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  • Copernicus GmbH  (6)
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  • Copernicus GmbH  (6)
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  • 1
    Online Resource
    Online Resource
    Copernicus GmbH ; 2023
    In:  Abstracts of the ICA Vol. 6 ( 2023-08-12), p. 1-2
    In: Abstracts of the ICA, Copernicus GmbH, Vol. 6 ( 2023-08-12), p. 1-2
    Type of Medium: Online Resource
    ISSN: 2570-2106
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2023
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    Copernicus GmbH ; 2019
    In:  Abstracts of the ICA Vol. 1 ( 2019-07-15), p. 1-2
    In: Abstracts of the ICA, Copernicus GmbH, Vol. 1 ( 2019-07-15), p. 1-2
    Abstract: Abstract. The past few decades have seen the development of automatically feature labelling when manual label placement was thought to be time and labour consuming. Emerging techniques like volunteered geographic information (VGI) collection are making label placement more complexed with many features in a limited space, especially for points of interest (POI). In order to improve the quality and the efficiency of point feature labelling, there have been massive researches focusing on issues like position models, assessment criteria and optimization methods. Most of the researches were using vector-based methods while raster-based methods were less used, because vector-based methods have the advantage of easy definition of features and labels but are usually followed by computation complexity problems for features with high density. In contrast raster-based methods are faster and more flexible, though being harder to represent features and labels precisely on the map grids. Considering that hexagon partitioning was rarely used in raster-based methods, compared with the most commonly used square portioning, and hexagon was potentially useful for its oblique sides and isotropic orientations, hexagonal grids were used in this research to investigate better point feature labelling approaches.A new raster-based method was promoted to figure out high quality label placement of POI in dense area. Labels were placed on a hexagonal map grids based on the principles that one Chinese character is set to one hexagon unit with the mathematical relationship of h = ((√3+1)/2)a, while h is the side length of a hexagon unit and a is the size of a Chinese character. Considering that hexagon grids are divided into flat topped type and pointy topped type, which leads to different orientations, split hexagons were promoted to extend orientations from 6 to 8 based on pointy topped grids. A hexagon is partitioned into two parts labelled ‘left’ and ‘right’ and a split hexagon is the combination of a ‘left’ part and a ‘right’ part separately from two neighboring hexagons, as shown in figure 1. Then every hexagon on the grid will have four status: not-occupied {(0,0)}, half-occupied {(0,1) and (1,0)} and both-occupied {(1,1)}. Based on the fundamental concepts above, specific definitions were made on how labels were supposed to be represented on hexagonal map grids, including the length, orientation, writing direction, character orientation and position of the labels.The approach first initially arranges labels of POI with different combinations of label orientations while pursuing coherence as much as possible, including procedures of rasterization of vector data, POI grouping and initial scheme computation. Every POI in a same group would have same label orientation and every POI group may have several accessible orientations thus making initial schemes diverse. Then a second positioning algorithm was conducted to handle overlapping (labels with POI, labels with labels) problems and improve the overall quality of labelling. The algorithm used the methods of position changing and label turning, which allow label to change its position around POI and sometimes change the orientation when it is necessary to avoid collisions. Quality of labels in a closed block was assessed from three aspects: preferential orientation, occlusion and spaciousness. POI data was chosen from restaurant, hotel and shop facilities and figure 2 showed one of the examples of label placement results using this method. The results have shown good orientation consistency of labels and occlusions were reduced to the lowest, though several label-label occlusions remained due to the limited space. After being compared with vector-based method, the approach has shown better performance on maintaining map legibility, aesthetics and harmony.
    Type of Medium: Online Resource
    ISSN: 2570-2106
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2019
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  • 3
    Online Resource
    Online Resource
    Copernicus GmbH ; 2023
    In:  Abstracts of the ICA Vol. 6 ( 2023-08-12), p. 1-2
    In: Abstracts of the ICA, Copernicus GmbH, Vol. 6 ( 2023-08-12), p. 1-2
    Type of Medium: Online Resource
    ISSN: 2570-2106
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2023
    Location Call Number Limitation Availability
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  • 4
    Online Resource
    Online Resource
    Copernicus GmbH ; 2023
    In:  Abstracts of the ICA Vol. 6 ( 2023-08-12), p. 1-2
    In: Abstracts of the ICA, Copernicus GmbH, Vol. 6 ( 2023-08-12), p. 1-2
    Type of Medium: Online Resource
    ISSN: 2570-2106
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2023
    Location Call Number Limitation Availability
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  • 5
    Online Resource
    Online Resource
    Copernicus GmbH ; 2019
    In:  Abstracts of the ICA Vol. 1 ( 2019-07-15), p. 1-2
    In: Abstracts of the ICA, Copernicus GmbH, Vol. 1 ( 2019-07-15), p. 1-2
    Abstract: Abstract. Compared with regular quadrilateral grid, regular hexagonal grid is isotropy and has higher cell compactness and sampling density. This gives regular hexagonal grid advantages in visual display, spatial analysis, and many other aspects. However, the studies of raster data mainly focus on regular quadrilateral grid, and various encoding methods are also focused on it. The researches on hexagonal raster data are relatively insufficient.In this paper, encoding and compression for regular hexagonal grid are studied. By introducing Gosper curve which has good spatial aggregation and takes into account the morphological structure of regular hexagonal grid, the bidirectional correlation between Gosper curve and regular hexagonal grid is established. Then, a new encoding framework is built to determine the Gosper coding of each grid unit. The lossless compression is completed by performing run-length coding on adjacent coding sets in the target region.
    Type of Medium: Online Resource
    ISSN: 2570-2106
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2019
    Location Call Number Limitation Availability
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  • 6
    Online Resource
    Online Resource
    Copernicus GmbH ; 2019
    In:  Abstracts of the ICA Vol. 1 ( 2019-07-15), p. 1-2
    In: Abstracts of the ICA, Copernicus GmbH, Vol. 1 ( 2019-07-15), p. 1-2
    Abstract: Abstract. As an important representation of LBS (Location Based Service), the indoor map provides users with facility location, indoor navigation, wayfinding and other necessary services. Compared with the common map, the indoor map has characteristics of detailed representation, 3D visualization, and real-time reaction. As far as POI (Point of Interest) representation is concerned, the common urban map just visualizes the location and the basic attribute in a simple way by relatively large scale representation. In the indoor map, however, the POI needs to represent the 3D location (level, longitude, latitude), the access path, and some detailed service information. Take the map of shopping mall as an example, traditionally, some services visualize restaurants that should have been distributed at different layers in a crowding way, with icons touching and overlapping with each other. Therefore, the LOD (level of detail) strategy needs to be applied to obtain adaptive representation for users with different objectives.To satisfy the requirements of the new indoor map about POI visualization, this study explores the multi-scale method in 3D indoor mapping. We develop an indoor map which is integrated into an outdoor base map and all the floors of the whole building are stacked vertically. In this way, the problem of icon clustering could be overcome to an extent, POI data are visualized vertically in indoor space, each floor can be taken out like opening a drawer in order to make sure that all the POIs can be seen clearly. We adopt a scale adaptive strategy to visualize POI data in the indoor map. At large scale, the general floor distribution indicating the main function of each floor and functional partition of each floor is represented by different colors. At medium scale, POI data are visualized by simple symbols which can represent basic attribute information. At small scale, detailed service information (e.g., opening hours, number of seats remaining, price range and user ratings of a restaurant) of a POI that users are particularly interested in is described by well-designed map symbols based on the combination of visual variables. In addition, our POI visualization method is user-adaptive. Different data, symbols or color schemes will be shown for users with different age group, gender or purpose of using map. Because this indoor map is adaptive to both scale and user, each scale of the map can provide different map users with decision support from a different perspective.
    Type of Medium: Online Resource
    ISSN: 2570-2106
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2019
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