Maps and Globes in Virtual Reality (1908.02088v1)

Abstract: This paper explores different ways to render world-wide geographic maps in virtual reality (VR). We compare: (a) a 3D exocentric globe, where the user's viewpoint is outside the globe; (b) a flat map (rendered to a plane in VR); (c) an egocentric 3D globe, with the viewpoint inside the globe; and (d) a curved map, created by projecting the map onto a section of a sphere which curves around the user. In all four visualisations the geographic centre can be smoothly adjusted with a standard handheld VR controller and the user, through a head-tracked headset, can physically move around the visualisation. For distance comparison, exocentric globe is more accurate than egocentric globe and flat map. For area comparison, more time is required with exocentric and egocentric globes than with flat and curved maps. For direction estimation, the exocentric globe is more accurate and faster than the other visual presentations. Our study participants had a weak preference for the exocentric globe. Generally, the curved map had benefits over the flat map. In almost all cases the egocentric globe was found to be the least effective visualisation. Overall, our results provide support for the use of exocentric globes for geographic visualisation in mixed-reality.

• The paper demonstrates that the exocentric globe delivers superior accuracy in spatial analysis compared to other VR geovisualizations.
• It employs a controlled experiment with 32 participants using Unity3D and HTC Vive to assess perceptual distortions and user comfort.
• The findings advocate for hybrid visualization techniques that combine the strengths of globes and flat maps while reducing motion sickness.

Overview of "Maps and Globes in Virtual Reality" by Yang et al.

The paper by Yalong Yang and collaborators focuses on the visualization of geographic data in virtual reality (VR), more specifically through various representations of the Earth. Four distinct visualization techniques are examined: the exocentric globe, the flat map, the egocentric globe, and the curved map. These visualizations are critically evaluated for their effectiveness in facilitating three specific spatial analysis tasks: distance comparison, area comparison, and direction estimation.

Methodology

The authors implemented the visualizations using the Unity3D engine and tested these on an HTC Vive headset. Each visualization technique is carefully crafted to either minimize perceptual or projection distortion, or both. Importantly, each representation allows users to adjust the geographic center with a VR controller and supports a degree of head-tracked interaction to change viewpoints. The paper's methodological rigor is demonstrated through a controlled experiment with 32 participants performing a comprehensive set of spatial analysis tasks.

Findings

The exocentric globe emerges as the most effective visualization across most tasks, outperforming alternative methods, particularly in terms of accuracy. The geometric representation of the globe ensures minimal distortion due to projection, which has substantial implications for user performance in distance and direction estimation tasks. However, a noted drawback is the limited visibility of only half the globe's surface, which presumably complicates some tasks, particularly those related to global spatial analysis.

The flat map, characterized by significant projection distortions, particularly in direction estimation, was found to be less effective in tasks requiring precise spatial judgment, such as small variation conditions in distance and area comparisons. Nevertheless, its ability to present the entire Earth's surface makes it time-efficient for certain tasks.

The egocentric globe, despite its immersive nature, was rated the lowest due to increased perceptual distortion and a pronounced propensity to induce motion sickness among participants. Its usage was further complicated by the excess physical movement it necessitated, resulting in generally slower task completion times.

The curved map offers a compromise between familiarity and immersion, performing well in direction estimation tasks, especially when compared to the flat map. Yet, it induces the second most motion sickness after the egocentric globe, which could impair prolonged use.

Implications and Future Work

This paper highlights the significance of visualization choices in VR applications, emphasizing the trade-offs between immersion, accuracy, and user comfort. Its findings endorse the exocentric globe for VR applications requiring global geovisualization while suggesting potential improvements through hybrid visualization methods that might leverage both maps and globes.

The authors propose future work to include further exploration on reducing motion sickness within the curved map and better understanding thematic map analysis tasks within VR. The paper opens a dialogue for creating hybrid systems enabling seamless transitions between exocentric globes and flat maps, thereby potentially overcoming each method's inherent limitations.

Conclusion

The research provides valuable insights for the development of VR geovisualization applications, crucial for mixed-reality environments catering to both collaborative and individual analytic tasks. While each visualization technique examined has specific advantages, the exocentric globe stands out as an excellent reference point for future advancements. The paper suggests a promising trajectory towards more dynamic, fluid visual interactions in VR, which may incorporate adaptive visualization techniques to negate the limitations observed within static representations.