SIST EN ISO 9241-394:2022

Ergonomics of human-system interaction - Part 394: Ergonomic requirements for reducing undesirable biomedical effects of visually induced motion sickness during watching electronic images (ISO 9241-394:2020)

This document establishes the requirements and recommendations for image contents and electronic display systems to reduce visually induced motion sickness (VIMS), while viewing images on electronic displays.
This document is applicable to electronic display systems, including flat panel displays, projectors with a screen, and virtual reality (VR) type of head mounted displays (HMDs), but not including HMDs that present electronic images on/with real-world scenes.
NOTE 1  This document assumes the images are viewed under appropriate defined conditions. See Annex B for the appropriate viewing conditions.
NOTE 2  This document is useful for the design, development, and supply of image contents, as well as electronic displays for reducing VIMS.
NOTE 3  ISO 9241‑392[3] provides guidelines for stereoscopic 3D displays, of which the methods are also used in HMDs.
NOTE 4  The International Telecommunication Union (ITU) generally sets the standards for broadcasting.

Ergonomie der Mensch-System-Interaktion - Teil 394: Ergonomische Anforderungen zur Reduzierung unerwünschter biomedizinischer Effekte der visuell induzierten Bewegungskrankheit bei der Betrachtung elektronischer Bilder (ISO 9241-394:2020)

Dieses Dokument legt die Anforderungen und Empfehlungen für Bildinhalte und elektronische Anzeigesysteme fest, um die visuell induzierte Bewegungskrankheit (VIMS) bei der Betrachtung von Bildern auf elektronischen Anzeigen zu reduzieren.
Dieses Dokument ist anwendbar für elektronische Anzeigesysteme, einschließlich Flachbildschirme, Projektoren mit einem Bildschirm und auf dem Kopf getragene Anzeigen (en: head mounted displays, HMDs) für virtuelle Realität (VR), jedoch nicht für auf dem Kopf getragene Anzeigen, die elektronische Bilder an oder mit realen Szenen darstellen.
ANMERKUNG 1   In diesem Dokument wird davon ausgegangen, dass die Bilder unter entsprechend definierten Bedingungen betrachtet werden. In Anhang B sind angemessene Betrachtungsbedingungen beschrieben.
ANMERKUNG 2   Dieses Dokument ist nützlich für die Gestaltung, Entwicklung und Bereitstellung von Bildinhalten sowie von elektronischen Anzeigen zur Reduzierung von VIMS.
ANMERKUNG 3   ISO 9241 392 [3] gibt Leitlinien für stereoskopische 3D-Anzeigen, deren Methoden auch in HMDs verwendet werden an.
ANMERKUNG 4   Die International Telecommunication Union (ITU) legt im Allgemeinen die Standards für die Ausstrahlung fest.

Ergonomie de l'interaction homme-système - Partie 394: Exigences ergonomiques pour la réduction des effets biomédicaux indésirables des cinétoses induites par stimulus visuel lors de l’observation d’images électroniques (ISO 9241-394:2020)

Le présent document établit les exigences et les recommandations pour les contenus d’images et les systèmes d’affichage électronique afin de réduire les cinétoses induites par stimulus visuel (VIMS), lors de la visualisation d’images sur des affichages électroniques.
Le présent document s’applique aux systèmes d’affichage électronique, y compris aux écrans plats, aux projecteurs avec un écran et aux casques stéréoscopiques (HMD) de type casque de réalité virtuelle (RV), mais pas aux HMD qui présentent des images électroniques sur/avec des scènes du monde réel.
NOTE 1        Le présent document suppose que les images sont visualisées dans des conditions définies appropriées. Voir Annexe B pour connaître les conditions de visualisation appropriées.
NOTE 2        Le présent document est utile pour la conception, le développement et la fourniture de contenus d’images, mais aussi d’affichages électroniques pour réduire les VIMS.
NOTE 3        L’ISO 9241‑392[3] fournit des lignes directrices pour les affichages 3D stéréoscopiques, dont les méthodes sont également utilisées dans les HMD.
NOTE 4        L’Union internationale des télécommunications (UIT) fixe généralement les normes pour la radiodiffusion.

Ergonomija medsebojnega vpliva človek-sistem - 394. del: Ergonomske zahteve za zmanjšanje neželenih biomedicinskih učinkov potovalne slabosti, ki jih povzročajo vizualni dražljaji pri gledanju elektronskih slik (ISO 9241-394:2020)

Ta dokument določa zahteve in priporočila za slikovne vsebine in elektronske prikazovalne sisteme za zmanjšanje potovalne slabosti, ki jo povzročajo vizualni dražljaji (VIMS) pri gledanju slik na elektronskih prikazovalnikih.
Ta dokument se uporablja za elektronske prikazovalne sisteme, vključno s ploskovnimi zasloni, projektorji z zaslonom in naglavnimi prikazovalniki (HMD) navidezne resničnosti (VR), ne uporablja pa se za naglavne prikazovalnike, ki elektronske slike prikazujejo prek prizorov iz resničnega sveta ali skupaj z njimi.
OPOMBA 1:   Ta dokument predpostavlja, da se slike gledajo v ustreznih, opredeljenih pogojih. Za ustrezne pogoje gledanja glej dodatek B.
OPOMBA 2:   Ta dokument je uporaben za oblikovanje, razvoj in posredovanje slikovnih vsebin, kot tudi za elektronske prikazovalnike za zmanjšanje potovalne slabosti, ki jo povzročajo vizualni dražljaji.
OPOMBA 3:   Standard ISO 9241-392 vsebuje smernice za stereoskopske 3D-prikazovalnike, pri čemer se metode iz tega standarda uporabljajo tudi pri naglavnih prikazovalnikih.
OPOMBA 4:   Standard običajno pripravi Mednarodna zveza za telekomunikacije (ITU).

General Information

• Status: Published
• Public Enquiry End Date: 30-Jan-2022
• Publication Date: 14-Jun-2022
• ICS: 13.180 - Ergonomics
• Technical Committee: VSN - Safety of machinery
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 08-Apr-2022
• Due Date: 13-Jun-2022
• Completion Date: 15-Jun-2022
• Ref Project: EN ISO 9241-394:2022 - Ergonomics of human-system interaction - Part 394: Ergonomic requirements for reducing undesirable biomedical effects of visually induced motion sickness during watching electronic images (ISO 9241-394:2020)

Standards Content (Sample)

SLOVENSKI STANDARD
01-julij-2022
Ergonomija medsebojnega vpliva človek-sistem - 394. del: Ergonomske zahteve za
zmanjšanje neželenih biomedicinskih učinkov potovalne slabosti, ki jih povzročajo
vizualni dražljaji pri gledanju elektronskih slik (ISO 9241-394:2020)
Ergonomics of human-system interaction - Part 394: Ergonomic requirements for
reducing undesirable biomedical effects of visually induced motion sickness during
watching electronic images (ISO 9241-394:2020)
Ergonomie der Mensch-System-Interaktion - Teil 394: Ergonomische Anforderungen zur
Reduzierung unerwünschter biomedizinischer Effekte der visuell induzierten
Bewegungskrankheit bei der Betrachtung elektronischer Bilder (ISO 9241-394:2020)
Ergonomie de l'interaction homme-système - Partie 394: Exigences ergonomiques pour
la réduction des effets biomédicaux indésirables des cinétoses induites par stimulus
visuel lors de l’observation d’images électroniques (ISO 9241-394:2020)
Ta slovenski standard je istoveten z: EN ISO 9241-394:2022
ICS:
13.180 Ergonomija Ergonomics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 9241-394
EUROPEAN STANDARD
NORME EUROPÉENNE
March 2022
EUROPÄISCHE NORM
ICS 13.180
English Version
Ergonomics of human-system interaction - Part 394:
Ergonomic requirements for reducing undesirable
biomedical effects of visually induced motion sickness
during watching electronic images (ISO 9241-394:2020)
Ergonomie de l'interaction homme-système - Partie Ergonomie der Mensch-System-Interaktion - Teil 394:
394: Exigences ergonomiques pour la réduction des Ergonomische Anforderungen zur Reduzierung
effets biomédicaux indésirables des cinétoses induites unerwünschter biomedizinischer Effekte der visuell
par stimulus visuel lors de l'observation d'images induzierten Bewegungskrankheit bei der Betrachtung
électroniques (ISO 9241-394:2020) elektronischer Bilder (ISO 9241-394:2020)
This European Standard was approved by CEN on 13 March 2022.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 9241-394:2022 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
The text of ISO 9241-394:2020 has been prepared by Technical Committee ISO/TC 159 "Ergonomics” of
the International Organization for Standardization (ISO) and has been taken over as EN ISO 9241-
394:2022 by Technical Committee CEN/TC 122 “Ergonomics” the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by September 2022, and conflicting national standards
shall be withdrawn at the latest by September 2022.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 9241-394:2020 has been approved by CEN as EN ISO 9241-394:2022 without any
modification.
INTERNATIONAL ISO
STANDARD 9241-394
First edition
2020-04
Ergonomics of human-system
interaction —
Part 394:
Ergonomic requirements for reducing
undesirable biomedical effects of
visually induced motion sickness
during watching electronic images
Ergonomie de l'interaction homme-système —
Partie 394: Exigences ergonomiques pour la réduction des effets
biomédicaux indésirables des cinétoses induites par stimulus visuel
lors de l’observation d’images électroniques
Reference number
ISO 9241-394:2020(E)
©
ISO 2020
ISO 9241-394:2020(E)
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

ISO 9241-394:2020(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Guiding concepts . 2
4.1 Contexts of image viewing . 2
4.2 Basis of guiding concepts . 3
4.3 Major factors of VIMS . 3
5 Ergonomic requirements and recommendations . 4
5.1 General . 4
5.2 Images presented in passive viewing environments . 5
5.2.1 Potentially unwanted conditions of visual rotation . 5
5.2.2 Potentially unfavourable conditions of visual rotation . 5
5.2.3 Basis of the requirements and recommendations . 5
5.2.4 Reference information on effects of visual motion combination . 6
5.3 Images presented in active viewing environments . 6
5.3.1 General. 6
5.3.2 Potentially unfavourable conditions of visual rotation . 6
5.3.3 Reference information on effects of visual motion combinations . 7
5.3.4 Potentially unfavourable conditions of large visual field images or VR-
type HMDs . 7
6 Conformance and usages of ergonomic recommendations . 7
6.1 General . 7
6.2 Measurement methods . 8
6.3 Procedure of conformance and report . 8
Annex A (informative) Overview of the ISO 9241 series . 9
Annex B (informative) Viewing conditions .10
Annex C (informative) Effects of visual motion combination .11
Annex D (informative) General methods of alleviating VIMS .15
Annex E (informative) Measurement method of visual global motion .17
Annex F (informative) Measurement method of time delay of head tracking .20
Annex G (informative) Sample procedure for assessing applicability and conformance .21
Annex H (informative) Individual viewer factors .23
Bibliography .24
ISO 9241-394:2020(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 159, Ergonomics, Subcommittee SC 4,
Human-system interaction.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
A list of all parts in the ISO 9241 series can be found on the ISO website.
iv © ISO 2020 – All rights reserved

ISO 9241-394:2020(E)
Introduction
With the advancement in image technologies, it is now possible to experience various new types of
images through different kinds of electronic displays, for example, ultra-high definition (UHD) images
and virtual reality images. These technologies make our daily lives more convenient and enable
different lifestyles.
The new products of advanced image technologies can be popularized both by solving technical issues
and by devising countermeasures for reducing incidences of undesirable biomedical effects, such as
visually induced motion sickness.
This document describes the basic and minimal conditions for reducing incidences of visually induced
motion sickness. It is intended to promote an environment in which viewers can enjoy the benefits of
images without the adverse effects of visually induced motion sickness. In such an environment, new
technologies for images can also be actively developed and applied in various fields. This document is
not intended to restrict the freedom of expression or artistic creativity in the image culture.
This document is based on scientific findings related to the possible undesirable effects of visually
induced motion sickness. In the future, this document could be revised as new scientific data become
available.
This document is part of the ISO 9241 series, which specifies human–system interaction standards.
Readers who need guidance on other aspects of human–system interaction can therefore refer to other
documents in the ISO 9241 series. See Annex A for an overview of the ISO 9241 series.
INTERNATIONAL STANDARD ISO 9241-394:2020(E)
Ergonomics of human-system interaction —
Part 394:
Ergonomic requirements for reducing undesirable
biomedical effects of visually induced motion sickness
during watching electronic images
1 Scope
This document establishes the requirements and recommendations for image contents and electronic
display systems to reduce visually induced motion sickness (VIMS), while viewing images on electronic
displays.
This document is applicable to electronic display systems, including flat panel displays, projectors with
a screen, and virtual reality (VR) type of head mounted displays (HMDs), but not including HMDs that
present electronic images on/with real-world scenes.
NOTE 1 This document assumes the images are viewed under appropriate defined conditions. See Annex B for
the appropriate viewing conditions.
NOTE 2 This document is useful for the design, development, and supply of image contents, as well as
electronic displays for reducing VIMS.
[3]
NOTE 3 ISO 9241-392 provides guidelines for stereoscopic 3D displays, of which the methods are also used
in HMDs.
NOTE 4 The International Telecommunication Union (ITU) generally sets the standards for broadcasting.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 9241-302 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
visually induced motion sickness
VIMS
motion sickness-like symptoms induced by perceived motion within the visual environment, such as
when watching movies and screen images of video games
Note 1 to entry: The symptoms can include dizziness, vertigo, sweating, odd feelings in the stomach, and nausea,
which can progress to vomiting.
ISO 9241-394:2020(E)
3.2
dizziness
physical unsteadiness, lack of balance, or light headedness
3.3
vertigo
sensation of rotation or movement of one’s self (subjective vertigo), or of rotation or movement of one’s
surroundings (objective vertigo), in any plane
3.4
postural instability
set of conditions in which voluntary movements cannot be well coordinated for maintaining posture
3.5
disorientation
loss of sense of direction, position, or relationship with the surroundings
3.6
visual global motion
wide spatial range of image motion in the visual field, composed of different velocities and directions
that are systematically aligned in a moving image
Note 1 to entry: There are generally six types of visual global motions that correspond to the different types of
motions of a camera during the capturing of images: rotation around and translation along the pitch, yaw, and
roll axes.
3.7
head-mounted display
HMD
display device that is worn on the head, is integrated into eyeglasses, or is built in as part of a helmet
or a hat
3.8
virtual reality
VR
set of artificial conditions created by computer and dedicated electronic devices that simulate visual
images and possibly other sensory information of a user’s surrounding with which the user is allowed
to interact
Note 1 to entry: The artificial conditions do not reflect a user’s real-time physical environment.
4 Guiding concepts
4.1 Contexts of image viewing
Two different viewing environments are defined for the contexts of image viewing to reduce VIMS. One
is the active viewing environment, in which either the motion, orientation or other displayed contents
of the images vary according to any viewers' actions, such as head movements or the manipulation of
controllers. The other is the passive viewing environment, in which any displayed contents of the images
do not vary with viewers' actions. In the active viewing environment, the changes in the displayed
contents are caused by tracking the head of the viewers, or by the viewers operating the controller. In
this document, the contexts of image viewing in the two viewing environments are the following:
— passive viewing environment:
— display device: flat panel display, projector, or head-mounted display;
— image generation: real-time rendering or playing recorded images;
— image size in visual angle: depending on applications and display device;
2 © ISO 2020 – All rights reserved

ISO 9241-394:2020(E)
— interactive type: none;
— active viewing environment:
— display device: flat panel display, projector, or head-mounted display;
— image generation: real-time rendering;
— image size in visual angle: depending on applications and display device;
— interactive type: head tracking and/or controller.
4.2 Basis of guiding concepts
This document provides the basic and minimal conditions for reducing incidences of VIMS primarily
from the viewpoint of nauseating symptoms, such as dizziness, sweating, headache, stomach awareness,
nausea, and vomiting. In this subclause, the references are verified as the bases for the guidelines
from literature and summaries, and also from their reported scores from the simulator sickness
questionnaire (SSQ).
Nauseating symptoms are reflected in the drop-out rates in various experiments of VIMS and simulator
[4]
training. The relationship between drop-out rates and SSQ total score (SSQ-TS) has been clarified .
[4]
The drop-out rates were also reported to be correlated with the nausea subscore of SSQ (SSQ-N) .
The conditions for reducing VIMS can be considered in terms of lowering SSQ-TS (and/or the SSQ-N) to
some extent. In fact, the severity index of VIMS described in C.4 is based on SSQ-TS.
Meanwhile, another aspect related to VIMS has been reported in the literature, i.e. disorientation
induced after exposures to VR. Disorientation is different from nauseating symptoms in that it affects
the equilibrium of the body. While postural fluctuation during exposure to VR is an adverse effect
from the viewpoint of physical safety during a VR experience, disorientation after exposure to VR is
paramount to be considered as an after-effect from the viewpoint of physical safety after returning to
the real environment. The disorientation after exposures to VR can be reflected by the disorientation
[5]
subscore of SSQ (SSQ-D) .
The different characteristics of the nauseating symptoms and disorientation after exposures to VR
are also to be considered in terms of temporal courses. When viewers are repetitively exposed to the
environments that easily induce VIMS, nauseating symptoms are known to be reduced significantly
by the habituation to the environments. Moreover, when viewers are repetitively exposed to virtual
environments, disorientation occurring every time after the viewers return to the real environment has
been reported to increase. In other words, postural fluctuations increase. Consequently, it is paramount
to consider this type of undesirable effect, i.e. disorientation, as well as nauseating symptoms. To reduce
disorientation, general methods described in D.1 and D.2 can be useful as countermeasures.
4.3 Major factors of VIMS
VIMS is known to be affected by various factors. Among them, the major factor is visual motion within
images. It can be either enhanced or attenuated by visual image factors, visual environmental factors,
and individual viewer factors.
VIMS can be reduced, to some extent, by considering other major factors such as those shown below,
depending on the context of image viewing. Therefore, to control VIMS, those different major factors
need to be simultaneously considered with an appropriate balance.
Passive viewing environment:
— amount of visual global rotation:
— different types of visual global rotations;
— velocity of visual global rotation;
ISO 9241-394:2020(E)
— viewing period;
— image size in visual field;
— fixation-point/visual-target;
— navigating velocity;
— predictive information of self-motion;
— independent background from visual motion.
Active viewing environment:
— amount of visual global rotation;
— different types of visual global rotations;
— velocity of visual global rotation;
— viewing period;
— image size in visual field;
— fixation-point/visual-target;
— navigating velocity;
— predictive information of self-motion;
— independent background from visual motion;
(for the environment especially by head tracking)
— match in visual field between virtual camera and display (especially for large visual field images or
VR type of HMD);
— match of head motion and visual motion (especially for large visual field images or VR type of HMD);
— delay in head tracking.
5 Ergonomic requirements and recommendations
5.1 General
To obtain the condition that sufficiently reduces the possibility of VIMS, visual image factors, visual
environmental factors, and individual viewer factors shall be considered. However, in this document,
the following are of principal concern:
— visual image factors, such as velocity and types of visual global motion and viewing period; and
— visual environmental factors, such as image size in visual field, fixation-point/visual-target,
luminance level of images, illuminance level of environment, image resolution, and delay of head
tracking.
For individual viewer factors, information can be found in Annex G.
NOTE The principles in 5.2 are easier to apply in the case of pre-recorded contents, which can be analysed
frame by frame. Interactive media, such as video games, can afford essentially limitless sequences throughout
the game, depending on the user's actions. In the case of video games, the requirements and recommendations
apply to typical sequences of play but cannot cover every eventuality of play.
4 © ISO 2020 – All rights reserved

ISO 9241-394:2020(E)
5.2 Images presented in passive viewing environments
5.2.1 Potentially unwanted conditions of visual rotation
Potentially unwanted conditions of visual rotation shall be avoided.
Potentially unwanted conditions of visual rotation are defined as those satisfying any of the following
conditions.
a) Total amount of yaw rotation within a 20-minute period at any time of images is more than 17 280°
(or 48 rounds).
b) Total amount of pitch rotation within a 20-minute period at any time of images is more than 15 120°
(or 42 rounds).
c) Total amount of roll rotation within a 20-minute period at any time of images is more than 14 400°
(or 40 rounds).
NOTE The criterion values above are applied while the image size in visual field is assumed as in the range of
30° × 17° to 70° × 40°.
5.2.2 Potentially unfavourable conditions of visual rotation
Potentially unfavourable conditions of visual rotation should be avoided.
Potentially unfavourable conditions of visual rotation are defined as those satisfying any of the
following conditions.
a) Total amount of yaw rotation within a 20-minute period at any time of images is more than 12 960°
(or 36 rounds).
b) Total amount of pitch rotation within a 20-minute period at any time of images is more than 11 520°
(or 32 rounds).
c) Total amount of roll rotation within a 20-minute period at any time of images is more than 10 800°
(or 30 rounds).
NOTE 1 The criterion values above are applied while the image size in visual field is assumed to be 30° × 17°
or larger.
NOTE 2 Visual images can be enlarged in certain use cases, such as in the medical field. In such cases, the
amount of rotation can be underestimated, if it is obtained by the actual camera rotation.
5.2.3 Basis of the requirements and recommendations
In 5.2.1, 5.2.2 and 5.3.2, the numerical criteria were set based on the relation between the dropout
rate and total amount of rotation presented in the images on electronic displays in the experiments of
[6]
VIMS . In this process, the dropout rate was obtained by transforming the experimentally obtained
SSQ-TS using Formula (1) (see Figure C.1):
2 2
Y = 0,0057X + 0,744X – 3,973 9, R = 0,352 4 (1)
where
X is the averaged SSQ-TS;
Y is the dropout rate (%).
Those relations between dropout rate and total amount of rotation are shown in Figure 1, with fitted
linear lines for each data of pitch, roll, and yaw-axes rotations. As shown in the graph, the criteria for
ISO 9241-394:2020(E)
the requirements are set in terms of 10 % of the dropout rate, while those for the recommendations are
set in terms of 7,5 % of the dropout rate.
Key
X total amount of rotation around a single axis within 20 min (°)
Y dropout rate (%)
yaw 1 criterion for recommendation of yaw
pitch 2 criterion for requirement of yaw
roll
Figure 1 — Relation between dropout rate and total amount of rotation around each
of three axes
5.2.4 Reference information on effects of visual motion combination
For considering the effects of visual motion combination, see C.3.
5.3 Images presented in active viewing environments
5.3.1 General
For images in the active viewing environments, the major factors to be considered are those of visual
motion described in 5.2 as well as those specific to these environments, such as:
— the time delay of changing images yoked to the signals from the head tracking or controllers;
— the consistency of visual field between virtual camera and presented images especially for large
visual field images or VR-type HMDs with head tracking system; and
— the consistency of direction and amount of head movements with image motion.
5.3.2 Potentially unfavourable conditions of visual rotation
Potentially unfavourable conditions of visual rotation, not caused by head movements, should be
avoided.
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ISO 9241-394:2020(E)
Potentially unfavourable conditions of visual rotation are defined as those satisfying either of the
following conditions.
a) Total amount of yaw rotation within a 20-minute period at any time of images are more than
17 280° (or 48 rounds).
b) Total amount of pitch rotation within a 20-minute period at any time of images are more than
15 120° (or 42 rounds).
c) Total amount of roll rotation within a 20-minute period at any time of images are more than 14 400°
(or 40 rounds).
Rotations above are not produced by head tracking.
NOTE 1 This document only describes the recommendations for visual rotation in active viewing
environments different from the passive viewing environment, which does not necessary indicate that active
viewing environments are generally less severe than passive viewing environments.
NOTE 2 The criterion values above are applied while the image size in the visual field is assumed to be
30° × 17° or larger.
NOTE 3 Visual images can be enlarged in certain use cases, such as in the medical field. In such cases, the
amount of rotation can be underestimated, if it is obtained by the actual camera rotation.
5.3.3 Reference information on effects of visual motion combinations
For considering the effects of visual motion combination, see C.3.
5.3.4 Potentially unfavourable conditions of large visual field images or VR-type HMDs
Potentially unfavourable conditions of large visual field images or VR-type HMDs should be avoided as
follows:
a) the field of view of the virtual camera and that of the images presented are matched as much as
reasonably achievable;
b) the direction and speed of the virtual camera motion and those of the user’s head motion are
matched as much as reasonably achievable.
NOTE 1 For the presentations of stereoscopic 3D images with a wide field view or the VR-type HMDs, refer to
[3]
ISO 9241-392 .
NOTE 2 Adjustments in matching the direction and speed of virtual camera motion and those of the user’s
head motion can be affected by several factors, including the static/dynamic characteristics of detecting the
devices in motion in HMDs.
NOTE 3 The time delay in visual image change corresponding to the displayed image of the user’s head
movements can affect VIMS. A study reported that the primary factor of time delay inducing VIMS was the
[7]
temporal variability . The sample measurement method is described in Annex F.
6 Conformance and usages of ergonomic recommendations
6.1 General
For developing image contents and electronic displays, this document provides the ergonomic
requirements and recommendations for reducing VIMS.
To comply with the requirements in Clause 5, the procedure described in 6.3 should be followed using
the evaluation methods described in 6.2.
ISO 9241-394:2020(E)
To follow the recommendations in Clause 5, the procedure described in 6.3 can be followed using the
evaluation methods described in 6.2.
6.2 Measurement methods
To evaluate electronic visual images according to the items described in 5.2.1, 5.2.2, and 5.3.2, the
measurement of pixelated video signals transmitted to electronic visual displays is essential. The
measurement method is described in Annex E.
6.3 Procedure of conformance and report
Conformance with this document is achieved by satisfying all the applicable requirements. For the
recommendations provided in this document, the evaluations of products can be reported. For reference
purposes, the clauses including the requirements and those including the recommendations are listed
in G.2. Users of this document shall evaluate the applicability of each requirement and should evaluate
the applicability of each recommendation. If a product is claimed to have met the applicable items in the
requirements, the procedure used in evaluating the product shall be specified. If a product is claimed
to have met the applicable items in the recommendations, the procedure used in evaluating the product
should be specified.
Annex G provides an example of both determining and recording the applicability of all the requirements
and recommendations in Clause 5, and for reporting that they have been evaluated. Other equivalent
forms of report are acceptable.
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ISO 9241-394:2020(E)
Annex A
(informative)
Overview of the ISO 9241 series
Table A.1 presents an overview of the structure of the ISO 9241 series.
The structure reflects the numbering of the original ISO 9241 standard; for example, displays were
originally ISO 9241-3 and are now the ISO 9241-300 series. In each section, the “hundred” is an
introduction to the section. For example, ISO/TR 9241-100 gives an introduction to the software-
ergonomics parts.
Table A.1 — Structure of the ISO 9241 series, Ergonomics of human–system interaction
Part Title
1 Introduction
2 Guidance on task requirements
11 Usability: Definitions and concepts
20 Accessibility guidelines for information/communication technology (ICT) equipment and services
21–99 To be assigned
100 Software ergonomics
200 Human–system interaction processes
300 Displays and display-related hardware
400 Physical input devices — Ergonomics principles
500 Workplace ergonomics
600 Environment ergonomics
700 Special application domains
800 To be assigned
900 Tactile and haptic interactions
ISO 9241-394:2020(E)
Annex B
(informative)
Viewing conditions
B.1 General
To reduce the potential for VIMS while viewing moving images, the appropriate viewing conditions are
important. It is useful for the providers of image content, electronic displays, and final products of image
presentation to inform the viewers of the following information regarding the viewing conditions.
B.2 Setting viewing position and posture
It is generally assumed that moving images are viewed with a certain viewing distance from the
electronic display surface. If the viewing distance is shorter than is assumed, visual fatigue can be
enhanced, which can affect the severity of VIMS. Moreover, shorter viewing distances generally lead to
[8][9][10]
larger image sizes of the visual field, which is known to possibly enhance VIMS .
For high-definition images with an aspect ratio of 16:9, the viewing distance is recommended as triple
[2]
the height of the display area (3H, or 3× height ), or as the range of triple to six-fold the height of the
[11]
display area . The viewing distance is one of the factors determining the visual field size of moving
images. Regardless of the viewing distance, it is useful for viewers to be informed of the assumed
viewing distance.
B.3 Confirmation of clear and appropriate visual images
While viewing stereoscopic images, if the viewer experiences double-vision or does not experience
stereopsis, it is appropriate that the viewer stops viewing the images and verifies the settings of the
stereoscopic image content, stereoscopic display, and viewing conditions. If the viewer experiences
discomfort while watching stereoscopic images, pseudostereopsis can have occurred, in which the left
and right images are reversed, thus resulting in reversed binocular parallax. If the viewer realizes that
pseudostereopsis has occurred, it is advisable to remove the cause of the pseudostereopsis or to stop
viewing the stereoscopic images.
Individual differences exist in how people experience stereopsis, visual fatigue, discomfort, and VIMS
when viewing stereoscopic images. If the viewer does not experience stereopsis or feels discomfort
even while viewing appropriately adjusted stereoscopic images and displays, it is advisable to stop
viewing the stereoscopic images.
B.4 Viewing period
Even when the conditions described in C.2 and C.3 are considered, a long period of image viewing can
induce visual fatigue and discomfort, which can affect the severity of VIMS. If the viewer experiences
visual fatigue, discomfort, or VIMS (typical symptoms are dizziness, vertigo, sweating, odd feelings in
the stomach, and nausea) while viewing the images, a break is advised.
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ISO 9241-394:2020(E)
Annex C
(informative)
Effects of visual motion combination
C.1 General
Images generally distributed as consumer products typically include various combinations of visual
motions, which have six degrees of freedom, indicating that those visual motions can be disintegrated
into the rotation around and the translation along the yaw, pitch, and roll axes. In 5.2 and 5.3, the
requirements and recommendations establish the numerical criteria in terms of a single-axis rotation.
For readers who are interested in considering the undesirable effects (on VIMS) of the visual motion
combination, the severity index of VIMS described in C.4 is useful.
The index is more informative, as shown in C.2 and C.3, because it describes the background
and rationale of the severity index of VIMS. Clause C.2 is also useful to understand the basis of the
requirements and recommendations described in 5.2.1, 5.2.2, and 5.3.2, in terms of how the dropout
rate is determined.
C.2 Dropout rate and SSQ total score
To consider the ergonomic guidelines for reducing incidences of VIMS, it is important to estimate the
severity of VIMS in a given condition. To estimate the severity of VIMS symptoms quantitatively, the
“severity index” is introduced. This is performed in two steps:
a) determining the scaling of VIMS; and
b) determining an index that relates VIMS severity to the scaling.
[12]
VIMS scaling may be realized by a score obtained using the SSQ , typically conducted before/after
exposures to moving images. In fact, SSQ has often been used for evaluating the severity of VIMS,
[4]
although it was originally developed for evaluating simulator sickness. Balk et al. reported that the
total score of SSQ obtained in his experiments correlated with the rate of dropout. Figure C.1 plots the
data shown in the literature reporting both SSQ total scores and the corresponding dropout rates. In
the graph, the fitted line to the data is also plotted, with which the dropout rate can be estimated from
the SSQ total score.
ISO 9241-394:2020(E)
Key
X averaged SSQ-TS
Y dropout rate (%)
2 2
1 Y = 0,0057X + 0,744X – 3,973 9, R = 0,352 4 Ujike et al. (2005)
Balk et al. (2013) Koslucher et al. (2015)
Reed et al. (2007) Exp.1 Park et al. (2006)
Reed et al. (2007) Exp.2 Cont. Stanney et al. (2003) after 15 min
Reed et al. (2007) Exp.2 S Stanney et al. (2003) after 30 min
Reed et al. (2007) Exp.2 F Stanney et al. (2003) after 45 min
Reed et al. (2007) Exp.2 S+F Stanney et al. (2003) after 60 min
Stanney et al. (1999) Ujike and Watanabe (2017)
Stanney et al. (2002)
Figure C.1 — Relation of averaged SSQ total score and dropout rate
C.3 SSQ total score and total amount of visual rotation around yaw, pitch, and
roll axes
A linear relation is shown between the total amount of visual rotation and SSQ total score, as shown
in Figure C.2. In the figure, two independent lines are fitted. One line has a relatively gentle slope for
the data obtained with images on electronic displays, and the other has a relatively steep slope for the
data obtained with a cylindrical drum. The two lines indicate that the SSQ total scores tend to increase
linearly as a function of the summation values of visual motion presented with the size in the visual
angle from 34° × 26° to 65° × 59°. Meanwhile, for the visual motion presented with an optokinetic drum,
the same type of linear function can be obtained, except that the slope is steep. This can indicate the
two factors of VIMS severity:
1) the effect of visual rotation; and
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ISO 9241-394:2020(E)
2) the effect of viewing environments.
This idea is similar to the motion sickness dose value (MSDV) that is calculated as the temporal
[1]
integration of frequency-weighted acceleration .
Key
X total amount of visual rotation (°)
Y SSQ-TS
1 fitted line for images on electronic displays; Diels and Howarth (2011)
stimulus size: 34° × 26° to 65° × 59° Keshavarz and Hecht (2011)
2 fitted line for images with cylindrical drum; Ujike et al. (2005)
stimulus size: full visual field
Bubka et al. (2006)
Bonato et al. (2009)
Figure C.2 — Relation of averaged SSQ total score and total amount of visual rotation
C.4 Severity Index of VIMS
The severity index of VIMS, I , is defined as Formula (C.1):
S
Ik=⋅kV⋅ M (C.1)
...