ISO/IEC 23488:2022

INTERNATIONAL ISO/IEC
STANDARD 23488
First edition
2022-05
Information technology — Computer
graphics, image processing and
environment data representation —
Object/environmental representation
for image-based rendering in virtual/
mixed and augmented reality (VR/
MAR)
Technologies de l'information — Infographie, traitement d'images
et représentation des données environnementales — Représentation
d'objets/environnements pour l'habillage à partir d'images réelles
dans la réalité virtuelle/mixte et augmentée (VR/MAR)
Reference number
© ISO/IEC 2022
© ISO/IEC 2022
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Published in Switzerland
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© ISO/IEC 2022 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms . 2
4 Domain and concepts .2
4.1 General . 2
4.2 Domain. 2
4.3 Concepts . 3
4.4 Basic components . 4
4.4.1 General . 4
4.4.2 Image set . 4
4.4.3 3D model . 5
4.4.4 3D model — Image set integration . 6
4.4.5 XML based object model . 6
5 Image-based representation usage example . 8
5.1 General . 8
5.2 Image-based rendering . 8
5.3 Multi-object representation . 9
6 Conformance . 9
6.1 Objective. 9
6.2 Minimum requirements . 10
Annex A (informative) Working example of the proposed information model .11
Bibliography .15
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© ISO/IEC 2022 – All rights reserved

Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are
members of ISO or IEC participate in the development of International Standards through technical
committees established by the respective organization to deal with particular fields of technical
activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international
organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the
work.
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 document 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 or
www.iec.ch/members_experts/refdocs).
Attention is drawn to the possibility that some of the elements of this document may be the subject
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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) or the IEC
list of patent declarations received (see https://patents.iec.ch).
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www.iso.org/iso/foreword.html. In the IEC, see www.iec.ch/understanding-standards.
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
body. A complete listing of these bodies can be found at www.iso.org/members.html and
www.iec.ch/national-committees.
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© ISO/IEC 2022 – All rights reserved

Introduction
As virtual reality (VR) and augmented reality (AR) expand to applications in entertainment and
education industries, many methods of augmenting reality to virtual space have been developed.
Because of this expansion, the technology of capturing and representing objects in real environments
is in high demand.
One of the proposed methods of capturing the real world is image-based representation. Image-based
representation is a technique that can be used in various applications that require 3D model rendering
at an arbitrary viewpoint, including virtual reality, augmented reality and video stabilization. Since
image-based representation is a predominant alternative to using 3D models in the growing VR/MAR
market, due to its realism, scalability, accuracy and efficiency, creating a standard for image-based
representation is required.
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© ISO/IEC 2022 – All rights reserved

INTERNATIONAL STANDARD ISO/IEC 23488:2022(E)
Information technology — Computer graphics, image
processing and environment data representation —
Object/environmental representation for image-based
rendering in virtual/mixed and augmented reality (VR/
MAR)
1 Scope
This document specifies an image-based representation model that represents target objects/
environments using a set of images and optionally the underlying 3D model for accurate and efficient
objects/environments representation at an arbitrary viewpoint. It is applicable to a wide range of
graphic, virtual reality and mixed reality applications which require the method of representing a
scene with various objects and environments.
This document:
— defines terms for image-based representation and 3D reconstruction techniques;
— specifies the required elements for image-based representation;
— specifies a method of representing the real world in the virtual space based on image-based
representation;
— specifies how visible image patches can be integrated with the underlying 3D model for more
accurate and rich objects/environments representation from arbitrary viewpoints;
— specifies how the proposed model allows multi-object representation;
— provides an XML based specification of the proposed representation model and an actual
implementation example (see Annex A).
2 Normative references
There are no normative references in this document.
3 Terms and definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1.1
camera parameter
extrinsic/external and intrinsic/internal attribute value of a (virtual or real) camera that describes
the mathematical relationship between the 3D coordinates of a point in the world space and the 2D
coordinates of its projection onto the image space
© ISO/IEC 2022 – All rights reserved

3.1.2
image patch
set of connected pixels of an image that has the same visibility information
Note 1 to entry: Image patch is synonymous to image.
3.1.3
tessellation
process of dividing a face into sub-faces using sub-sampled vertices to attain enhanced visibility
detection
3.1.4
viewpoint
rotation and position with respect to the reference coordinate system that determines visible parts of a
3D model in a representation system
Note 1 to entry: “Viewpoint” is different from “Camera (parameters)” in that it only includes the camera position
and pose, where as the “Camera” has more information such as the internal camera parameters (3.1.1) including
the focal length, field of view, near/far planes and skew parameters.
3.1.5
virtual image
image at an arbitrary viewpoint (3.1.4) that is generated by collecting visible photo information from
real images
3.1.6
world reference frame
coordinate reference frame used to express positions/orientations of the camera, 3D models and other
objects for a given scene
3.2 Abbreviated terms
IBR image-based rendering
XML extensible markup language
XSD XML schema definition
4 Domain and concepts
4.1 General
This clause describes the domain and key concepts. This includes the domain of image-based
representation of objects/environments and overall description of its details.
4.2 Domain
Geometric and optionally photometric information is essential when representing target objects/
environments as is done in ISO/IEC 19775-1. In this document, an alternative representation
method, image-based, is pursued in which the objects/environments are represented only using the
photogrammetric information (e.g. set of images and other related information) and optionally the
underlying 3D geometric information.
Therefore, the image-based representation of objects/environments first requires a set of images and
their photogrammetric information of the target objects/environments taken at various locations, and
the 3D model represented using vertices and faces and the association between these two (if needed).
Figure 1 shows the overall scene as represented a set of images (below), which have association to the
3D model (top). Note that with photogrammetric information alone, it is possible to render the target
objects/environments from an arbitrary viewpoint by using and blending the sampled images around.
© ISO/IEC 2022 – All rights reserved

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