SeeThroughBody: Mitigating Occlusion through Body Transparency to Enhance Touch Interaction between the Foot and Interactive Floor

Research Background and Issues

• Issues and Challenges: This study aims to address the inefficiency caused by user body occlusion during foot-ground interaction in virtual environments. Traditional touch interfaces are often affected by hand or body occlusion, particularly the full-body occlusion problem known as the Fat-foot Problem. This issue becomes more pronounced when using head-mounted displays (HMDs) for foot-based interactions.
• Significance: With the development of virtual reality technology, HMD-supported foot interaction applications are becoming increasingly prevalent, such as map navigation and virtual keyboards. Designing solutions that effectively reduce occlusion and optimize interaction experiences can enhance user efficiency and satisfaction.
• Research Motivation and Related Work: Existing studies have attempted to mitigate occlusion by adjusting the position of interactive elements or employing post-trigger display methods. However, these approaches are limited by spatial constraints and fail to fully improve the interaction experience. Research on hand transparency has demonstrated its potential to optimize interaction, but studies applying transparency to the body and feet in interaction remain insufficient.

Solution

• Method and Solution: The authors propose "SeeThroughBody," a method that reduces occlusion in virtual environments through transparent body rendering. This approach allows users to employ transparent or outline rendering during foot interactions to avoid body occlusion.
• Innovations: This method is the first to apply body transparency rendering to foot interactions, introducing two key design principles: interaction scenarios aimed at improving efficiency and holistic user experience scenarios. Specific design recommendations for implementing transparency are also proposed.
• Implementation Steps and Key Technologies:
  1. Explore the interaction effects of different body part visibilities (BodyPartsVisibility) and visualization styles (VisualizationStyles).
  2. Analyze the severity of occlusion issues and the impact of transparency on user performance (efficiency) and experience (usability, immersion).
  3. Conduct user studies using an optical tracking system and virtual reality headsets (HTC VIVE) to capture full-body movements and render the user’s body in the virtual environment in real time.

Research Outcomes

• Specific Findings:
  • Transparent and outline rendering significantly reduce occlusion issues, improving task completion time and reducing head movements.
  • Displaying the full body or thigh sections enhances user embodiment, increasing the sense of identification with the virtual body.
  • Transparent rendering achieves a good balance between efficiency and user experience.
• Advantages Over Existing Solutions: This approach improves interaction efficiency and user experience while addressing full-body occlusion issues. Compared to adjusting element positions or post-trigger displays, transparent rendering offers greater interaction flexibility and optimizes user immersion.
• Experimental and Evaluation Results:
  • In efficiency-driven interactions, Transparent-Foot and Outline-Foot performed the best.
  • For overall user experience, Transparent-All and Transparent-Thigh provided better immersion.
  • Experimental results were comprehensively evaluated through analysis of task completion times, head rotation angles, and user questionnaires.
• Limitations and Future Directions:
  • Limitations: The virtual body’s width and clothing were not precisely modeled; transparency was fixed at specific values, which may interfere with visual effects in complex backgrounds.
  • Future directions include:
    1. Enhancing the accuracy of virtual body modeling, such as incorporating 3D scanning technology.
    2. Investigating the application of transparency in augmented reality (AR) environments and assessing safety during interactions with real-world objects.
    3. Extending transparent rendering to hand interactions or other input methods.

Conclusion

"SeeThroughBody" is an innovative interaction design method that provides a novel solution to the occlusion issues in foot-based touch interfaces by optimizing body transparency and partial visibility. This method not only improves efficiency but also enhances user immersion, making it suitable for virtual reality application design. It offers valuable insights for integrating more complex environments and scenarios in the future.