We often receive requests from students, hobbyists, or
interested parties for more information about Virtual
Reality (VR). The following is an attempt
to provide an introduction to the topic, and to also supply
some links where further information may be found.
What is Virtual Reality (VR)?
Virtual Reality is generally a Computer Generated
that makes the user think that
he/she is in the real environment. One may also experience
a virtual reality by simply imagining it, like Alice in
Wonderland, but we will focus on computer generated virtual
realities for this discussion.
The virtual world is hosted on a computer
in the form of a database (e.g. terrain database or environment
database). The database resides in the memory of the
computer. The database generally consists of points in
, as well as textures
(images). vertices may be connected to form planes, commonly
referred to as polygons
. Each polygon consists
of at least three vertices. The polygon could have a specific
color, and the color could be shaded, or the polygon could
have a texture pasted onto it. Virtual objects will consist
of polygons. A virtual object will have a position
(x, y, z)
, an orientation (yaw, pitch, roll)
as well as attributes (e.g. gravity or elasticity)
The virtual world
is rendered with a computer.
Rendering involves the process of calculating the scene
that must be displayed (on a flat plane) for a virtual
camera view, from a specific point, at a specific orientation
and with a specific field of view (FOV). In the past the
central processing unit (CPU) of the computer was mainly
used for rendering (so-called software rendering
Lately we have graphics processing units (GPUs) that render
the virtual world to a display screen (so-called hardware
). The GPUs are normally situated on
graphics accelerator cards, but may also be situated directly
on the motherboard of the computer. Hardware rendering
is generally much faster than software rendering.
The virtual environment (also sometimes referred to as
a synthetic environment) may be experienced with a Desktop
, or with an Immersive VR System
With Desktop VR
a computer screen is normally
used as the display medium. The user views the virtual
environment on the computer screen. In order to experience
the virtual environment, the user must look at the screen
the whole time.
With Immersive VR
the user is 'immersed
in' or 'surrounded by' the virtual environment. This may
be achieved by using:
A Multi-Display System
A Head Mounted Display (HMD)
Immersive VR Systems provide the user with a wider field of view than Desktop VR Systems.
With Multi-Display Systems
the field of view (FOV) of the user is extended by using
several computer monitors, or projectors. When using projectors,
the image may be front-projected or back-projected onto
the viewing screen. Many simulators utilize three screens
(forward view, left view, right view) to provide an extended
FOV. The configuration where the user is surrounded by
projection screens are sometimes referred to as a cave
environment. The image may also be projected on a dome
that may vary in shape and size. With a multi-display
system the user may look around as if in the real world.
A Head Mounted Display (HMD)
consists of two miniature displays that are mounted
in front of the user's eyes with a headmount. Special optics enable the user to
view the miniature screens. The HMD also contains two headphones, so that the
user may also experience the virtual environment aurally. The HMD is normally
fitted with a Head Tracker
. The position (x,
y, z) and orientation (yaw, pitch, roll) of the user's head is tracked by means
of the Head Tracker. As the user looks around, the position and orientation information
is continuously relayed to the host computer. The computer calculates the appropriate
view (virtual camera view) that the user should see in the virtual environment,
and this is displayed on the miniature displays. For example, let's assume that
the virtual environment is the inside of a car, and that the user is sitting behind
the steering wheel. If the user looks forward, the head tracker will measure this
orientation, and relay it to the computer. The computer would then calculate the
forward view, and the user will see the windscreen, wipers and bonnet of the car
(the user will obviously also see the outside world, or out of window (OOW)
view). If the user looks down, the computer will present a view of the steering
wheel. If the user looks further down, the accelerator pedal, clutch (if present)
and brake pedal will be shown. The orientation information may also be used to
experience stereo and 3-D sound
. If the user looks straight forward,
he/she will hear the engine noise of the car. The volume and phase will be equal
for the right and left ear. If the user looks to the left, the volume of the engine
noise will be higher in the right ear and lower in the left ear. Trackers that
only track the orientation (yaw, pitch, roll) are referred to as 3 degree of freedom,
or 3 DOF
trackers, while trackers that also tracks the position
(x, y, z) are referred to as 6 DOF
Objects in the virtual world may be manipulated
by means of a Data
. A data glove measures the flexure
(bend) of the user's fingers. The user may grab a virtual
object and put it at a different spot. The user may also
throw the object. The position (x, y, z) and orientation
(yaw, pitch, roll) of the user's hand is measured with
a 6 DOF tracker. If it is a force-feedback
data glove, the user will also be able to deform the virtual
object, and feel the object (e.g. a tennis ball) resisting
In order to navigate
(e.g. walk or fly)
in the virtual world, a Space
Controller is used. The space controller could be
a normal joystick, or a computer mouse. For example, when
the mouse is moved forward, the user moves forward in
the virtual world, when it is moved to the left, the user
moves to the left, etc. Force-feedback joysticks or mice
could provide haptic cues to the user, e.g. when the user
moves into a virtual wall. Normal joysticks and computer
mice are usually used in Desktop VR Systems. In Immersive
VR Systems we normally use baseless joysticks as space
controllers. This enables the user to leave the desktop
and to interact with the virtual world while standing
It is also possible for different users to share
the same virtual world
. This is normally achieved
by connecting the host computers to a computer network.
Each user's host computer broadcasts the position and
orientation of the user in the virtual world. The users
may therefore 'see' each other in the virtual world. In
fact, users will see representations, referred to as avatars,
of each other in the virtual world. They will be able
to interact; working together or competing. The sharing
of virtual worlds is generally referred to as 'shared
virtual worlds', or as 'networked virtual reality'.
main human senses currently used to experience virtual
(as in tactile- and force-feedback)
is becoming more commonplace. Smell
are entering the marketplace, enabling the user to smell
the virtual world as well. Taste
will follow soon.
Applications of Virtual Reality (VR)
Virtual Reality is an ideal training
VR is ideal for the training of operators that perform
tasks in dangerous or hazardous environments
The trainee may practice the procedure in virtual reality
first, before graduating to reality-based training. The
trainee may be exposed to life-threatening scenarios,
under a safe and controlled environment. Examples of dangerous
or hazardous environments may be found in the following
Examples of the above are shown under the Products heading.
VR is also an ideal tool to train operators for:
Operation of Expensive Equipment
VR Training safeguards the equipment. Expensive
equipment normally also have high earning(production) potential.
With VR training it is also not necessary to take
the equipment out of production for training purposes.
Operation of Equipment with a High Running Cost
With VR Training huge savings on fuel, electricity and wear and tear could be effected.
The operator of a lunar (or Mars) lander has only one chance.
A communications satellite repairperson also have only a limited (and very expensive) window of opportunity
during which to complete the task. VR could Prepare people for this.
Emergency scenarios where reality-based training is not an option
It would not be realistic to implement a 'limited nuclear meltdown' for training purposes.
VR is an ideal Visualization
It helps the user to visualize complex data sets, or to reconstruct (or re-experience) real life scenarios that have been recorded.
Examples of VR as a visualization tool are shown under the Products
The following list of online publications/newsgroups offer a wealth of information
about Virtual Reality, and the VR Industry:
Jerry Isdale (vr.Isdale.com
These are discussed in more detail below.
On-line reference library as well as other relevant links.
Virtual reality articles as well as other relevant links.
You may visit www.VREfresh.com to read the latest issue
or to search the archives. When you subscribe, new issues
will be sent to you via e-mail about once every two
To subscribe, go to:
and follow the link to 'receive free VREfresh'.
Grigore C. Burdea
(Virtual Reality Technology
Grigore Burdea and Philippe Coiffet published
Virtual Reality Technology Second Edition
with a CD-ROM included.
You could also buy it from AMAZON.COM
* * * * * (5 stars rating)
An excellent text for student, instructor and expert.
The book has the potential to attract diverse audience
from students (and instructors), to the non-VR professionals,
and VR professional student and the instructor. The book,
the CD and the web site provide almost unparalleled support.
The introductory chapter deals primarily with a history
of VR, showing Chapters 2,3,and 4 consider the system
hardware, with chapters 2 and 3 concentrating on input/output
and chapter 4 focusing of the computer platforms.
For more details Please visit the authors website
The Media CD-ROM contains an extensive image gallery (more than 160 images) of 5DT Virtual Reality products and technology
demonstrators. The image gallery is supplemented by product descriptions, data sheets, presentations,
image captions and image descriptions, that could serve as a reference base for students, hobbyists and scientists alike.
Click on the button below to order your free 5DT Media CD-ROM.