Multi-level tree based approach for interactive graph visualization with semantic zoom
This work addresses the need for effective interactive graph visualization tools, particularly for tasks like memorization and recall, but it is incremental as it builds on prior studies comparing map-like to node-link representations.
The paper tackles the problem of visualizing large graphs by proposing the Zoomable Multi-Level Tree (ZMLT) algorithm for map-like visualizations, which maintains seven desirable properties such as appropriate representation at different detail levels and no edge crossings, and implements a functional prototype in a web browser.
Human subject studies that map-like visualizations are as good or better than standard node-link representations of graphs, in terms of task performance, memorization and recall of the underlying data, and engagement [SSKB14, SSKB15]. With this in mind, we propose the Zoomable Multi-Level Tree (ZMLT) algorithm for multi-level tree-based, map-like visualization of large graphs. We propose seven desirable properties that such visualization should maintain and an algorithm that accomplishes them. (1) The abstract trees represent the underlying graph appropriately at different level of details; (2) The embedded trees represent the underlying graph appropriately at different levels of details; (3) At every level of detail we show real vertices and real paths from the underlying graph; (4) If any node or edge appears in a given level, then they also appear in all deeper levels; (5) All nodes at the current level and higher levels are labeled and there are no label overlaps; (6) There are no edge crossings on any level; (7) The drawing area is proportional to the total area of the labels. This algorithm is implemented and we have a functional prototype for the interactive interface in a web browser.