Principles of multimedia

1. UNIT V: Virtual Reality and Multimedia
Concept
Forms of VR
VR application
VR devices: Hand gloves, head mounted tracking systems, VR
chair, CCD, VCR, 3D Sound system, head mounted display.
Virtual objects-
Basics of VRML.

2. Concept
Virtual reality is a technology that provides one with the sensation
and the control of perspective so that one experiences the
illusion of being in the presence of an object, within a situation,
or surrounded by a place.
VR relies on audio and video technologies augmented by a
computer interface that reads the movement of the participant's
body. These act as triggers that change the direction of sounds
and the perspective of sights so that one sees and hears an
artificial world that appears to respond to one's body movement
just as the real world does.

3. VR : Definition
“VR refers to a computer based application which provides a
human computer interface such that the computer and its devices
create a sensory environment which is dynamically controlled by
the actions of the individual so that the environment appears real to
the user.”
Important factors :
1. interactivity
2. sensory environment which is intended to appear real

4. What use is VR?
VR provides:
Augmented ( Having been
made greater in size or
value) Reality
(AR) is a term for a live direct or
indirect view of a physical
real-world environment
whose elements are
augmented by virtual
computer-generated
imagery.
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5. Anything else?
How about…
learning to hang-
glide?
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6. Is it as
easy as it
looks?
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7. I’m more of the down to earth type...
How about
learning to
drive a car?
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8. Hey, that wasn’t there a moment ago...
Things are easy
with VR.
Real Estate Agents
use it every day.
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9. Forms of virtual reality
There are 3 general forms of VR :
1. Through-the-window (computer or movie screen) – applied
extensively in games and movie theatres. It allows the
participants to look into the virtual world from a seat in the real
world. Although movie theatres allow for no true interactivity,
computer games allow some. In some cases the seats move
and vibrate in response to images portrayed eg roller coaster
ride. Any participant who looks away from the screen during the
experience 'fall out' of the world and back into the real world.
Another example of 'Through the window' virtual reality comes from
the field of dance, where a computer program called LifeForms
lets choreographers create sophisticated human motion
animations.

11. Forms of virtual reality
2. Immersive VR – done with a hear mounted gear which allows
the participant to enter and become immersed in the virtual
world. The principle difference between form 1 & 2 is that in the
former the user is in immersive environment and can turn
around, look behind at something of virtual world. Usually
immersive worlds are also interactive – the participant decides
where to travel.
With some applications, there is a treadmill interface to simulate
the experience of walking through virtual space.

13. Forms of VR ....
3. Second person VR : it uses a camera to capture the image of a
participant and insert it into the virtual world. Users then watch
their own images on a monitor interacting with objects in the
virtual world.
The viewer stands outside the imaginary world, but communicates
with characters or objects inside it. Mirror world systems use a
video camera as an input device. Users see their images
superimposed on or merged with a virtual world presented on a
large video monitor or video projected image. Using a digitizer,
the computer processes the users' images to extract features
such as their positions, movements, or the number of fingers
raised.

15. VR application
There are in general 3 types of VR applications :
1. Perambulation ( To inspect an area on foot) - this involves walking or
flying some sort of model of a virtual world eg walking through a
building. Here the main aspect is observation, interactivity is limited
and may focus on moving objects in virtual space.
2. Synthetic experience – allows participants to safely and cheaply
practice skills that are dangerous and expensive to develop in the real
world, for eg – perform surgery, flying aircrafts, operate a plant control
room etc.
3. Realization – allows the users to see and graphically manipulate
context dependant data. In a way, it extends the idea of manipulating
graphical charts in a spreadsheet package by graphically changing the
input data and observing the output. It allows manipulation of data
representation eg, foreign currency, inventory of items as if they are
real objects.

16. VR devices
Hand gloves – these include gloves for picking up virtual objects to
foot pedals, joysticks, wands etc. Data gloves or cyber gloves are
devices that send the hand position and its orientation. Eg
Nintendo Power Glove.
head mounted tracking systems – used to send the coordinates of the
participant's head, hands or body to the computer. Translatory and
rotary movements along the X, Y and Z direction is handled.
VR chair

17. VR devices
CCD (charge-coupled device) – is a device for the movement of
electrical charge, usually from within the device to an area
where the charge can be manipulated, for example conversion
into a digital value. Scanners use sensors called CCD.
VCR – device used to record and play audio and video information
using removable cassettes containing magnetic tape.
3D Sound system
head mounted display.

18. Hand gloves

19. head mounted tracking
systems

20. VR chair

21. CCD

22. 3D sound system
Head mounted display

23. Devices
Head Mounted Displays
(HMD):
was the first device
providing its wearer with
an immersive experience.
Evans and Sutherland
demonstrated a head-
mounted stereo display
already in 1965.

24. Binocular Omni-Orientation Monitor
(BOOM)
BOOM is a head
coupled stereoscopic
display device. Screens
and optical system are
housed in a box that is
attached to a multi-link
arm.

25. Cave Automatic Virtual Environment (CAVE)
• A room with projections on
all walls, floor and ceiling
• The users wear shutter
glasses to get a 3D view of
the world.
• The users are able to
move and control the
environment with some
kind of input mechanism
– Camera
– Device in hand

26. Virtual objects-
(http://www.multimediaphoto.com/english/virtual_object/index.html)
Virtual object interactions provide a close approximation of real-life
objects that can be examined as if holding them in one's hands.
Additionally, these interactions can be enhanced with other
multimedia to provide a more rich learning experience.
In optics, a virtual image is an image in which the outgoing rays
from a point on the object always intersect at a point. A simple
example is a flat mirror where the image of oneself is perceived
at twice the distance from oneself to the mirror. ...

27. Virtual reality modeling language - VRML
It is a format for describing three dimensional interactive worlds
and objects that can be used on the www. The idea of a platform
independent standard for 3D object originated in 1994, which
lead to the formation of VRML architecture group in 1995.
VRML is designed to meet 3 criteria :
Platform independence
Extensibility
Ability to work over low bandwidths (14.4 kbps)
Browsers for VRML are widely available for different platforms as
are authoring tools for generating VRML files. It is a standard file
format for representing 3D interactive vector graphics, designed
particularly with the www in mind. Animations, sounds, lighting
and other aspects of the virtual world can interact with the user
or may be triggered by external events such as timers.

28. Purpose and the Characteristics of VRML
VRML is capable of representing static and animated objects and it
can have hyperlinks to other media such as sound, movies, and
image. Interpreters (browsers) for VRML are widely available for
many different platforms as well as authoring tools for the
creation VRML files. VRML supports an extensibility model that
allows new objects to be defined and a registration process to
allow application communities to develop interoperable
extensions to the base standard. There is a mapping between
VRML elements and commonly used 3D application
programmer interface (API) features.

29. Structure of VRML file
The structure of a WRL File: VRML (*.wrl) files have 3 basic
elements:
1. A header which tells the browser that the file is VRML and
which version also. A header line is mandatory.
2. Comments are preceded by a #.
3. Nodes: Most everything else are nodes. Nodes generally
contain:
a. The type of node (required). Nodes always are in Capital
letters.
b. A set of curly braces {.....} (required)
c. A number of fields, all or some of which are optional. Note
that there is no mandatory ordering of fields.
d. Fields with that can have multiple values require braces
[...]. Fields always start with lowerCase letters.

30. Example
Here is a typical VRML file with a single node (don't worry if you
don't understand it):
# VRML V2.0 utf8
# A sample file with a single node
Transform {
translation 0 2 0
children [
Shape {
geometry Sphere {}
}
]
}

31. Typical VRML Shapes:
Box
Cylinder
Cone
Sphere
Text and font style