Virtual reality: A state-of-the-art survey

International Journal of Automation and Computing 6(4), November 2009, 319-325

DOI: 10.1007/s11633-009-0319-9

Virtual Reality: A State-of-the-Art Survey

Ning-Ning Zhou1,2,∗ Yu-Long Deng1,2

1School of Computing, Nanjing University of Posts and Telecommunications, Nanjing 210003, PRC2State Key Laboratory of Software Development Environment, Beihang University, Beijing 100191, PRC

Abstract: This paper presents a survey on virtual reality systems and provides an in-depth understanding toward the notion of

immersion, according to the semantic meanings of the terms “virtual” and “reality”. The paper analyses the structure and functions

of a virtual reality system and takes the three dimensional display as the immersive medium to identify the key issues for construction

of virtual environments. The paper also reviews the development of virtual reality technology and introduces new image processing

techniques into the design of virtual reality systems and virtual environments.

Keywords: Virtual reality, immersion, virtual, reality, image processing technology.

1 Introduction

In 1965, Sutherland[1], the founder of computer graphics,

presented in his paper the first virtual reality system called

“the ultimate display” which has multi-senses immersion

and interaction. Since then, virtual reality has become an

area of research in computing graphics and systems.

This paper reviews how current terms in relation to vir-

tual reality systems are defined and presents a new inter-

pretation toward the meanings for “virtual” and “reality”

based on the notion of immersion. The paper starts with

the analysis on the structure and functions of a virtual re-

ality system and takes the three dimensional display as the

immersive medium to identify the key issues for construc-

tion of virtual environments. This is mainly focused on the

image processing techniques involved in the construction of

the virtual environments and how the construction process

can be enhanced with computation speed and graphic qual-

ity. The paper also reviews the development of virtual re-

ality technology and introduces new image processing tech-

niques into the design of virtual reality systems and virtual

environments.

2 Virtual reality

The term “virtual reality”, was first proposed by Laniner

of American VPL Research Inc. In 1989, which described

the computer simulation technology. After decades of de-

velopment, virtual reality technology has been expanded

from its early applications in entertainment and simula-

tion training to the applications in areas of aeronautical

research, architecture, scientific visualization in medicine,

defense, education, and training. Despite its vide spectrum

of applications and its popular acceptance by society, there

have been a variety of understandings and interpretations

Manuscript received January 31, 2009; revised April 25, 2009This work was supported by National Basic Research Program

of China (973 Program) (No. 2005CB321901), fund of NanjingUniversity of Posts and Telecommunications (No. NY206010 andNo. NY207083), Open Fund of the State Key Laboratory of Soft-ware Development Environment, Beihang University, (No. BUAA-SKLSDE-09KF-03).*Corresponding author. E-mail address: [email protected]

in the functions and implications of virtual reality systems.

As a result, there are different meanings and definitions of

the term virtual reality.

2.1 Definitions based on technology

The widely accepted definition of virtual reality is given

by its technological nature. For example, one defini-

tion originates from the human machine interface which is

stated[2] as “virtual reality is a natural interaction tech-

nology”. By this definition, the user can immerse into a

computerized or simulated environment and make natu-

ral interactions with that simulation environment (such as

cockpit and operation scene). The interactions have to be

dependent on sensor devices and controlled with dedicated

graphic programs. In [3], the term virtual reality is defined

as a means of interaction, by which people can see, operate,

and interact with extra complex data through computers.

Some other definitions are given based on virtual reality

devices. One such definition is given in [1], which describes

virtual reality as being the provision of a three-dimension

reality that is realized by a series of sensor devices like head-

mounted display, data glove, and so on. In the definition

like this, virtual reality is interpreted as a software and

hardware environment. This environment simulates a real

word in which the user can operate and control the virtual

environment by special interacting devices such as input

systems, sensor bistouries, and video oculars.

In fact, virtual reality technology not only refers to the

hardware devices like immersive display, and sensor gloves,

but also includes the relating technologies and methods that

can generate natural simulation and provide real time ex-

perience.

According to the IEEE standard protocol submitted by

the “work group of virtual reality term”, virtual reality

is the computer system which can generate a man-made

world, in which the user can immerse, roam, and operate

objects.

A more complete definition is given in [4]. It defines vir-

tual reality as a people-centered closed system that is im-

plemented mainly by computers and uses the corresponding

interaction between human and machine with perceptual

320 International Journal of Automation and Computing 6(4), November 2009

system. This closed system contains the virtual environ-

ment, interface of software and hardware, and the physical

environment. With such definition, a virtual reality sys-

tem has to be supported by necessary devices via which the

user can interact with the object of the virtual environment

in a natural way and can obtain the real-time experience

and feelings of the physical environment by operating the

objects in the virtual environment. Importantly, user can

overcome the constraints of time and space and control the

elements which are intangible in the physical environment.

The definitions of virtual reality in terms of its technolog-

ical implication have encouraged researchers to explore new

dimensions beyond its current application demands. With

the development of computing hardware and software, es-

pecially the development of new three-dimension graphics

techniques, the impact of virtual reality on visualization

and simulation has fundamentally changed the way in which

people use computers. For instance, users would immerse

themselves in the virtual world to experience events and

obtain knowledge which would not possible in conventional

ways. Nevertheless, such immersion is presenting a new

challenge: it may confuse the user with virtual scenarios

and cause unreal information to be taken as real knowledge

and important fact. In an abstractive level, the representa-

tion between virtual and real, data and fact, true and false

need to be realized in a way that such confusion can be

eliminated.

2.2 Definition based on immersion

2.2.1 Semantics and philosophy

1) Semantic implications of virtual

The term “virtual” comes from Latin “virtus” and “virtu-

alis”. Its original meaning refers to a force or an inherent

ability which can produce certain effect. The explanation

of the word “virtual” can be summarized in two ways, one

being in fact, acting as what is described and the other

being not physically existing as such.

2) Semantic implications of reality

The semantic implications of the word “reality” in ma-

jor dictionaries are given in four forms. The first is that

something or everything is real, real existence. The second

refers to the quality or state of being real. The third is

defined as real-sense, resemblance to an original. The last

form is philosophically defined as the entity of substance

and noumenon of spirit.

3) Philosophical meanings of virtual and reality

Philosophers have also given descriptions to the terms

“virtual” and “reality”. In the 17th century, British

philosopher Locke[5] gave his description of the terms “vir-

tual” and “reality” from the perspective of the abstractive

concept. He said: “I think the idea of reality is a concept

that is based on nature, conforms to a thing that exists,

or conforms to an existence of a thing or prototype”[5]. He

also described: “People know the ‘outside’ object according

to all of their ideas on that object. When the idea does not

match with a real object or others′ ideas expressed by com-

mon language, the idea is considered as virtual”[5]. Locke′sdescription emphasized things that exist in nature. When

the idea conforms to an existing thing in nature, it is consid-

ered as real. When the idea does not conform to an existing

thing in nature, it is considered as virtual.

The German philosopher Leibniz[6] disproved the idea of

Locke at the end of the 17th century. He argued that the

“idea may have a foundation in nature but does not conform

to it. For example, the sensation to the color and heat is not

similar to any original or prototype. When an idea does not

match anything existing, but it is possible, it also can be

considered as real.”[6] He also believed that the “idea which

arbitrarily connects with a real thing by us is considered as

virtual.”[6] Leibniz′s description emphasized not only on a

thing existing in nature, but also on an idea that may not

be physically proven. In his opinion, the idea that did not

conform to anything in nature is considered as real if it is

possible, and only the absurd idea without any foundation

is considered as virtual.

People′s imagination that does not conform to an ex-

istence in our space and time is believed to be unreal at

present. However, it may exist in the past or appear in

the future, or exist in other worlds or just in our world but

cannot be known or perceived currently by people. With

space transforming and time passing, the idea may match

with an existence in certain time and space. Such an idea

should not be considered as virtual but can be considered

as real.

In 1945, Clarke[7], a British science fiction novelist, es-

tablished the mechanism of satellite communication. His

idea was scoffed at by scientists of that time and was be-

lieved to be impossible and virtual, but today, his idea has

become reality. In the 1960s, the author of the sci-fiction

“Solar Sailboat” imagined a sailboat with the power of sun-

light. The idea which conformed to nothing in nature in

those days was considered virtual and unreal. However, in

July 2001, Russia succeeded in launching a spacecraft with

the power of solar sail, named as “Universe No. 1”. Now

the idea of the solar sailboat is thought to be real, and it

indeed conforms to an existence. As a result, Leibniz′s de-

scription of virtual and reality is more comprehensive, and

it has enhanced the idea of Locke in time and space.

In the philosophy dictionary of Lalande, the term “vir-

tual” is defined. In common sense, virtual means a thing in

a certain object which can be realized; in a limited sense,

virtual is a predefined thing in an object with all the basic

conditions inside. These basic conditions which cannot be

seen from the outside will make the predefined thing reality.

Hence, virtual is connected with a possibility or potential,

which is opposite to reality. Virtual and reality are two

different terms but they are closely related with each other.

In the realism of modern virtual reality technology, the

perception and experience obtained by user in the virtual

world is the same as in the real world. The immersed sense

is the main feature of the virtual reality.

2.2.2 Immersion

In 1975, psychologist Csikszentmihalyi[8] first presented

flow theory and gave a series of definitions for flow.

Definition 1. “The state of being completely involved in

an activity for its own sake. The ego falls away. Time flies.

Every action, movement, and thought follows inevitably

N. N. Zhou and Y. L. Deng / Virtual Reality: A State-of-the-Art Survey 321

from the previous one, like playing jazz. Your whole being

is involved, and you are using your skills to the utmost.”

According to the definition of flow, it refers to a psy-

chological state of devoting oneself to a certain activity.

According to the degree of involvement in an activity, flow

falls into immersion, half-immersion, and apartness.

Definition 2. “The state of being completely involved

in an activity for its own sake and losing other unrelated

perceptions is called as immersion”.

Psychologists always use the word “immersion” to de-

scribe the unique experience in which people are completely

attracted by the activity and involved in it.

Definition 3. “When people participate in an activity or

environment, their minds are separated from the activity

and environment because of disinterest. This perception

and experience in mind is called apartness”.

Definition 4. “The degree of flow is between immersion

and apartness is called as half-immersion”.

2.2.3 New definition

Virtual reality creates a physical and a mental space for

people. The essence of it is a sense of space in which people′simagination can be realized. Besides this, in original ideas

of technology, the goal of virtual reality is to make people

get a kind of existence of sense perception in fact. People′sunderstanding of any existence in nature depends on the

perception of their minds. The degree of flow is a kind of

measuring of perception of mind. Therefore, the definition

of virtual reality based on the degree of flow has a more

comprehensive philosophical notion than on the technology.

Based on the degree of flow, a more general definition of

“virtual reality” is described as follows:

Definition 5. When people are apart from the world

constructed in their minds, the imaginary world is consid-

ered as a virtual world.

Definition 6. When people immerse into the world con-

structed in their minds, the imaginary world is considered

as a virtual reality.

Definition 7. When people half immerse the world con-

structed in their minds, the imaginary world is considered

as a medium virtual reality.

The imaginary world exists in the mind of the creator.

It can be the display of a real world or a pure conceived

world which exceeds the reality and can be expressed by a

certain medium. The technological feature of the definition

of virtual reality based on technology is a kind of digital

implementation means by which the user can create the

imaginary world by computer.

3 Display medium

The computerized virtual environment displaying the

imaginary world of the user′s mind is an example of vir-

tual reality. The virtual reality system discussed in the

following refers to such an environment.

3.1 Virtual and reality

There are three meanings for being virtual: 1) being in

fact, acting as what is described; 2) something assumed and

imagined, which does not or is not always in accord with

facts; 3) potential, possible. The meaning of reality refers to

something which accords with a real object and condition.

The real-time virtual environment dynamically created

by computer with dimensional information is the main part

of the virtual reality. The environment may conform to a

real object or condition and can be operated, or it is only

potential or possible.

When the user thinks about the virtual reality from out-

side the virtual environment, the meaning of the term “vir-

tual” in this environment is the contents created during the

computer simulation process. The contents may not consti-

tute a realistic environment and may not always conform to

the laws that govern a real world. This environment is thus

imaginary and fictitious. When the user immerses into such

an environment, it needs dedicated elements that should

make the user feel that he or she is seemingly inside a real

world. Hence, the meaning of the term “virtual” is being

in fact, acting as what is described in the aforementioned

definitions. When the user overcomes the restrictions of the

time and space imposed by the virtual environment, he or

she can explore and control the intangible elements in the

environment and obtain the knowledge that reflects the real

world. Thus, the meaning of virtual is being potential and

possible. The true notion of virtual reality is indeed that of

a possible reality.

3.2 Virtual reality technology

The study of virtual reality can be traced back to the

early times of the last century[9]. In 1929, Edward Link de-

veloped a simple mechanical fly simulator in which virtual

reality technology was first applied. The system made peo-

ple feel like they were in real flight scenarios. This makes

the advent of the mechanical simulator earlier than that

controlled by computer.

In 1962, inspired by holographic movies, Morton Heilig

patented the design called “sensorama”. The patent is the

first video device of virtual reality by which a user can feel

the vibration, sound, smell, and wind recorded in advance.

The head-mounted video is similar to the head mounted

display seen in the early 1990s.

In 1965, the founder of computer graphics, Sutherland[1]

inherited and developed the design of Heilig. In his paper,

Sutherland presented the basic concept of a virtual reality

system which had multi-senses, immersion, and interaction.

In 1966, funded by the navy scientific research office,

American MIT Lincoln Laboratory developed the first

head-mounted display (HMD) and applied the feedback de-

vices which simulate the force and tactile in the system

later.

In 1967, inspired by the conception of Sutherland′s sys-

tem, the University of North Carolina launched the GROPE

project which researched and developed force feedback de-

vices that made users feel computer simulated force.

In 1968, organized by Harvard University, Sutherland de-

signed the helmet mounted display and later a virtual sys-

tem which was considered as the first virtual reality system.

In 1970, American MIT Lincoln Laboratory developed a

full-fledged HMD system.


In 1973, Krurger[10] presented the term “artificial real-

ity”, which was the early term of virtual reality.

In 1987, Foley[11] published a paper entitled “Interfaces

for Advanced Computing” in the journal “Scientific Amer-

ican”. Another paper [12] about data gloves was also pub-

lished in this journal. These published papers about virtual

reality attracted people greatly.

In 1989, American Jarn Lanier formally presented the

term “virtual reality”.

In 1992, Sense8 Company developed the “WTK” pack-

age which can provide a higher level application in virtual

reality technology.

In March, 1994, virtual reality modeling language

(VRML) was first formally presented in the first WWW

conference in Genevese. After that, many modeling lan-

guages of VR have appeared such as X3D, Java3D, and so

on.

In 1994, Burdea and Coiffet[13] published a book about

virtual reality in which they summarized the basic charac-

ters of VR as 3I (imagination, interaction, and immersion).

In the 1990s, with the rapid development of computer

software, and hardware systems, it has become possible to

produce the real-time cartoon of image and sound based

on large-scale sets of data. More and more novel prac-

ticable in/output devices are provided in market and the

innovational design of the man machine interaction system

continues to be given life. All of these make a good foun-

dation for the development of virtual reality. Furthermore,

research on virtual reality technology has been carried out

in some countries in Europe and Asia, such as Japan and

China.

In Europe, the United Kingdom leads the development

of VR in some areas, especially in distributed parallel pro-

cessing, design of assistant devices (including feeling feed-

back) and the applications. The British Bristol Company

has pointed out that the application of VR should focus

on comprehensive technology and they are ahead in some

software and hardware.

The testing platform of a German computer graphics in-

stitute can be used to evaluate the influence of VR on future

systems and interfaces, and it also can provide advanced vi-

sual simulation technology to the user and producer.

The development of virtual reality technology in Japan

plays an important role in the relevant fields of the world.

They have achieved great success in developing a large scale

knowledge base and games in virtual reality.

Research on VR technology in China started in the 1990s.

We have made much progress but still fall behind the devel-

oped countries. The research results are outlined as follows:

The Xi′an Virtual Reality Engineering and Technology

Research Center is the first institute to carry out the re-

search on VR technology in China. “Potala Palace” cre-

ated by the Optical Memory National Engineering Research

Center (OMNERC) is a panorama VR system in which

QuickTime technology was applied. The Laboratory of

CAD & CG of Zhejiang University developed a desktop

real-time walkthrough system of an architecture environ-

ment. The CAD centre of the North China University

of Technology is one of the first institutes to study com-

puter animation. They have developed a multi-medium

display platform of communication images and the relative

audio database. Moreover, the first scientific educational

film “Similar” made by computer animation came from

the centre. In addition, other institutes have carried out

the research on VR such as the image processing and pat-

tern recognizing institute of Shanghai Jiao Tong University,

Computer institute of National University of Defense Tech-

nology, Computer Department of East China Shipbuilding

Institute, and so on.

Virtual reality is a combination of different technologies,

in which virtual environment rendering technology, inter-

face technology, and system integration technology are the

key technologies, and creating a virtual environment is a

core element in virtual reality research. Because of the ad-

vantage of image mosaic based rendering which makes full

use of the real sense of the image and enables the rapid

image display, it plays an important role in virtual envi-

ronment rendering. The technology of image mosaic based

rendering of a virtual environment involves a lot of image

processing technologies.

4 Image processing

The technology of image mosaic[14] based rendering of a

virtual environment involves image pretreatment technol-

ogy (image noise removal and restoration), image feature

detection technology, image matching technology, and im-

age fusion technology.

4.1 Image noise removal and restoration

Accurately extracting the interesting object is a precon-

dition in image based rendering of a virtual environment.

However, because of the effect of noise, it becomes dif-

ficult to get useful information from images. According

to the steps of obtaining images, we know that in images

the useful data always mix with noise. The existence of

noise obscures the boundary between the object and the

background, which makes it difficult to distinguish them.

This is a much confused problem in the computer visual

field. Therefore, noise reduction, image enhancement, and

restoration are becoming the very important steps in image

based rendering of a virtual environment.

Mean filter, median filter, and Wiener filter are the

classical noise removal algorithms. These methods can

remove noise but they obscure the edge as well. Fur-

ther, the improvement in traditional algorithms, fuzzy

mathematics[15], wavelet transformation[16] , and partial dif-

ferential equations (PDE)[17] have been widely adopted in

image noise removal and restoration. Furthermore, genetic

algorithm[18] , neural net algorithm[19], mathematical mor-

phologic theory[20], and rough sets[21] are also introduced

into image noise removal and restoration.

How to eliminate noise and preserve the edge and texture

details that make the image become more smooth and reach

to best effect the same time still need to be studied.


4.2 Image edge detection

Image matching based on contour features is the main

content of the image mosaic algorithm. The edge is cer-

tainly the most notable and intuitive contour feature of an

image. It retains useful information for image recognition,

and provides valuable and crucial feature parameters for

describing the meaning and contents of images. Edge de-

tection is a kind of operation on the “pixel” of the local area,

which is a typical signal processing problem. The amount

of information in the image is enormous, while edge infor-

mation is a kind of strict description of the image which

includes the most important information. So edge detec-

tion plays an important role in the pretreatment algorithm

of computer visuals.

For years, many research efforts have been made towards

effective image edge detection. In 1959, B. Jule first pre-

sented edge detection, after that various algorithms were

discussed. Traditional edge detection algorithms originated

in edge gray discontinuity, which detects edges by classical

differential operators such as the Sobel operator, Roberts

operator, Kirsch operator, Prewit operator, LoG filter oper-

ator, and Canny edge detector. The multi-scale method of

edge detection was first proposed by Rosenfeld. Because of

their simplicity being well-established and easy for compu-

tation, traditional edge detection algorithms are often used

and applied effectively after some improvement. But in gen-

eral, edges extracted by traditional detectors are broad and

they may give poor results for images with low contrast or

significant noise.

In the early of 1980s, since Pal and King[22] first intro-

duced fuzzy sets into image edge detection and proposed

a fuzzy edge detection algorithm using “min” and “max”

operators to detect image edges, new algorithms[23] have ap-

peared to which the fuzzy theory and other techniques are

applied. New mathematical and computational methods

such as the neural network[24], wavelet transformation[25] ,

mathematical morphologic theory[26] and rough sets[27]

have also been introduced into image edge detection. Nev-

ertheless, they are complex and lack portability, so to find

an effective edge detection methods, which are insensitive

to noise, precise in location, without an undetected true

edge and which will introduce the false edge has been the

aim of researchers for a long time.

4.3 Image matching

Image matching algorithm that locates the overlapped

position and area of two or more corresponding images is

the core part of an image mosaic. The speed and precision

of an image mosaic algorithm are subjected to the image

matching algorithm. As an important image research field,

it has attracted many scholars and experts. They have pre-

sented various matching algorithms from different aspects

such as measuring method of the matching degree, effective

search strategy, increasing the matching speed, improving

robustness of the algorithm, and so on. According to the

matching feature, image matching algorithm can be divided

into two classes: image matching based on grayness and im-

age matching based on feature.

Absolute balance search, cross correction, sequential

similarity detection algorithm (SSDA) moment invariants,

phase correction, and projection methods are the tradi-

tional image matching algorithms based on greyness.

High-level features must be extracted first in the im-

age matching based on feature. Features usually used in

a match are pixel (corner, edge point, etc.), edge, and re-

gion. By means of establishing the similarity measurement,

we can locate the position of the template in an image.

Similarity measuring is usually defined as a certain cost

function or distance function. Correction function, Haus-

dorff distance, mutual information are the classical similar-

ity measures. Common image matching methods based on

features are least-square error matching, measuring of dis-

tance and the relaxation method. Besides the feature point,

edge line and region, other features such as texture[28], and

semantic content[29], have been used in image matching.

There has been recent development in mathematical and

computational methods, such as the neural network[30],

cluster[31], genetic algorithm[32] , wavelet transformation[33] ,

ant colony algorithm[34], and rough sets[35]. These methods,

which are different from classical mathematics, have been

introduced into image matching. Nevertheless, because of

their complexity, poor portability and less matching preci-

sion to some images, robust and effective matching methods

are still in demand for fast, and stable results.

4.4 Image fusion

The image fusion method can process information from

images according to comprehensive application require-

ments and improving the utilization rate of image infor-

mation, the reliability of object recognition and the de-

gree of automation. Due to those high demands, image

fusion has been used in fields such as medicine, remote

sensing, computer visuals, weather forecasting, and military

object recognition. Especially in computer visuals, making

the matched images fuse to an image which is seemed un-

artificial and then creating a virtual environment which ap-

pears unfeigned and having good real-time is the important

application field of image fusion technology.

In general, image fusion technology is studied in the spa-

tial domain and transform domain. The methods in spatial

domain include a logical filter, weighted average method,

morphological method, image algebra method and simu-

lated annealing algorithm. The methods in the transform

domain mainly includes pyramid method and wavelet trans-

formation. Besides these methods, there are other methods

such as color space method, fake color method, and Kalman

filter method. Fusion algorithms always combined with the

average value, entropy value, standard deviation, and av-

erage grads reflects the tiny detail contrast and features of

texture change in an image and also reflects the articulation

of the image. The quality of fusion depends on the choice

of fusion rule and fusion operator, which is still a difficult

problem in image fusion.

In summary, traditional image processing methods have

many achievements and documents. In the research on im-

age, it not only includes the study and improvement of clas-


sical methods, but also includes the discussion of new meth-

ods combined with new mathematical theories. Although

these theories and methods have had much notable achieve-

ments which can not be obtained by traditional methods,

the results which can replace human visual function in ap-

plications are deficient. As a result, it is valuable to study

new theories and methods and design new image process-

ing methods which give out satisfactory results of image

analysis, according to the requirements of the specific ap-

plication.

The medium principle was established by Zhu and

Xiao[36] in the 1980s devised medium logic tools to build

the medium mathematics system, the corner stone of which

is medium axiomatic sets. In the formation of the medium

mathematics system, the medium concept which dynam-

ically reflects the fuzzy was first established, then the

medium logic system was built. Finally, the medium ax-

iomatic set theory based on medium logic was created. It

has a solid logic foundation. The medium mathematics sys-

tems have solved the set making of fuzzy predicates in the

sense of the basic theory of mathematics and extended pre-

cise quantity objects to fuzzy ones with mathematical foun-

dation, which extends the foundation of the logic and set

theory of classical mathematics.

The complexity of image information and the strong re-

lations among image pixels are evident, and problems with

uncertainty and inaccuracy will appear in the processing.

As a result, the medium mathematics system, a mathemat-

ical tool which deals with fuzzy and uncertain problems,

can be introduced into the image processing. This will pro-

vide some new methods and ideas to process images sys-

tematically and mathematically. Currently, it has achieved

interesting results in noise removal and restoration[37] , edge

detection[38], and image matching. Further research is to

apply these results to image mosaic based reddening of vir-

tual reality systems.

5 Conclusions

Research into virtual reality is widely spreading into a

spectrum of application areas. This paper provides an in-

depth understanding toward the existing definitions of the

terms virtual and reality and gives a new interpretation for

the abstractive notion of immersive systems found in virtual

reality systems. As a result, it reveals some subtle natural

aspects of virtual reality technology in terms of the needs

for the design, construction, and application of the virtual

environment.

The main contribution of this work resides in its inter-

pretation of the immersive nature of the display medium

existing in a virtual reality system and the following provi-

sion of the insight into the methods for the construction of

a vivid and real-time virtual environment via imaging pro-

cessing based on new mathematical models. It reveals that

those methods play an important role in the construction of

virtual environments. It also shows that image processing

based on new mathematical modeling presents a promis-

ing way ahead towards an effective and robust process for

design and construction of complex and large scale virtual

environments.

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Ning-Ning Zhou graduated fromSoutheast University (SEU), PRC in 1993.She received the M. Sc. degree from SEUin 1996 and the Ph.D. degree from SEUin 2009, respectively. She is currentlyan associate professor at the College ofComputer, Nanjing University of Postsand Telecommunications (NUPT), PRCand a visiting research fellow of StateKey Laboratory of Software Development

Environment, Beihang University, PRC.Her research interests include virtual reality and image pro-

cessing.

Yu-Long Deng graduated from Nan-jing University of Posts and Telecommuni-cations, PRC in 1996. He is currently alecturer at the College of Computer, Nan-jing University of Posts and Telecommuni-cations (NUPT), PRC and a visiting re-search fellow of State Key Laboratory ofSoftware Development Environment, Bei-hang University, PRC.

His research interests include computerarchitecture, algorithm, and artificial intelligence.

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Virtual reality: A state-of-the-art survey