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RESEARCH PAPER / 2026-04-09

Bridging the Gap between Micro-scale Traffic Simulation and 4D Digital Cityscapes

Longxiang Jiao, Lukas Hofmann, Yiru Yang ...Full author list in the original paper.

ETH Zurich +1 · ETH Zurich +1

Affiliations: ETH Zurich, University of Zurich

Abstract

While micro-scale traffic simulations provide essential data for urban planning, they are rarely coupled with the high-fidelity visualization or auralization necessary for effective stakeholder communication. In this work, we present a real-time 4D visualization framework that couples the SUMO traffic with a photorealistic, geospatially accurate VR representation of Zurich in Unreal Engine 5. Our architecture implements a robust C++ data pipeline for synchronized vehicle visualization and features an Open Sound Control (OSC) interface to support external auralization engines. We validate the framework through a user study assessing the correlation between simulated traffic dynamics and human perception. Results demonstrate a high degree of perceptual alignment, where users correctly interpret safety risks from the 4D simulation. Furthermore, our findings indicate that the inclusion of spatialized audio alters the user's sense of safety, showing the importance of multimodality in traffic simulations.

The following analysis is generated by AI and may contain errors. It is separate from the authors’ abstract and is not peer review.

Research summary

This paper effectively bridges the gap between abstract traffic simulation and immersive visualization, contributing a novel framework that enhances urban planning through real-time, multimodal simulations. The technical contributions, particularly in the areas of data synchronization and user perception evaluation, position this work as a meaningful advancement in the field of machine learning and urban simulation technologies.

Methodology

The paper presents a comprehensive methodology for integrating microscale traffic simulation with high-fidelity visualization in a VR environment. The use of the SUMO traffic simulation coupled with Unreal Engine 5 for immersive rendering is innovative, particularly in its implementation of a robust C++ data pipeline and an OSC interface for auralization. The asynchronous producer-consumer approach to handle network communication without freezing the rendering thread is a significant technical contribution. The detailed description of vehicle data processing, including interpolation and coordinate transformation, showcases a well-thought-out approach to ensuring smooth and realistic visualizations.

Results & evaluation

The user study conducted with 20 participants is a strong aspect of the paper, providing quantitative and qualitative insights into the effectiveness of the proposed framework. The results indicate a high degree of perceptual alignment between simulated dynamics and user perception, particularly highlighting the impact of spatial audio on perceived safety and realism. The statistical analysis, including paired t-tests, adds rigor to the findings, although the sample size could be considered a limitation.

Reproducibility

While the paper mentions that the code will be published later, the absence of a project URL or demo link limits immediate reproducibility. The detailed methodology, however, provides a solid foundation for other researchers to replicate the study, assuming access to the same tools and datasets.

Limitations

Key limitations include the uni-directional coupling of the simulation, which restricts real-time interactions between pedestrians and vehicles, and the reliance on external photorealistic city tiles that may not generalize well to other urban environments. Additionally, the potential for simulator sickness due to hardware limitations is acknowledged but not quantitatively evaluated.

Broader impact

The framework has significant implications for urban planning and transportation engineering, offering a tool that enhances stakeholder communication and public engagement through immersive simulations. The integration of multimodal feedback (visual and auditory) could lead to improved safety perceptions and urban design decisions. This paper effectively bridges the gap between abstract traffic simulation and immersive visualization, contributing a novel framework that enhances urban planning through real-time, multimodal simulations. The technical contributions, particularly in the areas of data synchronization and user perception evaluation, position this work as a meaningful advancement in the field of machine learning and urban simulation technologies.

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