VE Input Devices(I)

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VE Input Devices(I)

• Doug Bowman
• Virginia Tech
• Edited by Chang Song

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Goals and Motivation

• Provide practical introduction to the input
  devices used in VEs
• Examine common and state of the art input devices
• look for general trends
• spark creativity
• Advantages and disadvantages
• Discuss how different input devices affect
  interface design

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Input devices

• Hardware that allows the user to communicate with
  the system
• Input device vs. interaction technique
• Single device can implement many ITs

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Human-computer interface
User interface software
Input devices
System Software
Output devices
User
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Human-VE interface
Env. model
Display(s)
Simulation loop -render -check for
events -respond to events -iterate
simulation -get new tracker data
Tracking system
Input device(s)
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Input device characteristics

• Degrees of Freedom (DOFs) DOF composition
  (integral vs. separable)
• Range of reported values discrete/continuous/hybr
  id
• User action required active/passive/hybrid
• Intended use locator, valuator, choice,
• Frame of reference relative vs. absolute
• Properties sensed position, motion, force,

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Practical classification system

• Desktop devices
• Keyboards,
• 2D mice and trackballs,
• pen-based tables,
• joysticks,
• 6DOF devices for the desktop
• Tracking devices
• 3D mice
• Special-purpose devices
• Direct human input

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Desktop devices keyboards

• Chord keyboards1
• Arm-mounted keyboards2
• Soft keyboards (logical devices)

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Desktop devices 6-DOF devices

• 6 DOFs without tracking
• Often isometric
• Exs Fig. 4.4 SpaceBall 5000, SpaceMouse Plus,
  SpaceOrb

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Tracking Devices

• Motion tracking
• Eye tracking
• Data Gloves

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Tracking devices position trackers

• Measure position and/or orientation of a sensor
• Degrees of freedom (DOFs)
• Most VEs track the head
• motion parallax
• natural viewing

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Other uses for trackers

• Track hands, feet, etc.
• whole body interaction
• motion capture application
• Correspondence between physical / virtual objects
• Props5,6
• spatial input devices

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Tracking physical objects (props)
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Motion Tracking

• Critical characteristics
• Range, latency, jitter (noise or instability),
  and accuracy
• Different motion trackers
• Magnetic
• Mechanical
• Acoustic
• Inertial
• Optical
• Hybrid

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Electromagnetic trackers

• Exs Polhemus Fastrak, Ascension Flock of Birds
• Most common
• Used with conventional monitors (for fishtank VR)
  Small workbench displays
• Transmitter
• Receiver(s)
• Noisy
• Affected by metal objects -gt distort the magnetic
  field

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Inertial trackers

• Inertial measurement devices angular gyroscopes
  linear accelerometer
• Exs Intersense IS-300, Intertrax2
• Less noise, lag
• Only 3 DOFs (orientation)

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Optical/vision-based trackers

• Reflected or emitted light
• Exs Vicon, HiBall, ARToolkit
• Advantages
• accurate
• can capture a large volume
• allow for untethered tracking
• Disadvantages
• may require light emitting diodes(LEDs)
• image processing techniques
• occlusion problem

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Optical/vision-based trackers

• Outside-in or inside-out system
• Sensors/landmarks tracked objects/environment
• Setting up vision-based tracking system can be
  difficult

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Hybrid tracking

• Ex IS-600 / 900
• inertial (orient.)
• acoustic (pos.)
• additional complexity, cost

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Tracking devices eye tracking
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Tracking devices eye tracking

• User controlling a mouse pointer strictly with
  his eyes.
• Gazed direction based
• Head-tracker as an approximation to where the
  user is looking. Problem can occur.
• Improve these gaze-directed techniques

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Tracking devices bend-sensing gloves

• CyberGlove7, 5DT
• Reports hand posture
• Gesture
• single posture
• series of postures
• posture(s) location or motion

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Tracking devices pinch gloves

• Conductive cloth at fingertips
• Any gesture of 2 to 10 fingers, plus combinations
  of gestures
• gt 115,000 gestures

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Case study Pinch Gloves

• Pinch gloves are designed to be a combination
  device (add a position tracker)
• Very little has been done with Pinch Gloves in
  VEs - usually 1 or 2 gestures for
• Object selection
• Tool selection
• Travel

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Characteristics of Pinch Gloves

• Relatively low cost
• Very light
• Users hand becomes the device
• Users hand posture can change
• Allow two-handed interaction
• Huge number of possible gestures

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Characteristics of Pinch Gloves II

• Much more reliable than data gloves
• Support eyes-off input
• Can diminish Heisenberg effect
• Support context-sensitive gesture interpretation

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Pinch Gloves in SmartScene13

• Lots of two-handed gestures
• Scale world
• Rotate world
• Travel by grabbing the air
• Menu selection

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Pinch Gloves for menus

• TULIP system14
• ND hand selects menu, D hand selects item within
  menu
• Limited to comfortable gestures
• Visual feedback on virtual hands

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Pinch Gloves for text input

• Pinch Keyboard14
• Emulate QWERTY
• Pinch finger to thumb to type letter under that
  finger
• Move/rotate hands to change active letters
• Visual feedback

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Combining Bend-Sensing Data and Pinch Input

• Both the Pinch Gloves and bend-sensing gloves
  have limitations
• The Flex and Pinch input system is an example of
  an input device that combines the functionality
  of the Pinch Gloves system with the bend-sensing
  technology of a data glove
• Figure 4.15