Origin-Destination Flow Maps in Immersive Environments (1908.02089v1)

Abstract: Immersive virtual- and augmented-reality headsets can overlay a flat image against any surface or hang virtual objects in the space around the user. The technology is rapidly improving and may, in the long term, replace traditional flat panel displays in many situations. When displays are no longer intrinsically flat, how should we use the space around the user for abstract data visualisation? In this paper, we ask this question with respect to origin-destination flow data in a global geographic context. We report on the findings of three studies exploring different spatial encodings for flow maps. The first experiment focuses on different 2D and 3D encodings for flows on flat maps. We find that participants are significantly more accurate with raised flow paths whose height is proportional to flow distance but fastest with traditional straight line 2D flows. In our second and third experiment, we compared flat maps, 3D globes and a novel interactive design we call MapsLink, involving a pair of linked flat maps. We find that participants took significantly more time with MapsLink than other flow maps while the 3D globe with raised flows was the fastest, most accurate, and most preferred method. Our work suggests that careful use of the third spatial dimension can resolve visual clutter in complex flow maps.

• The paper evaluates various 2D and 3D origin-destination flow map representations for immersive virtual and augmented reality environments through three controlled user studies.
• Key findings indicate that a 3D globe representation with flow heights proportional to distance is the most accurate and efficient method, outperforming traditional 2D flat map depictions.
• The research suggests 3D visualizations in immersive spaces can overcome limitations of 2D map clutter and provides a foundation for future work in immersive data analytics, despite challenges with novel methods like MapsLink.

Evaluating Origin-Destination Flow Maps in Immersive Environments

The paper "Origin-Destination Flow Maps in Immersive Environments" by Yalong Yang et al. provides an in-depth examination of visualizing origin-destination (OD) flow data within immersive virtual- and augmented-reality environments. With the increasing prominence of head-mounted displays (HMDs) for both virtual reality (VR) and augmented reality (AR), there is a growing interest in how abstract data visualizations, such as OD flow maps, can be enhanced by such technologies. This paper investigates the efficacy of traditional 2D flow maps against innovative 3D representations, systematically exploring how different spatial presentations influence the readability and user interaction with global geographic flow data.

Methodology and Experiments

Three controlled user studies were conducted to evaluate the impact of different flow map representations:

1. Flow Representation in Flat Maps: The first paper compared different 2D and 3D flow encodings on flat maps. Five configurations were tested: 2D straight lines, 2D curves, and 3D flow tubes with varying height encodings (constant height, height proportional to quantity, and height proportional to distance). The paper concluded that while participants were fastest with 2D straight lines, they were most accurate with 3D flows where height was proportional to flow distance.
2. Reference Space Variation: The second paper expanded on varying the reference space by comparing a flat map with 2D flows, 3D flows on both flat and globular maps, and a novel MapsLink approach that utilized linked flat maps. Of note, the 3D globe with raised flows was identified as both the fastest and most accurate method, outperforming traditional flat map depictions even though potential occlusion issues were present.
3. Scalability with Dense Flow Data: The third paper focused on scalability by presenting denser flow datasets (with 200 and 300 flows). The paper confirmed the previously observed advantages of the 3D globe representation, which remained both accurate and efficient, even with increased data density.

Key Results and Implications

The findings indicate that conventional 2D origin-destination flow maps may not be optimally suited for immersive environments, particularly when dealing with complex datasets. The paper highlights several key points:

• 3D Globe Superiority: The 3D globe representation, where flow heights are proportionate to the distance between origin and destination, consistently proved to be the most effective across tasks, suggesting that 3D visualizations in immersive environments can overcome the limitations imposed by traditional 2D map clutter.
• MapsLink Challenges: The innovative MapsLink structure showed promise through increased interaction possibilities, yet user feedback and performance metrics revealed it to be less efficient, indicating potential areas for further refinement.
• User Interaction and Preference: Participants favored the 3D globe for its clarity and the minimal interaction effort required. The ability to navigate through flows via head movement or changing perspectives offered by VR headsets proved advantageous.

Future Directions

The enhancement of data visualizations within immersive environments is a burgeoning field. This research underscores the potential of 3D representations in overcoming traditional visualization challenges. Future work could include exploring collaborative and real-time interactions, utilizing AR with improved field-of-view, and incorporating additional data attributes within existing map structures. Further, evaluating such techniques across different user tasks and domains will provide broader insights into their applicability and usefulness.

In conclusion, Yang et al.'s rigorous approach to evaluating OD flow maps in VR environments provides significant insights into the potential benefits and challenges of utilizing 3D visualizations for complex data sets. The studies provide a solid foundation for future evaluations and developments in the immersive analytics domain.