SIST EN ISO 52915:2017

SLOVENSKI STANDARD
oSIST prEN ISO 52915:2016
01-oktober-2016
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Specification for Additive Manufacturing File Format (AMF) Version 1.2 (ISO/ASTM
52915:2016)
Spezifikation für ein Dateiformat für Additive Fertigung (AMF) Version 1.2 (ISO/ASTM
52915:2016)
Spécification normalisée pour le format de fichier pour la fabrication additive (AMF)
Version 1.2 (ISO/ASTM 52915:2016)
Ta slovenski standard je istoveten z: prEN ISO 52915
ICS:
25.030 3D-tiskanje Additive manufacturing
35.240.50 Uporabniške rešitve IT v IT applications in industry
industriji
oSIST prEN ISO 52915:2016 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 52915:2016
INTERNATIONAL ISO/ASTM
STANDARD 52915
Second edition
2016-02-15
Specification for Additive
Manufacturing File Format (AMF)
Version 1.2
Spécification normalisée pour le format de fichier pour la fabrication
additive (AMF) Version 1.2
Reference number
ISO/ASTM 52915:2016(E)
©
ISO/ASTM International 2016

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COPYRIGHT PROTECTED DOCUMENT
© ISO/ASME International 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, 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. In the United States, such requests should be sent to ASTM International.
ISO copyright office ASTM International
Ch. de Blandonnet 8 • CP 401 100 Barr Harbor Drive, PO Box C700
CH-1214 Vernier, Geneva, Switzerland West Conshohocken, PA 19428-2959, USA
Tel. +41 22 749 01 11 Tel. +610 832 9634
Fax +41 22 749 09 47 Fax +610 832 9635
copyright@iso.org khooper@astm.org
www.iso.org www.astm.org
ii © ISO/ASTM International 2016 – All rights reserved

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Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Terms and definitions . 1
3 Key considerations . 2
3.1 General . 2
3.2 Guidelines for the inclusion of future new elements . 3
4 Structure of this specification .3
5 General structure .4
6 Geometry specification .5
6.1 General . 5
6.2 Smooth geometry . 6
6.3 Restrictions on geometry . 7
7 Material specification .7
7.1 General . 7
7.2 Mixed and graded materials and substructures . 9
7.3 Porous materials . 9
7.4 Stochastic materials .10
8 Colour specification.10
8.1 General .10
8.2 Colour gradations and texture mapping .11
8.3 Transparency .12
9 Texture specification .12
10 Constellations .12
11 Metadata .13
12 Compression and distribution .13
13 Minimal implementation .14
Annex A (informative) AMF XML schema implementation guide .15
Annex B (informative) Performance data and future features .23
Bibliography .26
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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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent 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).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 261, Additive manufacturing, in cooperation
with ASTM F 42.91, Terminology, on the basis of a partnership agreement between ISO and ASTM
International with the aim to create a common set of ISO/ASTM standards on Additive Manufacturing.
This second edition cancels and replaces the first edition (ISO/ASTM 52915:2013), which has been
technically revised. This revision contains changes to normative language and details of a minimum
implementation, as well as corrections and clarifications.
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Introduction
This International Standard describes an interchange format to address the current and future needs
of additive manufacturing technology. For the last three decades, the stereolithography (STL) file
format has been the industry standard for transferring information between design programs and
additive manufacturing equipment. An STL file defines only a surface mesh and has no provisions
for representing colour, texture, material, substructure and other properties of the fabricated object.
As additive manufacturing technology is evolving quickly from producing primarily single-material,
homogeneous objects to producing geometries in full colour with functionally-defined gradations of
materials and microstructures, there is a growing need for a standard interchange file format that can
support these features.
The Additive Manufacturing File Format (AMF) has many benefits. It describes an object in such
a general way that any machine can build it to the best of its ability, and as such is technology
independent. It is easy to implement and understand, scalable and has good performance. Crucially, it
is both backwards compatible, allowing any existing STL file to be converted, and future compatible,
allowing new features to be added as advances in technology warrant.
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oSIST prEN ISO 52915:2016
INTERNATIONAL STANDARD ISO/ASTM 52915:2016(E)
Specification for Additive Manufacturing File Format
(AMF) Version 1.2
1 Scope
This International Standard provides the specification for the Additive Manufacturing File Format (AMF),
an interchange format to address the current and future needs of additive manufacturing technology.
The AMF may be prepared, displayed and transmitted provided the requirements of this specification
are met. When prepared in a structured electronic format, strict adherence to an extensible markup
[1]
language (XML) schema is required to support standards-compliant interoperability.
A W3C XML schema definition (XSD) for the AMF is available from ISO from http://standards.iso.
org/iso/52915 and from ASTM from www.astm.org/MEETINGS/images/amf.xsd. An implementation
guide for such an XML schema is provided in Annex A.
It is recognized that there is additional information relevant to the final part that is not covered by the
current version of this International Standard. Suggested future features are listed in Annex B.
This International Standard does not specify any explicit mechanisms for ensuring data integrity,
electronic signatures and encryptions.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
AMF consumer
software reading (parsing) the Additive Manufacturing File Format (AMF) file for fabrication,
visualization or analysis
Note 1 to entry: AMF files are typically imported by additive manufacturing equipment, as well as viewing,
analysis and verification software.
2.2
AMF editor
software reading and rewriting the Additive Manufacturing File Format (AMF) file for conversion
Note 1 to entry: AMF editor applications are used to convert an AMF from one form to another, for example,
convert all curved triangles to flat triangles or convert porous material specification into an explicit mesh surface.
2.3
AMF producer
software writing (generating) the Additive Manufacturing File Format (AMF) file from original
geometric data
Note 1 to entry: AMF files are typically exported by computer-aided design (CAD) software, scanning software or
directly from computational geometry algorithms.
2.4
attribute
characteristic of data, representing one or more aspects or descriptors of the data in an element
Note 1 to entry: In the XML framework, attributes are characteristics of elements.
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2.5
comments
all text elements associated with any data within the Additive Manufacturing File Format (AMF) to be
ignored by import software
Note 1 to entry: Comments are used for enhancing human readability of the file and for debugging purposes.
2.6
element
information unit within an XML document consisting of a start tag, an end tag, the content between the
tags and any attributes
Note 1 to entry: In the XML framework, an element can contain data, attributes and other elements.
2.7
extensible markup language
XML
standard from the WorldWideWeb Consortium (W3C) that provides for tagging of information content
within documents offering a means for representation of content in a format that is both human and
machine readable
Note 1 to entry: Through the use of customizable style sheets and schemas, information can be represented in a
uniform way, allowing for interchange of both content (data) and format (metadata).
[SOURCE: ISO/ASTM 52900:2015, 2.4.7]
2.8
STL
stereolithography
file format for model data describing the surface geometry of an object as a tessellation of triangles
used to communicate 3D geometries to machines in order to build physical parts
Note 1 to entry: The STL file format was originally developed as part of the CAD package for the early
stereolithography apparatus, thus referring to that process. It is sometimes also described as “Standard
Triangulation Language” or “Standard Tessalation Language”, though it has never been recognized as an official
standard by any standardization organization.
[SOURCE: ISO/ASTM 52900:2015, 2.4.16]
3 Key considerations
3.1 General
3.1.1 There is a natural trade-off between the generality of a file format and its usefulness for a specific
purpose. Thus, features designed to meet the needs of one community may hinder the usefulness of a file
format for other uses. To be successful across the field of additive manufacturing, the file format described
in this International Standard, the AMF, is designed to address the concerns listed in 3.1.2 to 3.1.7.
3.1.2 Technology independence. The AMF describes an object in such a general way that any machine
can build it to the best of its ability. It is resolution and layer-thickness independent and does not contain
information specific to any one manufacturing process or technique. This does not negate the inclusion
of features that describe capabilities that only certain advanced machines support (for example, colour,
multiple materials), but these are defined in such a way as to avoid exclusivity.
3.1.3 Simplicity. The AMF is easy to implement and understand. The format can be read and debugged
in a simple text viewer to encourage comprehension and adoption. Identical information is not stored in
multiple places.
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3.1.4 Scalability. The file size and processing time scales well with the increase in part complexity
and with the improving resolution and accuracy of manufacturing equipment. This includes being able
to handle large arrays of identical objects, complex periodic internal features (for example, meshes and
lattices) and smooth curved surfaces when fabricated with very high resolution.
3.1.5 Performance. The AMF enables reasonable duration (interactive time) for read-and-
write operations and reasonable file sizes for a typical large object. Detailed performance data are
provided in Annex B.
3.1.6 Backwards compatibility. Any existing STL file can be converted directly into a valid AMF file
without any loss of information and without requiring any additional information. AMF files are also
easily converted back to STL for use on legacy systems, although advanced features will be lost. This
format maintains the triangle-mesh geometry representation to take advantage of existing optimized
slicing algorithms and code infrastructure already in existence.
3.1.7 Future compatibility. To remain useful in a rapidly changing industry, this file format is easily
extensible while remaining compatible with earlier versions and technologies. This allows new features
to be added as advances in technology warrant, while still working flawlessly for simple homogeneous
geometries on the oldest hardware.
3.2 Guidelines for the inclusion of future new elements
3.2.1 Any new element proposed shall be applicable across all hardware platforms and technologies
that could conceivably be used to generate the desired outcome.
3.2.2 In support of the consideration above, new elements proposed for this International Standard
shall describe the final object, not how to build it. For instance, a hypothetical future element
might be allowed to tell an additive manufacturing system to leave the volume empty if possible.
However, an element that describes how to build a hollow volume shall
not be included since it assumes a particular fabrication process.
4 Structure of this specification
4.1 Format. Information specified throughout this specification is stored in XML 1.0 format. XML is a
text file comprising a list of elements and attributes. Using this widely accepted data format allows for
the use of many tools for creating, viewing, manipulating, parsing and storing AMF files. XML is human-
readable, which makes debugging errors in the file possible. XML can be compressed or encrypted or
both if desired in a post-processing step using highly optimized standardized routines.
4.2 Flexibility. Another significant advantage of XML is its inherent flexibility. Missing or additional
parameters do not present a problem for a parser as long as the document conforms to the XML standard.
Practically, the use of XML namespaces allows new features to be added without breaking old versions of
the parser, such as in legacy software.
4.3 Precision. This file format is agnostic as to the precision of the representation of numeric values.
It is the responsibility of the generating program to write as many or as few digits as are necessary for
proper representation of the target object. However, an AMF consumer should read and process real
numbers in double precision (64 bits).
4.4 Future amendments and additions. While additional XML elements can be added provisionally
to any AMF file for internal purpose, such additions shall not be considered part of this specification. An
unofficial AMF element may be ignored by any AMF consumer and may not be stored or reproduced by an
editor application. An element becomes official only when it is formally accepted into this specification.
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5 General structure
5.1 The AMF file shall begin with the XML declaration line specifying the XML version and
encoding, for example:

The XML version shall be 1.0. Only UTF-8 and UTF-16 should be specified. Unrecognized encodings
should cause the file to fail to load.
5.2 Whitespace characters and standard XML comments may be interspersed in the file and shall be
ignored by any interpreter, for example:

5.3 The remainder of the file shall be enclosed between start and end element tags.
This element denotes the file type and fulfils the requirement that all XML files have a single root element.
A version attribute denoting the version of the AMF standard the file is compliant with should be used.
Standard XML namespace attributes may also be used, such as the lang attribute designed to identify
the natural human language used. The unit system may also be specified (millimetre, inch, foot, metre or
micron). In the absence of a unit specification, the attribute value millimetres is assumed, for example:
xmins:amf=“www.astm.org/Standards/F2915-14”>
5.4 Enclosed within the element start- and end-tags, there are five top level elements, as
described in 5.4.1 to 5.4.5.
5.4.1 The object element defines a volume or volumes of material, each of which might also
reference a material identifier (ID) for AM processing. The object element shall also declare an object ID,
which shall be unique. At least one object element shall be present in the file. Additional objects are optional.
5.4.2 The optional material element defines one material for fabrication, each of which
declares an associated material ID. The material ID declared shall be unique and shall not be 0. If no
material element is included, a single default material is assumed.
5.4.3 The optional texture element defines one image or texture for colour or texture
mapping, each of which declares an associated texture ID. The texture ID declared shall be unique.
5.4.4 The optional constellation element hierarchically combines objects and
other constellations into a relative pattern for printing. The constellation element may also declare an
object ID, which shall be unique. If no constellation elements are specified, each object element shall be
imported with no relative position data. The consumer software may determine the relative positioning
of the objects if more than one object is specified in the file.
5.4.5 The optional metadata element specifies additional information about the
object(s) and elements contained in the file.
5.5 Only a single object element is required for a fully functional AMF file.
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6 Geometry specification
6.1 General
6.1.1 The top level element declares a unique ID and shall contain one child
element. The element shall contain two child elements: and . The
element may optionally reference a material.
6.1.2 The required element shall contain all vertices that are used in this object. Each
vertex is implicitly assigned an identifying integer in the order in which it is declared, starting at zero and
increasing monotonically. The required child element gives the position of the vertex
in three-dimensional (3D) space using the , and child elements.
6.1.3 After the vertex information, at least one element shall be included. Each volume
encapsulates a closed volume of the object. Multiple volumes may be included in a single object. Volumes
may share vertices at interfaces but shall not have any overlapping volume.
6.1.4 Within each volume, multiple child elements shall be used to define the triangles
that tessellate the surface of the volume. Each element shall reference three vertices from
the set of indices of the previously defined vertices. The indices of the three vertices of the triangles shall
be specified using the , and child elements. The vertices shall be ordered according to
the right-hand rule such that vertices are listed in counter-clockwise order as viewed from the outside
of the volume. Each triangle is implicitly assigned an identifying integer in the order in which it was
declared starting at zero and increasing monotonically (see Figure 1).
6.1.5 The geometry shall not be used to describe support structure. Only the final target structure shall
be described.
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NOTE The figure shows a basic AMF file containing only a list of vertices and triangles. This structure is
compatible with the STL standard and can be readable by a minimal implementation of an AMF consumer.
Figure 1 — Basic AMF file
6.2 Smooth geometry
6.2.1 By default, all triangles shall be assumed to be flat and all triangle edges shall be assumed to be
straight lines connecting their two vertices. However, curved triangles and curved edges may optionally
be specified to reduce the number of mesh elements required to describe a curved surface. Minimal AMF
consumer software (see Clause 13) may ignore curvature information associated with triangles.
6.2.2 During import, a curved triangle patch shall be recursively subdivided into four triangles to
generate a final temporary set of flat triangles. The depth of recursion shall be exactly five (that is, a
single curved triangle will be converted into 1 024 flat triangles).
6.2.3 During production, the producing software that generates curved triangles shall determine
automatically the number of curved triangles required to specify the target geometry to the desired
tolerance, knowing that the consuming software will perform five levels of subdivision for any curved
triangle.
6.2.4 To specify curvature, a vertex may contain a child element to specify the desired
surface normal at the vertex. The normal should be unit length and pointing outwards. If this normal is
specified, all triangle edges meeting at that vertex shall be curved so that they are perpendicular to that
normal and in the plane defined by the normal and the original straight edge.
6.2.5 If a vertex is referenced by two volumes, the normal is considered identically for each volume, but
its direction should be interpreted as consistent with the volume in consideration (so that it is pointing
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outwards). Vertices that have an ambiguous normal because they are common to multiple volumes
should not specify a normal.
6.2.6 A curved triangle shall not be more than 25 % out of plane and shall not include inflections.
6.2.7 When the curvature of the volume’s surface at a vertex is undefined (for example, at a cusp,
corner or edge), an element may be used to specify the curvature of a single nonlinear edge
joining two vertices. The curvature is specified using the tangent direction vectors at the beginning and
end of that edge. The element shall take precedence in case of a conflict with the curvature
implied by a element.
6.2.8 Normals should not be specified for vertices referenced only by planar triangles. Edge elements
should not be specified for linear edges in flat triangles.
6.2.9 When interpreting normal and tangents, secon
...