Virtual Reality _Artificial Reality_

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					Virtual Reality (Artificial Reality)

“A computer system used to create an artificial world in
which the user has the impression of being in that world
and with the ability to navigate through the world and
manipulate objects in the world.”

-C. Manetta and R. Blade
• A display connected to a digital computer gives us a
chance to gain familiarity with concepts not realizable
in the physical world. It is a looking glass into a
mathematical wonderland.

• The ultimate display would, of course, be a room
within which a computer can control the existence of

- Ivan E. Sutherland
Two Requirements of VR

   Immersive

   Interactive
Two Related Courses of VR

   Computer Graphics

   Computer Vision
      Two Ways to construct VR

      幾何式(Geometry-based)   影像式(Image-based)

對象    可以是完全不存在的物件或 針對存在的物件或場景
互動性   使用者可以完全自由地移動 使用者的移動受到限制
速度    逼真的影像描繪需要大量的 運算量與場景複雜度無關,
       運算,運算量與場景複雜  適用於即時系統
擬真度   影像品質較不真實              影像品質非常逼真
製作過程 物件幾何模型製作時間長, 不需物件幾何模型,製作
      3D掃描所需儀器價格昂貴 過程比較簡單
     Two Types of VR
Immersive : 3D environment seen through a head-mounted
display (HMD). In a completely immersive system the user has
no visual contact with the physical world.

Semi-immersive : Most advanced flight, ship and vehicle
simulators are semi-immersive. The cockpit, bridge, or driving
seat is a physical model, whereas the view of the world
outside is computer-generated (typically projected).
Two Parts of VR

   Augmented Virtuality

   Augmented Reality
         Evolution of VR

Adventure games, MUD(Multi-Users Dungeon) : Textually
described virtual worlds where the user perceives the virtual
environment through mental images like reading a novel.

Desktop : 3D virtual environment graphically displayed on a
desktop computer monitor.
      Evolution of

Projected : 3D environment projected onto a screen. Enables
a single user to demonstrate concepts to a group of people. A
CAVE (developed by University of Illinois), where several
screens are used to surround the user with images, is the most
advanced form of projected VR in use today.
      VR Technology
• Hardware capable of rendering real-time 3D graphics and
high-quality stereo sound.

• Input devices to sense user interaction and motion.

• Output devices to replace user's sensory input from the
physical world with computer-generated input.

• Software that handles real-time input/output processing,
rendering, simulation, and access to the world database in which
the environment is defined.
        Head Mounted Display (HMD)
• Can display either stereo or mono
    • Stereo images (binocular
    • Same image twice (binocular
    • Single image (uniocular)
• May be totally immersive or semi-
immersive (see-through)
• May include a built-in head-
• May have built-in stereo
Each eye
   sees a
  field of
         Alternative Displays
LCS (Liquid Crystal Shutter)
• Display shows left and right
images alternately, switching at
high speed between images

• Stereoscopic image is seen when
the display is viewed with special

• Typical 'Fishtank VR'
• Particularly good for large
audiences in a theatre

BOOM(Binocular Omni-Orientation Monitor) by Fakespace
• Uses a CRT to provide high-resolution display
• It is comfortable to use, since it does not have to be worn
• Has fast, accurate, built-in tracking
 VRD (Virtual Retinal Display)

 • Image is projected directly
 onto the retina (by Microvision)
       Motion Tracking Types

• Mechanical
   • Usually a mechanical arm attached to the tracked
   • Very accurate, short lag, but restrict movement

• Electromagnetic
   • Measures strength of magnetic fields in coils
   attached to objects
   • Fast, short lag, but often prone to interference
   • Limited range
    Motion Tracking Types
• Optical
   • Typically, pulsating LEDs monitored by a camera
   at a fixed position
   • Fast, reasonably short lag, but often prone to
   interference caused by ambient lighting
   • Line of sight problems

• Acoustic
   • Use ultrasound waves to measure position and
   • Slow and often imprecise
Interaction Devices

• 3D Mice

• Spaceballs

• Eye tracking

• Video camera and shadows

• Voice recognition

• Biological sensors
   Interaction Devices

Light Pen
Interaction Devices   • Data Gloves
   Interaction Devices

• Data Gloves

   • Hand and gesture tracking

   • Enables natural interaction with objects

   • Can use hand-signs to execute actions

• Full body suits

   • Motion capture

• Motion platforms

•Tactile feedback provides a sense of touch through,
typically, vibrating nodules or expanding air bubbles
inside a glove or suit

• Force feedback provides physical constraints

• Exoskeletons

• Joysticks, Hand controllers

• Important to create a sense of atmosphere

• Can greatly enhance feeling of presence

• Can be used to provide valuable depth cues,
aiding navigation

• Enables the user to perceive events that occur
outside the immediate field of view

• Audio feedback

• Need modeling tools to create objects (AutoCAD,
3D Studio, etc.)

• Designing objects is time-consuming

• Objects often need to be optimized for VR use
1. Architecture

2. Design and Prototyping

3. Education & Conferencing

4. Training

5. Medical

6. Business and Visualization

7. Art and Leisure

 • Walkthroughs to evaluate design decisions and
 present designs to customers

 • Demonstrate how a planned construction fits into
 the environment in which it is intended to be built
Design and

  • Use to create rapid prototypes rather than make clay
  models or full-scale mock-ups

  • Simulate assembly lines. For example, to evaluate
  the risk of interference or collision between robots,
  cars, and car parts
         Education & Conferencing
• Visualize concepts
• Visualize the past ('Virtual
• Virtual lectures and

• Collaborative work over the
• Virtual work groups
• Virtual conferences

Civilian and
military training

• Driving

• Flight simulators

• Ship simulators

• Tank simulators

 Train for hazardous or difficult operations
 • Nuclear plant maintenance
 • Learn to move in zero gravity
 • Practice locating and fixing faults in equipment
• Practice performing surgery
• Perform surgery on a remote patient

• Phobia therapy
• Use VR input devices and tele-presence to enable
handicapped people to do things that would otherwise be
impossible for them to do
• Enable people to visit/see places that they would be
otherwise unable to experience
• Use VR to teach new skills in a safe, controlled, environment
Business and

• 3D visualization of complex financial information
• Demonstrate customizable products to customers

Scientific Visualization
• View complex data sets to gain greater insight and
understanding of structure
• View complex molecular and geological structures
         Art and Leisure

• Virtual galleries
and museums
• Virtual theatres

• Games
• Sport simulators
Challenges of VR
   Hardware Technology
• More realistic graphics and audio (this is also a
software problem)

• Greater processor power

• Less lag

• Less obstructive input/output devices

• Better display technology
         Building worlds

• Creating models takes a long time and is a skill that
needs to be acquired

• We need better software tools to create objects, add
behavior to objects, and to handle interaction

• Optimizing models takes time and synchronizing
modifications can be difficult (CAD tools to/from VR
environment builder)
   Building worlds
• Implementing scripts and interaction is often
difficult for non-programmers

• Making accurate models of the physical world is
difficult. Devices such as laser scanners are making
this easier, but human intervention is still a necessary
and time consuming part of the modeling process

• Can we build knowledge-based systems to help us
capture the physical world?
       User Interaction Design

The user interface for a virtual environment needs to be
carefully designed to take into account the functional
requirements of the application and the limitations of
current technology

• How should the user interact with the virtual
• How should the computer provide feedback?
• What is the most meaningful way to visualize an
abstract object/process/structure?
• What does cyberspace (the Internet) look like?
• How do we improve navigational and spatial awareness?
       Human Factors
There are a number of factors that should be taken into
consideration when designing the user interface of a
virtual environment in order to minimize physical
discomfort for the user

• Latency causes user discomfort (simulation sickness,
• Well design and optimized models reduce latency and
improve rendering consistency
• Eye strain problems?
• Long-term physical and psychological effects?
 Distributed Virtual Environment

• How should users communicate?

• How do I know you are real and not an agent?

• Social effects of distributed VR?

• Technological: Lag, large numbers of users
simultaneously, etc.
        VR is a powerful user interface technology

• Choosing the best way to visualize information is

• VR enables the user to interact directly with information

• VR enables the user to see/experience things in new

• VR does not have to be immersive to be useful

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