Abstract: Animating objects' movements is widely used to facilitate tracking changes and observing both the global trend and local hotspots where objects converge or diverge. Existing methods, however, often obscure critical local hotspots by only considering the start and end positions of objects' trajectories. To address this gap, we propose RouteFlow, a trajectory-aware animated transition method that effectively balances the global trend and local hotspots while minimizing occlusion. RouteFlow is inspired by a real-world bus route analogy: objects are regarded as passengers traveling together, with local hotspots representing bus stops where these passengers get on and off. Based on this analogy, animation paths are generated like bus routes, with the object layout generated similarly to seat allocation according to their destinations. Compared with state-of-the-art methods through a quantitative experiment and a user study, RouteFlow better facilitates identifying the global trend and locating local hotspots while performing comparably in tracking objects' movements.

Motivation

Animating object movements along trajectories is crucial for understanding complex data. For example, in bird migration studies, animations help visualize movement trends and identify local hotspots where birds converge or diverge. These hotspots are key to understanding migration patterns, yet existing animation methods often fail to clearly highlight them, focusing too much on global trends or obscuring important details.

Recent techniques have attempted to address this, such as grouping transitions or reducing occlusion. However, they still struggle to balance global trends with local hotspots effectively.

To overcome this, we introduce RouteFlow, a system inspired by the bus route analogy. Objects are animated along shared paths, with local hotspots acting as key points where objects converge or diverge. This approach ensures both global trends and local hotspots are visible without occlusion, offering a clearer and more interactive way to explore trajectory data.

Formulation Highlight: Bus Route Analogy

In our animation system, RouteFlow, we use a real-world bus route analogy to design object movements. Objects with similar trajectories are grouped together, moving along shared animation paths like passengers on the same bus. Local hotspots act as "bus stops," where objects converge or diverge. This approach captures both global trends and local hotspots effectively, simplifying complex trajectories while preserving critical convergence points. The process is formulated as a sequential optimization problem, divided into two sub-problems: trajectory-driven path generation (similar to planning bus routes) and object layout generation (akin to seat allocation). This sequential approach ensures efficient path generation and minimizes occlusion.

Example Animations

Related Works

• A Vector Field Design Approach to Animated Transitions. TVCG 2018.
• Focus+Context Grouping for Animated Transitions. J Vis Lang Comput 2018.