ISO/IEC 3721:2023

INTERNATIONAL ISO/IEC
STANDARD 3721
First edition
2023-09
Information technology — Computer
graphics, image processing and
environmental data representation
—Information model for mixed and
augmented reality content — Core
objects and attributes
Reference number
© ISO/IEC 2023
© ISO/IEC 2023
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© ISO/IEC 2023 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms . 3
4 Overview . 4
5 Principles and Requirements . .5
6 MAR content model .6
6.1 Concept . 6
6.2 Use case diagram . 7
6.3 MAR content and its scene structure . 7
[6]
6.4 Major MAR system objects that are associated with the MAR content objects . 8
6.4.1 Sensor . 8
6.4.2 Real World Capturer::Sensor . 9
6.4.3 Tracker::Sensor . 9
6.4.4 Recognizer::Sensor . 10
7 MAR content classes .10
7.1 Overall class/object structure . 10
7.2 MARSNode. 12
7.3 TransformGroup::MARSNode .13
7.3.1 VirtualTG::TransformGroup::MARSNode . 14
7.3.2 RealTG::TransformGroup::MARSNode . 14
7.4 Spatial_Mapper::MARSNode .15
7.5 Event_Mapper::MARSNode . 16
7.6 MARObject::MARSNode . 17
7.6.1 VirtualObject::MARObject::MARSNode . 18
7.6.2 RealObject::MARObject::MARSNode . 19
7.7 Behaviour::MARSNode .22
7.8 MetaInfo::MARSNode . 23
8 Example usage scenarios .24
8.1 Marker based video see-through AR . 24
8.2 Location (GNSS) based video see-through AR . 24
8.3 Marker based AR for glass display . 25
8.4 Location based AR for glass display . 26
8.5 2D screen augmentation over a glass display . 27
8.6 Augmented virtuality with (multiple) live actor extracted and imported live from
a chroma-keying set-up . 27
9 Conformance .28
Bibliography .29
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© ISO/IEC 2023 – All rights reserved

Foreword
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This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 24, Computer graphics, image processing and environmental data representation.
Any feedback or questions on this document should be directed to the user’s national standards
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© ISO/IEC 2023 – All rights reserved

Introduction
Mixed and Augmented Reality (MAR) refers to a spatially coordinated combination of media/
information components that represent, on the one hand the physical real world and its objects and on
the other, those that are virtual, synthetic and computer generated. MAR, as an information medium,
strives to provide rich experience based on realism, presence and augmentation.
In this document, a comprehensive set of information constructs for representing mixed and
augmented reality (MAR) contents is described. This set of components extends the conventional ones
used for representing virtual reality (VR) contents, as MAR environments are technically realized as
virtual environments. The principles and requirements for the extension are laid out and the details
of the component model including (but not limited to) those for representing physical real world
objects, extending the virtual scene graph/structure to that for MAR (with the physical objects), how
to spatially the physical objects into the MAR scene graph, associating these content components to
the MAR system, and other miscellaneous constructs (e.g. event mapping, MAR events/ behaviours,
video backdrops, etc.). This document is designed for the ease, generality and extendibility, and this
is demonstrated with various examples and implementation results. The model will serve as a sound
basis for establishing standard and interoperable file formats MAR contents in the future.
The document also provides definitions for terms as related to these MAR content informational
components and their attributes.
The target audience of this document are mainly MAR system developers and contents designers
interested in specifying MAR contents to be played by an MAR system or browser. The standard will
provide a basis for further application standards or file formats for any virtual and mixed reality
applications and content representation.
The extension will be self-contained in the sense that it is independent from the existing virtual reality
information constructs, focusing only on the mixed and augmented reality aspects.
However, this document only specifies the information model, and neither promotes nor mandate to use
a specific language, file format, algorithm, device, implementation method, and standard. The standard
model is to be considered as the minimal basic model that can be extended for other purposed in actual
implementation,
This document is based on the MAR Reference model (ISO/IEC 18039) that specifies for the contents-
browser/player type reference architecture. The MAR content (in ISO/IEC 18039) is specified as the
input that describes the scene and objects’ behaviours, given to the browser/player which in turn
parses, simulates and renders it to the display. The standard is the information model for the content.
As an extension to the virtual reality based contents or scene structure, this standard is very much
related to the existing standard for VR scene representation such as ISO/IEC 19775-1 (X3D) and other
related on-going standards such as the image-based object/environment representation for VR/MAR
(ISO/IEC 23488) as well. There are also specific object models relevant to this standard such as those
for the live actors and entities (ISO/IEC 18040 and ISO/IEC 23490) an
...