Ownuse

Virtual Reality Foundations

Sven Loncaric, Ph.D.Faculty of Electrical Engineering and Computing

University of ZagrebE-mail: [email protected]

WWW: http://ipg.zesoi.fer.hr

Overview of Presentation

Introduction to virtual reality Overview of practical VR aspects Overview of VR research projects in biomedicine

Introduction to VR

Foundations of VR human senses perception

VR terminology Technologies enabling VR VR research areas

Human Senses

Senses receive information from outside and inside the body

Senses: external (receive information about outside environment) internal (receive information about internal environment)

External senses: sight, hearing, heat (distance receiving senses) taste, touch, smell (contact external senses)

Internal senses: hunger, fatigue, pain, thirst

Perception

Perception is the process by which we receive and interpret information from the world around us

Senses and brain form the basis for perception senses receive information from the environment brain interprets the received information

Perception is not determined only by sensory information but also by knowledge, emotion, and motivation

PARISIN THE

THE SPRING

ONCEUPON AA TIME

Learning and Perception

The example shows how learning influences the result of perception:

Deceiving Perception System

Idea: substitute real information received by human senses by artificially generated senses

Consequence: An impression of presence of a person in a virtual environment is created

In this manner we can replace real environment with a virtual environment

The person has impression of being immersed in a virtual environment

Virtual Reality

The impression of being present in a virtual environment that does not exist in reality is called virtual reality

The user has impression of presence in that world and can navigate through it and manipulate objects in the world

Current practical restrictions of virtual reality comes from the fact that we are unable to artificially generate sensory stimulus with high fidelity contact senses are very difficult to mimic (touch, smell, taste)

Immersive vs. Non-immersive VR

When computer generated sensory information is accurate the operator has the impression of being immersed into the virtual environment

This is called immersive virtual reality To create immersive VR a head-mounted display is

required so when the user moves the head the view is adjusted accordingly

In non-immersive VR systems user views virtual world through the monitor or the projection screen

Illustration of Virtual Reality

virtual environment

real environment real butdistant reality

virtual (artificial)environment

Augmented Reality

Sometimes it is not necessary to completely replace the real environment with virtual environment

In some applications it is enough to augment the real environment with some elements of virtual environment

This is called augmented reality Augmented reality = true + virtual reality Example: wearable computers

Illustration of Augmented Reality

augmented reality

real environment

realworld

virtualworld

Wearable Computers

Idea: computer should be worn as a watch or a suit

Provide many new applications including virtual reality

US Army uses such systems for maintenance of complex systems

e.g. for service of aviation systems and other vehicles service image and instructions are

superimposed on the real image visible in the transparent display

Telepresence

Also called virtual presence The purpose of a telepresence system is to create a

sense of physical presence at a remote location Telepresence is achieved by generating sensory

stimulus so that the operator has an illusion of being present at a location distant from the location of physical presence

Telepresence system extends operator’s sensory-motor facilities and problem solving abilities to a remote environment

Illustration of Telepresence

virtualenvironmentis a copy ofthe remoteenvironment

real environment

fastcommunicationnetwork

remoteenvironment

Teleoperation

Teleoperation system enables operation at a distant remote site by providing local operator with necessary sensory information to simulate operator’s presence at the remote location

Teleoperation is a special case of telepresence where in addition to illusion of presence at a remote location operator also has the ability to perform certain actions or manipulations at the remote site

Technologies Enabling VR

Virtual reality is a combination of several technologies that enable the realization of VR systems:1. advanced (fast) computers

2. advance computer communication networks

3. human-computer interfaces

Realization of VR Systems

Artificial sensory stimulus required for creation of virtual reality are generated by a computer

Input to the computer are parameters of the operator’s physical position and readouts of various human-computer interfaces

Based on the input computer generates required sensory data that is sent to human computer interfaces that create an illusion of immersion in a virtual environment

Fast computer networks enable exchange of information between remote locations

Computers for VR

General purpose computers are used with the following requirements: high processing power for real-time rendering of virtual

environments to generate visual stimulus powerful graphical subsystem for real-time stereo display of

rendered virtual environment

Popular platforms include Silicon Graphics, SUN, …, and even PC

Permanent advances in computer technology enable development of more complex VR systems

Distributed VR Systems

Distributed VR system consists of several networked computers and one virtual environment

Each computer tracks actions of one user and creates an illusion of user’s presence in the shared virtual environment

All users are present in the same virtual world although they may be physically at distant locations

In this manner it is possible to perform multi-user simulations with interactions between users

VR Research

Modeling of material properties Human-machine interfaces Haptic interfaces Visualization techniques

Modeling of Material Properties

Force propagation models Deformable models for tissue modeling Real-time deformations for simulations Volumetric elastic models

Human-Computer Interfaces

Haptic interfaces are particularly difficult to realize Force feedback Tactile, smell, and taste sensors Physiological and psychological effects of simulators

(cyberpathology)

Haptic Interfaces

Haptic interfaces are devices that allow human-machine interaction through force and touch

Areas of application include: telemanipulation (for work in hazardous or challenging

settings such as space and microsurgery) virtual environments (for human operator training, design

prototyping, and data visualization)

Visualization Techniques

Visualization is important for creating of good visual sensory information

Surface rendering advantage: hardware acceleration available on general

purpose workstations, faster disadvantage: cannot represent volume interior

Volume rendering advantage: can represent volume interior disadvantage: special hardware required for acceleration,

slower

VR Applications

VR systems enable user activities in the virtual world instead of the real world

VR systems are utilized for: education assessment of work skills training simulations 3-D visualizations computer-aided design teleoperation and telemanipulation

VR Application Areas

medicine visualizations (in biochemistry, engineering, ...) complex system design (e.g. fluid dynamics) mechanical engineering maintenance i service of complex systems military applications (flight simulators) art (visual, musical) industrial design games and entertainment

Conclusion

Virtual reality is a subject of active research Applications are in many areas of human activity