ISO/IEC 11072:1992
(Main)Information technology — Computer graphics — Computer Graphics Reference Model
Information technology — Computer graphics — Computer Graphics Reference Model
Defines a set of concepts and their inter-relationships which should be applicable to the complete range of future computer graphics standard. May be applied to verify and refine requirements for computer graphics; to identify needs for computer graphics standards and external interfaces; to develop models based on requirements for computer graphics; to define the architecture of new computer graphics standards; compare computer graphics standards.
Technologies de l'information — Infographie — Modèle de référence
General Information
Standards Content (Sample)
ISOAEC
INTERNATIONAL
STANDARD
First edition
1992-10-01
Information technology - Computer graphics -
Computer Graphics Reference Model
Technologies de /‘information - lnfographie - Mod&/e de rbfbrence
Reference number
ISO/IEC 11072rl992 (E)
Contents
Page
1v
Foreword
V
Introduction
1 Scope
2 Definitions
3 The Computer Graphics Reference Model
3.1 Environment model
3.2 External relationships
3.3 Environment structure
3.4 Data elements
3.4.1 Introduction
3.4.2 Composition
3.4.3 Collection store
3.4.4 Token store
3.4.5 Aggregation store
3.4.6 Environment state
3.5 Processing elements
3 5.1 Absorption
3.5.2 Manipulation
3.5.3 Distribution
3.5.4 Assembly
3.5.5 Emanation
3.6 Characteristics of specific environments
3.6.1 Environment details
3.6.2 Output primitives
3.6.3 Input tokens
3.6.4 Properties
3.6.5 Transformations
3.6.6 Fan-in and fan-out
3.7 Relationship between output and input
3.8 Internal interfaces
0 ISO/IEC 1992
All rights reserved. No part of this publication may be reproduced or utilized in any form
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without permission in writing from the publisher.
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Printed in Switzerland
ii
Annexes
A Existing standards and the CGRM 22
Graphical kernel system-IS0 7942 22
A.1
Graphical kernel system for three 22
A.2
dimensions-IS0 8805
Programmer’s hierarchical interactive 24
A.3
graphics system - ISO/IEC 9592
A.4 Interfacing techniques for dialogues with 24
graphical devices-ISO/IEC 9636
A.5 Metafile for the storage and transfer of 26
picture description information-IS0 8632
B The relationship of computer imaging to computer 27
graphics
C The relationship of window systems to computer
graphics 30
Cl Introduction 30
co2 Window systems 30
c’3 . Windowing considered
as an operator
C.4 Windowing considered as part of the
computer graphics system
C.4.1 Overview
C.4.2 Operations on windows
C. 4.3 Operations on window content
C. 4.4 Displaying windows
C.4.5 Input
D Bibliography
Foreword
IS0 (the International Organization for Standardization) and IEC (the International
Electrotechnical Commission) form the specialized system for worldwide standardization.
National bodies that are members of IS0 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. IS0 and IEC technical
committees collaborate in fields of mutual interest. Other international organizations,
governmental and non-governmental, in liaison with IS0 and IEC, also take part in the work.
In the field of information technology, IS0 and IEC have established a joint technical
committee, ISO/IEC JTC 1. Draft International Standards adopted by the joint
technical committee are circulated to national bodies for voting. Publication as an International
Standard requires 75 % of the national bodies casting
approval by at least
a vote.
International Standard ISO/IEC 11072 was prepared by Joint Technical Committee
ISO/IEC JTC I, Information technology.
Annexes A to D of this International Standard are for information only.
Introduction
The Computer Graphics Reference Model (CGRM) describes the conceptual
framework for computer graphics. Computer graphics is the creation of, manipulation
of, analysis of, and interaction with pictorial representations of objects and data using
computers.
The main purpose of the CGRM is to define concepts that shall be used to develop
computer graphics standards. Additional purposes are to explain relations between
SC24 standards and to provide a forum whereby areas outside computer graphics can
identify their relationships to computer graphics.
International Standards related to computer graphics include the following existing and
emerging areas:
a) Open Systems Interconnection - Basic Reference Model;
b) Virtual Terminal Protocols and Terminal Management;
c) File Transfer, Access and Management Protocols;
d) Office Document Architecture and Interchange;
e) Text and Office Systems;
f) Exchange of Product Model Data;
g) Character Sets and Coding;
h) Open Distributed Processing;
i) Image Processing and Interchange.
This International Standard shall be the basis for the development of specific standards
for computer graphics and will ensure their long term coherence based on objective
rational foundations. Existing computer graphics standards will not necessarily fit
precisely into the Reference Model. However, experience with current standards has
significantly influenced the model.
V
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INTERNATIONAL STANDARD
ISO/IEC 11072rl992 (E)
Information technology - Computer graphics -
Computer Graphics Reference Model
1 Scope
This International Standard, the Computer Graphics Reference Model (CGRM),
defines a structure within which current and future International Standards for computer
graphics shall be compared and their relationships described.
This International Standard defines a set of concepts and their inter-relationships which
should be applicable to the complete range of future computer graphics standards.
This International Standard may be applied to:
verify and refine requirements for computer graphics;
a)
b) identify needs for computer graphics standards and external interfaces;
c) develop models based on requirements for computer graphics;
d) define the architecture of new computer graphics standards;
e) compare computer graphics standards.
This International Standard does not define how computer graphics standards shall be
defined and developed. It does not specify the functional descriptions of computer
graphics standards, the bindings of those standards to programming languages, or the
encoding of graphical information in any coding technique or interchange format. It is
neither an implementation specification for systems incorporating computer graphics,
nor a basis for appraising the conformance of implementations.
ISOAEC 11072:1992 (E)
2 Definitions
For the purposes of this International Standard, the following definitions apply. An
alphabetical list is given at the end of this clause.
2.1 computer graphics: The creation of, manipulation of, analysis of and
interaction with pictorial representations of objects and data using computers.
2.2 application: The external object that uses computer graphics. Applications are
not modelled in the CGRM, but their interactions with computer graphics are modelled.
2.3 operator: The external object that observes the contents of the display and
generates physical input values. Operators are not modelled in the CGRM, but their
interactions with computer graphics systems are modelled.
2.4 environment: A subdivision of the CGRM at a given level of abstraction. The
definition of the environment includes the definition of its data elements and processing
elements. Specific names are given to the five environments: construction, virtual,
viewing, logical and realization (see 3.6.1).
2.4.1 construction environment: The environment that interfaces to the
application.
2.4.2 virtual environment: The environment between the construction and
viewing environments.
2.4.3 viewing environment: The environment between the virtual and logical
environments.
2.4.4 logical environment: The environment between the viewing and the
realization environments.
2.4.5 realization environment: The environment that interfaces to the
operator.
2.4.6 higher environment: An environment closer to the application.
2.4.7 lower environment: An environment closer to the operator.
2.4.8 entity: An item of information stored within an environment or passed
between environments. Entities are divided into three classes: input, output and
control.
2.4.9 fan-in: The merging of entities from multiple, independent sources to
produce a single stream (without changing individual entities) to be processed by a
single environment.
2.4.10 fan-out: The generation of multiple, independent entities from a single
entity without change. The generated entities are sent to independent environments.
2.5 external interfaces: The interfaces between the computer graphics system and
the outside world, the interfaces communicate with the operator, application, data
capture metafile and audit trail metafile.
2.5.1 operator interface: The interface between the realization environment and
the operator. This is the only interface between the operator and the graphics
system. \
2 S.2 application interface: The interface provided by the construction
environment to the application. This is the only interface between the application
and the graphics system.
2.5.3 data capture metafile: An external object for representing all or part of a
data element for storage, retrieval and transmission.
2.5.3.1 export: The process of generating a data capture metafile.
2.5.3.2 import: The action of setting part or all of a data element from a
data capture metafile.
2 S.4 audit trail metafile: An external object for representing the sequential
flow of information across the application interface.
2 o 6 processing element: A process in an environment: absorption, manipulation,
distribution, assembly, and emanation.
2 l 6o 1 absorption: A process which receives entities from the next higher
environment and processes them for use within its own environment. Specific
names are given to absorption at each environment level: preparation, production,
projection, completion and presentation.
preparation: The name given to absorption in the construction
2.6 l lo 1
environment.
2.6.1.2 production: The name given to absorption in the virtual
environment.
2.6.1.3 projection: The name given to absorption in the viewing
environment.
2.6.1.4 completion: The name given to absorption in the logical
.
environment.
2.6.1.5 presentation: The name given to absorption in the realization
.
environment.
2 l 6o2 emanation: A process which emanates token store and input control
entities to the next higher environment after processing them. Specific names are
given to emanation at each environment level: accumulation, abstraction, elevation,
generation and utilization.
2 l 6 l 2 l 1 accumulation: The name given to emanation in the realization
environment.
2.6.2.2 abstraction: The name given to emanation in the logical
environment.
2.6.2.3 elevation: The name given to emanation in the viewing
environment.
2.6.2.4 generation: The name given to emanation in the virtual
environment.
2.6.2.5 utilization: The name given to emanation in the construction
environment.
2.6.3 distribution: A process which distributes the composition and output
control entities to the next lower environment.
2.6.4 assembly: A process which receives entities from the next lower
environment for use within its own environment.
2.6.5 manipulation: A process which accesses and changes the contents of
data elements.
2.7 data element: A store in an environment: composition, collection store, token
store, aggregation store, and environment state.
2.7.1 composition: A spatially structured set of output primitives in a given
environment. Specific names are given to the composition at each environment
level: model, scene, picture, graphical image and display.
2.7.1.1 model: The name given to the composition in the construction
environment.
2.7.1.2 scene: The name given to the composition in the virtual
environment.
The name given to the composition in the viewing
2.7.1.3 picture:
environment.
2.7.1.4 graphical image: The name given to the composition in the logical
environment.
2.7.1.5 display: The name given to the composition in the realization
environment.
2 l 7.2 collection store: A storage facility for collections.
collection: A set of output entities which are named and may be
2.7.2.1
structured. A collection may be manipulated to produce all or part of a
composition in the same environment.
A storage facility for aggregations.
2.7.3 aggregation store:
2.7.3.1 aggregation: A set of input entities which are named and may be
structured. An aggregation may be manipulated to produce one or more input
tokens in the token store in the same environment.
2.7.4 token store: A structured set of input tokens in a given environment.
Specific names are given to the token store at each environment: lexeme store,
information store, selection store, directive store and instruction store.
2.7.4.1 lexeme store: The name given to the token store in the realization
environment.
2.7.4.2 information store: The name given to the token store in the
logical environment.
2.7.4 l 3 selection store: The name given to the token store in the viewing
environment.
directive store: The name given to the token store in the virtual
2.7.4.4
environment.
2.7.4.5 instruction store: The name given to the token store in the
construction environment.
2.7.5 environment state: Entities in the environment separate from other data
elements: composition, collection store, token store, aggregation store.
2.7 l 6 editing: The change of entities within data elements in an environment.
2.8 output primitive: An atomic unit for graphical output in a given environment.
There may be more than one class of output primitive. Geometric and other properties
may be bound to an output primitive at its creation or later.
2.9 input token: An atomic unit for graphical input in a given environment. There
may be more than one class of input token. Geometry and other properties may be
bound to an input token at its creation or later.
2.9.1 property: A value that may be used by an output primitive or input token to
specify its geometry or other characteristics.
2.9.2 geometric property: A property which is subject to modification by
geometric transformations.
2.9.2.1 geometric transformation: A transformation that modifies the
...
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