Interaction






Interaction






Sketchpad






Types of Devices






Common Devices






Reading Devices

Polling

Event driven






Feedback

Change in response to users' actions

Lets users know that they're interacting

Immediate, simple response often useful

Can be visual, auditory, haptic






Latency

Delay between an action and its result

Humans very aware of latency > ~ 100 milliseconds

Many delays inherent in different stages of hardware/software
"End-to-end" latency = total delay

Long latency slows up user
Irregular latency even worse


Latency is distinct from update speed






Resolution

Measure of how many distinct values a device can report


On/off switch = 1 bit resolution


"Non-analog" joystick = 3 values (+1, 0, -1) for X and for Y

8 bit resolution joystick = 256 possible values for X and for Y

16 bit resolution joystick = 65536 possible values for X and for Y






Noise

Signal = the information we want to communicate to the computer (e.g. button state, pointer position)

Noise = variations in the signal, outside of our control

Examples:

Applications may need to allow for noise in input data






Fitts' Law

From human movement research - Paul Fitts, 1954

Predicts time needed to move from a starting position to a target - e.g. to point at something

D = distance to target
W = width of target







Light pen


SAGE air-defense system, circa 1957





Light pen


IBM 2250 graphics station, 1973





Graphics tablet

Wacom graphics tablet and pen





Trackball


"industrial duty" trackball, circa 1970





Sonic pen


Ohio State University, circa 1970





6 DOF tracking


Polhemus electromagnetic tracker





Put-That-There






Videoplace






Pyglet Input



Creative Commons License
This document is by Dave Pape, and is released under a Creative Commons License.