Output Devices - I
Universidade de Aveiro Departamento de Electrónica, Telecomunicações e Informática
Realidade Virtual e Aumentada 2016/2017 Beatriz Sousa Santos
What is Virtual Reality?
“A high-end user interface that involves real-time simulation and interaction through multiple sensorial channels.” (vision, sound, touch, smell, taste) (Burdea and Coiffet., 2003)
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Output Devices: Graphics, 3-D Sound, and Haptic Displays
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(Burdea and Coiffet., 2003)
The human senses need specialized interfaces
• Graphics displays for visual feedback
• 3-D audio hardware for localized sound
• Haptic interfaces for force and touch feedback
Only a few examples of experimental devices providing smell olfactory and taste feedback
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The ultimate display?
"The ultimate display would, of course, be a room within which the computer can control the existence of matter. A chair displayed in such a room would be good enough to sit in. Handcuffs displayed in such a room would be confining, and a bullet displayed in such a room would be fatal.” (Ivan Sutherland, 1965)
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Visual Displays
“A graphics display is a computer interface that presents synthetic world images to one or several users interacting with the virtual world.”
(Burdea and Coiffet., 2003)
• Personal displays: Main technologies:
- HMDs (VR/AR)
- Binoculars LEDs/OLEDs
- Monitor-based displays/active glasses LCDs
- Autostereoscopic displays lenticular/barrier
• Large volume displays:
–Workbenches
– Caves projectors
– Walls, domes
– Surface … …
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Human Visual System
And depth perception
• Vision is the dominant sensorial channel
• Depth perception in mono images is based:
- on occlusion (one object blocks another from view)
- shadows
- textures
- motion parallax
(closer images appear to move more than distant ones)
(Burdea and Coiffet., 2003)
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• Depth perception in stereo is based on steropsis
(when the brain registers and fuses two images)
• Image parallax means that the two eyes register different images
(horizontal shift)
• The amount of shift depends on the “inter-pupillary distance”
(IPD) (varies for each person in the range of 53-73 mm)
• Works in the near field (to a few meters from the eye)
Left eye, right eye images
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• Many of the perceptual cues we use to visualize 3D structures are available in 2D projections
• Such cues include: – occlusion (one object partially covering another) – perspective (point of view) – familiar size (we know the real-world sizes of many objects) – atmospheric haze (objects further away look more washed out)
• Four cues are missing from 2D media:
– stereo parallax—seeing a different image with each eye – movement parallax—seeing different images when we move the head – accommodation—the eyes’ lenses focus on the object of interest – convergence—both eyes converge on the object of interest
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• All 3D display technologies (stereoscopic displays) provide at least stereo parallax
• Autostereoscopic displays provide the 3D image without needing any eyewear
• Volume displays provide a “real” 3D image
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Item is no longer available
Stereopsis
Stereo ="solid" or "three-dimensional“
opsis = appearance or sight
'binocular vision‘ , 'binocular depth perception' , 'stereoscopic depth perception'
• Stereopsis is the impression of depth that is perceived when a scene is viewed with both eyes by someone with normal binocular vision
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• Binocular disparity is due to the different position of our two eyes
Projection plane
eyes
object
Right eye image Left eye image
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Projection plane
eyes
object (Hearn and Baker, 2002)
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• In 1838 Charles Wheatstone published an explanation of stereopsis due from differences in the horizontal positions of images in the two eyes
• Béla Julesz invented in the 1960s the Random Dot Stereograms
• This led to the invention of the autostereogram: single images to be viewed without the stereoscope
Pocket stereoscope and stereogram
(http://en.wikipedia.org/wiki/Stereoscopy)
Random dot stereogram
(Rock, 1984) http://en.wikipedia.org/wiki/ Random_dot_stereogram
Autostereograms • Are designed to create the
visual illusion of a 3D scene from a 2D image
• There are two ways of viewing:
- wall-eyed
- cross-eyed
• When viewed in the opposite way the shape perceived in 3D is reversed
• Appear to "pop up" (or "pop down") out of the printed paper
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We should be able to see the word “STEREO”
Wiggle stereoscopy
Simple stereogram viewing technique; no glasses are needed Alternates between the left and right images of a stereogram Most people can get a crude sense of dimensionality due to persistence and parallax 16
Wiggle stereoscopy
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None Slight Strong
3D Effect ?
3D with moving mages: the Pulfrich effect
• To experience the Pulfrich Effect use a pair of sunglasses
• Look through one of the dark lenses with one eye and nothing through the other
• Place the dark glass on the leading side of the motion
• In this case: dark glass on left
• Be sure to look at the screen with both eyes
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http://www.youtube.com/watch?v=1mnWI_u_zBg
• 3D effects with nothing more than "normal" video
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http://www.youtube.com/watch?v=1mnWI_u_zBg
None Slight Strong
3D Effect ?
Pulfrich effect
The photoreceptors in the retina respond more sluggishly when the scene is less bright
The image viewed through the colored lens is slightly outdated
A moving object, viewed with one eye brighter than the other, appears either in front of or behind the true track, depending upon direction of motion
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http://www.youtube.com/watch?v=p7hMaPW26bM http://www.open.edu/openlearn/science-maths-
technology/science/across-the-sciences/measure-the-pulfrich-effect
• Need to present two images of the same scene
• The two images can be presented:
• at the same time on two displays (HMD)
• time-sequenced on one display (active glasses)
• spatially-sequenced on one display (auto-stereoscopic displays)
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Implications for Stereo Viewing devices
Left eye, right eye images
(Burdea and Coiffet., 2003)
Common ways to produce a 3D sensation
• Anaglyphs: two colored images and color coded glasses (red/cyan(green))
• Two images with different light polarization and polarizing glasses
– Linear and circular
• Double frame-rate displays combined with LCD shutter glasses
• Autostereoscopic displays
– Parallax barrier and lenticular lens
• Head Mounted Displays (HMDs)
and “exotic displays”
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• All show the right image to the right eye and the left image to the left eye!
• All these technologies provide:
• stereo parallax
• When combined with head tracking,
they can provide
• movement parallax
for a single viewer
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Anaglyph images
Cyan/ red image pairs (or other opposite color pairs) that can be viewed through “colored coded” glasses
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Cyan – right eye image
Red – left eye image
3D Movies ?
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Put on your glasses!
• Advantages of using cyan/red glasses:
– are generally inexpensive
– don't require any power
– don't require synchronization with the display
– do not suffer from flicker
• Disadvantages:
– Inaccurate color rendering
– Headaches after a long exposure
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Polarized light stereoscopy
• 3D movies have used polarized technology since the 1930s
• Two images are projected on the same screen through different polarizing filters
• Gray linear-polarizing filters are easily manufactured, thus correct color rendition is possible
• Two types of polarization can be used: • Linear • Circular
Vertical polarizer
Circular polarized light
http://en.wikipedia.org/ wiki/Polarized_3D_glasses
Verical polarization of light
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• Advantages of polarized glasses:
– are generally inexpensive
– don't require any power
– don't require synchronization with the display
– do not suffer from flicker
• Disadvantages:
– The images for polarized glasses may have to share the screen simultaneously, and therefore cannot have full resolution
– There are incompatible polarized systems (circular or linear polarized)
– The head should not be tilted to maintain the 3D effect with linear polarization
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http://www.inition.co.uk/3D-Technologies/zalman-trimon-range
Shutter glasses for stereoscopic displays
• Active-shutter glasses are small LCD screens that alternately dim the left and right "lenses" in succession
• They are synchronized with the display usually through IR or radio signals
• Each eye can see the image intended for it
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• Can be bought for < 100€
• Need a battery
Passive (polarized) versus active (shutter)?
• Active
– Better image quality
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• Passive
– cheaper
– lighter
– batteryless
– syncless glasses
Visual Displays
“A graphics display is a computer interface that presents synthetic world images to one or several users interacting with the virtual world.”
(Burdea and Coiffet., 2003)
• Personal displays: Main technologies:
- HMDs (VR/AR)
- Binoculars LEDs/OLEDs
- Monitor-based displays/active glasses LCDs
- Autostereoscopic displays lenticular/barrier
• Large volume displays:
–Workbenches
– Caves projectors
– Walls, domes
– Surface … …
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Main technologies of Visual Displays
- LCD displays
- OLED displays
- Autostereoscopic displays: lenticular/barrier
- Projectors
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LCDs (Liquid Crystal Displays)
Layers in a LCD States of a LCD
Colour LCD
OLEDs advantages
• Robust Design
• Viewing Angles
• High Resolution
• “Electronic Paper”
• Production Advantages
• Video Capabilities
• Hardware Content
• Power Usage
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Main Properties of Visual Displays
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Visual presentation properties:
• Color
• Spatial resolution
• Contrast
• Number of display channels
• Focal distance
• Opacity
• Masking
• Field of view (FOV)
• Field of regard (FOR)
• Head position information
• Graphics latency tolerance
• Temporal resolution
Logistic Properties:
• User mobility
• Interface with tracking
• Environment requirements
• Associability with other sense displays
• Portability
• Throughput
• Encumbrance
• Safety
• Cost
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Focal distance
Focal distance is the measurement between the participant's eyes and the virtual image. (A) projection display - distance to the display screen. (B) HBD create a virtual image at some distance beyond the physical display
Field of view (FOV) and Field of regard (FOR)
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(Sherman and Craig, 2003)
FOR is a measure of the amount of coverage a given display provides when head motion and other factors are considered. (A) Head-based displays can easily provide a loo% FOR, (B) stationary displays are limited to the area of the screens
FOV is the amount of the viewer's visual field covered by a display. Head-based displays (A) tend to have smaller, fixed FOV angles compared with those possible in projection- based displays
Visual Displays: a possible taxonomy (Burdea and Coiffet, 2003)
• Personal displays:
- HMDs (VR/AR)
- Binoculars
- Monitor-based displays/active glasses
- Autostereoscopic displays
• Large volume displays:
– Workbenches
– Caves
– Walls, domes
– Surface … …
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Visual Displays: another taxonomy (Sherman and Craig, 2003)
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• Head-based (occlusive)
• Non-occlusive head-based
• Handheld
• Monitor- based (Fishtank)
• Projection Displays Stationary displays
Personal Displays
A Visual display that outputs a virtual scene destined to be viewed by a single user. Such image may be monoscopic or stereoscopic, monocular (for a single eye) or binocular (displayed on both eyes).
• Head Mounted Displays (HMDs)
• 3-D Binoculars (hand supported)
• Auto-stereoscopic displays
(desk supported)
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HMD integration in a VR system
simple HMD
More professional HMD
(Burdea and Coiffet., 2003) 47
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- Bright, crisp, high-contrast OLED display
- Stereo
- High resolution full-color SXGA 1280×1024 pixels
- 60º field of view
- Integrated yaw/pitch/roll tracker
- Self contained, lightweight (450 g)
- Integrated high-quality stereo audio and microphone
- Price ~$13000
zSight™ OLED professional HMD (Sensics)
http://sensics.com/head-mounted-displays/zsight-integrated-sxga-hmd/
Vuzix 920AR MaxReality
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Twin high-resolution 640 x 480 LCD displays Equivalent to a 67-inch screen (at ~ 3 m) 60 Hz progressive scan update rate Ultra-low video distortion 31-degree diagonal field of view 24-bit true color (16 million colors) Independent +2 to -5 diopter focus adjustment Two discrete VGA (640 x 480) video cameras 30 frames/s video capture 640 x 480 USB video camera – no proprietary drivers required 6 DOFs tracker – yaw, pitch, roll, and x, y, z 3-axes magneto-resistive sensors 3-axes accelerometers 3-axis gyros Auto re-centering to adjust from drift Includes tracker and gyro calibration software
Price: ~$1700
http://www.vuzix.com/UKSITE/ar/products_wrap920ar.html
Personal 3D Viewer HMZ-T2
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Display Device - OLED Panel 2 Display Resolution – 1280 x 720 Horizontal viewing angle- 45º Aspect Ratio - 16 - 9 Gradation - RGB 24bit Price ~1000$
http://www.sony.co.uk/electronics/head-mounted-display-products/hmz-t3w
Oculus Rift
http://www.oculusvr.com/
2014, DK2: - low persistence OLED display to eliminate
motion blur and judder (two of the biggest contributors to simulator sickness)
- It also makes the scene appear more visually stable, increasing the potential for presence
- 960×1080 pixels per-eye display improves clarity, color, and contrast.
Price: ~~$350
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Google Glass (2013)
http://www.youtube.com/watch?v=JSnB06um5r4
https://www.google.com/glass/start/
https://developers.google.com/glass/develop/overview
Display - reflects light into the wearer's eye Camera – photos and video Touchpad – on the side Micro – voice control 1500 $
Google glass (2015)
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http://www.pcadvisor.co.uk/feature/gadget/google-glass-release-date-uk-price-specs-3436249/
Meta Glasses
• 3D See Through Display
- Resolution: 960 x 540 pixels per eye
- FOV : 35 degree field of view
• Cameras
- 3D Time-of-flight depth camera
- Color (RGB) Camera
• Head Tracking
- 360 degree tracking
- Accelerometer, gyroscope and compass
• Audio
- Dolby 3D audio
- Two built-in microphones
55 https://www.spaceglasses.com/
Hololens Microsoft AR glasses – announced for 2016
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http://www.itpro.co.uk/mobile/24780/microsoft-hololens-release-date-rumours-specs-pricing-3
Virtual Binoculars
(Burdea and Coiffet., 2003) 58
• Handheld, interactive, immersive displays
• combine high-resolution microdisplays with adjustable, wide field-of-view optics
• Have a familiar form (pair of binoculars)
• May have a tracker as accessory
Examples:
Virtual Binocular SX
Virtual Binocular SV
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Virtual Binocular SX
Price: $7,900
Virtual Binocular SV
Price: $20,900
• Two technologies:
lenticular
barrier
• Do not require use of special glasses
• Allow several vantage points
Passive - do not track user’s head (restrict user’s position)
Active - track the head motion (give more freedom)
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Auto-stereoscopic displays
• Autostereoscopic displays found practical uses in applications:
– in which 3D depth perception is vital: e.g. - scientific/medical visualization of complex 3D structures - remote robot manipulation in dangerous environments – where the novelty of stereo parallax is a selling point e.g. - computer games - advertisement
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Lenticular:
– an array of cylindrical lenslets is placed in front of the pixel raster
– lenslets direct the light from adjacent pixel columns to different viewing slots at the ideal viewing distance
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Each of the viewer’s eyes sees light from only every second pixel column
Parallax barrier:
– a barrier mask is placed in front of the pixel raster
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Each of the viewer’s eyes sees light from only every second pixel column
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Key Features:
- Large 19” diagonal screen
- 3D mode without glasses
- Digital (DVI-D) and analog (VGA) inputs
- 1280 x 1024 resolution
- Super fast 8ms response time
- Price ~$4000
Optional Video Expansion Box
http://www.tomshardware.com/reviews/dti,323.html
Virtual Window – 19 (2001)
Sharp autostereoscopic laptop
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- 15” diagonal display
- 1024x768 resolution
- 2D and 3 D mode
- uses parallax barrier
Item is no longer available
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PHILIPS BDL5231VS 1080P 52'' LCD FLAT (2015) • Autostereoscopic 3D • Full HD LCD display, 1920 x 1080p • High brightness for clearer images • SmartPower for energy saving ~ 9000 euros
Holographic displays
• The image source is based on standard flat panel technology of which the image is seen upon a nine optical layer glass panel
• Objects appear to float in space
• For the maximum 3D effect, the background seen through the display should be several feet behind the display and dark in color
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http://www.eonreality.com/eon-holographic-i
Large Volume Displays • Allow several co-located users to view a monoscopic or stereoscopic view of
the virtual world
- monitor-based large volume displays
- projector-based large volume displays
• Allow more freedom of motion vs. personal displays.
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Monitor-based Large Volume Displays
• Use active or passive glasses
• Several users can look at a monitor
• Can have a single monitor, or multiple side-by-side monitors
• If side-by-side, image continuity becomes an issue
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Projector based Large-volume displays
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• Workbanch-type displays
• CAVE type displays
• Wall-type displays
• Domes
The old Fakespace “ImmersaDesk” workbench
Tilted surface
Reflector mirror Floor CRT projector (not shown)
Viewing Cone
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Workbench-type display
geometries Baron
V-desk
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Item is no longer available
CAVE 3-D large volume display (Fakespace Co.)
(Plato’s allegory of the cave, where a philosopher contemplates reality and illusion ...)
CRT Projector
Mirror
Screen
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CAVEs
CAVE 3-D large volume display (Fakespace Co.) 78
Fakespace Systems Inc., a world leader in immersive visualization systems, announced the commercial availability of a digital version of the CAVE(R) at SIGGRAPH 2014
- Digital projection provides:
- extra clarity and
- richer colours
http://www.mechdyne.com/cave.aspx http://www.mechdyne.com/filesimages/Media%20Images/Cave/Cave%20Diagram%202012.pdf
Enter the CAVE
http://www.mechdyne.com/cave2.aspx
CAVE 2TM
“near-seamless, 320-degree,
panoramic 2D/3D virtual
environment that matches
human visual acuity . . .
The CAVE2™ is a revolutionary
system that supports
information-rich analysis with
stunning immersive visuals
and intuitive interaction tools”
• Accommodate several users
• A single projector on a large wall means small image resolution
• Tiled displays place smaller images side-by-side so they need multiple projectors
• Images need to have overlap, to assure continuity
• However overlap from two projectors means intensity discontinuity (brighter
images in the overlap areas) • Projectors need to modulate intensities to dim their light for overlap pixels
Wall-type displays
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http://www.mechdyne.com/portable-3d-display.aspx
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• Widely installed immersive reconfigurable visual environment
• Adequate for applications that will benefit from more than one display configuration (there is a mobile version)
• Walls can be moved independently to create new formats (7.5' x 10' )
• Has three walls and one floor screen • In < 5 min can become: - A flat wall display - An angled theater,
- An L-shape - A CAVE-like immersive room
FLEX TM - Reconfigurable immersive display
http://www.mechdyne.com/flex.aspx http://www.mechdyne.com/plex.aspx
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Wall-type displays
Typical uses:
• Multi-disciplinary research
• Product design reviews
• Large audience presentations
• Computational fluid dynamics
• Geophysical exploration and training
• Terrain mapping and situational awareness
• Any application where multiple display modes would be beneficial
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Dome-type display Immersadome
http://inition.co.uk/3D-Technologies/immersive-display-immersadome-range
- 3D immersive visual environment
- Up to 20 people (depending on dome size)
- Resolution: 1400 x 1050
- 180°horizontal x 135°vertical (distortion
free projection)
- Multiple control options (mouse, keyboard, joystick, tracker-ball, haptic)
- Applications:
- museums, - group training - flight or driver simulation…
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Tiled composite image from four projectors
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Tiled composite image from four projectors after adjustment
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Advantages: • Accommodate many users (tens to hundreds)
• Give users more freedom of motion
Disadvantages: • Large cost (up to millions of dollars)
• Even with several displays resolution is low (larger area)
Dome-type displays
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http://www.mechdyne.com/immersive-domes.aspx
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Dome type displays
VisionDome 5(m); 2 to 20 users; price > $85,000.00
http://www.vrealities.com/products/vr-domes/visiondome-5
Visual Displays: another taxonomy (Sherman and Craig, 2003)
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• Head-based (occlusive)
• Non-occlusive head-based
• Handheld
• Monitor- based (Fishtank)
• Projection Displays Stationary displays
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Benefits of Stationary Displays (Fishtank and Projection)
• Higher resolution (than most HMDs)
• Wider field of view
• Longer user endurance (i.e., can stay immersed for longer periods)
• Higher tolerance for display latency
• Greater user mobility (fewer cables)
• Less encumbering
• Lower safety risk
• Better for group viewing
• Better throughput
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Benefits of Head-based Displays (Occlusive and Non-occlusive)
• Lower cost (for lower resolution models)
• Complete field of regard
• Greater portability
• Can be used for augmenting reality
• Can occlude the real world
• Less physical space required
• Less concern for room lighting and other environmental factors
Benefits of Hand-based Displays
• Greater user mobility
• Greater portability
• Can be combined with stationary VR displays
Main bibliography
- G. Burdea and P. Coiffet, Virtual Reality Technology, 2nd ed. Jonh Wiley and Sons, 2003
- Craig, A., Sherman, W., Will, J., Developing Virtual Reality Applications: Foundations of Effective Design, Morgan Kaufmann, 2009
- J. Vince, Introduction to Virtual Reality, Springer, 2004
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Aknowledgement
The author of these slides is greteful to:
• G. Burdea and P. Coiffet for making available the slides supporting their book
• All colleagues and students that have contributed in any way
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