3D User Interface Output Hardware

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					3D User Interface
Output Hardware
               3.1 Introduction
   Examine Visual, auditory, and haptic
    display devices and
   See how they effect 3D UI design and
       An understanding of display device
        characteristics will help the 3D UI
        developer make informed decision about
        which interaction techniques are best
        suited for particular display configuration
        and application.
              3.1 Introduction
   Display Devices (Output Devices)
     Visual
     Auditory
     Haptic (force and touch)
     Olfactory or sense of smell (Davide et al.
      2001) in rare case
   More detail
       Stanney(2002), Sherman and Craig(2003),
        Durlach and Mavor(1995)
       3.1.1 Chapter Roadmap
   Sec 3.2 : Visual display, characteristics,
    visual cues, different types of visual display
   Sec 3.3 : Auditory display, spatial audio cues,
    3D sound generation, pros and cons of
    different sound system configurations
   Sec 3.4 : Haptic display devices. Haptic cues
   Sec 3.5 : some guidelines and strategies for
    choosing display devices for particular
    system and applications
           3.2 Visual Display
   3.2.1 Visual Display Characteristics
     Field of regard (FOR) and Field of View
     Spatial resolution

     Screen geometry

     Light transfer mechanism

     Refresh rate

     Ergonomics
                   FOR & FOV
   FOR : the amount of the physical space
    surrounding the user in which visual
    images are displayed
       Cylindrical display, 360 degree horizontal
   FOV : the maximum number of degree
    of visual angle that can be seen
    instantaneously on a display
       Large, flat projection screen, horizontal
        FOV might be 80 or 120 degrees
                 FOR & FOV
   For HMD, FOV might be 40 degrees but the
    user could make a 360 degree turn and
    always see the visual images.
   A display device’s FOV must be less than or
    equal to the maximum FOV of the human
    visual system (about 200 degrees)
   A display device’s FOV will be lower than that
    if additional optics such as stereo glasses are
   FOV α is always lee than and equal to the
    FOR β. In general, the user at each instant
    can view α degree out of the full β degrees.
                Spatial Resolution
   A measure of a display quality
       Dpi : dots per inch
   Common Misuses
       The resolution ≠ # of pixels
   The resolution depends on both the number of pixels
    and the size of the screen.
       Two visual display devices with the same number of pixels
        but different screen size will not have the same resolution.
   The user distance to the visual display device affects
    the spatial resolution.
       The further the user is from the display, the higher the
        perceived resolution
                Screen Geometry
   A variety of different shapes
     Rectangular
     L-shaped

     Hemispherical
           Distortion at the edges of the display surface
       Hybrid
                   Light Transfer
   How the light actually gets transferred onto
    the display surface
       Front projection,
       Rear projection
       Laser light directly onto the retina
   The light transfer method often dictates what
    types of 3D UI techniques are applicable
       When using a front-projected display device, 3D
        direct manipulation tech. do not work well.
                   Refresh Rate
   Refresh rate
       The speed with which a visual display device
        refreshes the display images from the frame buffer
       Significant effect on visual quality. The visual
        display can show them at its refresh rate limit.
       Lower refresh rates (e.g., below 50-60 Hz) can
        cause flickering images.
   Frame Rate
       The speed with which images are generated by
        graphics system and placed in the frame buffer.
   Important display characteristic
   As comfortable as possible
               3.2.2 Depth Cues
    Visual depth cues can be broken into 4
       Monocular, static cues
       Oculomotor cues
       Motion parallax
       Binocular disparity and stereopsis
   More detail
       May and Badcock(2002); Wickens, Todd, and
        Seidler(1989); Sedgwick(1988); and Sekuler and
          Monocular, Static Cues
   Refer to depth information that can be
    inferred from static image viewed by a single
   Also called “Pictorial cue”
   These cues include
       Relative size
       Height relative to the horizon
       Occlusion
       Linear and aerial perspective
       Shadows and lighting
       Texture gradient
          Monocular, Static Cues
   Relative size
       Figure 3.1
   Height relative to the horizon
       Figure 3.1
   Occlusion
       Figure 3.2
   Linear and aerial perspective
       Figure 3.2
        more color saturation and brightness
   Shadows and lighting
       Figure 3.3
   Texture gradient
       Figure 3.4
               Oculomotor Cues
   Depth cues derived from muscular tension in
    the viewer’s visual system
       Accommodation
       Convergence
   Accommodation
       The physical stretching and relaxing of the eye
        lens; Fig. 3.5(left)
   Convergence
       The rotation of the viewer’s eyes so images can be
        fused together at varying distance
                 Motion Parallax
   Depth information is conveyed
       when objects are moving relative to the viewer
        (stationary-viewer motion parallax)
       When the viewer is moving relative to stationary
        objects (moving-viewer motion parallax)
   Motion parallax causes
       objects closer to the viewer to move quickly
        across the visual filed and
       objects father away from the viewer to move more
       Figure 3.6
   Dynamic depth cues
Binocular Disparity and Stereopsis
   Binocular disparity: Refer to the
    difference between two different images
    with two eyes.
   Stereopsis
       The fusion of these two images provides a
        powerful depth cue by presenting a single
        stereoscopic image. The effect is called
 Depth Cue Relevance and
Relationship to visual Display
     3.2.3 Visual Display Types
   Monitor
   Surround-screen display
   Workbenches
   Hemispherical display
   Head-mounted display
   Arm-mounted display
   Virtual retinal display
   Autostereoscopic display
3.2.3 Visual Display Device Types
   A review of Input and Output Devices
    for 3D Interaction 발표 자료 참조
     Joseph J. Laviola Jr. Brown University
     Computer Graphics Lab

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