3D User Interface Output Hardware

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3D User Interface Output Hardware
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3.1 Introduction

• Examine Visual, auditory, and haptic display
  devices and
• See how they effect 3D UI design and development.
• 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.

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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)

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3.1.1 Chapter Roadmap

• Sec 3.2 Visual display, characteristics, visual
  cues, different types of visual display devices.
• 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

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3.2 Visual Display

• 3.2.1 Visual Display Characteristics
• Field of regard (FOR) and Field of View (FOV)
• Spatial resolution
• Screen geometry
• Light transfer mechanism
• Refresh rate
• Ergonomics

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FOR FOV

• FOR the amount of the physical space
  surrounding the user in which visual images are
  displayed
• Cylindrical display, 360 degree horizontal FOR
• 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

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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 devices FOV must be less than or equal
  to the maximum FOV of the human visual system
  (about 200 degrees)
• A display devices FOV will be lower than that if
  additional optics such as stereo glasses are
  used.
• FOV a is always lee than and equal to the FOR ß.
  In general, the user at each instant can view a
  degree out of the full ß degrees.

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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

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Screen Geometry

• A variety of different shapes
• Rectangular
• L-shaped
• Hemispherical
• Distortion at the edges of the display surface
• Hybrid

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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.

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Refresh Rate

• Refresh rate
• The speed with which a visual display device
  refreshes the display images from the frame
  buffer (Hz)
• 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.

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Ergonomics

• Important display characteristic
• As comfortable as possible

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3.2.2 Depth Cues

• Visual depth cues can be broken into 4
  categories
• 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
  Blake(1994)

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Monocular, Static Cues

• Refer to depth information that can be inferred
  from static image viewed by a single eye.
• Also called Pictorial cue
• These cues include
• Relative size
• Height relative to the horizon
• Occlusion
• Linear and aerial perspective
• Shadows and lighting
• Texture gradient

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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

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Oculomotor Cues

• Depth cues derived from muscular tension in the
  viewers visual system
• Accommodation
• Convergence
• Accommodation
• The physical stretching and relaxing of the eye
  lens Fig. 3.5(left)
• Convergence
• The rotation of the viewers eyes so images can
  be fused together at varying distance

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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
  slowly
• Figure 3.6
• Dynamic depth cues

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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
  Stereopsis

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Depth Cue Relevance and Relationship to visual
Display
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3.2.3 Visual Display Types

• Monitor
• Surround-screen display
• Workbenches
• Hemispherical display
• Head-mounted display
• Arm-mounted display
• Virtual retinal display
• Autostereoscopic display

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3.2.3 Visual Display Device Types

• A review of Input and Output Devices for 3D
  Interaction ?? ?? ??
• Joseph J. Laviola Jr. Brown University
• Computer Graphics Lab