# Many-to-Many Geographically-Embedded Flow Visualisation: An Evaluation

## TL;DR

This paper evaluates different visualisation techniques for complex many-to-many geographic flow data, comparing their effectiveness through user studies and introducing a new visualisation called MapTrix.

## Contribution

It introduces MapTrix, a novel visualisation for dense flow data, and provides a comparative evaluation of its performance against existing methods.

## Key findings

- OD Maps and MapTrix perform similarly in user tasks.
- Bundled node-link flow maps do not scale well with data complexity.
- Performance of OD Maps and MapTrix remains consistent on larger datasets.

## Abstract

Showing flows of people and resources between multiple geographic locations is a challenging visualisation problem. We conducted two quantitative user studies to evaluate different visual representations for such dense many-to-many flows. In our first study we compared a bundled node-link flow map representation and OD Maps [37] with a new visualisation we call MapTrix. Like OD Maps, MapTrix overcomes the clutter associated with a traditional flow map while providing geographic embedding that is missing in standard OD matrix representations. We found that OD Maps and MapTrix had similar performance while bundled node-link flow map representations did not scale at all well. Our second study compared participant performance with OD Maps and MapTrix on larger data sets. Again performance was remarkably similar.