Focus+Glue+Context: an improved fisheye approach for web map services

  • Authors:

  • Daisuke Yamamoto;Shotaro Ozeki;Naohisa Takahashi

  • Affiliations:

  • Nagoya Institute of Technlogy, Showa-ku, Nagoya, Aichi, Japan;Nagoya Institute of Technlogy, Showa-ku, Nagoya, Aichi, Japan;Nagoya Institute of Technlogy, Showa-ku, Nagoya, Aichi, Japan

  • Venue:
  • Proceedings of the 17th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems
  • Year:
  • 2009

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Abstract

This paper proposes a method for generating a Focus+Glue+Context map for Web map services by improving existing fisheye views methods for cartographic data. While many studies have focused on fisheye views, the problems of the excessively large distortions that maps have over their entire area and/or the high density of roads in the borders of the maps have yet to be resolved. To completely remove the distortions in both the Focus and the Context areas, we propose the inclusion of a Glue area between the two areas. Moreover, we propose the following features. (1) We propose the Dynamic Displacement function to generate a Focus and a Glue having an arbitrary convex or star-shaped polygon. (2) Since the Glue area absorbs all distortion from the Focus and the Context areas, the density of roads along the angular direction of the Glue will be excessively high. To reduce the density of roads, we propose the Following Paths algorithm to display only those roads that are along the radial direction and that are reached from the Focus area to the Context area. This method enables users to understand a map easily with high visibility of the Glue area. (3) To realize Web map services, we have to generate a map quickly. Therefore, the Glue area is generated dynamically, while the Focus and the Context areas display previously generated static maps. These maps are composited in a client Web browser by the Dynamic Map Composition method. We developed a prototype of our system that implements these features and evaluated the advantages of the proposed method. The new system can contribute to novel Web map services with fisheye views.