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GB/T 42869-2023 (GB/T42869-2023, GBT 42869-2023, GBT42869-2023)
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GB/T 42869-2023: PDF in English (GBT 42869-2023)

GB/T 42869-2023
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 01.100.01
CCS J 04
Requirements for three-dimensional model simplification
and lightweight of mechanical products
ISSUED ON: AUGUST 06, 2023
IMPLEMENTED ON: DECEMBER 01, 2023
Issued by: State Administration for Market Regulation;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 4
4 Abbreviations ... 5
5 Requirements for three-dimensional model simplification ... 5
5.1 General requirements ... 5
5.2 Simplification requirements in part modeling ... 6
5.3 Simplification requirements for assembly model applications ... 6
5.4 Simplification requirements in finite element modeling ... 7
5.5 Simplification requirements for issuing applications ... 7
6 Requirements for lightweight three-dimensional models ... 7
6.1 General requirements ... 7
6.2 Lightweight requirements for collaborative research and development ... 8
6.3 Lightweight requirements for assembly simulation ... 8
6.4 Lightweight requirements for three-dimensional processes ... 9
6.5 Lightweight requirements for three-dimensional electronic interactive publications .. 9
6.6 Lightweight requirements for visual display ... 9
Annex A (informative) Example of three-dimensional model simplification ... 11
A.1 Simplification in part modeling ... 11
A.2 Simplification for assembly model applications ... 11
A.3 Simplification in finite element modeling ... 12
A.4 Simplification for distributing applications ... 13
Annex B (informative) Examples of lightweight for three-dimensional models ... 14
Requirements for three-dimensional model simplification
and lightweight of mechanical products
1 Scope
This document specifies the requirements for simplification and lightweight of three-
dimensional models of mechanical products.
This document is suitable for three-dimensional model construction of mechanical
products and simplification and lightweight processing in application scenarios such as
simulation, visualization, data sharing and exchange.
2 Normative references
The following referenced documents are indispensable for the application 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.
GB/T 24734.11, Technical product documentation -- Digital product definition data
practices -- Part 11: Levels of geometrical detail
GB/T 26099.1, General principles of three-dimensional modeling for mechanical
products -- Part 1: General requirements
GB/T 26099.2, General principles of three-dimensional modeling for mechanical
products -- Part 2: Part modeling
GB/T 26099.3, General principles of three-dimensional modeling for mechanical
products -- Part 3: Assembly modeling
GB/T 26100, General principles of digital mock-up for mechanical products
3 Terms and definitions
For the purposes of this document, the terms and definitions defined in GB/T 26099.1,
GB/T 26099.2, GB/T 26099.3, GB/T 26100 as well as the followings apply.
3.1 simplification
A three-dimensional model construction or processing method that allows certain
features not to be constructed, certain parts or components not to be assembled,
f) Name the simplified model file in accordance with the provisions of GB/T 26099.1.
Consider the inheritance with the original model name.
5.2 Simplification requirements in part modeling
5.2.1 Three-dimensional model simplification in part modeling meets the following
requirements:
a) The external interface of the model shall not be simplified and its assembly shall
not be affected;
b) Some features related to manufacturing, such as internal threads, external threads,
undercuts, etc., are allowed to be omitted or simplified in expression. However,
when the simplified model is used for projection to generate two-dimensional
engineering drawings, it shall meet the relevant regulations of mechanical
drawing;
c) For several groups of holes with the same diameter and distributed in a certain
regular pattern, only one feature can be constructed. Other similar features can be
simplified by the center line;
d) Features such as printing, engraving, and knurling allow simplified expression in
the form of stickers. When necessary, it can also be accompanied by comments;
e) When modeling standard parts and purchased parts, the internal structure
unrelated to installation is allowed to be simplified, but basic information that
affects the model assembly design such as the maximum geometric outline,
installation interface, extreme position, and mass attributes shall be included;
f) Under the conditions that meet the usage requirements, low-order surfaces can be
used instead of high-order surfaces.
5.2.2 See Figure A.1 in Annex A for a simplification example in part modeling.
5.3 Simplification requirements for assembly model applications
5.3.1 Three-dimensional model simplification for assembly model applications meets
the following requirements.
a) When assembly models are used for visual display, such as in digital factories or
digital production line visual display applications, for assembly models of
production lines, machine tools, logistics and other equipment, if the internal
details do not need to be displayed, a simplified method without assembly can be
used. If some external subtle features do not affect the display effect, simple
shapes (cylinder, cube, etc.) can be used instead of the simplified method of
complex shapes.
b) Generally, it is advisable to remove the modeling history information in the
original model and base it on the business needs of different application scenarios
in a). Choose to retain, partially remove or completely remove assembly structure,
annotations, attributes, views, colors and other information;
c) The lightweight model formed after surface processing can reduce the size of the
model file through surface reduction, merging primitives, deleting invisible
surfaces, patching or deleting holes, etc., so as to meet the requirements of the
visualization software and hardware system;
d) For point cloud models obtained by reverse engineering methods, it is advisable
to convert mesh surfaces into NURBS surfaces or other parameter expressions to
reduce model file size;
e) For a large number of repeated parts, only the geometric data of one part can be
recorded, but the position information of all parts shall be saved to reduce the
amount of data. At the same time, the recorded geometric data information of the
parts and all parts shall be used during the visualization process. location
information to reconstruct all parts and position them correctly;
f) Multiple LOD level representations shall be provided to meet visualization and
accuracy requirements;
g) The lightweight model file naming shall be in accordance with the provisions of
GB/T 26099.1. Consider inheritance from the original model’s name.
6.2 Lightweight requirements for collaborative research and development
The lightweight of three-dimensional models in collaborative R&D applications meets
the following requirements:
a) It shall be based on the needs of product data sharing and exchange, browsing and
circle reading in collaborative R&D applications. Determine the lightweight
model file format. Choose lightweight processing tools;
b) The lightweight model file format, unit system and scale shall be consistent.
Model accuracy shall meet the requirements of all parties involved in
collaborative R&D;
c) The assembly structure information in the original model shall be included;
d) Annotations and marking information shall be saved in lightweight model files.
6.3 Lightweight requirements for assembly simulation
The lightweight three-dimensional model for assembly simulation applications shall
meet the following requirements:
a) According to the assembly process simulation in assembly simulation applications,
as well as the interference inspection and simulation requirements between
components, between components and tooling, determine the lightweight model
file format and select lightweight processing tools;
b) Contain assembly structure and assembly relative position information in the
original model.
6.4 Lightweight requirements for three-dimensional processes
Three-dimensional model lightweight for three-dimensional processes shall meet the
following requirements:
a) According to the process model visual display and human-computer interaction
requirements in three-dimensional process visualization publishing applications,
the lightweight model file format is determined. Choose lightweight processing
tools;
b) Contain assembly structure, annotations, attributes, views, colors and other
information in the original model.
6.5 Lightweight requirements for three-dimensional electronic interactive
publications
The lightweight three-dimensional model for three-dimensional electronic interactive
publications shall meet the following requirements:
a) The lightweight model file format is determined based on the model-based product
installation, use, repair and maintenance interaction requirements and the type of
interactive display platform in the three-dimensional electronic interactive
publication application. Choose lightweight processing tools;
b) Contain assembly structure, annotations, attributes, views, colors and other
information in the original model.
6.6 Lightweight requirements for visual display
The lightweight three-dimensional model for visual display shall meet the following
requirements:
a) According to the purpose of visual display, such as concept display before product
manufacturing, publicity display after product manufacturing, and training
display such as operation/maintenance, as well as the software and hardware
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.