Virtual Reality Foundations

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Virtual Reality Foundations

• Sven Loncaric, Ph.D.
• Faculty of Electrical Engineering and Computing
• University of Zagreb
• E-mail sven.loncaric_at_fer.hr
• WWW http//ipg.zesoi.fer.hr

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Overview of Presentation

• Introduction to virtual reality
• Overview of practical VR aspects
• Overview of VR research projects in biomedicine

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Introduction to VR

• Foundations of VR
• human senses
• perception
• VR terminology
• Technologies enabling VR
• VR research areas

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Human Senses

• Senses receive information from outside and
  inside the body
• Senses
• external (receive information about outside
  environment)
• internal (receive information about internal
  environment)
• External senses
• sight, hearing, heat (distance receiving senses)
• taste, touch, smell (contact external senses)
• Internal senses hunger, fatigue, pain, thirst

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Perception

• Perception is the process by which we receive and
  interpret information from the world around us
• Senses and brain form the basis for perception
• senses receive information from the environment
• brain interprets the received information
• Perception is not determined only by sensory
  information but also by knowledge, emotion, and
  motivation

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Learning and Perception

• The example shows how learning influences the
  result of perception

PARIS IN THE THE SPRING
ONCE UPON A A TIME
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Deceiving Perception System

• Idea substitute real information received by
  human senses by artificially generated senses
• Consequence An impression of presence of a
  person in a virtual environment is created
• In this manner we can replace real environment
  with a virtual environment
• The person has impression of being immersed in a
  virtual environment

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Virtual Reality

• The impression of being present in a virtual
  environment that does not exist in reality is
  called virtual reality
• The user has impression of presence in that world
  and can navigate through it and manipulate
  objects in the world
• Current practical restrictions of virtual reality
  comes from the fact that we are unable to
  artificially generate sensory stimulus with high
  fidelity
• contact senses are very difficult to mimic
  (touch, smell, taste)

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Immersive vs. Non-immersive VR

• When computer generated sensory information is
  accurate the operator has the impression of being
  immersed into the virtual environment
• This is called immersive virtual reality
• To create immersive VR a head-mounted display is
  required so when the user moves the head the view
  is adjusted accordingly
• In non-immersive VR systems user views virtual
  world through the monitor or the projection screen

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Illustration of Virtual Reality
real but distant reality
real environment
virtual environment
virtual (artificial) environment
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Augmented Reality

• Sometimes it is not necessary to completely
  replace the real environment with virtual
  environment
• In some applications it is enough to augment the
  real environment with some elements of virtual
  environment
• This is called augmented reality
• Augmented reality true virtual reality
• Example wearable computers

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Illustration of Augmented Reality
real environment
augmented reality
real world
virtual world
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Wearable Computers

• Idea computer should be worn as a watch or a
  suit
• Provide many new applications including virtual
  reality
• US Army uses such systems for maintenance of
  complex systems
• e.g. for service of aviation systems and other
  vehicles
• service image and instructions are superimposed
  on the real image visible in the transparent
  display

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Telepresence

• Also called virtual presence
• The purpose of a telepresence system is to create
  a sense of physical presence at a remote location
• Telepresence is achieved by generating sensory
  stimulus so that the operator has an illusion of
  being present at a location distant from the
  location of physical presence
• Telepresence system extends operators
  sensory-motor facilities and problem solving
  abilities to a remote environment

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Illustration of Telepresence
remote environment
real environment
virtual environment is a copy of the
remote environment
fast communication network
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Teleoperation

• Teleoperation system enables operation at a
  distant remote site by providing local operator
  with necessary sensory information to simulate
  operators presence at the remote location
• Teleoperation is a special case of telepresence
  where in addition to illusion of presence at a
  remote location operator also has the ability to
  perform certain actions or manipulations at the
  remote site

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Technologies Enabling VR

• Virtual reality is a combination of several
  technologies that enable the realization of VR
  systems
• 1. advanced (fast) computers
• 2. advance computer communication networks
• 3. human-computer interfaces

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Realization of VR Systems

• Artificial sensory stimulus required for creation
  of virtual reality are generated by a computer
• Input to the computer are parameters of the
  operators physical position and readouts of
  various human-computer interfaces
• Based on the input computer generates required
  sensory data that is sent to human computer
  interfaces that create an illusion of immersion
  in a virtual environment
• Fast computer networks enable exchange of
  information between remote locations

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Computers for VR

• General purpose computers are used with the
  following requirements
• high processing power for real-time rendering of
  virtual environments to generate visual stimulus
• powerful graphical subsystem for real-time stereo
  display of rendered virtual environment
• Popular platforms include Silicon Graphics, SUN,
  , and even PC
• Permanent advances in computer technology enable
  development of more complex VR systems

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Distributed VR Systems

• Distributed VR system consists of several
  networked computers and one virtual environment
• Each computer tracks actions of one user and
  creates an illusion of users presence in the
  shared virtual environment
• All users are present in the same virtual world
  although they may be physically at distant
  locations
• In this manner it is possible to perform
  multi-user simulations with interactions between
  users

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VR Research

• Modeling of material properties
• Human-machine interfaces
• Haptic interfaces
• Visualization techniques

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Modeling of Material Properties

• Force propagation models
• Deformable models for tissue modeling
• Real-time deformations for simulations
• Volumetric elastic models

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Human-Computer Interfaces

• Haptic interfaces are particularly difficult to
  realize
• Force feedback
• Tactile, smell, and taste sensors
• Physiological and psychological effects of
  simulators (cyberpathology)

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Haptic Interfaces

• Haptic interfaces are devices that allow
  human-machine interaction through force and touch
• Areas of application include
• telemanipulation (for work in hazardous or
  challenging settings such as space and
  microsurgery)
• virtual environments (for human operator
  training, design prototyping, and data
  visualization)

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Visualization Techniques

• Visualization is important for creating of good
  visual sensory information
• Surface rendering
• advantage hardware acceleration available on
  general purpose workstations, faster
• disadvantage cannot represent volume interior
• Volume rendering
• advantage can represent volume interior
• disadvantage special hardware required for
  acceleration, slower

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VR Applications

• VR systems enable user activities in the virtual
  world instead of the real world
• VR systems are utilized for
• education
• assessment of work skills
• training
• simulations
• 3-D visualizations
• computer-aided design
• teleoperation and telemanipulation

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VR Application Areas

• medicine
• visualizations (in biochemistry, engineering,
  ...)
• complex system design (e.g. fluid dynamics)
• mechanical engineering
• maintenance i service of complex systems
• military applications (flight simulators)
• art (visual, musical)
• industrial design
• games and entertainment

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Conclusion

• Virtual reality is a subject of active research
• Applications are in many areas of human activity