Week 6 2 virtual displays virtual environments
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Week 6-2: Virtual Displays & Virtual Environments. Week 6 Topics. Lecture 6-1 3D Displays Navigation & Self-Motion Lecture 6-2 A Virtual Display for Speed Perception of Heading Perception of Time to passage. 36. 01. 02. 03. 10. 3750. 5620. 5. -5. -10.

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Week 6-2: Virtual Displays & Virtual Environments

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Week 6-2: Virtual Displays & Virtual Environments


Week 6 Topics

  • Lecture 6-1

    • 3D Displays

    • Navigation & Self-Motion

  • Lecture 6-2

    • A Virtual Display for Speed

    • Perception of Heading

    • Perception of Time to passage


36

01

02

03

10

3750

5620

5

-5

-10

Virtual Displays for Speed?


Virtual Displays for Speed

  • Design Features

    • Flow vectors presented as moving arrows: speed and direction of arrows indicates magnitude and direction of speed error: arrows stop moving if pilot is at the target speed (prevents adaptation)

    • Overall size of arrows also changes as a function of speed -- arrows disappear if no speed error

      • size changes in steps: “attention grabbing”

      • reduces reliance on acceleration detection

    • Stimulus-Response (SR) compatibility: direction of arrows indicates direction of throttle movement to correct speed


Virtual Displays for Speed

  • Testing the Virtual Display: Cox & Dyre (2000)

    • Dual Task: fly simulator through “waypoints” while simultaneously maintaining target altitude and speed

    • Single Tasks: autopilot controls flight-path or speed


Virtual Displays for Speed

  • Measures:

    • Speed error

    • Altitude error

    • Missed waypoints

    • Subjective workload: NASA-TLX


Virtual Displays for Speed

  • Measures:

    • Speed error

    • Altitude error

    • Missed waypoints

    • Subjective workload: NASA-TLX


Virtual Displays for Speed

  • Measures:

    • Speed error

    • Altitude error

    • Missed waypoints

    • Subjective workload: NASA-TLX


Perception of Heading

  • Cues in Optical Flow

    • Expansion point or

      focus of radial outflow

      (Warren et al., 1988)

    • problem:

      eye movements

    • Differential Motion Parallax (Cutting, 1986)

    • Flow Symmetry (Dyre & Andersen, 1997)


Perception of Heading

Rotational Flow due to Eye Movement

Translational (Optical) Flow

Retinal Flow (Translation + Rotation)


Perception of Heading

  • Active closed loop control vs. Passive open-loop judgments

    • Active controllers (drivers) can perceive heading in a manner fundamentally different than passive viewers (passengers): Dyre, Warren, & Garness (1996)

      • Controllers -- more global?

      • Passengers -- more local?

    • Consistent with active-passive differences for motion sickness and spatial orientation

      • Armstrong (1939), Reason & Brand (1975)

      • Larish and Andersen (1995)


Perception of Heading

  • Field of view effects

    • Central visual field is necessary and sufficient for accurate judgments of heading

      • Warren & Kurtz (1992), Crowell & Banks (1993), Atchley & Andersen (1999)

    • Problems

      • used small fields of view (19” monitor) presented at different retinal eccentricities

      • controlled fixation

      • used discrete, open-loop judgments

      • did not present symmetrical fields of view to periphery


p(q, f)

f

a

r

H

q

Perception of Heading: Information Basis


Peripheral Vision & Perception of Heading

  • Richman & Dyre (1999);

    Dyre, Morrow, and

    Richman (2000)

    • Used large,

      symmetrical fields

      of view for

      peripheral

      stimulation

      (90 x 34 deg of

      visual angle)

    • measured active control performance

    • free fixation: field of view mask or “porthole” yoked to observer’s gaze direction

    • Examined both yaw and pitch control


Apparatus for Yoking Gaze to Display


Central + Peripheral (Full) Visual Field

(image contrast inverted)


Central Visual Field Condition

(image contrast inverted)


Peripheral Visual Field Condition

(image contrast inverted)


Central-Peripheral Visual Fields: Results

  • Results of

    • Peripheral visual fields benefit performance

    • Peripheral vision as good as central vision when peripheral regions of flow are orthogonal to control axis

Dyre, Morrow, and Richman (2000)


Perception of Time to Contact

  • Time to Contact

    • specified by the size of an object scaled by its expansion rate (change in size)

      • size changes exponentially as an object approaches

        (object size)/(change in object size)

    • other factors that influence judgments

      • object size (large objects appear nearer)

      • Object expansion rate (dX/dt)

      • observer motion combined with object motion:

        lowers time to contact estimates


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