東海大学紀要情報通信学部
Proc. Schl. ITE Tokai Univ.
vol.4,No1,2011,pp.34-39
Vol. ,No. ,2011,pp. -

Paper
Paper

Study on Parallax Affect on Simulator Sickness
in One-screen and Three-screen Immersive Virtual Environment
by
Chompoonuch JINJAKAM *1 and Kazuhiko HAMAMOTO*2(Received on April 25, 2011 and accepted on July 21, 2011)

Abstract
Virtual environment induces simulator sickness effect for some users. The purpose of this research is to
study the simulator sickness relative with different parallax affect in one-screen and three-screen HoloStage TM ,measured by Simulator Sickness Questionnaire. The results show three-screen induced simulator sickness lessthan one-screen and parallax 6.50 cm decrease simulator sickness than parallax 2.00 cm. The top-three highest
simulator sicknesses are eyestrain, general discomfort and fatigue. And effect from the Oculomotor (O) is morethan from the Disorientation (D) and more than from the Nausea (N) or represented as O>D>N.
Keywords: Immersive virtual environment, simulator sickness questionnaire, t-test, HoloStage TM

2. Methods

1. Introduction
2.1 Experiment

Virtual environment has become currently considerable

The experiment has been done with HoloStage TM systemand omnipresent technology in several fields as entertainment[11] as shown in Fig. 1. The HoloStage TM has three sides of

purpose, training, medicine, architecture and telepresence.
Although this new technology is wildly used, some users

2×4, 2×2, and 2×4 meters for front side, right side and bottom

indicate symptom from virtual environment. There areside, respectively. The system consists of five stereoscopic

reseach about simulator sickness in virtual army training

channels eye-tracked projection system powered by thereport [1]-[2]. And universal research as propose the reason

VR4MAX extreme multi-channel rendering software.

of simulator sickness depends on frequency of simulator
motion mismatch [3], effect of environment characteristics[4], effect of field of view on presense, enjoyment, memory[5]. Groups of research proposed the simulator sickness fromeye gazing by adjusted the scene [7-9] or intensity [10].
These beneficial researchs help to improve future content of
virtual environment.
This paper studies parallax affect of virtual environmentby using post-test Simulator Sickness Questionnaire (SSQ) toevaluate the simulator sickness from the virtual animation in
one-screen and three-screen HoloStageTM.
Fig. 1 HoloStage TM system in Tokai University*1 and *2 are with the Department of Information
The procedure tested by using VR4MAX software to set
Media Technology, School of Information and Tele
the parallax for distance between eyes in the scene period.
communication Engineering, Tokai University, 2-3The distance between eyes is set to 2.00 centimeters (cm) for
23 Takanawa, Minatoku, Tokyo, 108-8619 JAPAN(phone: +81-3-3441-1171 fax: +81-3-3447-6005,
less parallax and 6.50 cm which is normal distance between
e-mail: chompoonuch@kmitl.ac.th, hama@keyaki.
cc.u-tokai.ac.jp).
―1―Vol. XXXI, 2011

− 34 −

Chompoonuch Jinjakam and Kazuhiko Hamamoto
Study on Parallax Affect on Simulator Sickness in One-screen and Three-screen Immersive Virtual Environment

The results are evaluated by the famous Simulator

human eyes for normal parallax for one-screen andthree-screen HoloStageTM

system.

Sickness Questionnaire (SSQ) [14-17] for post experiments.

The animation control same virtual walking for every

The SSQ consist of 16 symptom questions;generalsubject, the city-walkthrough simulation is used. The

discomfort, fatigue, headache, eyestrain, difficulty focusing,

walkthrough in scene as shown in Fig. 2 includes random

increased

turn left, turn right and cross the bridge for two minutes

concentrating, fullness of head, blurred vision, dizzy (eyesperiod of time.

open), dizzy (eye closed), vertigo, stomach awareness andsalivation,

sweating,

nausea,difficulty

burping. The answer choices are none (0), slightly (1),2.2 Subjects

moderate (2) and severe (3) feeling sickness in each symptom.

Twenty-three healthy subjects participated in the study.

The percentage in mean of each degree of symptom is shown

The entire subjects are Japanese student in Tokai University
and all of them have experienced in HoloStageTM

in Fig. 3.

system. The

authors explain a purpose and the contents of the study to100

subjects, and obtained consent. The gender of subjects is

80

irrelevant referred to [12] reported that virtual environment
Percentage (%)

The subject divided into 4 groups of testing;1)

One-screen HoloStagesystem with 2.00 cm parallax;

HoloStageTM

systemwith

2.00

One-screen (parallax 6.50 cm)
Three-screen (parallax 6.50 cm)

60
50
40
30
19.79
10.61

10

between 21-28 years with age average of 23.67.
Three-screen

Three-screen (parallax 2.00 cm)

75.00

20

6 subjects (5 Male persons and 1 female person) age
2)

One-screen (parallax 2.00 cm)

83.33

70

creates the similar effect on both male and female person.
TM

92.77
86.36

90

14.58
6.02

5.21

3.03 2.08 1.20

0

0

1

2

0.00 0.00 0.00 0.00

3

Mean in severe of symptom (μ)

cmparallax; 5 subjects (4 Male persons and 1 female

Fig. 3 The mean of each degree of SSQ symptom

person) age between 22-24 years with age average of(0, 1, 2, 3; none, slightly, moderate, severe feeling)

22.80.
3)

4)

One-screen HoloStageTM system with 6.50 cm parallax;

For overall 16 SSQ questions, most subjects respond no

6 subjects (5 Male persons and 1 female person) age

effect (or 0) as 75.00%, 86.36%, 83.33% and 92.77%

between 21-26 years with age average of 22.83.

represent to group 1, group 2, group 3 and group 4,

Three-screen

HoloStageTM

systemwith

6.50

respectively.

cm

parallax; 6 subjects (6 Male persons) age between 22-25

The experiment reports slightly feeling sickness (or 1)

years with age average of 23.33.

as 19.79%, 10.61%, 14.58% and 6.02% and moderate
sickness (or 2) as 5.21%, 3.03%, 2.08% and 1.20% in orderof group 1, group 2, group 3 and group 4, respectively.
Nobody responds for severe symptom (or 3) in SSQ.
3.2 Analysis in sixteen questions
Mean (μ) and Standard Deviation (SD) by weightingwith number of subjects in each group for sixteen equations
are shown in Fig. 4 (in the last page). Three highest-means
for the one-screen system with 2.00 cm parallax comes fromgeneral discomfort and fatigue (μ=0.83), fullness of head
(μ=0.67) and difficulty concentrating (μ=0.50). While
reporting no symptom for headache, increased salivation,

Fig. 2 Scene of experimentsweating and burping.
Three highest-means for the three-screen system with

One subject group is tested for only one experiment in

2.00 cm parallax are from eyestrain (μ=1.00), generalorder to avoid familiarity of the scene due to repeateddiscomfort and headache (μ=0.80) and fullness of head andexposure as suggested in [13].

blurred vision (μ=0.60). While reporting no symptom forvertigo, stomach awareness and burping.
Three highest-means for the one-screen system with

3. Results

6.50 cm parallax are from general discomfort (μ=0.83),
3.1 Analysis in mean degree of symptom

eyestrain (μ=0.50) and vertigo (μ=0.33). While reporting no―2―− 35 −

Proc. Sch. ITE
Tokai University

Study on Parallax Affect on Simulator Sickness in One-screen and Three-screen Immersive Virtual Environment
Study on Parallax Affect on Simulator Sickness in One-screen and Three-screen Immersive Virtual Environment

symptom for headache, sweating, blurred vision, dizzy (eyes(μ=0.33), more than disorientation (μ=0.11) and more thanclosed) and burping.

nausea (μ=0.04) or (O>D>N).

Three highest-means for the three-screen system with
4. T-test Evaluation

6.50 cm parallax comes from fatigue and eyestrain (μ=0.67),
general discomfort and difficulty concentrating (μ=0.50) anddifficulty focusing (μ=0.33). While reporting no symptom for

The results of four groups; one-screen/parallax 2.00 cm,

sweating, nausea, dizzy (eye open), stomach awareness andone-screen/parallax 6.50 cm, three-screen/parallax 2.00 cm

burping.

and three-screen/parallax 6.50 cm are evaluation by t test,

However, Fig.4 (in the last page) shows graph in high

two tailed type, to indicate the significant difference ofmean is high standard deviation that indicate the data issimulator sickness between each group in sixteen questions

spread out over a wide range of values or just few subjects

and Nausea, Oculomoter and Disorientation cluster.

have prestige severe feeling.
4.1 Analysis in sixteen questions
3.3 Analysis in Nausea, Oculomotor and Disorientation

We set α=0.05 then t=2.0003. Fig. 6 shows mean ofGroup the symptoms from the questionnaire to threesimulator sickness in sixteen questions of each group

distinct symptom clusters [14], by group the symptom

experiment that connected with black line on blue virtical bar

increased salivation, nausea, stomach awareness and burpingof standard error plot. Average mean of four groups is 0.30

as Nausea (N), symptom headache, eyestrain, difficulty±0.13.

focusing and blurred vision as Oculomotor (O), and symptom

1.1
0.9
0.7
0.5
0.3
0.1
-0.1

dizzy (eye open), dizzy (eye closed) and vertigo as
Disorientation (D). The average score of three distinct
symptom clusters is shown in Fig. 5.

1-2
ScreenParallax

Fig. 6 Comparative relation between mean ofscreen-parallax pairs in sixteen quesions
Table 1 Evaluation between groups in sixteen questions
Group
Fig. 5 The comparative results between three distinct
symptom clusters

one-screen system with 2.00 cm parallax is oculomotorA

One-screen/Parallax 2.00 cm

A

B

0.30

Three-screen /Parallax 6.50 cm

A

B

0.23

B

0.19

/Parallax 6.50 cm

0.40

The symbol letter in Table 1 shows that groups not(μ=0.25), more than disorientation (μ=0.17) and more thanconnected by same letter have significant difference.

nausea (μ=0.13) or (O>D>N).

Therefore, either first three groups above or last three groups

The most effect for the mean of degree of symptom forbelow of Table 1 do not have significant difference of

three-screen system with 2.00 cm parallax is oculomotor

simulator sickess. Only the simulator sickness result of(μ=0.60) that outstanding highest, more than disorientation

three-screen/parallax 2.00 cm and one-screen/parallax 6.50

(μ=0.20) and more than nausea (μ=0.15) or (O>D>N).

cm has significant difference.

The most effect for the mean of degree of symptom forone-screen system with 6.50 cm parallax is oculomotor and

4.2 Analysis in Nausea cluster

disorientation (μ=0.17) and more than nausea (μ=0.13) or

In Nausea cluster, we set α=0.05 then t=2.17881 for t test.

((O=D)>N).

The mean of four groups is 0.13±0.15 shown in Fig. 7.

The most effect for the mean of degree of symptom for
Three-screen system with 6.50 cm parallax is oculomotor

Vol. XXXI, 2011

Least Sq Mean

Three-screen /Parallax 2.00 cm

One-screen

The most effect for the mean of degree of symptom for

Symbol―3―− 36 −

Chompoonuch Jinjakam and Kazuhiko Hamamoto
Study on Parallax Affect on Simulator Sickness in One-screen and Three-screen Immersive Virtual Environment

6.50 cm that do not have significant difference of simulator
sickness in Oculomotor cluster.
4.4 Analysis in Disorientation cluster
In Disorientation cluster, we set α=0.05 then t=2.30600
for t test. Fig. 9 shows mean of four groups is 0.17±0.18.

Fig. 7 Comparative relation between mean ofscreen-parallax pairs in Nausea cluster
Table 2 Evaluation between groups in Nausea cluster
Group

SymbolLeast Sq Mean

Three-screen /Parallax 2.00 cm

A

0.15

One-screen/Parallax 6.50 cm

A

0.13

Fig. 9 Comparative relation between mean ofOne-screen/Parallax 2.00 cm

A

0.13

screen-parallax pairs in Disorientation cluster

Three-screen /Parallax 6.50 cm

A

0.04

Table 4 Evaluation between groups in Disorientation cluster
Group

SymbolLeast Sq Mean

and then four groups do not have significant difference ofThree-screen /Parallax 2.00 cm

A

0.20

simulator sickness in Nausea cluster.

One-screen/Parallax 2.00 cm

A

0.17

One-screen/Parallax 6.50 cm

A

0.17

Three-screen /Parallax 6.50 cm

A

0.11

Result shows every group is connected with same letter,

4.3 Analysis in Oculomotor cluster
In Oculomotor cluster, we set α=0.05 then t=2.17881 forResult shows every group is connected with same letter,and then four groups do not have significant difference of

1.2
1
0.8
0.6
0.4
0.2
0
-0.2

simulator sickness in Disorientation cluster.
5. Discussion

simulator sickness less than one-screen and parallax 6.50 cm,

3-6.5

3-2

1-6.5

The experimentation results show three-screen induced
1-2

Mean
0.25
±0.257642

t test. Fig.8 shows mean of four groups is 0.25±0.26.

as normal distance between human eyes, decreased simulotor

1-2

sickness than parallax 2.00 cm, as shown in Fig. 3, especially,

ScreenParallax

about parallax affect in Table 1.

Fig. 8 Comparative relation between mean of

Parallax 2.00 cm, especially for small display like TV, isscreen-parallax pairs in Oculomotor cluster

usually better than 6.50 cm. Because the distance betweeneyes and display is shorter than real distance between eyes

Table 3 Evaluation between groups in Oculomotor cluster
Group
Three-screen /Parallax 2.00 cm

SymbolA

and an object which is shown in display. Actually, 2.00 cm ofcameras distance is usually used in a consumer 3D video

Least Sq Mean
0.70

camera(forexample,Panasonic

HDC-TM750

andThree-screen /Parallax 6.50 cm

B

0.34

VW-CLT1). However, IVE can provide a real environmentOne-screen/Parallax 2.00 cm

B

0.25

according to the distance between eyes and an object (3DOne-screen/Parallax 6.50 cm

B

0.17

scene). Therefore, parallax can be set to the real distance
between eyes. Conversely, 2.00 cm is too short to feelappropriate 3D sense in Immersive Virtual Environment.

Result shows only three-screen/parallax 2.00 cm has

On the other hand, the comparative results between threesignificant difference from others; three-screen/parallax 6.50

distinct symptom clusters from Fig. 5 shows the oculomotor

cm, one-screen/parallax 2.00 cm and one-screen/parallax―4―− 37 −

Proc. Sch. ITE
Tokai University

Study on Parallax Affect on Simulator Sickness in One-screen and Three-screen Immersive Virtual Environment
Study on Parallax Affect on Simulator Sickness in One-screen and Three-screen Immersive Virtual Environment

case, three-screen system affected to simulator sickness more

[4]

Roy A. Ruddle, “The Effect of Environment Characteristics andthan one-screen system. It caused by distortion in passenger's

User Interaction on Levels of Virtual Environment Sickness,”view. If a subject is a driver by wearing eye track glasses, theIEEE Virtual Reality 2004, March 27-31, USA, pp.141-285.

subject can be immersed in complete virtual environment.

[5]James Jeng-Weei Lin, Henry B.L. Duh, Donald E. Parker,

However, if a subject is a passenger, the passenger view is

Habkb Abi-Rached and Thomas A. Furness, “Effect of Field ofdistorted around border of screens.

View on Presence, Enjoyment, Memory, and Simulator

The top-three highest simulator sicknesses are eyestrain,

Sickness in a Virtual Environment” Proceedings of the IEEE

general discomfort and fatigue, consecutively. The subject

Virtual Reality 2002 (VR'02).

responds sweating in only three-screen with 2.00 cm parallax[6]

Chin-Teng Lin, Shang-Wen Chuang, Yu-Chien Chen, Li-Wei

case, also with highest score for eyestrain. None of subjects

Ko, Sheng-Fu Liang and Tzyy-Ping Jung, “EEG Effects ofreport for burping or feel severe sickness in every symptom.

Motion Sickness Induced in a Dynamic Virtual Reality

The highest effect to subjects comes from oculomotor,

Environment,” Proceedings of the 29 th Annual International

and are more than the disorientation and more than the

Conference of the IEEE EMBS, August 23-26, 2007, France,

nausea (O > D > N). This result represents "seeing" is most

pp.3872-3875.

important problem for virtual environment.

[7]

Patrick J. Sparto, Susan L. Whitney, Larry F. Hodges, Joseph M.
Furman and Mark S. Redfern, “Simulator Sickness When

6. Conclusion

Performing Gaze Shifts within a Wide Field of View Optic
Flow Environment: Prelimianary Evidence for Using Virtual

In this study, simulator sickness in Immersive Virtual

Reality

Environment was investigated according to parallax and the[8]

The results show that parallax should be set to 6.50 cm in[9]

There remains an investigation about the relationship[10] Norihiro

VirtualReality,”

Auris

Nasus

Sugita,MakotoYoshizawa

and

MakotoAbe,“Evaluation of Adaptation to Visually Induced Motion Sickness
by Using Physiological Index Associated with Baroreflex

Government

Function,” Proceedings of the 29 th Annual International(MONBUKAGAKUSHO: MEXT) for all supports. The

Conference of the IEEE EMBS, August 23-26, 2007, France,

authors would like to thank sincere to Mr. Satoshi Suzuki andpp.303-306.

Mr.Yuta Odagiri for their kindly management during the[11] Christie Digital Systems USA, Inc.

period of all experiments.

[12] T. D. Parsons, P. Larson, K. Kratz, M. Thiebaux, B. Bluestein, J.
G. Buckwalter, and A. A. Rizzo, “Sex Differences in Mental

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Chompoonuch Jinjakam, one of the authors would like[2]

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Acknowledgment[1]

Seizo Ohyama, et.al, “Automatic Responses During Motion
Sickness

between parallax and convergence in IVE in the future.

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the

of

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Vol. XXXI, 2011―5―
− 38 −

Simulated

MotionUsing

the

Simulator

Sickness

Chompoonuch Jinjakam and Kazuhiko Hamamoto
Study on Parallax Affect on Simulator Sickness in One-screen and Three-screen Immersive Virtual Environment[16] Sean D. Young, Bernard D. Adelstein and Stephen R. Ellis,[17] Mi-Hyun Choi, et.al, “Long-term Study of Simulator Sickness:“Demand Characteristic of a Questionnaire Used to Assess

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August 9-12, Changchun, China, pp.20-25.

1.40

1.20

1.00

0.33
0.00

0.17

0.17

0.17

0.17

0.17
0.20

0.33

0.40
0.17

Blurred vision Dizzy (eye
open)

0.00
0.00
0.00
0.00

Fulless of
head

0.00

Diffuculty
concentrating

0.00

0.17

0.17

0.17
0.17

0.20
0.17

0.33
Nausea0.00

Sweating

0.00

0.17
0.20
0.17
0.00
0.00

Increased
salivation

0.60

0.50

0.50

Difficulty
focusing

0.00

Eyestrain

0.40

0.40
0.17
0.17

0.33

0.50
0.17

0.17

0.40
Headache

0.00

Fatigue

0.00

Generaldiscomfort

0.00

0.00

0.67
0.60

0.67
0.50
0.00

0.20

0.00

0.17

0.40

0.17

0.40

0.60

0.50

0.67

0.80

0.83

0.83
0.80
0.83

Mean in severe of symptom(μ)

1.00

0.80

One-screen (parallax 2.00 cm)
Three-screen (parallax 2.00 cm)
One-screen (parallax 6.50 cm)
Three-screen (parallax 6.50 cm)

Dizzy (eyeclosed)VertigoStomachawareness

Burping

Sixteen-questions of Simulator Sickness QuestionnaireFig. 4 Mean of sixteen questions for four-group experiments―6―− 39 −

Proc. Sch. ITE
Tokai University