Understanding & ModelingInput Devices

QuestionsHow do common input devices work?How can we think about the larger space of all possible input devices?Can we predict human input performance?What about uncommon input devices (multitouch, tangible interfaces, )?Will this be on the exam? Yes.

Todays lecture in graphic form

I think my keyboard is broken.Whenever I have a few keys pressed down, some keys suddenly dont work anymore; at other times phantom characters appear.Whats going on?

Keyboard

Microprocessor and Controller

Row/Column Scanning9 lines and 20 keyshttp://v.youku.com/v_show/id_XMTI5NjE0OTQ4.html

Closeup

One key down

3 Keys Down

Encoding keyboard: Keys conflictC1-R1-C2-R23 or 4 keysQ,W,A,S

http://www.upsdn.net/html/2006-10/760.html

A Layered FrameworkFrom: Hartmann, Follmer, Klemmer: Input Devices are like Onions

MouseMouse. Engelbart and English ~1964

Encoder wheel for scrollingLeft buttonRight button

IR emitterIR detectorslotted wheel (between emitter & detector)

Sensing: Rotary Encoder

Sensing: Fwd rotation

Sensing: Backwd Rotation

Solutions: Use two Out-of-Phase Detectors

Sensing: Rotary Encoder

Transformationcxt = max(0, min( sw, cxt-1+dx*cd ))cyt = cxt: cursor x (horizontal) position in screen coordinates at time tdx: mouse x movement delta in mouse coordinatessw: screen widthcd: control-display ratio

Device AbstractionClick, DoubleClick, MouseUp, MouseDown, MouseMove

What about optical mice?Source: http://spritesmods.com/?art=mouseeye

Source: http://spritesmods.com/?art=mouseeye

Trackball, Trackpad

TrackpointIndirect, force sensing, velocity controlNonlinear transfer function

Joystick

A design space of input devicesCard, S. K., Mackinlay, J. D., and Robertson, G. G. 1991.A morphological analysis of the design space of input devices. ACM TOIS 9, 2 (Apr. 1991), 99-122.

Which is faster?

Which is faster?Engelbart

Experiment: Mice are fastest!

Fittss lawTime Tpos to move the hand to target (size S) which is distance D away is given by:Tpos = a + b log2 (D/S + 1) Index of Difficulty (ID) Only relative precision mattersExam Question Material!Source: Landay, James. Human Abilities. CS160 UC Berkeley.

Tpos = a + b log2 (D/S + 1)Device Characteristics(bandwidth of human muscle group & of device)a: start/stop time (intercept) b: speed (slope)

Bandwidth of Human Muscle Groups

Why is mouse fastest?Why these results?Time to position mouse proportional to Fittss Index of Difficulty ID.[i.e. how well can the muscles direct the input device] Therefore speed limit is in the eye-hand system, not the mouse.Therefore, mouse is a near optimal device.

Fittss law example

Which will be faster on average?pie menu (bigger targets & less distance)

Fittss law in Windows &Mac OSThe Apple menu inMac OS X v10.4 Tiger.Windows 95: Missed by a pixelWindows XP: Good to the last drop

In office 2007Larger, labeled controls can beclicked more quicklyMagic Corner: Office Button in theupper-left cornerMini Toolbar: Close to the cursorSource: Jensen Harris, An Office User Interface Blog : Giving You Fitts. Microsoft, 2007.

Uncommon Input DevicesAssumptions so far:Single user, working in front of a desktop PCMain tasks are typing and pointingEfficiency rulesWhat if we change these assumptions?Design for enjoyment / engagementDesign for multi-user scenarios

Position+Orientation: Nitendo Wii

Camera based input: IO BrushSource: Kimiko Ryokai, http://web.media.mit.edu/~kimiko/iobrush/

Multi-touchJeff Han, Perceptive Pixelhttp://www.tudou.com/programs/view/LfwscZ1iUXc/

Hybrids: Devices on TablesHartmann, Bjrn, Morris, M.R., Benko, H., and Wilson, A.Augmenting Interactive Tables with Mice & Keyboards. In Proceedings of UIST 2009.

http://www.vid3o.net/view/v_AvkV286mI/uist09-augmenting-interactive-tables-with-mice-keyboards.html

Hybrids: Multi-touch on MiceMouse 2.0: Multi-touch Meets the MouseNicolas Villar, Shahram Izadi, Dan Rosenfeld, Hrvoje Benko, John Helmes, Jonathan Westhues, Steve Hodges,Eyal Ofek, Alex Butler, Xiang Cao and Billy Chen. Proceedings of UIST 2009.http://www.disclose.tv/action/viewvideo/31170/Mouse_2_0_from_Microsoft/

Linkshttp://bjoern.orghttp://research.microsoft.com/apps/video/default.aspx?id=144849