1. Input
Touch v.s In-air gesture

2. Mouse
State-transition model
Idle Tracking Active
sliding mouse on tablemouse in-air move mouse on table
mouse placed
on table
mouse lifted
from table
button
pressed
button
released

3. Touch
State-transition model
Idle Active
finger move in-air finger move on device
finger landed
finger lifted
No Tracking State!

4. Touch
What's the problem?
preview to guide user toward right activity
feedback to reduce false-negative error

5. Touch
Solution
1. Recreate logical tracking state
2. New UI not relying on tracking state

6. In-air Gesture
State-transition model
Active
body/finger move in air
Live Mic
Always On!

7. In-air Gesture
“clutch”
Differentiate physical actions that are intended to drive
the computing system from those that are not.
Mouse lift hand from mouse or lift mouse in air
Touch lift hand from the digitizer
In-air gesture ?

8. In-air Gesture
“clutch”
Differentiate physical actions that are intended to drive
the computing system from those that are not.
Mouse lift hand from mouse or lift mouse in air
Touch lift hand from the digitizer
In-air gesture No Mechanism in the hardware
false positive errors ++
false negative errors ++

9. In-air Gesture
Solution
1. Reserved action
2. Reserved clutch
3. Multi-modal input

10. In-air Gesture
When suitable?
Interaction at a distance
Hands are busy / dirty
Physical limitation
3D output