis chapter summarises cartographic generalisation operators used to generalise geospatial data. It includes a review of recent approaches that have been tested or implemented to generalise networks, points, or groups. Emphasis is placed on recent advances that permit additional flexibility to tailor generalisation processing in particular geographic contexts, and to permit more advanced types of reasoning about spatial conflicts, preservation of specific feature characteristics, and local variations in geometry, content and enriched attribution. Rather than an exhaustive review of generalisation operators, the chapter devotes more attention to operators associated with network generalisation, which illustrates well the logic behind map generalisation developments. Three case studies demonstrate the application of operators to road thinning, to river network and braid pruning, and to hierarchical point elimination. The chapter closes with some summary comments and future directions.04A - Beitrag SammelbandPublikation Editorial(Taylor & Francis, 23.01.2020) Touya, Guillaume; Bereuter, Pia; Raposo, Paulo01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Variable-scale maps in real-time generalisation using a quadtree data structure and space deforming algorithms(Taylor & Francis, 13.04.2017) Bereuter, Pia; Weibel, RobertVariable-scale maps have been advocated by several authors in the context of mobile cartography. In the literature on real-time map generalisation, however, corresponding methods that resolve cartographic conflicts by deformation of the underlying map space together with the map foreground, are underrepresented. This paper demonstrates how the concept of a malleable space can be applied as a part of the generalisation process and incorporated into the overall methodology of point generalisation. Two different algorithms are used, a density-equalising cartogram algorithm and Laplacian smoothing. Both methods work in real-time and are data-driven. In addition, they allow for a parameterisation in combination with a quadtree data structure, as well as a combination with ’classic’ generalisation operators (e.g. selection, aggregation, displacement) based on the quadtree. The quadtree serves both as a spatial index for fast retrieval and search of points, and as a density estimator to inform generalisation operators. The use of the quadtree as a common spatial index provides a tool to combine variable-scale maps with classic generalisation. A combination of the two allows, at small map scales, the maintenance of detail in dense areas and data reduction in sparse areas. Additionally, it facilitates building a modular workflow for real-time map generalisation.01A - Beitrag in wissenschaftlicher Zeitschrift
