TrajFlow: Nation-wide Pseudo GPS Trajectory Generation with Flow Matching Models
This work addresses the need for scalable and diverse GPS trajectory generation for applications like urban planning and traffic management, representing a novel advancement in the field.
The paper tackles the problem of generating pseudo-GPS trajectory data to overcome privacy and cost issues with real data, introducing TrajFlow, a flow-matching-based model that outperforms diffusion-based and other baselines at urban, metropolitan, and nationwide scales using a dataset with millions of trajectories across Japan.
The importance of mobile phone GPS trajectory data is widely recognized across many fields, yet the use of real data is often hindered by privacy concerns, limited accessibility, and high acquisition costs. As a result, generating pseudo-GPS trajectory data has become an active area of research. Recent diffusion-based approaches have achieved strong fidelity but remain limited in spatial scale (small urban areas), transportation-mode diversity, and efficiency (requiring numerous sampling steps). To address these challenges, we introduce TrajFlow, which to the best of our knowledge is the first flow-matching-based generative model for GPS trajectory generation. TrajFlow leverages the flow-matching paradigm to improve robustness and efficiency across multiple geospatial scales, and incorporates a trajectory harmonization and reconstruction strategy to jointly address scalability, diversity, and efficiency. Using a nationwide mobile phone GPS dataset with millions of trajectories across Japan, we show that TrajFlow or its variants consistently outperform diffusion-based and deep generative baselines at urban, metropolitan, and nationwide levels. As the first nationwide, multi-scale GPS trajectory generation model, TrajFlow demonstrates strong potential to support inter-region urban planning, traffic management, and disaster response, thereby advancing the resilience and intelligence of future mobility systems.