ISO/TS 23301:2023

TECHNICAL ISO/TS
SPECIFICATION 23301
Second edition
2023-12
STEP geometry visualization services
Services de visualisation de la géométrie STEP
Reference number
© ISO 2023
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: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 High level business scenarios .4
4.1 General . 4
4.2 Check for updates . 4
4.3 Visualization number 1 . 4
4.4 Visualization number 2 . 5
4.5 Retrieve product lifecycle management (PLM) data of a product . 5
4.6 Archiving . 5
4.7 Spatial query . . 5
5 Information requirements . 5
5.1 Review of geometry, topology and shape definitions . 5
5.2 Geometry data set definition . 6
5.3 Metadata for STEP geometry services . 7
5.3.1 General . 7
5.3.2 Extensible metadata platform (XMP) . 7
5.3.3 Included namespaces . 8
5.3.4 sgs namespace . 8
5.4 Large model presentation — Bounding boxes . 10
5.5 Large model presentation — Occurrence tree . 10
5.6 Cybersecurity context and requirements . 10
6 Implementation requirements .11
6.1 General principles . 11
6.2 XMP sidecar file . 11
6.3 ISO/IEC 21778:2017 JSON . 12
6.4 ISO 10303-21 .12
6.5 10303 XML implementations .12
6.6 QIF-XML . 12
6.7 ISO/IEC 19775-1 (X3D) . 13
6.8 ISO 17506 (COLLADA) .13
6.9 3D PDF . 13
6.10 ISO 14306 . . 13
7 Geometry services specification . .13
7.1 Description . 13
7.2 REST API . 13
7.3 Service definition . 14
8 Conformance requirements .16
Annex A (informative) Information object registration.17
Annex B (informative) Reference Data Library (RDL) listing .18
Annex C (informative) XMP sidecar file example .23
Annex D (informative) Example of XMP metadata in ISO 10303-21 .24
Annex E (informative) Example of XMP metadata set in X3D .25
Annex F (informative) 2021 pilot report .26
Annex G (informative) Use case — Spatial query.28
iii
Annex H (informative) Occurrence tree .29
Bibliography .30
iv
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).
ISO draws attention to the possibility that the implementation of this document may involve the use
of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO had not received
notice of (a) patent(s) which may be required to implement this document. However, implementers are
cautioned that this may not represent the latest information, which may be obtained from the patent
database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all
such patent rights.
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 jointly by Technical Committee ISO/TC 184, Automation systems and
integration, Subcommittee SC 4, Industrial data, in collaboration with Joint Technical Committee ISO/
IEC JTC 1, Information technology, Subcommittee SC 24, Computer graphics, image processing and
environmental data representation and ISO/TC 171, Document management applications, Subcommittee
SC 2, Document file formats, EDMS systems and authenticity of information.
This second edition cancels and replaces the first edition (ISO/TS 23301:2021), which has been
technically revised.
The main changes are as follows:
— addition of a new high-level business scenario: spatial query;
— addition of a new requirement: large model presentation: bounding boxes;
— addition of a new requirement: large model presentation: occurrence tree;
— addition of a new metadata: this URI defining the URI of the current data set;
— updates in the services definition;
— addition of a new service: get_available_formats.
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.
v
Introduction
There is a confirmed opportunity for industries to have a structured approach on 3D product
visualization and to enable integration of product data in visualization applications, across the life cycle
of the product in all areas of a company.
The integrated standard for the exchange of product model data (STEP) in the enterprise processes has
great value to contribute to this goal.
Business scenarios exist related to the visualization of product data other than geometry (e.g. metadata,
production data, financial data).
The ability to trustfully share, distribute, collect, store, maintain, transfer, process and present product
data associated with its geometry to support business processes distributed in enterprise networks is
a key component of the digital transformation of our industries.
As long as data sets are managed by a single management system, we can ensure quality and traceability
of the data set. However, when data is shared with partners in a supply chain, the data sets are usually
copied and extracted from their initial management system and they lose all the traceability and links
with the other product data. This document provides a solution to this problem.
This document is the first of a series of documents to provide an integrated framework using the
ISO 10303 series to allow the consumption of product data in supply-chains and in companies
using geometries as human-computer interface to access these product data through visualization
applications. This is realized by using metadata to support the audit trail of the transformation of a
geometry definition, and web services based on the utilisation of these metadata. This framework can
also be used for automated product data consumption by software.
Annex A contains an identifier that unambiguously identifies this document in an open information
system.
vi
TECHNICAL SPECIFICATION ISO/TS 23301:2023(E)
STEP geometry visualization services
1 Scope
This document defines a set of metadata to support the audit trail of the transformation of a geometry
definition, while it is distributed and shared in supply-chains, to ensure the traceability of geometric
model data. It also defines a set of web services based on the utilisation of these metadata.
The following are within the scope of this document:
— metadata definitions for geometry transformation audit trail:
— syntax for storing these metadata in geometry data sets in various formats;
— conformance level for implementers and business processes;
— definitions of web services to query the geometric model data set and its associated metadata.
The following are outside the scope of this document:
— service specifications for CAD operations;
— specifications of a cybersecurity infrastructure to enable web services;
— the technical implementation of a STEP geometry services client or server;
— any geometric model definition;
— any product and manufacturing information (PMI) definition;
— archiving.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 8601-1, Date and time — Representations for information interchange — Part 1: Basic rules
ISO 10303-21, Industrial automation systems and integration — Product data representation and exchange
— Part 21: Implementation methods: Clear text encoding of the exchange structure
ISO 14306:2017, Industrial automation systems and integration — JT file format specification for 3D
visualization
ISO 16684-1:2019, Graphic technology — Extensible metadata platform (XMP) — Part 1: Data model,
serialization and core properties
ISO 16684-3, Graphic technology — Extensible metadata platform (XMP) specification — Part 3: JSON-LD
serialization of XMP
TM
ISO 17506, Industrial automation systems and integration — COLLADA digital asset schema specification
for 3D visualization of industrial data
ISO/IEC 19775-1, Information technology — Computer graphics, image processing and environmental data
representation — Extensible 3D (X3D) — Part 1: Architecture and base components
ISO/IEC 21778:2017, Information technology — The JSON data interchange syntax
3 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
boundary representation solid model
B-rep
type of geometric model in which the size and shape of a solid is defined in terms of the faces, edges and
vertices which make up its boundary
1)
[SOURCE: ISO 10303-2:20— , 3.3.5]
3.2
constructive solid geometry
CSG
type of geometric modelling in which a solid is defined as the result of a sequence of regularized Boolean
operations operating on solid models
[SOURCE: ISO 10303-2:20—, 3.3.11]
3.3
derived geometry
geometric representation generated from another representation
Note 1 to entry: The derivation is realized by actions such as using another representation method, another
format, approximations, simplification.
EXAMPLE A "6-face B-rep" (3.1) is derived from a CSG (3.2) "solid block".
3.4
converted geometry
result of changing the data format of a geometry
Note 1 to entry: The import and export operations in a CAD system, produce converted geometry.
Note 2 to entry: Converted geometry is a kind of derived geometry (3.3).
3.5
design intent
intentions of the designer of a model with regard to how it may be instantiated or modified
Note 1 to entry: The aspects of design intent relevant to ISO 10303-108 are concerned with the information
represented in the parameters and constraints associated with a model. More generally, design intent also
includes the procedural or construction history of a model, which is the subject of ISO 10303-55. All aspects of
design intent influence the behaviour of a model under editing operations.
[SOURCE: ISO 10303-2:20—, 3.16.10]
1) Under preparation. Stage at the time of publication: ISO/FDIS 10303-2:2023.
3.6
geometry data set
serialized representation of geometry data which can be exchanged between two systems
Note 1 to entry: The geometry data set can be instantiated into a single file, a set of files, a web service payload or
the result of a database query.
3.7
geometry service
web-service supporting retrieval of geometry-related data
Note 1 to entry: Geometry related data can be:
— a geometry data set (3.6) or one of its subsets;
— geometric properties of a geometry data;
— metadata related to a geometry data set;
— non-geometric product data related to a geometry identifier.
3.8
level of detail
LOD
description of detail and extent of geometric model information
3.9
native geometry
native CAD
data format used to write to memory using the authoring CAD application's CAD kernel
Note 1 to entry: This capability is used in order to save the original geometry (3.11) model as data and to reuse it
without any loss with the original authoring tool. Original geometry is often considered to be replicated only by
reading the native geometry from memory into the CAD / modelling application using the same system, version
or installation, used to initially author the original geometry, although even this is not guaranteed.
3.10
occurrence tree
flat representation of an assembly structure where each individual is represented and has its own
attributes, e.g. placement
Note 1 to entry: See an example of occurrence tree in Annex H.
3.11
original geometry
geometry as defined by a modeler (human being) in a CAD tool using CAD authoring functions based on
mathematical constructs
Note 1 to entry: The original geometry is the first initial geometry construction that holds the design intent.
Note 2 to entry: This is also often referred to as native CAD (3.9). However, a native CAD is in fact referring to
the native CAD kernel and CAD format of the CAD tool manipulating the geometry. It therefore can also be any
geometry derived from another CAD format.
Note 3 to entry: Geometry as initially authored in a CAD / modelling application using that tool's geometric
modelling system, operations, and database. The author's design intent (3.5), as well as the characteristics and
artefacts of the application's implementation of geometric and solid modelling algorithms, are present in the
original geometry, thus distinguishing it from "exact geometry". Original geometry can take on many forms, e.g.
B-rep (3.1), CSG (3.2), hybrid, tessellated, and be modelled using many modelling paradigms, e.g. procedural,
explicit, dual, parametric features with construction history.
Note 4 to entry: While often misused and interchanged for each other, original geometry is distinguished from
native geometry (3.9).
3.12
product and manufacturing information
PMI
non-geometric attributes in 3D CAD and collaborative product development systems necessary for
manufacturing product components and assemblies
Note 1 to entry: PMI may include geometric dimensions and tolerances, symbols, notes, surface finish, and
material specifications.
[SOURCE: ISO 10303-2:20—, 3.1.233]
3.13
tessellated geometry
geometry composed of a large number of planar tiles, usually of triangular shape
Note 1 to entry: Tessellated geometry is frequently used as an approximation to the exact shape of an object.
[SOURCE: ISO 10303-2:20—, 3.3.46]
3.14
3D visualization
visual presentation on a screen or another media of graphical and textual three-dimensional
representations of a set of data representing an object, information or results of a computational
process in order to facilitate capture of the understanding of the object, for visual information sharing
with users and sometimes to promote decision process by a human looking at the data visualized in a
medium
[SOURCE: ISO 14306:2017, 3.1.1]
4 High level business scenarios
4.1 General
Geometry services can be deployed in a large variety of business scenarios. Some of them are presented
below.
4.2 Check for updates
A supplier receives, from an original equipment manufacturer (OEM), a 3D model of a part that the
company has to manufacture.
During the development process, the supplier and the OEM can access the version information that the
supplier has and confirm that it is the appropriate version through web services.
The following metadata shall be available: creator, name, ID and URI of the 3D model, from the 3D model
owner and from the 3D model provider. It also needs the level of detail (LOD) of the data set to confirm
that it can execute its task with the available information.
4.3 Visualization number 1
A user shall perform a review and receives a metadata file.
The user queries the repository with the product Id/version in the metadata file to get the data set to
load and visualize.
The query specifies the format and LOD to review.
The following metadata shall be available: ID and URI of the 3D model from the 3D model provider.
4.4 Visualization number 2
From a large assembly data set already loaded for fast visualization, query the repository for a more
detailed representation of a part with special concern [exact boundary representation (B-rep) with
PMI].
The following metadata shall be available: ID and URI of the 3D model from the 3D model provider.
4.5 Retrieve product lifecycle management (PLM) data of a product
A user is viewing a part in a visualization software. The current data set contains only geometry.
Query the repository with the product ID/version to get PLM attributes of this product and display
them in the viewer.
The following metadata shall be available: ID and URI of the 3D model from the 3D model owner.
4.6 Archiving
Ensure traceability from the original geometry data set in a Product Data Management (PDM) system
and the geometry data set in an archiving system.
The following metadata shall be available: ID, URI, creation date, name, creator of the 3D model from
the 3D model owner.
4.7 Spatial query
Retrieve a low LOD representation of a large assembly (e.g. aircraft, energy plant, ship) in a web viewer.
Using this simplified representation, define a 3D spatial query to send to the server to get a sub-
assembly with a more detailed geometry (tessellation or exact geometry).
The following metadata shall be available: ID and URI of the 3D model from the 3D model provider.
5 Information requirements
5.1 Review of geometry, topology and shape definitions
The concepts defined below are extracted from ISO 10303-41, ISO 10303-42, ISO 10303-43.
This document considers a geometry data set as a collection of geometric models as defined in
ISO 10303-42.
The geometric models in ISO 10303-42 provide data specifications describing the precise size and shape
of three-dimensional solid objects. The geometric shape models provide a complete representation of
the shape, which in many cases includes both geometric and topological data. Included here are the
two classical types of solid model, constructive solid geometry (CSG) and B-rep. Tessellation is another
common representation for geometry which provides light-weight data sets but is less accurate than the
two previous solid model types, but which other entities, providing a rather less complete description
of the geometry of a product, and with less consistency constraints, are also included.
The geometric models are composed of geometric and topological data. Their primary application is for
explicit representation of the shape or geometric form of a product model. The shape representation
has been designed to facilitate stable and efficient communication when mapped to a physical file.
The geometry is exclusively the geometry of parametric curves and surfaces. It includes the point,
curve and surface entities and other entities, functions and data types necessary for their definition.
A common scheme has been used for the definition of both two-dimensional and three-dimensional
geometry. All geometry is defined in a coordinate system which is established as part of the context of
the item which it represents.
The topology is concerned with connectivity relationships between objects rather than with the
precise geometric form of objects. ISO 10303-42 defines the basic topological entities and specialized
subtypes of these. In some cases, the subtypes have geometric associations. Also included are functions,
particularly constraint functions, and data types necessary for the definitions of the topological entities.
In addition to the geometric models, other product related information can be instantiated in a geometry
data set, e.g. saved view and display attributes, e.g. colour, transparency, texture, PMI represented as
graphical geometry helpers or semantic metadata, links to product metadata.
5.2 Geometry data set definition
The geometry data set is a collection of models as defined in ISO 10303-42 with or without assembly
structure. In addition to the geometric models, other product related information can be instantiated in
a geometry data set, e.g. PMI represented as graphical geometry helpers or semantic metadata, links to
product metadata.
The geometry data set can be instantiated into a single file, a set of files (see Figure 1), a web service
payload or by the result of a database query.
EXAMPLES Simple shape CSG, simple shape B-rep, complex part without PMI, complex part with PMI,
assembly of parts with tessellated shapes and PMI.
Key
product
reference to product or part
part (geometry)
STEP P21 file
STEP XML file
other file
data set
A single file
B external references
C nested assembly
Figure 1 — Examples of geometry data set file organization
5.3 Metadata for STEP geometry services
5.3.1 General
Geometry data sets can be linked together as long as they are under the management of a single PLM
system. This allows audit trails and transformation processes to be controlled.
Once a geometry data set is taken out of a PLM system, the traceability to the evolution of this data
set is lost. There is a need for a mechanism that allows keeping track of the geometry data set origins
and evolutions. Figure 2 illustrates how the metadata are added when a geometry data set leaves the
management system of the original geometry data set owner and is modified by other actors before
arriving in a destination system.
Figure 2 — Updates of metadata
In addition to data traceability, information searching and big data analysis, especially in the web
environment, benefit from using semantic metadata to index information from geometry data sets in a
multiplicity of formats.
5.3.2 Extensible metadata platform (XMP)
Metadata shall be represented in Extensible Markup Language (XML) and the grammar of the XML
representing the metadata shall be defined according to the extensible metadata platform (XMP)
specification ISO 16684-1. XMP is a technology for embedding metadata into documents and was first
published in ISO 16684-1 in 2012.
5.3.3 Included namespaces
XMP metadata is organized into namespaces (see ISO 16684-1:2019, 6.2) and may include properties
from one or more namespace. There is no requirement that all properties from a namespace shall be
present. The namespaces definitions included in this document are given in Table 1.
Table 1 — Included namespaces
Namespace Property
Dublin Core dc : c ont r ibut or
dc: creator
dc: format
dc : t i t le
XMP basic xmp: CreateDate
xmp: CreatorTool
xmp: ModifyDate
XMP media management xmpMM: InstanceID
xmpMM: DocumentID
xmpMM: OriginalDocumentID
5.3.4 sgs namespace
This document describes the STEP geometry services namespace that contains the additional
characteristics needed to satisfy the audit trail requirement.
— The field namespace URI is https:// standards .iso .org/ iso/ ts/ 23301/ ed -2/ en
— The preferred field namespace prefix is sgs.
The properties defined in the STEP Geometry Services namespace are provided in Table 2.
The list of ISO 23301 (this document) metadata and their description is given in Table 3.
Table 2 — sgs namespace
Namespace Property
STEP Geometry Services sgs: level -of -detail
sgs: modification -type
sgs: modification -comments
sgs: original -URI
sg s: SH A 3 -256
sg s: s ou r c e - U R I
Table 3 — Metadata name and description
23301 name XMP Description
created-by dc: creator Reference of the organization responsible for
the original geometry data set
creation-date xmp: CreateDate Validation date of the original geometry data
set
format dc: format Reference to the standards serialization format
of the current data set, mime-type
id xmpMM: InstanceID Uniquely identifies the current geometry data
set in the management system of the organisa-
tion modifying the data set.
Different versions of geometry data set shall
have different InstanceID but may have the
same DocumentID.
TTabablele 3 3 ((ccoonnttiinnueuedd))
23301 name XMP Description
Level-of-detail sgs: level -of -detail Multi-valued enumeration describing the type
of LOD of the geometry as defined in the geom-
etry descriptions of EN 17412-1.
Reference Data Library https:// standards .iso
.org/ iso/ ts/ 23301/ ed -2/ rdl/ 23301 .owl classes
shall be used to specify this attribute.
Annex C describes the valid values, their identi-
fications and their definitions.
modification-type sgs: modification- type Multi-valued enumeration describing the type
of the modifications, transformations or addi-
tions made to the data set. The valid values for
this enumeration are defined in the ISO 23301
(this document) Reference Data Library in
https:// standards .iso .org/ iso/ ts/ 23301/ ed -2/
rdl/ 23301 .owl.
Annex B describes the valid values, their identi-
fications and their definitions.
modification-comments sgs: modification- comments Free text providing details on the modification
modified-by dc : c ont r ibu t or Reference of the organization responsible for
the last modification of the geometry data set
modified-date xmp: ModifyDate Last modification date of the geometry data
set as defined in the management system of the
organization modifying the data set
name dc : t i t le Name of the geometry data set
original-id xmpMM: OriginalDocumentID Identifier of the geometry data set in the man-
agement system of the organisation issuing
the original geometry representing the design
intent
This value links a geometry data set to its orig-
inal source.
original-URI sgs: original -URI URI to the OriginalDocumentID
software xmp: CreatorTool Software used to generate the current data set
source-id xmpMM: DocumentID Uniquely identifies the geometry data issued
by the management system of the organisation
which has provided the data set.
Different versions of a geometry data set may
have the same DocumentID.
source-URI sg s: s ou r c e - U R I URI of the DocumentID
this-URI rdf: about URI of the current data set
SHA3-256 s g s: S H A 3 -256 Hash key of the geometry data set
The data format for each metadata value is defined in Table 4.
In the metadata sets the URI elements have two specific purposes within a distributed services
architecture that operates on STEP defined geometry.
One purpose is to ensure integrity and validity of the product of the service, giving the user of the
service confidence that the correct and expected input was used to the service. A common use case
would be a product whose geometric definition changes with successive revisions. Each revision should
have a unique URI that both the producer of the original data and the user of the service can agree on;
the knowledge of this URI can be shared even if the service user does not have authority to view the
original data. The service user can examine the metadata packet, either embedded in the product or in
a sidecar file, to verify that the correct revision was used as original data.
An additional purpose of the metadata is to allow the service user to retrieve the original data. In this
case, the URI identifier, should also be a URL. As a global URL, it is irrelevant to the user whether the
URL is served by the same service provider or by another data provider. The use case for which this
purpose is applicable is a search application, in which the service product is used to determine if the
original data should be retrieved. A specific case is a 3D visualization application that allows a user to
select a product part and retrieve the original geometry for further analysis.
5.4 Large model presentation — Bounding boxes
To support use cases for large models such as a full car or airplane section, it is necessary to provide
services and data allowing a simplified view of the full model.
See the description of a typical use case in Annex G.
The objective is to provide bounding boxes in the assembly structure for all nodes of the assembly.
A bounding box is defined by two corner points. The bounding box has its edges parallel to the part
coordinate system.
Using this information, a viewer can display an overview of the model without needing to load the
geometry (tessellated geometry or precise geometry). Then the user can identify the parts they need
with a more precise representation.
This also allows a viewer to optimize the visualization of a large model by loading the parts which are
closer to the camera first.
5.5 Large model presentation — Occurrence tree
For very large models, such as a full airplane, a submarine or an energy plant, an assembly structure
with bounding boxes (AP242 XML with bounding boxes) will be very large and provide a lot of
information which is useless for many use cases.
For a light overview of a very large model, the objective is to provide an occurrence tree of the model,
with bounding boxes.
The targeted format is JSON to ease online and distributed scenarios.
The minimum information that shall be provided for this occurrence tree is:
— The list of all products, with either their part name or identifier, or both, the name of the file that
contains the definition of the product, and the bounding box of the product in its coordinate system.
— Occurrence tree, providing for each occurrence:
— its depth in the tree;
— the rank of the product in the products list;
— the position matrix, or rotation and translation, of the occurrence in the referential of the root
of the assembly. This placement is the composition of the relative placements of its parents.
Using this information, the application can compute the bounding box of each occurrence in the
referential of the root of the assembly.
5.6 Cybersecurity context and requirements
The specifications shall be implemented within the cybersecurity industry context and requirements
needed for a specific use case.
This document does not specify any cybersecurity requirements related to the implementation of this
document.
The specification of the web services in Clause 7 shall be associated with a cybersecurity infrastructure.
6 Implementation requirements
6.1 General principles
The metadata shall be provided as a set of property-value pairs within the data set, either embedded in
the files forming the data set, using the geometry description format chosen for data serialization, or in
a separate file called sidecar file in XMP format.
The following clauses describe how to implement the metadata either in a sidecar file or embedded in
existing standards format.
6.2 XMP sidecar file
When the geometry description format cannot embed the metadata, an XMP “sidecar” file can be used
to store and transfer the metadata. This XMP file can also be used when the geometry files already exist
in the repository and cannot or should not be modified.
XMP sidecar files are written in XML or JSON.
The sidecar file can include a SHA3-256 hash key of the geometry data set. This hash shall not be
computed on a set of files which includes the side car file. It shall only cover the geometry files.
An example of the sidecar file is available in Annex C.
Figure 3 shows an assembly with XMP sidecar files.
Figure 3 — XMP sidecar files with fully shattered assembly
6.3 ISO/IEC 21778:2017 JSON
For a geometry data set serialized as JSON format, the metadata shall conform to ISO 16684-3.
6.4 ISO 10303-21
For ISO 10303-42 and ISO 10303-242 geometries in ISO 10303-21 ASCII implementations, metadata
shall be defined either in:
— the ANCHOR section of the ISO 10303-21 file as simple type anchor items. An example is provided in
Annex D; or
— XMP sidecar file.
6.5 10303 XML implementations
Use XMP sidecar file.
6.6 QIF-XML
The following XML schema shall be referenced by the data that shall be provided as a set of property-
value pairs in the header part of the data set, using the geometry description format chosen for data
serialization.
Use XMP sidecar file.
6.7 ISO/IEC 19775-1 (X3D)
The metadata are contained in a MetadataSet element. This MetadataSet element shall be a child node
of the X3D CADAssembly node containing the converted geometry data set.
Each metadata is represented by a MetadataString element with a containerField attribute set to
“value”, the name attribute to the metadata name and the value attribute to the value of the metadata.
NOTE 1 The complete specification of the X3D Metadata Nodes is available at https:// www .web3d .org/
documents/ specifications/ 19775 -1/ V3 .3/ Part01/ components/ core .html #Metadata
NOTE 2 The complete specification of the X3D CADGeometry Component is available at https:// www .web3d
.org/ documents/ specifications/ 19775 -1/ V3 .3/ Part01/ components/ CADGeometry .html
An example of the metadata implementation in X3D is available in Annex E.
6.8 ISO 17506 (COLLADA)
Use XMP side car.
6.9 3D PDF
XMP metadata format is used to store the metadata in a 3D PDF data set.
Provide the instantiation of the metadata using XMP.
6.10 ISO 14306
Use XMP side car.
7 Geometry services specification
7.1 Description
A service in conformance with this document provides access to the following resources:
— geometry data set or one of its subsets;
— geometric properties of a geometry data set;
— metadata related to a geometry data set;
— non-geometric product data related to a geometry identifier.
EXAMPLE
Give me the 3D visualization representation of this STEP part with this ID. Is the 3D visualization format
[AP242|X3D|JT|COLLADA]?
Tell me what the visualization formats are that you can deliver to me for this part.
Give information (quality metadata) about this geometry data set.
The pilot described in Annex F was used to demonstrate the applicability of the web services.
7.2 REST API
There are three types of responses:
— a single geometry file with ISO 23301 (this document) metadata and the mime-type of the file;
— an AP242 XML product data file without geometry;
— an AP242 XML product data file with external references to geometry files [with ISO 23301 (this
document) metadata].
The query can include the response mime-type for single geometry files.
NOTE Assembly structures are described in AP242 XML files.
7.
...