Zoomless Maps: External Labeling Methods for the Interactive Exploration of Dense Point Sets at a Fixed Map Scale

Area of Science:

• Computational Cartography
• Geographic Information Systems (GIS)
• Human-Computer Interaction (HCI)

Background:

• Visualizing dense spatial data on small screens (smartphones, smartwatches) presents significant cartographic challenges.
• Current map exploration relies heavily on zooming and panning, which can lead to loss of context and graphical clutter.
• High feature density on small displays necessitates novel approaches beyond traditional map interaction techniques.

Purpose of the Study:

• To introduce novel external labeling methods for navigating dense point-of-interest data on small-screen devices.
• To enable users to explore features without constant zooming, maintaining map context.
• To provide a unified algorithmic framework for various interaction techniques in external labeling.

Main Methods:

• Developed external labeling methods where labels are placed at the map boundary and connected to features via leaders.
• Implemented interaction techniques (sliding, paging, stacking) to systematically select and display subsets of features.
• Proposed a generic algorithmic framework to model these interaction techniques as optimization problems, solved by exact algorithms and heuristics.

Main Results:

• Demonstrated the effectiveness of external labeling for dense spatial data visualization on limited screen real estate.
• Evaluated algorithms considering label ranking, leader length, and leader spacing, showing flexibility and performance on real-world data.
• Quantified the strengths and weaknesses of sliding, paging, and stacking interaction variants.

Conclusions:

• External labeling methods offer a viable solution for exploring dense spatial datasets on small devices without compromising context.
• The unified algorithmic framework provides a flexible approach to optimize label placement and interaction techniques.
• The proposed methods enhance user experience in mobile cartographic applications by improving feature accessibility and reducing interaction overhead.