Mobiles are not different from desktops because they are small but because they are connected and personal. Likewise, large displays are different not because they are large, but because they are public and collaborative.
Touch displays add an extra layer of complexity not in other products in that they are routinely — and unusually: simultaneously — multi-modal. A single user may be at arm's reach interacting with the display while others stand well back observing. A single interface paradigm cannot do all this at once, but is needed.
- Control from a desktop - Control from a tablet - Very coarse control - Fine control up close
- Group - Individual And usually both at the same time... mostly only one interacts at a time
Proposed design guidelines: (must be validated, of course) - Near (close range) interaction is only along the sides. - Dupe on both sides, or move between them? Need to provide for left and right hand use. - The near user, touching the screen, should be out of the way of far users. Hence edge placement again. - Near user cannot see the far use. Dupe the screen for them? - When visual sensors are available, make near use only pop out when users are nearby. - Not distracting to others??? - Can use bezel anchoring of the hand (hold/touch the bezel, as happens with tablets) - Feedback on obscuring. Sensors, when available, should indicate this. - Repeat all existing TV guidelines for distant use, but validate those; can do much with math as far as angular resolution, contrast ratios without research.
List of research topics: - Accuracy of touch - Bet it changes due to device position. Level, above head, etc. - Touch enhanced by anchoring to the bezel? - MEASURE gorilla arm, don't just assume. Make people use for a while and observe, measure changes over time. - How to account for near/far sizing? Does the small near use annoy and distract? - Pixel density. Some near guidelines may have to go back to old ones, like no italics, due to low density. - Perception of no-bezel use. Wall-to-wall or multi-screen interfaces, can user work with close-range control, can they find it, will they stabilize on the screen or not?