Josh Stephens Comp 6620

Characteristics Degrees of Freedom: particular, independent way that a body moves in space Input type/Frequency of data: Discrete: single data value (e.g. Boolean value) Continuous: generate multiple data valuse (e.g. pixel coordinates) How much physical interaction is required. Purely active: require user to perform some form of physical activity Purely passive: does not require physical activity, continues to operate even when untouched Intended Use: position/orientation information, produce real number values, indicate element of a set

Categories Desktop input devices Tracking devices 3d mice Special purpose input devices Direct human input

Desktop Input Devices Keyboards 2d mice and trackballs Pen-based tablets Joysticks 6-DOF devices for desktop

Keyboards Traditional desktop input device Discrete Chord keyboard Held in one hand User presses combinations of keys for a single alphanumeric input

Chord Keyboard

2d Mice and trackballs Made popular by WIMP interface design 2 components: Manually continuous 2d locator for positioning a cursor and generating 2d pixel coordinates Set of discrete components Relative devices: report how far they have moved rather than where they are Trackball more feasible for 3d environments

Pen-Based Tablets Same as mice and trackballs, except with the addition of a manually continuous component Use of a stylus to generate 2d coordinates “pen and paper” interface

Joysticks Traditionally used on desktop Combination of manually continuous 2d locator and a set of discrete components Isotonic Joystick: Cursor typically continues moving in the direction the joystick is pointing Isoteric Joystick: large spring constant so they cannot be perceptibly moved. Output varies with the force the user applies to the device

6 DOF Input Devices Move objects dynamically in 3 dimensions Useful in manipulating virtual objects

Tracking devices Motion trackers Eye trackers Data gloves

Motion Tracking Magnetic tracking Mechanical tracking Acoustic tracking Inertial tracking Optical tracking Hybrid tracking

Eye Tracking Purely passive input devices used to determine where the user is looking Uses corneal reflections detected by a camera Electro-oculography: measures the skin’s electric potential differences using electrodes placed around the eye

Data gloves Bend sensing gloves: detect hand postures Pinch Gloves: determines if a user is touching 2 or more fingertips together

3D Mice User physically moves them in 3d space Handheld Place motion trackers inside a structure User Worn Makes the device an extension of they user’s hand

Direct Human Input Obtain data directly from signals generated by the human body. User becomes the input device.