Not a member yet? Register for full benefits!

PiVOT: Personalised View Overlays for Tabletops

Developed by researchers at the University of Bristol 's Interaction and Graphics department, PiVOT is a project designed to allow a group of people to interact with the same interactive display table system,by providing a personalised view of the data space on the table to each user, but at the same time, providing a central, shared view of the data so everyone can see the big picture.

It's designed to bring the VR system used by tabletop display systems more into the mainstream by increasing their usefulness still further.

At it's heart, a tabletop display is just that; a table or desk surface – or even a counter top – which displays an interactive image on a display screen seamlessly embedded into the surface. They are usually both haptic and multitouch enabled, so they can be used like a touchscreen system, but at the same time sturdy and hard-wearing enough to be used interchangeably as an actual desk.

This image from the 2007 film Chrysalis illustrates the concept behind these tabletop displays perfectly. Whilst in reality, no interactive table system has achieved the level of seamless integration with the office environment as is shown here, this is very much the goal everyone is striving for.


PiVOT is intended as a sizeable step in that direction, by providing enhancement and improved interaction software, as well as a relatively minor change in hardware, independent of any particular make of tabletop display. It was unveiled at the 25th ACM UIST symposium, in October this year. UIST is a central symposium for innovations in the field of HCI (Human, Computer Interaction) so it has already received considerable attention across the VR hardware fields.

The hope if the researchers is that the minor hardware changes, and the software that governs them, will be incorporated by the major tabletop display manufacturers. The key is a change in the liquid crystal display itself. Using pretty much the same technology as the latest 3D television systems, PiVOT's display is multi-layered using polarised light. It relies on refraction.

The top of the table, above the liquid crystal itself, is a polarised filter. The liquid crystals underneath are polarised in two layers, one horizontal, one vertical. The filter is arranged on the surface in such a way that it only lets the horizontal light through as you approach a viewing angle of less than 90 degrees, approaching 45. At 90 degrees or more, it blocks the horizontally polarised beams and only lets the vertically polarised through. In other words, as you change angle relative to the table, your vision shifts between the layers, and you get a different image.


The PiVOT system is always displaying both images. The personalised images split up into a grid divided between the users, and the main image share the same spatial location. It is only simple light polarisation filtering that keeps them separate, depending on the angle the user views the table from.


So, because you are looking nearly straight down at the table immediately in front of you, you see a personalised image projected on that space in front of you. But as you look out across the table, the angle changes, and approaches 45 degrees or less. At this point, the personalised image is no-longer visible, and instead you see the main image everyone else sees. A person directly opposite you on the other hand, again sees a personal image when they look straight down, but when they look over at your side of the table, because of the low angle they don't see your image, and instead they see the main one.

So, no matter where you sit, you will always have two views: One intended solely for the user sitting there, and one intended for everyone.

The personalised views function very much like individual user accounts, with a defined area on the table set aside for each user, and where that user can play with the data in their own unique ways, to follow their own line of reasoning. If you were to get up from the table and walk around it, your own personal image would not follow you; rather it stays next to the seat you originally occupied, and as you move round the table, you see the personal workspaces of each of the other users present. Always however, across from you on the other side of the table, you see the main image, same as everyone else sees. Because it is produced by polarised light, it always moves away from you, maintaining a steady distance, unless you crouch down, so your view of the table in front of you, changes with the angle.

Lower your head far enough to be looking across the table at approximately 45 degrees or less rather than approaching 90 degrees, and the communal image will seem to move closer to you, until it occupies the space your personal view area took up. On the flip side, lean forwards just a little, and you are looking straight down at the table again. However close you are to the table doesn't matter. Only the sharp angle does. Suddenly your personalised view snaps back into focus, at the exact moment as the communal one becomes invisible again.

Professor Sriram Subramanian, head of the research group and a professor of HCI in the Department of Computer Science's Interaction and Graphics group discussed the table's design at some length. As he stated: “The tabletop system has been created by using an arrangement of liquid crystals. Users can come together and view shared content or by leaning forward can get personalised views that are only visible from that particular view point.”

“For example, when looking at a city map, if I want to see traffic information I can lean forward and see the traffic-overlay while other people can, at the same time, lean forward and see the elevation information for a particular street. Everyone else who is not leaning forward will continue to see the undistorted city map. Their view will not interfere with mine, even if it is on the same spatial location.”

As a final trick as it were, the personalised polarised view uses two layers,not one; both polarised in very similar ways. This provide the potential, if the user wishes, to have an auto-stereoscopic 3D image in their personal workspace, without disturbing the main image at all.

Currently one prototype system exists, which is being used by the team to develop interactive, collaborative applications to demonstrate the design's usefulness in a variety of different situations – and in so doing sell the concept to table manufacturers.

PiVOT demonstration Video


Digital tabletop system with views on demand

25th ACM UIST symposium 2012

Large Image Display: Chrysalis: Natural User Interface in Paperwork

PiVOT: Personalized View-Overlays for Tabletops

Staff Comments


Untitled Document .