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.

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.

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. interactivity2. sensory environment which is intended to appear real

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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Anything else?

How about… learning to hang-glide?

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Is it as

easy as it

looks?

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I’m more of the down to earth type...

How about

learning to

drive a car?

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Hey, that wasn’t there a moment ago...

Things are easy

with VR.

Real Estate Agents

use it every day.

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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.

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.

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.

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.

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

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.

Hand gloves

head mounted tracking systems

VR chair

CCD

3D sound system

Head mounted display

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.

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.

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

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. ...

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 independenceExtensibilityAbility 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.

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.

Structure of VRML fileThe 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.

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 nodeTransform { translation 0 2 0 children [ Shape { geometry Sphere {} } ]}

Typical VRML Shapes:

BoxCylinder

ConeSphere

Text and font style