Semi-Cave as an Example of Multimedia Dedicated to Study the

Impact of Audiovisual Environment on Human Psychophysiology

Dariusz Sawicki

, Agnieszka Wolska

, Mariusz Wisełka

1,2

Jarosław Żukowski

Michał Sołtan

and Wojciech Związek

Warsaw University of Technology, Institute of Theory of Electrical Engineering,

Measurements and Information Systems, Warsaw, Poland

Central Institute for Labour Protection - National Research Institute (CIOP-PIB), Warsaw, Poland

Image Recording Solutions, Warsaw, Poland

Keywords: Multimedia, Virtual Environment, Immersive VR, CAVE.

Abstract: Cave (Cave Automatic Virtual Environment) is an example of a multimedia installation that allows

perceiving virtual reality (VR) in its best form. The aim of the work is to present a cave solution defined for

specific applications. The low-budget concept called SEMI-CAVE has been proposed in order to study the

impact of audiovisual environment on human psychophysiology. This approach enables to create virtual

indoor or outdoor workplaces, with reference to many aspects of human psychophysiology like wellbeing,

fatigue, mood and alertness. Virtual environment allows taking into account any visual factor or element

important in real workplaces. One of the rarely considered is glare, which is also intended in the research.

Overview of known and applied VR solutions and analysis of their properties allowed selecting a solution

adjusted to specific expectations and requirements. On the other hand, according to VR taxonomy, we have

proposed solution which can be treated as the new form of VR realization – unusual combination of well-

known CAVE and CAVE2 designs. The first stage (closed part) of project realization is presented in the

paper.

1 INTRODUCTION

1.1 Motivation

The virtual reality (VR) has become one of the most

interesting and, at the same time, the most important

achievements of computer science in recent years.

The VR technique is most often used in computer

games and various forms of entertainment.

However, many areas of science can be shown,

where the use of VR techniques not only speeds up

the study, but also facilitates them or sometimes

simply allows conducting the research.

The proposed realization – SEMI-CAVE – is an

example of multimedia laboratory of modeling

lighting scene, images and sounds. It is one of the

laboratories which were built in the scope of project

Tech-Safe-Bio, which was realized in recent years in

Central Institute for Labour Protection - National

Research Institute (CIOP-PIB). The objective of the

Tech-Safe-Bio project was to construct the

infrastructure and to equip the scientific laboratories

group functioning in the structure of CIOP-PIB with

modern research equipment. This action was

necessary to create the potential for high quality

advanced research in line with strategic national and

European research programmes (TECH-SAFE-BIO,

2015). The new building with the wide range of

bot, L., DeFanti, T., Brown, M., Jeong, B., Jagodic,

Centre for Research and Development on Work

Processes and Safety Engineering. The state-of-the-

art laboratories are adjusted to conduct interdiscipli-

nary research focused on protection of health and

safety of workers among others in the scope of:

impact of physical environment on workers and

design of workplaces using virtual reality techniques

and computer simulations which are attached to

research area planned in SEMI-CAVE laboratory.

1.2 The Aim of the Article

The main aim of this paper is to present the

realization of multimedia SEMI-CAVE laboratory as

Sawicki D., Wolska A., WiseÅ

Cka M., Å

zukowski J., SoÅ

Ctan M. and ZwiÄ

Ezek W.

Semi-Cave as an Example of Multimedia Dedicated to Study the Impact of Audiovisual Environment on Human Psychophysiology.

DOI: 10.5220/0006497601030110

In Proceedings of the International Conference on Computer-Human Interaction Research and Applications (CHIRA 2017), pages 103-110

ISBN: 978-989-758-267-7

a specific VR installation developed for the study

the impact of audiovisual environment on human

psychophysiology in the interdisciplinary research.

The project involves the combination of properties

of known solutions type CAVE and CAVE2, not

previously used in such a scale.

2 VIRTUAL REALITY – THE

SURVEY OF DIFFERENT

REALIZATIONS

The first virtual environment as a CAVE (Cave

Automated Virtual Environment) prototype was

built in 1991 (Cruz-Neira, et al., 1992). The number

of publications concerning only different technical

solutions of VR has exceeded 20 per year for many

years (Kim, et al., 2013). Many review articles have

been published (Kim, et al., 2013, Zhou, et al., 2009,

Muhanna, 2015), according to which few basic

categories of technical solutions for VR could be

distinguished.

2.1 CAVE

The first CAVE installation displays images in rear-

projection system on three walls, ceiling and floor. It

was built as a cube of 2.1 m side length. But in the

reality the whole installation occupied much more

space, because of outer projectors and support

structure (Cruz-Neira, et al., 1992). Later on six

walls cube appeared but also realization of two walls

(Nichols and Petel, 2002), four walls (CAVE

Automatic) and five walls (Sony 4K) are known.

Contemporary, the most expanded solution included

projection on 15 side walls, floor and ceiling

(DeFanti, et al., 2009). Different image resolutions

of the range from 1024x768 (Juarez, et al., 2010) to

6000x4096 pixels were applied for single wall image

(CAVE Automatic). There are also CAVE solutions

based on sphere (Fernandes, et al., 2003), or mixed

solutions where the sphere is inside the cube

(Mazikowski and Lebiedź, 2014). Apart rear-

projection the inside CAVE projection on the walls

is also used (Jacobson and Lewis, 2005). It gives

opportunity to get CAVE of much more space at the

comparable dimensions of all installation.

The main problem of all CAVE solutions is

complicated graphical representation. The special

attention is paid on image stitching (Sajadi and

Majumder, 2011) and quality dependency on angle

of observation and observer’s position (CAVE VR,

2014).

The most important applications of big CAVE

installations are vehicle simulators (flight, car, etc.)

which allow almost completely limit the risk of

accident during the tests or training (Muhanna,

2015). CAVE is also implemented in contents

presentations for advertising and marketing purposes

(Sony 4K), entertainment and education. It is also

worth mentioning about medical applications,

patients immersed in virtual reality can, for example,

fight phobias (Emmelkamp, 2004).

In the wrong designed CAVE installations the

user could feel strong and long lasted vision

disorders. On the other hand, even in properly

designed CAVE, people could have sense of

isolation, disorientation, frustration, or even panic

(Nichols and Petel, 2002).

2.2 CAVE2

According to technological development the

projectors were exchanged to LCD monitors. This

solution (CAVE2) gives both possibility of

considerable reduction of installation space and

achievement of considerable higher image resolution

(Febretti, 2013). But the visibility of small space

gaps between screens constitute the main

disadvantage of that solution. It could make difficult

immersion into virtual reality (Leigh, et al., 2007,

Krumbholz, et al., 2005), especially in small

installation.

The chosen CAVE2 solutions make easy the

leading of training (Leigh, et al., 2007) and monitor

the processes and events (Lambda Table) (Leigh, et

al., 2007, Krumbholz, et al., 2005). The extension of

multimodal interaction could make these solutions

efficient for medical applications (3D Visualization)

and interdisciplinary applications, which use

computer technologies (Febretti, 2013).

2.3 Binocular Head based VR

The lowest space virtual reality is technical solution

based on helmet or head mounted display (HMD)

(Melzer and Moffitt, 1997). It is VR realization in a

form of local view which is available individually

for each participant thanks to special glasses which

displays images for left and right eye separately.

There are several products (HTC Vive, Oculus Rift,

PlayStation VR), commercial available of that

solution. These devices are equipped in additional

sensors for head position identification (Muhanna,

2015, Spec Comparison). The cheapest solution,

especially popular in recent years, is smartphone

usage as a display of binoculars (Review: VR BOX

II, Samsung: Gear VR). This is most commonly

used for computer games.

The basic advantage of HMD is fully indepen-

dence from complicated installation construction.

HMD could be used in any place and only needs the

computer with adequate software. In comparison to

CAVE it is huge costs reduction. On the other hand

this solution requires additional equipment (e.g.

gloves) and doesn’t allow to fully sensory and

motion identification with VR environment.

Additional problem is related with motion sickness,

related to labyrinth dysfunction (Davis, et al., 2015).

In the beginning it seemed that HMD would

displace CAVE solutions for financial reason. But it

hasn’t happened. Nevertheless HMD solutions are

currently often used. Among professional

applications the most important are education and

training (especially military) (Muhanna, 2015,

Castaneda and Pacampara, 2015), and robot control

(Kot and Novák, 2014).

3 EXPECTATIONS FROM

VIRTUAL REALITY RELATED

TO PLANNED STUDIES ON

THE IMPACT OF

AUDIOVISUAL

ENVIRONMENT ON HUMAN

PSYCHOPHYSIOLOGY

Having the spectrum of virtual reality technical

solutions as well as related costs of theirs realization

we had to consider the best solution to achieve the

main goal – virtual reality dedicated to study the

impact of audiovisual environment on human

psychophysiology. Virtual reality and created this

way virtual environment which allows users

performing different tasks in a specific audiovisual

environment that he or she is familiar with or not.

The approach which enables us to create sounds and

visualization of different indoor or outdoor places,

workstations, interiors of different colors and

furnishings etc. That way we can create the light

scenes, images and related sounds that could

influence the human psychophysiology with

reference to: wellbeing, comfort, fatigue, relax,

mood and alertness. Taking into account the great

importance of spectral light distribution on human

circadian rhythm, fatigue, mood, mental

performance and efficiency the virtual environment

will be used for many studies concerning those

aspects. It should be possible to adjust visual

environment to the users’ needs, preferences and

health. We expected to create the virtual

environment as one of new method for visual

environment forming and study its influence on

people. A change of real visual environment to carry

out research on its influence on human is not

possible or very expensive. Creating in virtual

environment an apparent visual environment of real

places allows avoid that.

One of the planned applications of virtual

environment is creation of unique laboratory for

extended glare investigation. Virtual reality should

enable to put inside the programmable glare sources

and create different background luminance or the

images of real working environment. The studies

concerning objective and subjective glare evaluation

with participation of healthy people or people with

different visual impairments let us to develop

methods of glare evaluation and verify actual glare

indexes.

Our virtual reality could be possibly great tool

for managers / employers that want to prepare

workplaces for their subordinates. With a help of

virtual environment we can now not only look at

visualization on the screen, but as well "enter" inside

the workplace we want to create. Or even invite the

team to see and consult our idea first in VR – before

we prepare the finished project.

Virtual reality will be used to create an exact

environment in order to test different abilities that

users possess such as: reaction time, creativity,

ability to logical thinking etc. While they complete

multiple tasks inside of virtual environment, their

execution time, approach and abilities of problem

solving can be registered and marked. Based on that

information we can distinguish properties of task

and individual behaviour.

The installation of virtual environment should be

equipped with simple and intuitive mechanism of

control. Simple control panel that allows staff to

change scene quickly, to view, for example,

panoramic pictures. In the future such mechanism

could be further enhanced and upgraded in order to

allow better and easier control over shown content

while also increasing interaction level and

immersion of participant inside of room. This way

organization of hardware and application should be

today open enough that it cannot block

developments in the future.

Virtual reality is not just images. Sound

information is also very important. The project

should include a good sound system that correlates

acoustic impressions with visual impressions and

ensures consistent interpretation of the proper spatial

directions in both cases. At the same time, it is worth

noting that regardless of spatial sound system, the

project must include the possibility of simple

communication between staff and participants of

experiments.

Safety of participants should be guaranteed by

monitoring cameras. Continuous display of what is

happening inside the room allows staff to react

within seconds on any unexpected or dangerous

events.

4 MEETING EXPECTATIONS –

ANALYSIS AND SOLUTION

SELECTION

The expectations and plans related to virtual reality

presented in paragraph 3 were the starting point to

choose the best category of installation in a limited

financial budget. Firstly the solutions which use

binocular head based VR were rejected, because

they don’t give the opportunity of teamwork with

eventual using the real working equipment (like

office accessories) in VR room. At the same time

actually there is no possibility to obtain very high

level of luminance using those technical solutions of

VR. This way it would not give us a chance to do

studies on glare in that virtual environment, what

was one of our expectations from VR. It made us to

choose CAVE category of virtual environment.

One of the arguments in favor for choosing the

type of virtual reality was the need of relatively big

dimensions of the room (VR space). The cube of

wall size length of 2.5 m to 3m like in a CAVE with

rear-projection – was dedicated for one person

staying inside. Enlargement of the VR room leads to

increasing the size of all solution, even if special

projectors of short focal length would be used. On

the other hand the glass floor would increase the

costs significantly without possibility to put any test

stand on it.

In result of considerations of different solutions

the decision of realization the CAVE environment

with direct – inside projection was made. It is related

to compromise between big space inside for

experiments and lack of image on floor and ceiling.

That way we worked out the concept of SEMI-

CAVE, with display images on four walls. This

solution has got also disadvantages. The main was

the necessity of increasing the number of projectors,

what is related to geometrical problems with

stitching images. It was assumed that our virtual

reality will be realized in a room of dimensions:

8.6m x 4.3m and the minimum height of image will

be 2.8m. Such room sizes seem to be a reasonable

compromise between the simulations of the working

environment and the immersion benefits of the

virtual environment.

An independent analysis was carried out for

possibility of glare simulation. Known solutions

(Clear, 2012) give the opportunity to study only

Table 1: The comparison of different VR realizations and our proposition (SEMI-CAVE).

CAVE

rare

projection

CAVE

inside (front)

projection

CAVE2

LCD/monitors

HMD SEMI-CAVE

VR space (room size) Very small Any size (cost) Any size (cost) Any size Any size (cost)

The whole installation size Very large

Small

(like VR space)

Medium

(a little bigger

than VR space)

Depend on

installation

Small

(like VR space)

Mixed realisation

(e.g. VR background + real

furniture)

- + + + + - - + +

Team working

- + +

- -

(only in VR)

Feeling of participant,

disorders

- - - - - - -

Possibility of development,

(expansion)

NO YES Difficult NO YES

Glare simulation NO NO

YES

(special

equipment)

NO YES

Cost Very high Medium High Low Medium

single glare source influence on human perception.

And don’t give the possibility to take into account

the luminous environment in any working

environment. To make it possible in virtual reality it

is necessary to see the image consistent with the

image of working environment and at the same time

the glare sources of real luminance (at the level of

million cd/m

) should appear. This solution is not

possible in a standard CAVE and HMD. We

assumed to introduce to the room new semi-

transparent wall to display on it the image from

projector. At the same time beyond that wall the

special designed programmable panel with LED

sources of very high luminance will be placed. As a

result the observer inside the CAVE would

experience environment similar to the real working

environment (image form projectors) and glare

(LEDs light beam through the semi-transparent

wall). The analysis of available semi-transparent

screens and LEDs showed the possibility of correct

realization of that solution. Unfortunately because of

the high costs of that solution the realization of that

idea will be carried out at the next stage. It is worth

to notice that proposed solution combines features of

CAVE and CAVE2.

The comparison of different VR realizations and

set of basic properties of our proposition (SEMI-

CAVE is presented in Table 1.

5 SEMI-CAVE – REALIZATION

In the implementation the following assumptions for

the SEMI-CAVE system were adopted:

 Room 8.6m x 4.3m x 6m, with internal

projection.

 Minimum image height: 2.8m.

 Additional room (control room) adjoining the

wall.

 Projection: providing a shadow-free approach,

assuming that participant with a height of

1.7m can be in minimal distance of 1m to the

image (to all four walls of the room).

5.1 Installation and Projection

The assembly of all components was realized using

a truss suspended to the ceiling and stabilized to the

walls of the room. The truss design was based on

modular elements that have been chosen to ensure

the load capacity and stability of the structure and

deflection resistance for the whole of the planned

installation. The truss has been placed at a height of

3.8m. Projectors, sound system, lighting fixtures and

intercom with voice communication system to server

room have been installed on the truss (Figure 1).

Six projectors with the following parameters

were selected for displaying images: brightness at

level of 4000 lm ANSI, WUXGA resolution

(1920x1200), LCOS matrix. The LCOS matrix

minimizes image pixelization. The projector has

Figure 1: Arrangement of projectors in the room.

built-in edge blending mechanism. Short throw

optics with Lens Shift and Keystone Correction in

two directions made it possible to obtain the

expected shadow free area of work (Figure 2). The

transmission of the image from the computer in the

control room was realized in the HDMI technology.

The location of the projectors at a distance of 2.45m

from the wall provided a 4.3m x 2.8m image. One

projector for shorter walls and two for longer walls

were installed.

Figure 2: Arrangement of projectors against walls -

providing the right work area.

The audio system was implemented in 5.1

surround sound. Speakers were chosen to ensure

proper listening in the VR room. The HiFi amplifier

and other control elements were placed in the

control room.

There are two subsystems complementing the

installation. The voice communication subsystem

(intercom) based on four ball speakers arranged to

provide a uniform level of sound and the visual

monitoring subsystem based on two cameras

displaying a real-time image on a 22"monitor in a

control room with the possibility of data recording.

5.2 Computer System

The SEMI-CAVE computer system consists of two

computers connected by standard 1Gb Ethernet

network. Operation carried out by computers was

distributed functionally, therefore, only

synchronization tasks are realized via Ethernet. The

first computer generates images and displays them

over the projectors. It is a computer based on 2 Intel

Xeon processors, with 64GB RAM and SSD Hard

Drive.

The heart of the computer are three high

performance graphics cards GTX980 4GB Strix OC

connected via SLIs bridge. Each card supports two

images (two projectors). GTX980 cards have been

selected for configuration, although they are not

supported by nvidia's standard multi-monitor

projection software (Mosaic). This means that, using

them, it is not possible to display and synchronize 6

images simultaneously. So, this solution does not

support our project.

Nvidia is forcing customers to purchase

significantly more expensive graphics cards that are

not more efficient but are compatible with the

corresponding software standard. We had to solve

this problem. A special shader driver has been

Figure 3: Alley from the Warsaw Saski Garden in SEMI-CAVE. View of the entire laboratory.

developed that allows displaying and synchronizing

images. Our driver allows effectively displaying and

synchronizing 6 images from GTX980 cards. This

solution made it possible to make the full use of the

equipment in SEMI-CAVE laboratory. The purpose

of the second computer is to support the audio

subsystem and to manage additional functions.

Figure 4: Alley from the Warsaw Saski Garden in SEMI-

CAVE. The garden lamp in the corner of the laboratory.

6 SUMMARY

The project of the multimedia SEMI-CAVE

Laboratory required an analysis of needs on the one

hand, and implementation possibilities on the other.

Hence, a review of the state-of-the-art solutions was

essential to make proper decisions. For the purpose

of this paper, it has been supplemented by

contemporary publications. The results of the

analysis of existing solutions, spatial possibilities

and the budget indicated the necessity of developing

a low-budget concept called SEMI-CAVE. The first

stage of SEMI-CAVE installation has been built and

despite some limitations (image height max 2.8 m,

no ceiling and floor display) it meets our

expectations. The proposed solution is an unusual

combination of well-known CAVE and CAVE2

designs – never before practiced together in such a

scale.

The laboratory was initially launched in the end

of 2015. The first work involved calibration and

geometry support. As part of the experiment, a

method of acquiring images for viewing with the use

of photographic equipment. Obtained images and

impressions of viewers have confirmed the

correctness of the concept (Figures 3 and 4) in terms

of image display. At the same time the initial

experiments confirmed sufficient immersion into

virtual reality.

The new display subsystem supporting the used

graphics cards has been developed. The used

projectors combine the images in edge blending

technology. This solution gives excellent results at

the initial stage of display. However, to provide full

control over the geometry of the merged images, the

new blending subsystem is currently being

developed. It will provide not only the control of the

geometry at the single pixel level, but also control

over color and luminance of stitched parts. On the

other hand, we are currently working on creating VR

so that it will be possible to define a specific scene

and working conditions for the future research.

In the future, first of all, we plan to attempt to

obtain financing in the form of a grant. This would

allow building a semi-transparent wall with a set of

high power LEDs and thus complete the second

stage of the project. This would give the opportunity

to conduct research related to simulation of glare

and also conduct many other works with an

extended user interface.

ACKNOWLEDGEMENTS

This paper has been based on the results of a

research task carried out within the scope of the

fourth stage of the National Programme

"Improvement of safety and working conditions"

partly supported in 2017–2019 within the scope of

research and development --- by the Ministry of

Science and Higher Education / National Centre for

Research and Development. The Central Institute for

Labour Protection -- National Research Institute is

the Programme's main coordinator.

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