Virtual Environments

Ruth Aylett

Aims of the course

1. To demonstrate a critical understanding of modernVE systems, evaluating the strengths andweaknesses of the current VR technologies

2. To be able to describe the main components of avirtual reality system and explain the importance andimpact of real-time constraints

3. To be able to evaluate appropriate display andinteraction capabilities for specific VR applicationsand justify a choice

4. To be able to apply basic VE construction skills tothe creation of small-scale systems

Overview of course

Lectures cover the whole area– Software and hardware– An issue of breadth v depth

Practical/lab work– VRML/X3D tutorial– Scenegraph programming in

OpenSceneGraph– Limited coverage of modelling

Projected topics

Intro, History, VRML, Human factors Display systems, audio, input devices Scenegraph programming, OpenSceneGraph,

system life-cycle Modelling, physics, haptics, volumetric

rendering Immersion, visualisation, IVEs, Distributed

systems, Avatars and agents, Games Engines,Applications

Books

Somewhat problematic– Virtual reality technology: Burdea & Coiffet

• Good but VERY expensive– Designing Virtual Reality Systems, Kim

• OK, but limited scope– Essential Virtual Reality, Vince

• Also Ok but very descriptive– The VRML Sourcebook

• Very comprehensive on VRML– X3D: Extensible 3D Graphics for Web Authors

• See http://x3dgraphics.com/

WARNING

Not everything is written on the slides– Lectures are there to convey verbal information– On which you may be examined

You are recommended to take notes– And if you don’t, this is your problem…

You are expected to read around– Some papers are provided– The web is an excellent resource

Seehttp://www.macs.hw.ac.uk/modules/F24VS2/VRcourse.html– Or go via my teaching page at

www.macs.hw.ac.uk/~ruth/teaching.html

Definition

Virtual Reality or a Virtual Environment is auser-interface technology that allows humansto visualise and interact with computergenerated environments through humansensory channels in real-time

The ultimate display…

Sutherland:– “The ultimate display would, of course, be a room

within which the computer can control theexistence of matter. A chair displayed in such aroom would be good enough to sit in. Handcuffsdisplayed in such a room would be confining, anda bullet displayed in such room would be fatal.With appropriate programming such a displaycould literally be the Wonderland into which Alicewalked.” Ivan Sutherland, 1965

The StarTrek Holodeck:

VE topics

Human– Immersion, presence, engagement

Hardware– Display systems, interaction devices,

model-capture tools

Software– Modelling, programming, rendering

Why Use a VE? The real is too costly or dangerous to work with

– (e.g. oilrig, nuclear plant)

Why Use a VE?• The real does not exist anymore - e.g.heritage

Why Use a VE? The real does not exist yet

– (construction, architects, design) Agecroft Prison

Why Use a Virtual Environment? The real is difficult to visualise

– (pin hole surgery, scientific data)

Virtual laparoscopic port-site simulator offering realistic variation in theappearance, attitude, and magnification of the image, depending on

the location of the virtual scope

Main Components

VR Run-timeEnvironment

3D ModelDatabase

Virtual EnvironmentGenerator

Position &OrientationTracking

Tracking HardwareTracking Interface

HapticFeedback Haptic Hardware

Haptic Interface

AuditoryDisplay Audio Hardware

Auditory Interface

Graphics HardwareVisualDisplay

Visual Interface

Human SensesAs virtual environments try to simulate the real world, byconstructing them we require knowledge on how to “fool theuser’s senses”Contribution of human senses [heilig92] sight….…………………………………….70% hearing…….……………………………….20% smell…………………………………….….5% touch…………………………………….….4%

Sight has been traditionally been the focus of most VR research, howeverresearchers are starting to realise this depends on the task.

VE: Output TechnologiesNon-Immersive Semi-Immersive Augmented ImmersiveEnvironments

Flat Displays Reality Rooms HM Displays CAVE

Virtual Window Stereo Glasses HM Displays HM ImmersiveDisplays

VR: Data Input Devices

Hand Held Laser Scanner

Microscribe3D Digitizer

Laser Scanning Range Finder

Real WordCapture

Real TimeData Capture

AnimationCapture

Haptic Interfacing Devices

1. Haptic Gripper 4. 3D Mouse 7. FF Steering Wheel

2. Haptic Stick 5. Dataglove 8. FF Joystick

3. Haptic Fingertips 6. Haptic Mouse

Graphics Pipeline3D

DATA TRANSFORM3D DATA IN

CAMERACOORDS

TRANSFORM2D DATA IN

SCREENCOORDS

DATAFULLY ONSCREEN

HIDDEN SURFACE & RENDERFINALIMAGE

Learn about scenegraphs with these appletshttp://www.cs.brown.edu/exploratories/ freeSoftware/catalogs/scenegraphs.html

Scene graph - the concept

Decomposition of a Geometric Model

The object to be modelled is (visually)analysed, and then decomposed intocollections of primitive shapes.

The tree diagram provides a visualmethod of expressing the “composedof” relationships.

More On Scene Graphs

- Root

- Rotate

- Group

- Translate

- Scale

Scene Graph A data structure that stores the completeinformation about the 3D scene:

–geometry (“what” the object is)–appearance (“how” the object should look)–behaviours (possible procedures that can change the form of the object)–global entities that affect all objects (such as viewpoints, lights, sounds,background object.

Note that in VR (as opposed to animation and 3D graphics) a scenegraph can be a dynamic structure, and behaviours can dynamicallyadd, delete, and modify the scene.

Animation Versus VR

Animation: images pre-rendered and played back insequence– As in film

VR - images drawn in real-time in response to theusers position and actions in the world– In VR the user has total control of what they see

The overlap between the technologies is typically inwalk throughs and fly-pasts– Small animated sequences may be invoked (cut scenes)

VR Versus CAD

CAD stresses modelling accuracy VR stresses sensory realism VR allows the user to walk, stop, touch, manipulate objects

within the world VR has lighting, materials, textures There is convergence between the two areas Many VR packages will import CAD data

Applications Data visualisation

– Oil industry; networks; scientific Publicity and Marketing Product design

– Rapid prototyping, Maintenance Ergonomics Urban planning Collaborative working Training

Research issues

Understanding the impact– What works and what doesn’t on people

Better displays– Better resolution, quicker update, non-intrusive stereo,

volumetric rendering Better interaction

– Better interaction devices; better haptics– Non-intrusive interaction: gesture, glance, facial expression,

social responsiveness Embodying intelligence

– Adding knowledge– Adding autonomous characters