Universidade de Aveiro Departamento de Electrónica, Telecomunicações e Informática Output Devices - I Realidade Virtual e Aumentada 2017/2018 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) 2
Output Devices: Graphics, 3-D Sound, and Haptic Displays (Burdea and Coiffet., 2003) 3
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 4
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) 5
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 6
Human Visual System And depth perception Vision is the dominant sensorial channel (Burdea and Coiffet., 2003) 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) 7
Depth perception in stereo is based on stereopsis (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) 3-5% of people are stereoblind (Jerald., 2016) 8
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 9
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 VR systems use the first type (stereoscopic displays) https://voxon.co/stl-renderingvoxon-vx1-3d-volumetric-display 10
Stereopsis object Projection plane Stereo ="solid" or "three-dimensional opsis = appearance or sight eyes '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 Binocular disparity is due to the different position of our two eyes 11
(Hearn and Baker, 2002) object Right eye image Left eye image Projection plane eyes 12
Implications for Stereo Viewing devices 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) Left eye, right eye images (Burdea and Coiffet., 2003) 13
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 14
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 In Virtual Reality the technologies used are: - Different light polarization and polarizing glasses - Double frame-rate displays combined with LCD shutter glasses 15
Vertical polarizer Polarized light stereoscopy 3D movies have used polarized technology since the 1930s Verical polarization of light 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 Circular polarized light http://en.wikipedia.org/ wiki/polarized_3d_glasses 16
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: https://www.inition.co.uk/extraordinarytechnology/stereoscopic-3d-displays/ 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 17
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 Can be bought for < 100 Need a battery 18
Passive (polarized) versus active (shutter)? Passive Active cheaper lighter batteryless syncless glasses Better image quality 19
Visual Displays in Virtual Reality 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/hand held LEDs/OLEDs - Monitor-based displays/active glasses LCDs - Autostereoscopic displays lenticular/barrier Large volume displays: Workbenches Caves projectors Walls, domes Surface 20
Main Properties of Visual Displays 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 21
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) HMDs create a virtual image at some distance beyond the physical display 22
Field of view (FOV) and Field of regard (FOR) 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 projectionbased displays (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 23
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 25
Visual Displays: another taxonomy (Sherman and Craig, 2003) Head-based (occlusive) Non-occlusive head-based Handheld Monitor- based (Fishtank) Projection Displays Stationary displays 26
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) 27
HMD integration in a VR system simple HMD More professional HMD (Burdea and Coiffet., 2003) 28
Example of a professional HMD zsight OLED HMD (Sensics) - 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 http://sensics.com/portfolio-posts/zsight/ 29
The low cost Head-Mounted Displays: Oculus Rift 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: ~~$400 http://www.oculusvr.com/ 31
Oculus Rift and human factors in VR http://www.youtube.com/watch?v=iacas_ranee 32
Oculus Rift vs PlayStation VR: What is the best VR gaming headset? https://www.wareable.com/vr/oculus-rift-vs-playstation-vr 33
HTC Vive Price: ~~$700 https://www.vive.com/eu/ 34
Headsets using Smartphones: Google Cardboard https://en.wikipedia.org/wiki /Google_Cardboard 35
https://techcrunch.com/2016/11/10/googles-daydream-view-mademe-a-believer-again-in-consumer-vr/ 36
Popular Augmented Reality Headsets: Google Glass (2013) Display - reflects light into the wearer's eye Camera photos and video Touchpad on the side Micro voice control 1500 $ https://www.wired.com/story /google-glass-2-is-here/ http://www.youtube.com/watch?v=jsnb06um5r4 https://www.google.com/glass/start/
Google glass (2015) http://www.pcadvisor.co.uk/feature/gadget/google-glass-release-date-uk-price-specs-3436249/ 38
Google glass (2017?) https://www.wired.com/story/google-glass-2-is-here/ 39
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 Now there is a new version: Meta2 https://www.metavision.com/ 40
Hololens Microsoft AR glasses Developement edition: 3000 $ https://www.microsoft.com/en-us/hololens/ Thyssenkrupp a new vision to elevator maintenance: Preparing the visit: On site: https://www.youtube.com/watch?v=8owhgiyr4ns
Hand Held devices - Binoculars (older and more expensive) - Tablets/ smartphones (more and more used for AR) (Jerald, 2016) 42
Virtual Binoculars 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 (Burdea and Coiffet., 2003) 43
Virtual Binocular SX Price: $20,900 Virtual Binocular SV Price: $7,900 45
Auto-stereoscopic displays 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) 46
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 Each of the viewer s eyes sees light from only every second pixel column Commercial examples: - 45 ; 1920 x 1080 pixels; 8 view points - 84 ; 3840 x 2160 pixels; 16 view points http://www.alioscopy.com/ en/3ddisplays.php 48
Parallax barrier: a barrier mask is placed in front of the pixel raster Each of the viewer s eyes sees light from only every second pixel column 49
Holographic displays The image source is based on standard flat panel technology of which the image is seen upon glass panel with several optical layers 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 http://www.eonreality.com/eonholographic-i 50
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. 51
Projector based Large-volume displays CAVE type displays Wall-type displays Domes Workbanch-type displays 53
CAVEs CRT Projector Screen Mirror CAVE 3-D large volume display (Fakespace Co.) (Plato s allegory of the cave, where a philosopher contemplates reality and illusion...) 55
Enter the CAVE http://www.mechdyne.com/cave.aspx
Examples of several CAVE configurations and prices http://www.visbox.com/products/cave/ 58
CAVE 2 TM 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 http://www.mechdyne.com /cave2.aspx
Wall-type displays 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 http://www.mechdyne.com/portable-3d-display.aspx 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 60
FLEX TM - Reconfigurable immersive display 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 http://www.mechdyne.com/flex.aspx http://www.mechdyne.com/plex.aspx 62
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 63
Issue: Tiled composite image from four projectors 65
Tiled composite image from four projectors after adjustment 66
Dome-type display Immersadome - 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 http://inition.co.uk/3d-technologies/immersivedisplay-immersadome-range 67
Dome-type displays Advantages: Accommodate many users (tens to hundreds) Give users more freedom of motion http://pacificdomes.com/immersivevirtual-reality-dome-environments/ Disadvantages: Large cost (up to millions of dollars) Even with several displays resolution is low (larger area) 68
Dome type displays VisionDome 5(m); 2 to 20 users; price > $85,000.00 http://www.vrealities.com/products/vr-domes/visiondome-5 69
Visual Displays: another taxonomy (Sherman and Craig, 2003) Head-based (occlusive) Non-occlusive head-based Handheld Monitor- based (Fishtank) Projection Displays Stationary displays 71
Benefits of Stationary Displays (monitor and projection based) 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 72
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 73
Main bibliography - G. Burdea and P. Coiffet, Virtual Reality Technology, 2 nd ed. Jonh Wiley and Sons, 2003 - Craig, A., Sherman, W., Will, J., Developing Virtual Reality Applications: Foundations of Effective Design, Morgan Kaufmann, 2009 - Jerald, J., The VR Book: Human-Centered Design for Virtual Reality, ACM and Morgan & Claypool, 2016 74