Multi-Touch Interactions on a Spherical Display

Hrvoje Benko, et al., Microsoft Research

Summary

This paper presents Sphere, a multi-user, multi-touch spherical display with shared projection and sensing paths and 360 degrees access without shadowing or occlusion effects. They also present some new interaction techniques and applications based on Sphere.

Details

Authors were attracted to the concept of a spherical display because of its 360 degrees field of view. While existing such devices were display only, authors combined a Magic Planet display with an IR camera to use the same optical axis as the projector for touch sensing. Touch sensing happens in IR spectrum using light from an IR illumination ring and hence is not disturbed by projector which has an IR cut filter to operate in visible spectrum only. The raw image from sphere is normalised, binary encoded and labelled to enable tracking using a C ++ library. Real time interaction requires runtime spherical distortion correction projection and sensing which was achieved using a vertex shader. Similarly content data needs to be authored in cylindrical or 3D Cartesian models.

Authors present a sample application for photo and video browsing which incorporates basic multi touch gestures such as drag, rotate and scale. To facilitate collaboration, auto-rotating (to ensure alignment irrespective of radial position), flicking (inertial flick movement) and send-to-dark-side (flat hand for 1s to send onto other side) were introduced. Circular menu items are selected by using orb like bimanual gestures. Another application for spherical data viewing introduced tether axis to to tether the manipulation of data display. Two games were also created using entire touch area.

User study provided following observations:

• Photo/video browsing happened independently but data display proved to be a problem due to conflict in multi-user inputs.
• Users were more willing to interact if display were left with ‘messy’ objects.
• Radial heat maps showed that there existed no master user position for Sphere although users tend to stay at one position initially.
• Many users requested zoom functionality in maps.

Review

The device sounds like a futuristic concept which could very well be used in public displays, education and sophisticated control. Zoom functionality in maps could be introduced by zooming only the region indicated by user so that displays for other users remains unchanged. In all a very exciting read.

Disclaimer

The work discussed above is an original work presented at UIST 2008 by the authors/affiliations indicated at the starting of this post. This post in itself was created as part of course requirement of CPSC 436.