ETSI GR CIM 052 V1.1.1 (2025-01)

Context Information Management (CIM); VR and AR for Smart Learning: Guidelines for using NGSI-LD to train personnel in Smart Industries

DGR/CIM-0052

General Information

• Status: Not Published
• Technical Committee: CIM - cross-cutting Context Information Management
• Current Stage: 12 - Citation in the OJ (auto-insert)
• Due Date: 10-Jan-2025
• Completion Date: 13-Jan-2025

Standards Content (Sample)

GROUP REPORT
Context Information Management (CIM);
VR and AR for Smart Learning: Guidelines for using NGSI-LD
to train personnel in Smart Industries
Disclaimer
The present document has been produced and approved by the cross-cutting Context Information Management (CIM) ETSI
Industry Specification Group (ISG) and represents the views of those members who participated in this ISG.
It does not necessarily represent the views of the entire ETSI membership.

2 ETSI GR CIM 052 V1.1.1 (2025-01)

Reference
DGR/CIM-0052
Keywords
API, augmented reality, IoT, NGSI-LD, smart
industry
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3 ETSI GR CIM 052 V1.1.1 (2025-01)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Definition of terms, symbols and abbreviations . 7
3.1 Terms . 7
3.2 Symbols . 7
3.3 Abbreviations . 7
4 Immersive technologies used for Smart Learning based on 3D representation of real environments . 8
4.1 Types of immersive technologies and their use . 8
4.1.0 Foreword . 8
4.1.1 AR-based content . 8
4.1.2 VR-based content . 8
4.1.3 MR-based content . 9
4.2 Smart Learning and Immersive experiences. 9
4.2.1 Standards . 9
4.2.1.1 Overview . 9
4.2.1.2 XAPI . 9
4.2.1.3 SCORM . 14
4.2.1.4 ETSI ISG ARF . 16
4.2.2 De-facto standards . 17
4.2.2.1 Overview . 17
4.2.2.2 OpenXR . 17
4.2.2.3 WebXR . 17
4.2.3 Common methodologies and best practices . 17
5 Mapping of xAPI to NGSI-LD . . 20
5.1 Preliminary Overview . 20
5.1.0 Foreword . 20
5.1.1 Similarities with NGSI-LD . 20
5.1.2 Limitations . 20
5.2 Mapping . 21
5.2.1 Overview . 21
5.2.2 Statement . 21
5.2.3 Actor . 22
5.2.3.1 Overview . 22
5.2.3.2 Agent . 22
5.2.3.3 Group . 22
5.2.4 Verb . 23
5.2.5 Object . 24
5.2.5.1 Overview . 24
5.2.5.2 Activity . 24
5.2.6 Result . 26
5.2.7 Context . 27
5.2.8 Attachments . 28
6 Using NGSI-LD with XR scenarios . 29
6.1 Overview . 29
6.2 Guidelines. 29
6.3 Proof of concepts . 30
6.3.1 Introduction. 30
6.3.2 APP Tracking Software for LET . 30
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6.3.2.1 Overview . 30
6.3.2.2 3D Application . 30
6.3.2.3 LMS . 31
6.3.2.4 APP . 31
6.3.2.5 Data and operations workflows . 31
7 Improvements to NGSI-LD . 33
7.1 Introducing 3DProperty type for properties . 33
7.1.1 Overview . 33
7.1.2 Data Model . 34
7.1.3 Query Language . 35
7.2 Collisions between user @context and core @context . 36
7.2.1 Overview . 36
7.3 Introducing Temporal Interval Query. 37
7.3.1 Overview . 37
7.3.2 Scenario and objective . 37
7.3.3 Proposed "interval" aggregation function . 37
Annex A: Change history . 40
History . 41

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5 ETSI GR CIM 052 V1.1.1 (2025-01)
Intellectual Property Rights
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ETSI in respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the
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the oneM2M Partners. GSM and the GSM logo are trademarks registered and owned by the GSM Association.
Foreword
This Group Report (GR) has been produced by ETSI Industry Specification Group (ISG) cross-cutting Context
Information Management (CIM).
Modal verbs terminology
In the present document "should", "should not", "may", "need not", "will", "will not", "can" and "cannot" are to be
interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.

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6 ETSI GR CIM 052 V1.1.1 (2025-01)
1 Scope
The present document focuses on the selection of relevant and representative implementations, methodologies, and
standards employed in the training of personnel within Smart Industries. It establishes guidelines for the effective use of
the NGSI-LD API in Smart Learning applications enhanced by VR/AR technologies. Additionally, it includes the
mapping of at least one Smart Learning standard to NGSI-LD to ensure compatibility and interoperability across
various platforms.
2 References
2.1 Normative references
Normative references are not applicable in the present document.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] Milgram, Paul, H. Takemura, A. Utsumi, F. Kishino (1994), "Augmented Reality: A class of
displays on the reality-virtuality continuum", Proceedings of SPIE - The International Society for
Optical Engineering Vol. 2351. Retrieved 2021-06-01.
[i.2] Meta, Immersive Experiences: "Best Practices".
[i.3] Billy T.M. Wong, Kam Cheong Li: "Research and Practice in Smart Learning: A Literature
TM
Review", in IEEE Access, pp. 23-26, 2020.
[i.4] ISO/IEC TR 23844:2023: "Information technology for learning, education, and training —
Immersive content and technology".
[i.5] ISO/IEC 5927:2024: "Computer graphics, image processing and environmental data representation
— Augmented and virtual reality safety — Guidance on safe immersion, set up and usage".
[i.6] Experience API (xAPI) Standard.
[i.7] ADL: "Documentation about xAPI data model and features". ®
[i.8] ADL: "Sharable Content Object Reference Model SCORM ".
[i.9] IETF RFC 2046 (November 1996): "Multipurpose Internet Mail Extensions (MIME) Part Two:
Media Types".
[i.10] ETSI GS ARF 004-2 (V1.1.1) (08/2021): "Augmented Reality Framework (ARF) Interoperability
Requirements for AR components, systems and services Part 2: World Storage and AR Authoring
functions".
[i.11] "Minerva project", HT s.r.l, P.M.F. s.r.l, Sfera s.r.l, European Project F/190045/01-02-03/X44.
[i.12] Khronos GROUP: "OpenXR". ®
[i.13] W3C Immersive Web Working and Community Groups: "WebXR".
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7 ETSI GR CIM 052 V1.1.1 (2025-01) ®
[i.14] OGC 06-103r4 V1.2.1: "OpenGIS Implementation Standard for Geographic information - Simple
feature access - Part 1: Common architecture".
[i.15] IETF RFC 5646: "Tags for Identifying Languages".
[i.16] ISO 8601 (2019): "Data elements and interchange formats — Information interchange —
Representation of dates and times.
[i.17] IETF RFC 7946: "The GeoJSON Format".
3 Definition of terms, symbols and abbreviations
3.1 Terms
Void
3.2 Symbols
Void
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
3D three-Dimensional
ADL Advanced Distributed Learning
API Application Programming Interface
APP Achievements, Progress and Position tracking software for LET
AR Augmented Reality
ARF Augmented Reality Framework
ETSI European Telecommunications Standards Institute
GPS Global Positioning System
GS Group Specification
HMD Head Mounted Display
IEC International Electrotechnical Commission
IEEE Institute for Electrical and Electronic Engineers
IETF International Engineering Task Force
IRI Internationalized Resource Identifier
IRL Internationalized Resource Locator
ISG Industry Specification Group
ISO Internation Standardization Organisation
JSON JavaScript Object Notation
LBS Location-Based Service
LET Learning, Education and Training
LMS Learning Management System
MR Mixed Reality
OpenXR Open standard for virtual and augmented reality
RFC Request For Comments
s.r.l. società a responsabilità limitata ®
SCORM Sharable Content Object Reference Model
SRS Spatial Reference System
TR Technical Report
UI/UX User Interface/User eXperience
VR Virtual Reality
W3C World Wide Web Consortium
XAPI eXperience API
XR eXtended Reality
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4 Immersive technologies used for Smart Learning
based on 3D representation of real environments
4.1 Types of immersive technologies and their use
4.1.0 Foreword
Based on the available literature [i.1], the realm of immersive technologies is characterized by the 'distance' between the
3D experiences developed and the reality on which they are based. The main category of immersive content is the
eXtended Reality (XR), it is the full range of virtual content added to the real environment. This spectrum includes
various technologies ranging from the simplest augmentation of reality of Augmented Reality (AR), to more complex
and virtual experiences of Mixed Reality (MR) and Virtual Reality (VR) technologies. The usage of immersive
technologies is growing, these enhance the quality and the efficiency of traditional Learning, Education and Training
(LET) environments and make experiences more inclusive than ever.

Figure 4.1.0-1: The reality-virtuality continuum diagram
4.1.1 AR-based content
AR-based content [i.4] consists of overlaying the real world with virtual 3D objects. This type of content requires
mobile devices or compatible see-through devices. These immersive experiences are the least computationally
demanding among others and are consumed daily by millions of people around the world. In fact, AR face filters,
popular mobile games, and many interior design customization applications use AR technology to create engaging and
personalized experiences. AR-based content includes:
• Location-Based Service (LBS) applications, heavily use Global Positioning System (GPS), gyroscope sensor
and can rely on images to gather information about user's position in the real world.
• Image and object recognition applications, make use of the device's camera module to recognize marker,
images and objects and make possible to instantiate 3D objects on the plane of the scanned asset (museum or
school applications and face filter used in social networks as reference).
• Projection applications, are limited to small projectors installed on a device that project images directly to the
user's retinas or eyeglasses to display additional real-time information about the environment.
4.1.2 VR-based content
Virtual Reality-based (VR-based) content [i.4] is played through a Head Mounted Display (HMD) device, which
typically needs high computing and graphics rendering capabilities and is often used with a pair of controllers for hand
gestures and input devices. There are two distinct types of experiences:
• 360° images applications, use panoramic images of real environment that can be virtually visited by the user,
it is possible to play even on mobile devices.
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• 3D simulations applications, place 3D objects in a virtual environment that can be manipulated and
interactable, this type of content needs devices with high specification (heavily used in gaming, simulations
and training).
4.1.3 MR-based content
The Mixed Reality (MR) merges the best of both Augmented Reality (AR) and VR technologies, this type of content is
characterized by the fusion of 3D synthetic objects and real world environments. MR technology allows users to
interact with digital objects that co-exists with the tangible physical world, they can be even anchored to real world
locations to be viewed through devices that need cameras such as HMD devices, smartphones or glasses. This
technology is growing rapidly and the rate of adoption of devices capable of these features will increase in the near
future.
4.2 Smart Learning and Immersive experiences
4.2.1 Standards
4.2.1.1 Overview
Clause 4.2.1 will present standards and de-facto standards about technical requirements, data models, implementation
and User Interface/User eXperience (UI/UX).
At the moment, there are no available standards [i.4] for eXtended Reality (XR) experiences themselves or their
implementations. However, there are standards related to peripherals, safety of HMD devices, image processing, 3D
rendering, and audio; some of these are the same as those used in other software, such as video games or interactive
experiences. XAPI and SCORM are the two standards in e-learning experiences data model, eXperience API (XAPI) in
particular is the one used the most in interactive immersive learning experiences. The IEEE and Khronos group [i.4] are
the main organizations that work on de-facto standards on VR and MR technologies, Khronos Group released OpenXR
(open standard for virtual and augmented reality), that makes possible for developers to write code that runs
everywhere, so it is a common interface for immersive applications.
4.2.1.2 XAPI
xAPI is a specification for learning technologies developed by Advanced Distributed Learning (ADL) [i.6] that makes
possible to collect data about the online and offline experiences that users may have. APIs (Application Programming
Interfaces) capture data from different technologies in a consistent format. In this way, very different systems can
communicate securely by collecting and sharing the flow of activities with the xAPI vocabulary. xAPI has a syntax
based on basic statements: an actor, a verb and an object.
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Figure 4.2.1.2-1: xAPI statement's diagram
The statement can also be expanded by adding more pieces of information; in Figure 4.2.1.2-1 on the left are
represented the three basic main components of an xAPI statement, the optional components are on the right.
In the proposed statement are also present the result and context objects in addition to the actor, verb and object which
are mandatory.
{
"actor": {
"name": "Sally",
"mbox": "mailto:[e-mail]"
},
"verb": {
"id": "http://adlnet.gov/expapi/verbs/completed",
"display": { "en-US": "completed" }
},
"object": {
"id": "http://example.com/activities/solo-hang-gliding",
"definition": {
"type": "http://adlnet.gov/expapi/activities/assessment",
"name": { "en-US": "Solo Hang Gliding" },
"extensions": {
"http://example.com/gliderClubId": "test-435"
}
}
},
"result": {
"completion":true,
"success": true,
"extensions": {
"http://example.com/flight/averagePitch": 0.05
}
},
"context": {
"extensions": {
"http://example.com/weatherConditions": "rainy"
}
}
}
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The verb element allows the recording of the individual passages of which the student's interaction with a content is
composed. From the tracking it emerges that the student has chosen a certain type of activity (attempted) and has begun
to do it (accessed), has progressed and answered the questions provided by that activity (answered), has completed it
(completed) and has successfully passed it (passed) up to the highest level of comprehension and competence
(mastered). Below is a list of the main components of an xAPI statement:
• Actor, the subject of the action performed, can be an Agent, an Anonymous or Identified Group (of Agent)
[i.7]:
Table 4.2.1.2-1
Agent property
Attribute name Type Description Required
name String The complete name of the user. Optional.
The value of this attribute has to be Required only if Agent is used as object
objectType String
"Agent". of a statement
An Inverse Functional Identifier at choice (Table 4.2.1.2-4)
Required
Table 4.2.1.2-2
Anonymous Group property
Attribute name Type Description Required
objectType String The value of this attribute has to be "Group". Required
name String The name of the Group. Optional
member Array of Agent Objects The member list of the Group. Required

Table 4.2.1.2-3
Identified Group property
Attribute name Type Description Required
objectType String The value of this attribute has to be "Group". Required
name String The name of the Group. Optional
member Array of Agent Objects The member list of the Group. Optional
An Inverse Functional Identifier at choice (Table 4.2.1.2-4) Required

Table 4.2.1.2-4
Inverse Functional Identifiers
Attribute name Type Description
openid URI An openID that uniquely identifies the Agent.
Object that incapsulate information about a user existing account on e.g. LMS or
account Object
intranet (Table 4.2.1.2-5).
mbox mailtoIRI The email address of the user.
mbox_sha1sum String The hex-encoded SHA1 hash of a mail to IRI (i.e. the value of an mbox property).

Table 4.2.1.2-5
Account Object
Attribute name Type Description Required
homePage IRL The canonical home page for the system the account is on. Required
The unique id or name used to log in to this account. This is
name String Required
based on FOAF's accountName.
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• Verb, the action performed by the Actor [i.7]:
Table 4.2.1.2-6
Verb property
Attribute name Type Description Required
Corresponds to a Verb definition. Each Verb definition
id IRI Required
corresponds to the meaning of a Verb, not the word.
The human readable representation of the Verb in one
display LanguageProperty Recommended
or more languages. It serves as a description.

• Object, the object of the action performed can be a Statement, Group, Agent or an Activity. For example,
"Ken pressed a button", "Marie interviewed Ken", "Marie commented on 'Ken pressed a button' " are all
different actions that imply different object of the action itself [i.7]:
Table 4.2.1.2-7
Object of Activity type
Attribute name Type Description Required
objectType String HAS TO be Activity when present. Optional
id IRI An identifier for a single unique Activity. Required
definition Object Metadata of the activity (Table 4.2.1.2-8). Optional

Table 4.2.1.2-8
Definition Object
Attribute name Type Description Required
name LanguageProperty The human readable/visual name of the Activity. Recommended
description LanguageProperty A description of the Activity. Recommended
type IRI The type of Activity. Recommended
Resolves to a document with human-readable
moreInfo IRL Optional
information about the Activity.
Interaction properties, more at [i.7].
extensions Object A map of other properties as needed. Optional

Table 4.2.1.2-9
Object of StatementRef type
Attribute name Type Description Required
objectType String HAS TO be StatementRef. Required
The UUID of the Statement used as
id UUID Required
Object.
NOTE: In this case the Object is a pre-existing Statement referred by its UUID [i.7].

Table 4.2.1.2-10
Object of SubStatement type
Attribute name Type Description Required
objectType String HAS TO be SubStatement. Required
NOTE: In this case the Object is a new Statement, called SubStatement, which is similar to a StatementRef but self
contained into a Statement, it does not represent an event that has already occurred. The SubStatement has to
be a valid Statement in addition to other SubStatement requirements like not containing "id", "stored", "version"
or "authority" properties [i.7].

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Here is an example of Object of SubStatement type [i.7]:
{
"actor": {
"objectType": "Agent",
"mbox":"mailto:[e-mail]"
},
"verb" : {
"id":"http://example.com/planned",
"display":{
"en-US":"planned"
}
},
"object": {
"objectType": "SubStatement",
"actor" : {
"objectType": "Agent",
"mbox":"mailto:[e-mail]"
},
"verb" : {
"id":"http://example.com/visited",
"display":{
"en-US":"will visit"
}
},
"object": {
"objectType": "Activity",
"id":"http://example.com/website",
"definition": {
"name" : {
"en-US":"Some Awesome Website"
}
}
}
}
}
Table 4.2.1.2-11
Result property
Attribute name Type Description Required
The score of the Agent in relation to the success or quality of the
score Object Optional
experience (Table 4.2.1.2-12).
success Boolean Indicates whether or not the attempt on the Activity was successful. Optional
completion Boolean Indicates whether or not the Activity was completed. Optional
response String A response appropriately formatted for the given Activity. Optional
duration Duration Period of time over which the Statement occurred. Optional
extensions Object A map of other properties as needed. Optional
NOTE: Result is an optional property that represents the outcome of the related Statement [i.7].

Table 4.2.1.2-12
Score Object
Attribute name Type Description Required
Decimal number between -1 and The score related to the experience as
scaled Recommended
1, inclusive modified by scaling and/or normalization.
The score achieved by the Actor in the
Decimal number between min and
experience described by the Statement.
raw max (if present, otherwise Optional
This is not modified by any scaling or
unrestricted), inclusive
normalization.
Decimal number less than max (if The lowest possible score for the
min Optional
present) experience described by the Statement.
Decimal number greater than min The highest possible score for the
max Optional
(if present) experience described by the Statement.

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Table 4.2.1.2-13
Context property
Attribute name Type Description Required
The registration that the Statement is
registration UUID Optional
associated with.
Instructor that the Statement relates to, if
instructor Agent (MAY be a Group) Optional
not included as the Actor of the Statement.
Team that this Statement relates to, if not
team Group Optional
included as the Actor of the Statement.
A map of the types of learning activity
context that this Statement is related to.
contextActivities contextActivities Object Optional
Valid context types are: parent, "grouping",
"category" and "other".
Revision of the learning activity associated
revision String Optional
with this Statement. Format is free.
Platform used in the experience of this
platform String Optional
learning activity.
Code representing the language in which
String (as defined in IETF the experience being recorded in this
language Optional
RFC 5646 [i.15]) Statement (mainly) occurred in, if applicable
and known.
Another Statement to be considered as
statement Statement Reference Optional
context for this Statement (Table 4.2.1.2-9).
A map of any other domain-specific context
relevant to this Statement. For example, in a
extensions Object flight simulator altitude, airspeed, wind, Optional
attitude, GPS coordinates might all be
relevant.
NOTE: Context, is an optional property that adds contextual information to the Statement. It can contain information
about the instructor, the environment of the activity and more [i.7].

• Attachment, can be an important part of the Learning experience, it could be an essay, a video, an image, etc.
These Attachments are meant to be stored in and retrievable from an LRS [i.6], [i.7].
• Extensions, are available in different part of an xAPI statement as the result and context properties. In every
case, extensions are meant to add information and to extend those properties for specific use. The content can
be relevant to only one application or it can be a standard used in many scenarios. Extensions are in form of a
map with key:values format, the specification makes clear that the keys of an extensions map has to be IRIs
[i.7] and that the values of an extensions can be any JSON value or data structure [i.7]. The meaning of
extensions mapping values is defined by the developer or organization that controls the IRI of the key. Here is
an example of extensions used in the result property of a statement:
"result": {
"extensions": {
"http://example.com/profiles/meetings/extensions/reviewlocation":
"C:\\meetings\\minutes\\examplemeeting.one"
},
"success": true,
"completion": true,
"response": "We agreed on some example actions.",
"duration": "PT1H0M0S"
}
The example proposes highlights on how extensions can enrich statements information and adding more clues, in this
case, on the result of the learning experience.
4.2.1.3 SCORM
Sharable Content Object Reference Model (SCORM) is a specification for learning technologies developed by ADL
[i.8] to address e-learning interoperability. It is heavily used in today e-learning experiences even if xAPI is proposed as
the new standard that, one day, could replace it. The main concept of SCORM is the Sharable Content Object (SCO)
that defines a certain training unit or experience even if small in scale. The educational content has to be a stand alone
experience (it cannot depend on other external content or other SCO). The LMS has the role of distributing the SCOs to
rd
learners and taking track of progress. SCORM 1.2 and SCORM 2004 3 Edition are the main versions of SCORM,
but as of today SCORM 1.2 is used more than the 2004 version.
ETSI
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SCORM 2004 3 Edition added new features that were not available in version 1.2, but even after that, SCORM 1.2 is
the most used version of the standard today thanks to its ease of adoption. Here is a breakdown of the key elements of
cmi.core data models:
1) Student Information:
- cmi.core.student_id: Unique ID of the student (Read-Only).
- cmi.core.student_name: Name of the student (Read-Only).
2) Lesson Information:
- cmi.core.lesson_location: Current location in the lesson (Read/Write).
- cmi.core.credit: Whether the learner will be credited for the lesson ("credit" or "no-credit") (Read-
Only).
- cmi.core.lesson_status: Completion status of the lesson ("passed", "completed", "failed", "incomplete",
"browsed", "not attempted") (Read/Write).
- cmi.core.entry: Indicates if the learner is starting the lesson anew or resuming ("ab-initio", "resume", "")
(Read-Only).
3) Scoring Information:
- cmi.core.score.raw: The learner's score (Read/Write).
- cmi.core.score.max: Maximum possible score (Read/Write).
- cmi.core.score.min: Minimum possible score (Read/Write).
4) Session Information:
- cmi.core.total_time: Total time spent in the lesson (Read-Only).
- cmi.core.session_time: Time spent in the current session (Write-Only).
- cmi.core.exit: How the learner left the lesson ("time-out", "suspend", "logout", "") (Write-Only).
Here is a breakdown of the key elements of cmi data models:
1) Suspend and Launch Data:
- cmi.suspend_data: Stores data between sessions (Read/Write).
- cmi.launch_data: Data provided to the lesson when it starts (Read-Only).
2) Comments.
3) cmi.comments: Learner's comments about the lesson (Read/Write).
4) cmi.comments_from_lms: Comments from the LMS about the lesson (Read-Only).
5) Objectives:
- cmi.objectives._count: Number of objectives stored (Read-Only).
- cmi.objectives.n.id: Unique ID for each objective (Read/Write).
- cmi.objectives.n.score.raw: Score for each objective (Read/Write).
- cmi.objectives.n.score.max: Maximum score for each objective (Read/Write).
- cmi.objectives.n.score.min: Minimum score for each objective (Read/Write).
- cmi.objectives.n.status: Completion status of each objective ("passed", "completed", "failed",
"incomplete", "browsed", "not attempted") (Read/Write).
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6) Student Data:
- cmi.student_data.mastery_score: Score needed to master the lesson (Read-Only).
- cmi.student_data.time_limit_action: Action to take when time limit is exceeded ("exit,message",
"exit,no message", "continue,message", "continue, no message") (Read-Only).
7) Interactions:
- cmi.interactions.n.result: Result of an interaction ("correct", "wrong", "unanticipated", "neutral", or a
decimal value) (Write-Only).
4.2.1.4 ETSI ISG ARF
Augmented Reality Framework (ARF) is an ETSI Industry Specification Group (ISG, like ETSI ISG CIM) that
developed the Group Specification ETSI GS ARF 004-2 [i.10]. It is a framework for immersive and functional AR
experiences designed by the ETSI ISG ARF; it is an important standard in the immersive AR experiences landscape as
it gives a well formed workflow of steps for the creation of such applications.
The framework is composed by different technologies and functions, one of the main concepts of the standard (and the
one that will be covered the most in the present document) is the World Storage function (in ETSI
GS ARF 004-2 [i.10] that is described all the steps required to help the immersive application to maintain the relative
poses of object in the real world thanks to concepts like Trackables, GeoTrackables, Features and World Anchors:
• Trackables: "are models of parts of the real world […] of which features are available and/or could be
extracted. [They] provide a Coordinate Reference System in which a pose can be expressed."
• GeoTrackables: "are set of positions and orientation on earth in a geodetic referential."
• Features: "are characteristics of a real world element that can be searched, recognized or tracked […]
[They] are extracted from Trackables and store in a World Storage function. Positions and orientations of
Features shall be expressed in the Coordinate Reference System of the Trackable from which they have been
extracted."
• World Anchors: "represents a fixed position in relation to one or more elements of the real world […].
[They] shall define a Coordinate Reference System of the real world […], may have zero, one or several AR
Assets placed on its coordinate reference system."
Using a combination of Trackables of different nature (like QR Codes, images, objects and signs) and World Anchors
it is possible to determine the right pose relative to real world points of interest. Trackables and Worl
...