Virtual Environments. Ruth Aylett

Transcription

1 Virtual Environments Ruth Aylett

2 Aims of the course 1. To demonstrate a critical understanding of modern VE systems, evaluating the strengths and weaknesses of the current VR technologies 2. To be able to describe the main components of a virtual reality system and explain the importance and impact of real-time constraints 3. To be able to evaluate appropriate display and interaction capabilities for specific VR applications and justify a choice 4. To be able to apply basic VE construction skills to the creation of small-scale systems

3 Overview of course Lectures cover the whole area Software and hardware Practical/lab work VRML/X3D tutorial Scenegraph programming in OpenSceneGraph Interfacing interactive devices Limited coverage of modelling Lab visits To see some of equipment in use

4 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, Distributed systems, Avatars and agents, Augmented reality, Games Engines, Applications

5 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

6 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 See Or go via my teaching page at

7 Definition Virtual Reality or a Virtual Environment is a user-interface technology that allows humans to visualise and interact with computer generated environments through human sensory channels in real-time

8 Three types of system Fully immersive all-encompassing worlds The original vision Augmentations or overlays to the real world Augmented or mixed reality Through the window non-immersive worlds

9 The ultimate display Sutherland: The ultimate display would, of course, be a room within which the computer can control the existence of matter. A chair displayed in such a room would be good enough to sit in. Handcuffs displayed in such a room would be confining, and a bullet displayed in such room would be fatal. With appropriate programming such a display could literally be the Wonderland into which Alice walked. Ivan Sutherland, 1965 The StarTrek Holodeck:

10 VE topics Human Immersion, presence, engagement Hardware Display systems, interaction devices, model-capture tools Software Modelling, programming, rendering

11 Why Use a VE? The real is too costly or dangerous to work with (e.g. oilrig, nuclear plant)

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

13 Why Use a VE? The real does not exist yet (construction, architects, design) Agecroft Prison

14 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 the appearance, attitude, and magnification of the image, depending on the location of the virtual scope

15 Main Components Visual Display Visual Interface Graphics Hardware Auditory Display Auditory Interface Audio Hardware VR Run-time Environment Haptic Feedback Haptic Interface Haptic Hardware Position & Orientation Tracking Tracking Interface Tracking Hardware 3D Model Database Virtual Environment Generator

16 Human Senses As virtual environments try to simulate the real world, by constructing them we require knowledge on how to fool the user 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, however researchers are starting to realise this depends on the task.

17 VE: Output Technologies Non-Immersive Semi-Immersive Augmented Immersive Environments Flat Displays Reality Rooms HM Displays CAVE Virtual Window Stereo Glasses HM Displays HM Immersive Displays

18 VR: Data Input Devices Real Word Real Time Capture Data Capture Hand Held Laser Scanner Microscribe 3D Digitizer Laser Scanning Range Finder Animation Capture

19 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

20 Graphics Pipeline 3D DATA TRANSFORM 3D DATA IN CAMERA COORDS TRANSFORM 2D DATA IN SCREEN COORDS FINAL IMAGE HIDDEN SURFACE & RENDER DATA FULLY ON SCREEN

21 Scene graph - the concept Decomposition of a Geometric Model The object to be modelled is (visually) analysed, and then decomposed into collections of primitive shapes. The tree diagram provides a visual method of expressing the composed of relationships. Learn about scenegraphs with these applets freesoftware/catalogs/scenegraphs.html

22 More On Scene Graphs - Root - Group - Rotate - Translate - Scale

23 Scene Graph A data structure that stores the complete information 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 scene graph can be a dynamic structure, and behaviours can dynamically add, delete, and modify the scene.

24 Animation Versus VR Animation: images pre-rendered and played back in sequence As in film VR - images drawn in real-time in response to the users position and actions in the world In VR the user has total control of what they see The overlap between the technologies is typically in walk throughs and fly-pasts Small animated sequences may be invoked (cut scenes)

25 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

26 Applications Data visualisation Oil industry; networks; scientific Publicity and Marketing Product design Rapid prototyping, Maintenance Ergonomics Urban planning Collaborative working Training

27 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