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