This document provides an overview of virtual reality, including its foundations in human senses and perception. It describes key VR terminology and technologies that enable VR like head-mounted displays. Applications of VR discussed include education, training, simulations, teleoperation and more. Research areas are also outlined such as modeling of materials, human-computer interfaces, haptics, and visualization techniques.

1. Virtual Reality Foundations
Sven Loncaric, Ph.D.
Faculty of Electrical Engineering and Computing
University of Zagreb
E-mail: sven.loncaric@fer.hr
WWW: http://ipg.zesoi.fer.hr

2. Overview of Presentation
q Introduction to virtual reality
q Overview of practical VR aspects
q Overview of VR research projects in biomedicine

3. Introduction to VR
q Foundations of VR
s human senses
s perception
q VR terminology
q Technologies enabling VR
q VR research areas

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

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

6. Learning and Perception
q The example shows how learning influences the result
of perception:
PARIS ONCE
IN THE UPON A
THE SPRING A TIME

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

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

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

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

11. Augmented Reality
q Sometimes it is not necessary to completely replace
the real environment with virtual environment
q In some applications it is enough to augment the real
environment with some elements of virtual
environment
q This is called augmented reality
q Augmented reality = true + virtual reality
q Example: wearable computers

12. Illustration of Augmented Reality
real environment
augmented reality
real virtual
world world

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

14. Telepresence
q Also called virtual presence
q The purpose of a telepresence system is to create a
sense of physical presence at a remote location
q 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
q Telepresence system extends operator’s sensory-
motor facilities and problem solving abilities to a
remote environment

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

16. Teleoperation
q Teleoperation system enables operation at a distant
remote site by providing local operator with necessary
sensory information to simulate operator’s presence
at the remote location
q 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

17. Technologies Enabling VR
q 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

18. Realization of VR Systems
q Artificial sensory stimulus required for creation of
virtual reality are generated by a computer
q Input to the computer are parameters of the
operator’s physical position and readouts of various
human-computer interfaces
q 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
q Fast computer networks enable exchange of
information between remote locations

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

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

21. VR Research
q Modeling of material properties
q Human-machine interfaces
q Haptic interfaces
q Visualization techniques

22. Modeling of Material Properties
q Force propagation models
q Deformable models for tissue modeling
q Real-time deformations for simulations
q Volumetric elastic models

23. Human-Computer Interfaces
q Haptic interfaces are particularly difficult to realize
q Force feedback
q Tactile, smell, and taste sensors
q Physiological and psychological effects of simulators
(cyberpathology)

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

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

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

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

28. Conclusion
q Virtual reality is a subject of active research
q Applications are in many areas of human activity