Showing papers by "Kazuo Misue published in 2019"

Mental Map Preservation for Progressively Labeling Railway Networks

Abstract: Schematizing railway networks for better readability is often achieved by aligning railway lines along the octilinear directions. However, such railway map layouts require further adjustment when placing station name labels. In this article, the authors present a novel approach to automating the placement of station names around the railway network while maximally respecting its original layout as the mental map. The key idea is to progressively annotate stations from congested central downtown areas to sparse rural areas. This is accomplished by introducing the sum of geodesic distances over the railway network to properly order the stations to be annotated first, and then elongating the line segments of the railway network while retaining their directions to spare enough labeling space around each station. Additional constraints are also introduced to restrict the aspect ratios of the region confined by the railway network for better preservation of the mental map.

Scale-Aware Cartographic Displacement Based on Constrained Optimization

Abstract: The consistent arrangement of map features in accordance with the map scale has recently been technically important in digital cartographic generalization. This is primarily due to the recent demand for informative mapping systems, especially for use in smartphones and tablets. However, such sophisticated generalization has usually been conducted manually by expert cartographers and thus results in a time-consuming and error-prone process. In this paper, we focus on the displacement process within cartographic generalization and formulate them as a constrained optimization problem to provide an associated algorithm implementation and its effective solution. We first identify the underlying spatial relationships among map features, such as points and lines, on each map scale as constraints and optimize the cost function that penalizes excessive displacement of the map features in terms of the map scale. Several examples are also provided to demonstrate that the proposed approach allows us to maintain consistent mapping regardless of changes to the map scale.

Evaluation of Effectiveness of Glyphs to Enhance ChronoView

Abstract: ChronoView is a visualization method of representing periodic features of the occurrence of events. It expresses a set of time stamps in the position on a plane. Although ChronoView offers high space efficiency, it can generate ambiguous representations. To solve this problem, glyphs have been exploited as ChronoView markers. This paper explains a user study conducted to investigate the effectiveness of the Star Glyph and Ring Glyph. The study shows that glyphs contribute to an accurate reading of temporal features. It also shows that Star Glyph and Ring Glyph have different features. It is clear that, whereas Ring Glyph dominates the time range reading, Star Glyph dominates the comparison of frequencies in the unit of time.

Graph Drawing with Morphing Partial Edges

Abstract: A partial edge drawing (PED) of a graph is a variation of a node-link diagram. PED draws a link, which is a partial visual representation of an edge, and reduces visual clutter of the node-link diagram. However, more time is required to read a PED to infer undrawn parts. The authors propose a morphing edge drawing (MED), which is a PED that changes with time. In MED, links morph between partial and complete drawings; thus, a reduced load for estimation of undrawn parts in a PED is expected. Herein, a formalization of MED is shown based on a formalization of PED. Then, requirements for the scheduling of morphing are specified. The requirements inhibit morphing from crossing and shorten the overall time for morphing the edges. Moreover, an algorithm for a scheduling method implemented by the authors is illustrated and the effectiveness of PED from a reading time viewpoint is shown through an experimental evaluation.

Evaluation of Representation Fidelity to Similarity in ChronoView

Abstract: ChronoView is a visualization method representing periodic features of event occurrence times. It represents each event group (i.e., each set of time stamps) as a position on a plane. While ChronoView has high space efficiency, it has representational ambiguity. For example, while two similar sets must be placed at positions close to each other, two sets placed at positions close to each other need not always be similar. A three-dimensional development of ChronoView has been proposed to solve this problem. This paper presents a numerical experiment to evaluate how similarities between event groups are faithfully represented by Euclidean distance in a presentation space. The experiment shows that the three-dimensional ChronoView's faithfulness is higher than that of two-dimensional ChronoView and lower than that of three-dimensional multidimensional scaling (MDS) but comparable to that of two-dimensional MDS.

Graph Drawing with Morphing Partial Edges

Abstract: A partial edge drawing (PED) of a graph is a variation of a node-link diagram. PED draws a link, which is a partial visual representation of an edge, and reduces visual clutter of the node-link diagram. However, more time is required to read a PED to infer undrawn parts. The authors propose a morphing edge drawing (MED), which is a PED that changes with time. In MED, links morph between partial and complete drawings; thus, a reduced load for estimation of undrawn parts in a PED is expected. Herein, a formalization of MED is shown based on a formalization of PED. Then, requirements for the scheduling of morphing are specified. The requirements inhibit morphing from crossing and shorten the overall time for morphing the edges. Moreover, an algorithm for a scheduling method implemented by the authors is illustrated and the effectiveness of PED from a reading time viewpoint is shown through an experimental evaluation.