ISO 19123-1:2023
(Main)Geographic information — Schema for coverage geometry and functions — Part 1: Fundamentals
Geographic information — Schema for coverage geometry and functions — Part 1: Fundamentals
This document defines a conceptual schema for coverages. A coverage is a mapping from a spatial, temporal or spatiotemporal domain to attribute values sharing the same attribute type. A coverage domain consists of a collection of direct positions in a coordinate space that can be defined in terms of spatial and/or temporal dimensions, as well as non-spatiotemporal (in ISO 19111:2019, “parametric”) dimensions. Examples of coverages include point clouds, grids, meshes, triangulated irregular networks, and polygon sets. Coverages are the prevailing data structures in a number of application areas, such as remote sensing, meteorology and mapping of depth, elevation, soil and vegetation. This document defines the coverage concept including the relationship between the domain of a coverage and its associated attribute range. This document defines the characteristics of the domain. The characteristics of the attribute range are not defined in this document, but are defined in implementation standards. Consequently, the standardization target of this document consists of implementation standards, not concrete implementations themselves.
Information géographique — Schéma de la géométrie et des fonctions de couverture — Partie 1: Principes de base
Le présent document définit un schéma conceptuel pour les couvertures. Une couverture est une mise en correspondance d'un domaine spatial, temporel ou spatiotemporel avec des valeurs d'attributs partageant le même type d'attribut. Un domaine de couverture se compose d'un ensemble de positions directes dans un espace de coordonnées qui peut être défini en termes de dimensions spatiales et/ou temporelles, ainsi que de dimensions non-spatiotemporelles (dans l'ISO 19111:2019, «paramétriques»). Parmi les exemples de couverture, citons les nuages de points, les grilles, les maillages, les réseaux irréguliers de triangles et les ensembles de polygones. Les couvertures sont les structures de données courantes dans divers champs d'application, notamment la télédétection, la météorologie, la cartographie de la profondeur, de l'altitude, du sol et de la végétation. Le présent document définit le concept de couverture, y compris la relation entre le domaine d'une couverture et sa plage d'attributs associée. Le présent document définit les caractéristiques du domaine. Les caractéristiques de la plage d'attributs ne sont pas définies dans le présent document, mais elles sont définies dans des normes de mise en œuvre spécifiques. Par conséquent, la cible de normalisation du présent document consiste en des normes de mise en œuvre, et non en des mises en œuvre concrètes.
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INTERNATIONAL ISO
STANDARD 19123-1
First edition
2023-06
Geographic information — Schema for
coverage geometry and functions —
Part 1:
Fundamentals
Information géographique — Schéma de la géométrie et des fonctions
de couverture —
Partie 1: Principes de base
Reference number
ISO 19123-1:2023(E)
© ISO 2023
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ISO 19123-1:2023(E)
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© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ISO 19123-1:2023(E)
Contents Page
Foreword .v
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, abbreviated terms and notation . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms . 8
4 Conformance . 8
4.1 Notation . 8
4.2 Interoperability and conformance testing . 9
4.3 Organization . 9
5 Coverages .10
5.1 Overview . 10
5.2 Coverage packages . 11
5.3 Probing coverages: evaluate() function .12
5.4 Domain of a coverage . 12
5.4.1 Concept . .12
5.4.2 Coordinates . 13
5.4.3 Mathematical versus physical coordinates . 14
5.4.4 Coordinate reference systems and axes . 14
5.4.5 Coverage classification along topological dimensions . 16
5.5 Range of a coverage . 16
5.6 Interpolation. 17
5.6.1 Concept . . 17
5.6.2 Discrete and continuous coverages . 18
5.7 Common point rule . 19
5.8 Realization variants . 19
5.8.1 Overview . 19
5.8.2 Geometry/value pair view . 19
5.8.3 Domain/range view .20
5.8.4 Partitioned view . 21
5.8.5 Functional view . 21
5.9 Envelope . 21
6 Multi-point coverages .22
7 Grid coverages .23
7.1 Overview . 23
7.2 Grids . 24
7.2.1 Grid definition. 24
7.2.2 Grid axis types . 27
7.3 Rectified and referenceable grid coverages .30
7.4 Grid cells . 31
7.4.1 Grid cell concept . 31
7.4.2 Pixel-in-centre, pixel-in-corner . 32
7.5 Grid coverage . 32
7.6 Further grid coverage types .33
8 Multi-curve coverages .34
8.1 Overview .34
8.2 General multi-curve coverages . 35
8.3 Segmented curve coverages . 35
9 Multi-surface coverages .36
9.1 Overview . 36
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ISO 19123-1:2023(E)
9.2 General multi-surface coverages . 36
9.3 Further surface coverages . 37
9.3.1 General . 37
9.3.2 Thiessen polygon coverages. 37
9.3.3 Triangulated irregular networks (TINs) .38
10 Multi-solid coverages .39
Annex A (normative) Conformance tests .41
Annex B (informative) Interpolation methods .45
Annex C (informative) Sequential enumeration .49
Annex D (normative) Legacy data-centric coverage specification .60
Bibliography .77
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ISO 19123-1:2023(E)
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 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).
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 by Technical Committee ISO/TC 211, Geographic information/Geomatics,
in collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/
TC 287, Geographic Information, in accordance with the Agreement on technical cooperation between
ISO and CEN (Vienna Agreement), in collaboration with the Open Geospatial Consortium (OGC), and in
collaboration with the IEEE GRSS Earth Science Informatics Technical Committee.
This first edition cancels and replaces ISO 19123:2005, which has been technically revised.
The main changes are as follows:
— the document has been renamed as “Part 1: Fundamentals”, since a new “Part 2: Coverage
Implementation Schema” has been published;
— the text has been simplified for better understanding;
— concepts, while in principle unchanged, have been defined more rigorously and some errors have
been corrected;
— the approach to standardization taken in this document has been changed. This edition of the
document defines a high-level, generic concept of coverages with an interface definition from
which many different (not necessarily interoperable) implementation structures can be derived.
The previous edition of this document, ISO 19123:2005, defined a single generic data structure
for coverages. The previous model remains valid as one of the many possible data structures
that can implement the ISO 19123-1 interface. This data structure, which is defined in Annex D,
supports backward compatibility. Standardization targets that referenced ISO 19123 can continue
referencing those same classes, although new realizations are not encouraged to do so. It is noted,
however, that the coverage definition terms in Clause 3 which are owned by other documents have
been updated to refer to newer editions of the documents (including their definitions) where such
newer editions are available;
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ISO 19123-1:2023(E)
— all operations except evaluate() have been removed, for simplification purposes. ISO 19123-3 now
specifies the operations requirements;
— the Scope has been extended to include Mesh;
— the concept of discrete and continuous coverages has been generalized to achieve an improved
conceptual basis and to allow for coverages which are discrete along some domain axes and
continuous along other domain axes. This is achieved by using the coordinate reference system axes
as the basis for the definitions so that any axis individually can be discrete or continuous. Since this
is a generalization of the previous concept it is backward compatible. As a side effect, this reworking
has greatly simplified the structure of this document;
— updates in ISO 19103 have been reflected, and corresponding adjustments have been made where
necessary. The informative Annex on “UML notation” has been deleted since UML notation is now
described in ISO 19103;
— all coordinate-related definitions are based on ISO 19111, and corresponding adjustments have
been made to this document as necessary;
— the definition of image CRS has been moved from ISO 19111 to this document;
— the definition of interpolation is based on the interpolation definition of ISO 19107 in order to avoid
duplicate and diverging definitions;
— the UML diagrams have been redrawn for clarity, in order to correct errors, and to follow the new
conventions established in ISO/TC 211;
— the bibliography has been revised to include additional references and has been reformatted.
A list of all parts in the ISO 19123 series can be found on the ISO website.
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.
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ISO 19123-1:2023(E)
Introduction
This document defines, at a high, implementation-independent level, the notion of coverages as digital
representations of space-time varying phenomena, corresponding to the notion of a field in physics.
Such coverages can be discrete or continuous.
Historically, geographic information has been treated in terms of two fundamental data types called
"vector data" and "raster data".
"Vector data" deals with discrete phenomena, each of which is conceived of as a feature. The spatial
characteristics of a discrete real-world phenomenon are represented by a set of one or more geometric
primitives (points, curves, surfaces or solids). Other characteristics of the phenomenon are recorded as
feature attributes. Usually, a single feature is associated with a single set of attribute values. ISO 19107
provides a schema for describing features in terms of geometric and topological primitives.
"Raster data", on the other hand, deals with phenomena that vary over space and time, mathematically
described by “fields”. It contains a set of values, each associated with one of the elements in an array of
points or cells. Raster data is often associated with a method for interpolating values at spatial positions
between the points or within the cells.
The coverage concept, originally adopted from the Abstract Specification of the Open Geospatial
[15]
Consortium (OGC), generalizes these and further data structures, such as point clouds, into a model
for representing phenomena that vary continuously over space and time, and possibly over further
dimensions such as spectral bands. Formally, a coverage is a function from a spatial (such as horizontal
x and y and vertical height or depth), temporal, other (in ISO 19111:2019 nomenclature: parametric)
domain or any combination thereof to values of some data type.
A coverage consists of a set of spatio-temporally extended geometric (often geographic) objects,
each with associated attribute values. The spatio-temporal locations with which attribute values are
associated are called “direct positions”.
Formally, a coverage itself is a subtype of a feature as defined in ISO 19101-1. The coverage feature is
a set of features all sharing some key properties, such as the same attribute definition and coordinate
reference system.
NOTE Direct positions can be of different dimensions. For example, in a raster image modelled as a coverage,
the direct positions will be the grid points; in a multi-solid coverage a direct position is given by the interior of a
3D solid.
In practice, coverages encompass regular and irregular grids, point clouds and general meshes.
Examples include raster data, point clouds, meshes such as triangulated irregular networks and
polygon sets. Coverages are multi-dimensional, including examples such as 1D sensor timeseries, 2D
satellite images, 3D x/y/t image timeseries and x/y/z geophysical voxel data, and 4D x/y/z/t climate
and ocean data. Coordinate axes of such coverages can have spatial, temporal, or any other meaning,
and they can be combined freely for n-dimensional coverages.
EXAMPLE The electromagnetic spectrum is an example of an axis with neither spatial nor temporal
semantics. Such a spectral axis can be defined as a “parametric CRS” as established in ISO 19111.
A coverage which provides values only at the direct positions is called “a discrete coverage”. If
interpolation information is added so that values can be obtained also between the coverage’s direct
positions, such a coverage is called “a continuous coverage”.
Just as the concepts of discrete and continuous phenomena are not mutually exclusive, their
representations as discrete coverages are not mutually exclusive. The same phenomenon can be
represented as either a discrete feature or a coverage, depending on the particular context and
requirements. A city can be viewed as a discrete coverage that returns a single value for each attribute,
such as its name, area and total population, but it can also be represented as a continuous coverage that
returns values such as population density, land value or air quality index for each location in the city.
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ISO 19123-1:2023(E)
A coverage, moreover, can be derived by bundling a collection of discrete features sharing a common
attribute definition, the values of the coverage at each position being the values of the attributes of
the feature located at that position. Conversely, a collection of discrete features can be derived from a
coverage by extracting all direct positions with their associated attribute values.
The previous edition of this document, ISO 19123:2005, addressed coverage modelling on both
a conceptual and (to some extent) an implementation level, effectively mixing both. Coverage
modelling has now been split into two separate, but related documents: ISO 19123-1 (this document),
which establishes an abstract, high-level coverage model, and ISO 19123-2, which establishes an
implementation-level model ensuring interoperability, based on the concepts of ISO 19123-1. A
corresponding high-level processing model for coverages is defined in ISO 19123-3.
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INTERNATIONAL STANDARD ISO 19123-1:2023(E)
Geographic information — Schema for coverage geometry
and functions —
Part 1:
Fundamentals
1 Scope
This document defines a conceptual schema for coverages. A coverage is a mapping from a spatial,
temporal or spatiotemporal domain to attribute values sharing the same attribute type. A coverage
domain consists of a collection of direct positions in a coordinate space that can be defined in terms of
spatial and/or temporal dimensions, as well as non-spatiotemporal (in ISO 19111:2019, “parametric”)
dimensions. Examples of coverages include point clouds, grids, meshes, triangulated irregular networks,
and polygon sets. Coverages are the prevailing data structures in a number of application areas, such
as remote sensing, meteorology and mapping of depth, elevation, soil and vegetation. This document
defines the coverage concept including the relationship between the domain of a coverage and its
associated attribute range. This document defines the characteristics of the domain. The characteristics
of the attribute range are not defined in this document, but are defined in implementation standards.
Consequently, the standardization target of this document consists of implementation standards, not
concrete implementations themselves.
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 19103, Geographic information — Conceptual schema language
ISO 19107, Geographic information — Spatial schema
ISO 19111, Geographic information — Referencing by coordinates
3 Terms, definitions, abbreviated terms and notation
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
analytical coverage
coverage where the mapping function from domain to range is given by an analytical mathematical
function
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ISO 19123-1:2023(E)
3.1.2
axis
tuple of axis name, axis abbreviation, axis direction, axis unit and further
information
Note 1 to entry: This definition is established in accordance with ISO 19111:2019, Table 26 and subclause 10.4.
Note 2 to entry: Inside a coordinate reference system (CRS) containing several axes the axis names are required
to be pairwise different.
Note 3 to entry: The axis unit (of measure) defines the set of values which can be used as a coordinate along this
axis. These can be numbers (such as in Latitude and Longitude) or general strings (such as in timestamps or
special identifiers like “FL100” in aviation).
3.1.3
cell
neighbourhood around a direct position in a coverage grid, not overlapping with any other
direct position neighbourhood in the coverage grid
Note 1 to entry: Coverage cell is synonymous to grid cell.
Note 2 to entry: All cells of a grid coverage together establish a tessellation (i.e. complete, overlap-free cover) of
the grid space.
3.1.4
continuous coverage
coverage that returns values for both direct positions and positions between direct positions
3.1.5
coordinate
one of a sequence of measures designating the position of a point
Note 1 to entry: In a coordinate reference system, the coordinate numbers are usually qualified by units. Some
coordinates may use a unit representation, for example date/time conformant with ISO 8601-1. When coordinates
are an index (ordinal coordinates) they are unitless (which possibly can be represented by a unit of 1).
[SOURCE: ISO 19111:2019, 3.1.5, modified — Original note 1 to entry has been amended.]
3.1.6
coordinate reference system
coordinate system that is related to an object by a datum
[SOURCE: ISO 19111:2019, 3.1.9, modified — Notes 1 and 2 to entry have been deleted.]
3.1.7
coordinate system
set of mathematical rules for specifying how coordinates are to be assigned to points
Note 1 to entry: A coordinate system contains an ordered sequence of one or more axes; their names are required
to be pairwise different.
[SOURCE: ISO 19111:2019, 3.1.11, modified — Note 1 to entry has been added.]
3.1.8
coordinate tuple
tuple composed of coordinates
Note 1 to entry: The number of coordinates in the coordinate tuple equals the dimension of the coordinate
system; the order of coordinates in the coordinate tuple is identical to the order of the axes of the coordinate
system.
[SOURCE: ISO 19111:2019, 3.1.13]
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ISO 19123-1:2023(E)
3.1.9
coverage
function which returns values from its range for any direct position within its domain
3.1.10
coverage coordinate reference system
coverage CRS
coordinate reference system (CRS) in which all coordinates in a coverage domain are expressed
Note 1 to e
...
NORME ISO
INTERNATIONALE 19123-1
Première édition
2023-06
Information géographique — Schéma
de la géométrie et des fonctions de
couverture —
Partie 1:
Principes de base
Geographic information — Schema for coverage geometry and
functions —
Part 1: Fundamentals
Numéro de référence
ISO 19123-1:2023(F)
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ISO 19123-1:2023(F)
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© ISO 2023
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y compris la photocopie, ou la diffusion sur l’internet ou sur un intranet, sans autorisation écrite préalable. Une autorisation peut
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Publié en Suisse
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ISO 19123-1:2023(F)
Sommaire Page
Avant-propos .v
Introduction .vii
1 Domaine d'application .1
2 Références normatives .1
3 Termes, définitions, termes abrégés et notation . 1
3.1 Termes et définitions . 1
3.2 Abréviations. 8
4 Conformité . 9
4.1 Notation . 9
4.2 Interopérabilité et test de conformité . 9
4.3 Organisation . 10
5 Couvertures .11
5.1 Vue d'ensemble . 11
5.2 Packages de couverture . .12
5.3 Sondage de couvertures: fonction evaluate() .12
5.4 Domaine d'une couverture . 13
5.4.1 Concept . .13
5.4.2 Coordonnées. 14
5.4.3 Coordonnées mathématiques ou coordonnées physiques . 14
5.4.4 Systèmes de référence de coordonnées et axes . 15
5.4.5 Classification des couvertures selon des dimensions topologiques . 17
5.5 Plage d'une couverture . 17
5.6 Interpolation. 18
5.6.1 Concept . . 18
5.6.2 Couvertures discrètes et continues . 19
5.7 Règle de point commun.20
5.8 Variantes de réalisation . 20
5.8.1 Vue d'ensemble. 20
5.8.2 Vue de la paire géométrie/valeur . 21
5.8.3 Vue domaine/plage . 21
5.8.4 Vue partitionnée .22
5.8.5 Vue fonctionnelle. 23
5.9 Enveloppe . 23
6 Couvertures à points multiples .24
7 Couvertures en grille .25
7.1 Vue d'ensemble . 25
7.2 Grilles . 26
7.2.1 Définition de la grille .26
7.2.2 Types d'axes de la grille .29
7.3 Couvertures en grilles rectifiées et référençables . 32
7.4 Cellules de grille . 33
7.4.1 Concept de cellules de grille . 33
7.4.2 Pixel au centre, pixel en angle .34
7.5 Couverture en grille .34
7.6 Autres types de couverture en grille . 36
8 Couvertures à courbes multiples .37
8.1 Vue d'ensemble . 37
8.2 Généralités concernant les couvertures à courbes multiples . 37
8.3 Couvertures par courbes segmentées .38
9 Couverture à surfaces multiples .38
9.1 Vue d'ensemble .38
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ISO 19123-1:2023(F)
9.2 Généralités concernant les couvertures à surfaces multiples .39
9.3 Autres couvertures de surface . 39
9.3.1 Généralités .39
9.3.2 Couvertures par polygones de Thiessen .40
9.3.3 Réseaux irréguliers de triangles (TIN) . 41
10 Couvertures à solides multiples .42
Annexe A (normative) Tests de conformité .43
Annexe B (informative) Méthodes d'interpolation .47
Annexe C (informative) Énumération séquentielle .51
Annexe D (normative) Spécification héritée de couverture centrée sur les données .63
Bibliographie .81
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ISO 19123-1:2023(F)
Avant-propos
L'ISO (Organisation internationale de normalisation) est une fédération mondiale d'organismes
nationaux de normalisation (comités membres de l'ISO). L'élaboration des Normes internationales est
en général confiée aux comités techniques de l'ISO. Chaque comité membre intéressé par une étude
a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,
gouvernementales et non gouvernementales, en liaison avec l'ISO participent également aux travaux.
L'ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui
concerne la normalisation électrotechnique.
Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont
décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier, de prendre note des différents
critères d'approbation requis pour les différents types de documents ISO. Le présent document a
été rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir
www.iso.org/directives).
L’ISO attire l’attention sur le fait que la mise en application du présent document peut entraîner
l’utilisation d’un ou de plusieurs brevets. L’ISO ne prend pas position quant à la preuve, à la validité
et à l’applicabilité de tout droit de brevet revendiqué à cet égard. À la date de publication du présent
document, l’ISO n'avait pas reçu notification qu’un ou plusieurs brevets pouvaient être nécessaires à sa
mise en application. Toutefois, il y a lieu d’avertir les responsables de la mise en application du présent
document que des informations plus récentes sont susceptibles de figurer dans la base de données de
brevets, disponible à l'adresse www.iso.org/brevets. L’ISO ne saurait être tenue pour responsable de ne
pas avoir identifié tout ou partie de tels droits de propriété.
Les appellations commerciales éventuellement mentionnées dans le présent document sont données
pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un
engagement.
Pour une explication de la nature volontaire des normes, la signification des termes et expressions
spécifiques de l'ISO liés à l'évaluation de la conformité, ou pour toute information au sujet de l'adhésion
de l'ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles
techniques au commerce (OTC), voir www.iso.org/avant-propos.
Le présent document a été élaboré par le comité technique ISO/TC 211, Information géographique/
Géomatique, en collaboration avec le comité technique CEN/TC 287, Information geographique, du Comité
européen de normalisation (CEN) conformément à l’Accord de coopération technique entre l’ISO et le
CEN (Accord de Vienne), en collaboration avec l'Open Geospatial Consortium (OGC), et en collaboration
avec l'IEEE GRSS Earth Science Informatics Technical Committee (IEEE GRSS ESI TC)
Cette première édition annule et remplace l'ISO 19123:2005, qui a fait l’objet d’une révision technique.
Les principales modifications sont les suivantes:
— le document a été renommé «Partie 1: Principes de base», car une nouvelle «Partie 2: Schéma de la
mise en place de la couverture» a été publiée;
— le texte a été simplifié pour une meilleure compréhension;
— les concepts, bien qu'inchangés dans leur principe, ont été définis de manière plus rigoureuse et
certaines erreurs ont été corrigées;
— l'approche de normalisation adoptée dans le présent document a été modifiée. Cette édition du
document définit un concept générique de haut niveau de couvertures avec une définition d'interface
à partir de laquelle de nombreuses structures de mise en œuvre différentes (pas nécessairement
interopérables) peuvent être dérivées. L'édition précédente du présent document, l'ISO 19123:2005,
définissait une seule structure de données générique pour les couvertures. Le modèle précédent
reste valable comme l'une des nombreuses structures de données possibles permettant de mettre
en œuvre l'interface de l'ISO 19123-1. Cette structure de données, qui est définie à l'Annexe D, prend
en charge la rétrocompatibilité. Les cibles de normalisation qui faisaient référence à l'ISO 19123
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ISO 19123-1:2023(F)
peuvent citer ces mêmes classes, bien que les nouvelles réalisations ne soient pas encouragées à
le faire. Il est à noter, cependant, que les termes de définition de la couverture de l'Article 3 qui
appartiennent à d'autres documents ont été mis à jour pour faire référence à des éditions plus
récentes de ces documents (y compris leurs définitions), lorsque ces éditions plus récentes sont
disponibles;
— toutes les opérations, à l'exception de evaluate(), ont été supprimées à des fins de simplification. Les
exigences relatives aux opérations sont désormais spécifiées dans l'ISO 19123-3;
— le domaine d'application a été étendu pour inclure le maillage;
— le concept de couvertures discrètes et continues a été généralisé afin d'obtenir une base conceptuelle
améliorée et de permettre des couvertures qui sont discrètes le long de certains axes de domaine
et continues le long d'autres axes de domaine. Pour ce faire, les axes du système de référence de
coordonnées sont utilisés comme base pour les définitions, de sorte que chaque axe peut être discret
ou continu. Comme il s'agit d'une généralisation du concept précédent, elle est rétrocompatible. Ce
remaniement a permis de simplifier considérablement la structure du présent document;
— les mises à jour de l'ISO 19103 ont été prises en compte et les ajustements correspondants ont
été apportés partout où cela était nécessaire. L'annexe informative sur la «notation UML» a été
supprimée, car la notation UML est désormais décrite dans l'ISO 19103;
— toutes les définitions relatives aux coordonnées sont basées sur l'ISO 19111, et les ajustements
correspondants ont été apportés dans le présent document où cela était nécessaire;
— la définition du SRC d'image a été déplacée de l'ISO 19111 vers le présent document;
— la définition de l'interpolation est basée sur la définition de l'interpolation de l'ISO 19107 afin
d'éviter les définitions redondantes et divergentes;
— les diagrammes UML ont été redessinés pour plus de clarté, afin de corriger les erreurs et de
respecter les nouvelles conventions établies par l'ISO/TC 211;
— la bibliographie a été révisée de sorte à inclure des références supplémentaires et a été réorganisée.
Une liste de toutes les parties de la série ISO 19123 se trouve sur le site web de l’ISO.
Il convient que l’utilisateur adresse tout retour d’information ou toute question concernant le présent
document à l’organisme national de normalisation de son pays. Une liste exhaustive desdits organismes
se trouve à l’adresse www.iso.org/fr/members.html.
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ISO 19123-1:2023(F)
Introduction
Le présent document définit, à un niveau élevé et indépendant de la mise en œuvre, la notion de
couverture en tant que représentation numérique de phénomènes variant dans l'espace-temps,
correspondant à la notion d'un domaine en physique. Ces couvertures peuvent être discrètes ou
continues.
L'information géographique a toujours été traitée en termes de deux types fondamentaux de données:
les «données vectorielles» et les «données matricielles».
Les "données vectorielles" se concentrent sur des phénomènes discrets, chacun d'entre eux étant
considéré comme une entité. Un ou plusieurs ensembles de primitives géométriques (points, courbes,
surfaces ou solides) représentent les caractéristiques spatiales d'un phénomène discret du monde réel.
D'autres caractéristiques du phénomène sont enregistrées en tant qu’attributs de l'entité. Souvent,
une seule entité est associée à une seule série de valeurs attributaires. L'ISO 19107 fournit un schéma
permettant de décrire les entités en termes de primitives géométriques et topologiques.
Les «données matricielles» se concentrent, quant à elles, sur les phénomènes réels qui varient dans
l'espace et le temps, décrits mathématiquement par des «champs». Elles comprennent un ensemble
de valeurs, chacune associée à l'un des éléments dans un regroupement de points ou de cellules. Les
«données matricielles» sont souvent associées à une méthode d'interpolation des valeurs en des
positions spatiales entre les points ou à l'intérieur des cellules.
Le concept de couverture, emprunté à l'origine de la spécification abstraite de l'Open Geospatial
[15]
Consortium (OGC), généralise ces structures de données ainsi que d'autres, comme les nuages de
points, en un modèle permettant de représenter des phénomènes qui varient de façon continue dans
l'espace et dans le temps, et éventuellement dans d'autres dimensions comme les bandes spectrales.
Sur le plan formel, une couverture est une fonction d'un domaine spatial (tel que les x et y horizontaux
et la hauteur verticale ou la profondeur), temporel, autre (dans la nomenclature de l'ISO 19111:2019
paramétrique) ou toute combinaison de ceux-ci à des valeurs d'un certain type de données.
Une couverture consiste en un ensemble d'objets géométriques (souvent géographiques) étendus dans
l'espace et dans le temps, chacun ayant des valeurs d'attribut associées. Les emplacements spatio-
temporels auxquels les valeurs d'attributs sont associées sont appelés «positions directes».
Sur le plan formel, une couverture est elle-même un sous-type d'entité, telle que définie dans
l'ISO 19101-1. Cette entité est un ensemble d'entités partageant toutes certaines propriétés clés, telles
que la même définition d'attribut et le même système de référence de coordonnées.
NOTE Les positions directes peuvent être de différentes dimensions. Par exemple, dans une image matricielle
modélisée comme une couverture, les positions directes seront les points de la grille; dans une couverture multi-
solide, une position directe est donnée par l'intérieur d'un solide 3D.
En pratique, les couvertures englobent les grilles régulières et irrégulières, les nuages de points et
les maillages généraux. Parmi les exemples, citons les données matricielles, les nuages de points, les
maillages, tels que les réseaux irréguliers de triangles et les ensembles de polygones. Les couvertures
sont multidimensionnelles et comprennent des exemples tels que des séries temporelles de capteurs 1D,
des images satellites 2D, des séries temporelles d'images 3D x/y/t et des données de voxels géophysiques
x/y/z, ainsi que des données climatiques et océaniques 4D x/y/z/t. Les axes de coordonnées de ces
couvertures peuvent avoir une signification spatiale, temporelle, ou toute autre signification, et ils
peuvent être combinés librement pour des couvertures à n dimensions.
EXEMPLE Le spectre électromagnétique est un exemple d'axe sans sémantique spatiale ou temporelle. Cet
axe spectral peut être défini comme un «SRC paramétrique» tel que défini dans l'ISO 19111.
Une couverture qui ne fournit des valeurs qu'aux positions directes est appelée «couverture discrète».
Si des informations d'interpolation sont ajoutées de sorte que des valeurs peuvent être obtenues
également entre les positions directes de la couverture, cette couverture est appelée «couverture
continue».
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ISO 19123-1:2023(F)
De même que les concepts de phénomènes discrets et continus, leurs représentations en tant que
couvertures discrètes ne s'excluent pas mutuellement. Le même phénomène peut être représenté soit
comme une entité discrète, soit comme une couverture, selon le contexte et les besoins particuliers.
Une ville peut être perçue comme une couverture discrète qui assigne une seule valeur pour chaque
attribut, comme son nom, sa superficie et sa population totale, mais elle peut aussi être représentée
comme une couverture continue qui renvoie des valeurs telles que la densité de population, la valeur du
terrain ou l'indice de qualité de l'air en chaque point de la ville.
En outre, une couverture peut être dérivée en regroupant un ensemble d'entités discrètes partageant
une définition d'attribut commune, les valeurs de la couverture en chaque position correspondant aux
valeurs attributaires d'une entité située à cette position. À l'inverse, un ensemble d'entités discrètes
peut résulter d'une couverture, en extrayant toutes les positions directes avec leurs valeurs d'attributs
associées.
L'édition précédente du présent document, ISO 19123:2005, traitait de la modélisation de la couverture
à la fois au niveau conceptuel et (dans une certaine mesure) au niveau de la mise en œuvre, en
combinant effectivement les deux. La modélisation de la couverture a été divisée en deux documents
distincts, mais liés: L'ISO 19123-1 (le présent document), qui établit un modèle de couverture abstrait
de haut niveau, et l'ISO 19123-2, qui établit un modèle de mise en œuvre garantissant l'interopérabilité,
s'appuyant sur les concepts de l'ISO 19123-1. Un modèle de traitement de haut niveau correspondant
pour les couvertures est défini dans l'ISO 19123-3.
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NORME INTERNATIONALE ISO 19123-1:2023(F)
Information géographique — Schéma de la géométrie et
des fonctions de couverture —
Partie 1:
Principes de base
1 Domaine d'application
Le présent document définit un schéma conceptuel pour les couvertures. Une couverture est une mise
en correspondance d'un domaine spatial, temporel ou spatiotemporel avec des valeurs d'attributs
partageant le même type d'attribut. Un domaine de couverture se compose d'un ensemble de positions
directes dans un espace de coordonnées qui peut être défini en termes de dimensions spatiales et/ou
temporelles, ainsi que de dimensions non-spatiotemporelles (dans l'ISO 19111:2019, «paramétriques»).
Parmi les exemples de couverture, citons les nuages de points, les grilles, les maillages, les réseaux
irréguliers de triangles et les ensembles de polygones. Les couvertures sont les structures de
données courantes dans divers champs d'application, notamment la télédétection, la météorologie, la
cartographie de la profondeur, de l'altitude, du sol et de la végétation. Le présent document définit le
concept de couverture, y compris la relation entre le domaine d'une couverture et sa plage d'attributs
associée. Le présent document définit les caractéristiques du domaine. Les caractéristiques de la plage
d'attributs ne sont pas définies dans le présent document, mais elles sont définies dans des normes de
mise en œuvre spécifiques. Par conséquent, la cible de normalisation du présent document consiste en
des normes de mise en œuvre, et non en des mises en œuvre concrètes.
2 Références normatives
Les documents suivants sont cités dans le texte de sorte qu’ils constituent, pour tout ou partie de leur
contenu, des exigences du présent document. Pour les références datées, seule l’édition citée s’applique.
Pour les références non datées, la dernière édition du document de référence s'applique (y compris les
éventuels amendements).
ISO 19103, Information géographique — Langage de schéma conceptuel
ISO 19107, Information géographique — Schéma spatial
ISO 19111, Information géographique — Système de références par coordonnées
3 Termes, définitions, termes abrégés et notation
3.1 Termes et définitions
Pour les besoins du présent document, les termes et définitions suivants s’appliquent.
L’ISO et l’IEC tiennent à jour des bases de données terminologiques destinées à être utilisées en
normalisation, consultables aux adresses suivantes:
— ISO Online browsing platform: disponible à l’adresse https:// www .iso .org/ obp
— IEC Electropedia: disponible à l’adresse https:// www .electropedia .org/
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ISO 19123-1:2023(F)
3.1.1
couverture analytique
couverture où la fonction de mise en correspondance du domaine à la plage est donnée par une fonction
mathématique analytique
3.1.2
axe
uplet du nom, de l'abréviation, de la direction et de l'unité de l'axe et
d'autres informations
Note 1 à l'article: Cette définition est établie conformément à l'ISO 19111:2019, Tableau 26 et paragraphe 10.4.
Note 2 à l'article: Dans un système de coordonnées de référence (SCR) contenant plusieurs axes, les noms des
axes doivent être différents par paire.
Note 3 à l'article: L'unité (de mesure) de l'axe définit l'ensemble des valeurs qui peuvent être utilisées comme
coordonnées le long de cet axe. Il peut s'agir de nombres (comme latitude et longitude) ou de chaînes de caractères
générales (comme dans les horodatages ou les identificateurs spéciaux tels que «FL100» dans l'aviation).
3.1.3
cellule
voisinage autour d'une position directe dans une grille de couverture, ne se superposant
...
Style Definition
ISO/FDIS 19123-1:20222023(E)
...
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Secretariat: SIS
Formatted: Different first page header
ISO TC 211/WG 6 Formatted
...
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Date: 2022-11-082023-02-03
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Geographic information — Schema for coverage geometry and functions — Part 1:
Formatted: zzCover, Left
Fundamentals
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ISO/FDIS 19123-1:####:2023(E)
© ISO 20222023
Formatted: Font color: Blue
Formatted: std_publisher, Font color: Blue
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part
Formatted: Font color: Blue
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
Formatted: Font color: Blue
permission. Permission can be requested from either ISO at the address below or ISO’s member body
Formatted: Font: 11 pt, Font color: Blue
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
Formatted: Font: 11 pt, Font color: Blue, English (United
Kingdom)
Email: copyright@iso.org
Website: www.iso.orgwww.iso.org
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Kingdom)
Published in Switzerland
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ISO/FDIS 19123-1:20222023(E)
Contents
Foreword . v
Introduction . vii
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, abbreviated terms and notation . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms . 8
4 Conformance . 8
4.1 Notation . 8
4.2 Interoperability and conformance testing . 9
4.3 Organization . 9
5 Coverages. 10
5.1 Overview . 10
5.2 Coverage packages . 11
5.3 Probing coverages: evaluate() function . 12
5.4 Domain of a coverage . 12
5.5 Range of a coverage . 16
5.6 Interpolation . 16
5.7 Common point rule . 18
5.8 Realization variants . 18
5.9 Envelope . 21
6 Multi-point coverages . 22
7 Grid coverages . 22
7.1 Overview . 22
7.2 Grids . 23
7.3 Rectified and referenceable grid coverages . 29
7.4 Grid cells . 30
7.5 Grid coverage . 31
7.6 Further grid coverage types . 32
8 Multi-curve coverages . 33
8.1 Overview . 33
8.2 General multi-curve coverages . 33
8.3 Segmented curve coverages . 34
9 Multi-surface coverages . 34
9.1 Overview . 34
9.2 General multi-surface coverages . 35
9.3 Further surface coverages . 35
10 Multi-solid coverages . 36
Annex A (normative) Conformance tests . 38
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ISO/FDIS 19123-1:####:2023(E)
Annex B (informative) Interpolation methods .42
Annex C (informative) Sequential enumeration .46
Annex D (normative) Legacy data-centric coverage specification .55
Bibliography .73
Foreword . vi
Introduction . viii
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, abbreviated terms and notation . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms .10
4 Conformance .10
4.1 Notation .10
4.2 Interoperability and conformance testing .11
4.3 Organization .12
5 Coverages .14
5.1 Overview .14
5.2 Coverage packages .15
5.3 Probing coverages: evaluate() function .17
5.4 Domain of a coverage .17
5.4.1 Concept .17
5.4.2 Coordinates .18
5.4.3 Mathematical versus physical coordinates .19
5.4.4 Coordinate reference systems and axes .20
5.4.5 Coverage classification along topological dimensions .23
5.5 Range of a coverage .23
5.6 Interpolation .24
5.6.1 Concept .24
5.6.2 Discrete and continuous coverages .26
5.7 Common point rule .27
5.8 Realization variants .27
5.8.1 Overview .27
5.8.2 Geometry/value pair view .28
5.8.3 Domain/range view .28
5.8.4 Partitioned view .30
5.8.5 Functional view .31
5.9 Envelope .31
6 Multi-point coverages .33
7 Grid coverages .34
7.1 Overview .34
7.2 Grids .36
7.2.1 Grid definition .36
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ISO/FDIS 19123-1:20222023(E)
7.2.2 Grid axis types. 41
7.3 Rectified and referenceable grid coverages . 45
7.4 Grid cells . 48
7.4.1 Grid cell concept . 48
7.4.2 Pixel-in-centre, pixel-in-corner . 49
7.5 Grid coverage . 49
7.6 Further grid coverage types . 52
8 Multi-curve coverages . 54
8.1 Overview . 54
8.2 General multi-curve coverages . 54
8.3 Segmented curve coverages . 54
9 Multi-surface coverages . 56
9.1 Overview . 56
9.2 General multi-surface coverages . 57
9.3 Further surface coverages . 58
9.3.1 General . 58
9.3.2 Thiessen polygon coverages . 59
9.3.3 Triangulated irregular networks (TINs) . 61
10 Multi-solid coverages . 61
Annex A (normative) Conformance tests . 65
Annex B (informative) Interpolation methods . 72
Annex C (informative) Sequential enumeration . 77
Annex D (normative) Legacy data-centric coverage specification. 96
Bibliography . 121
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ISO/FDIS 19123-1:####:2023(E)
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 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 by Technical Committee ISO/TC 211, Geographic information/Geomatics, in
collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/TC
287, Geographic Information, in accordance with the Agreement on technical cooperation between ISO
and CEN (Vienna Agreement), and in collaboration with the Open Geospatial Consortium (OGC).
This first edition cancels and replaces the first edition (ISO 19123:2005), which has been technically
revised.
The main changes are as follows:
— The standardthe document has been renamed to beas “Part 1: Fundamentals”, since a new “Part 2:
Coverage Implementation Schema” has been published.;
— The— the text has been simplified for better understanding.;
— Conceptsconcepts, while in principle unchanged, have been defined more rigorously and some errors
have been corrected.;
— The— the approach to standardization taken in thethis document has been changed. This
versionedition of ISO 19123-1the document defines a high-level, generic concept of coverages with
vi © ISO 2021 – All rights reserved
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ISO/FDIS 19123-1:20222023(E)
an interface definition from which many different (not necessarily interoperable) implementation
structures can be derived. The previous versionedition of the standardthis document, ISO 19123,
defined a single generic data structure for coverages. ItThis remains valid as one of the many possible
data structures that can implement the ISO 19123-1 interface. This data structure, which is defined
in Annex D, allows for backward compatibility in the sense that standardization targets that
referenced ISO 19123 can continue referencing these same classes, although new realizations are not
encouraged to do so. NoteIt is noted, however, that the coverage definition terms in Clause 3 3 which
are owned by other standardsdocuments have been updated to refer to newer versionseditions of
the standardsdocuments (including their definitions) where such newer versionseditions are in
place.
— All— all operations except evaluate() have been removed, for simplification purposes –. ISO
1
19123-3 takes:— is to take over the operations part.;
— The scopethe Scope has been extended to include Mesh.;
— The— the concept of discrete and continuous coverages has been generalized to achieve an
improved conceptual basis and to allow for coverages which are discrete along some domain axes
and continuous along other domain axes. This is achieved by using the coordinate reference system
axes as the basis for the definitions so that any axis individually can be discrete or continuous. Since
this is a generalization of the previous concept it is backward compatible. As a side effect, this
reworking has greatly simplified the structure of thethis document.;
— Updatesupdates in ISO 19103 have been reflected, and corresponding adjustments have been made
where necessary; the informative Annex on “UML notation” has been deleted since this is now
described in ISO 19103.
— All— all coordinate-related definitions are based on ISO 19111, and corresponding adjustments
have been made in all places necessary.;
— Definition— the definition of image CRS has been moved from ISO 19111 to this document.;
— Definition— the definition of interpolation is now is based on the interpolation definition of ISO
19107 in order to avoid duplicate and diverging definitions.;
— The— the UML diagrams have been redrawn for clarity, correctingin order to correct errors, and
to follow the new conventions established in TC211ISO/TC 211.
The— the bibliography has been revised to include additional references and has been reformatted.
A list of all parts in the ISO 19123 series can be found on the ISO website.
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.
1
Under preparation. Stage at the time of publication: ISO/FDIS 19123-3:2023.
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ISO/FDIS 19123-1:####:2023(E)
Introduction
This document defines, at a high, implementation-independent level, the notion of coverages as digital
representations of space-time varying phenomena, corresponding to the notion of a field in physics. Such
coverages can be discrete or continuous.
Historically, geographic information has been treated in terms of two fundamental types called "vector
data" and "raster data.".
“Vector data” deals with discrete phenomena, each of which is conceived of as a feature. The spatial
characteristics of a discrete real-world phenomenon are represented by a set of one or more geometric
primitives (points, curves, surfaces or solids). Other characteristics of the phenomenon are recorded as
feature attributes. Usually, a single feature is associated with a single set of attribute values. ISO 19107
provides a schema for describing features in terms of geometric and topological primitives.
“Raster data”,, on the other hand, deals with phenomena that vary over space and time, mathematically
described by “fields”. It contains a set of values, each associated with one of the elements in an array of
points or cells. It is often associated with a method for interpolating values at spatial positions between
the points or within the cells.
The coverage concept, originally adopted from the Abstract Specification of the Open Geospatial
[15]
Consortium (OGC) [15],), generalizes these and further data structures, such as point clouds, into a
model for representing phenomena that vary continuously over space and time, and possibly over further
dimensions such as spectral bands. Formally, a coverage is a function from a spatial (such as horizontal x
and y and vertical height or depth), temporal, other (in ISO 19111:2019 nomenclature: parametric)
domain or any combination thereof to values of some data type.
A coverage consists of a set of spatio-temporally extended geometric (often geographic) objects, each
with associated attribute values. The spatio-temporal locations with which attribute values are
associated with are called “direct positions”.
Formally, a coverage itself is a subtype of feature as defined in ISO 19101-1. This feature is a set of
features all sharing some key properties, such as the same attribute definition and coordinate reference
system.
NOTE directDirect positions can be of different dimensions. For example, in a raster image modelled as a
coverage, the direct positions will be the grid points; in a multi-solid coverage a direct position is given by the
interior of a 3D solid.
In practice, coverages encompass regular and irregular grids, point clouds, and general meshes. Examples
include raster data, point clouds, meshes such as triangulated irregular networks, and polygon sets.
Coverages are multi-dimensional, including examples like 1D sensor timeseries, 2D satellite images, 3D
x/y/t image timeseries and x/y/z geophysical voxel data, and 4D x/y/z/t climate and ocean data.
Coordinate axes of such coverages can have spatial, temporal, or any other meaning, and they can be
combined freely for n-dimensional coverages.
EXAMPLE The electromagnetic spectrum is an example forof an axis with neither spatial nor temporal
semantics. Such a spectral axis can be defined as a “parametric CRS” as established in ISO 19111:2019.
A coverage which provides values only at the direct positions is called “a discrete coverage”; if
interpolation information is added so that values can be obtained also between the coverage’s direct
positions, such a coverage is called “a continuous coverage”.
viii © ISO 2021 – All rights reserved
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ISO/FDIS 19123-1:20222023(E)
Just as the concepts of discrete and continuous phenomena are not mutually exclusive, their
representations as discrete coverages are not mutually exclusive. The same phenomenon can be
represented as either a discrete feature or a coverage, dependentdepending on the particular context and
requirements. A city can be viewed as a discrete coverage that returns a single value for each attribute,
such as its name, area and total population, but it can also be represented as a coverage that returns
values such as population density, land value or air quality index for each location in the city.
A coverage, moreover, can be derived by bundling a collection of discrete features sharing a common
attribute definition, the values of the coverage at each position being the values of the attributes of the
feature located at that position. Conversely, a collection of discrete features can be derived from a
coverage by extracting all direct positions with their associated attribute values.
The previous edition of this document, ISO 19123:2005, addressed coverage modelling on both a
conceptual and (to some extent) an implementation level, effectively mixing both. Coverage modelling
has now been split into two separate, but connected documents: ISO 19123-1 (this document), which
establishes an abstract, high-level coverage model, and ISO 19123-2, which establishes an
implementation-level model ensuring interoperability, based on the concepts of ISO 19123-1. A
corresponding high-level processing model for coverages is defined in ISO 19123-3.
© ISO 2021 – All rights reserved ix
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 19123-1:2023(E)
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Geographic information — Schema for coverage geometry and
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coverage geometry and functions —
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ISO/FDIS 19123-1:2023(E)
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 19123-1
ISO/TC 211
Geographic information — Schema for
Secretariat: SIS
coverage geometry and functions —
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Fundamentals
Information géographique — Schéma de la géométrie et des fonctions
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NATIONAL REGULATIONS. © ISO 2023
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ISO/FDIS 19123-1:2023(E)
Contents Page
Foreword .v
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, abbreviated terms and notation . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms . 8
4 Conformance . 8
4.1 Notation . 8
4.2 Interoperability and conformance testing . 9
4.3 Organization . 9
5 Coverages .10
5.1 Overview . 10
5.2 Coverage packages . 11
5.3 Probing coverages: evaluate() function .12
5.4 Domain of a coverage . 12
5.4.1 Concept . .12
5.4.2 Coordinates . 13
5.4.3 Mathematical versus physical coordinates .13
5.4.4 Coordinate reference systems and axes . 14
5.4.5 Coverage classification along topological dimensions . 16
5.5 Range of a coverage . 16
5.6 Interpolation. 17
5.6.1 Concept . . 17
5.6.2 Discrete and continuous coverages . 18
5.7 Common point rule . 19
5.8 Realization variants . 19
5.8.1 Overview . 19
5.8.2 Geometry/value pair view . 19
5.8.3 Domain/range view .20
5.8.4 Partitioned view . 21
5.8.5 Functional view . 21
5.9 Envelope . 21
6 Multi-point coverages .22
7 Grid coverages .23
7.1 Overview . 23
7.2 Grids . 24
7.2.1 Grid definition. 24
7.2.2 Grid axis types . 27
7.3 Rectified and referenceable grid coverages .30
7.4 Grid cells . 31
7.4.1 Grid cell concept . 31
7.4.2 Pixel-in-centre, pixel-in-corner . 32
7.5 Grid coverage . 32
7.6 Further grid coverage types .33
8 Multi-curve coverages .34
8.1 Overview .34
8.2 General multi-curve coverages . 35
8.3 Segmented curve coverages . 35
9 Multi-surface coverages .36
9.1 Overview . 36
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ISO/FDIS 19123-1:2023(E)
9.2 General multi-surface coverages . 36
9.3 Further surface coverages . 37
9.3.1 General . 37
9.3.2 Thiessen polygon coverages. 37
9.3.3 Triangulated irregular networks (TINs) .38
10 Multi-solid coverages .38
Annex A (normative) Conformance tests .41
Annex B (informative) Interpolation methods .45
Annex C (informative) Sequential enumeration .49
Annex D (normative) Legacy data-centric coverage specification .60
Bibliography .77
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ISO/FDIS 19123-1:2023(E)
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 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 by Technical Committee ISO/TC 211, Geographic information/Geomatics,
in collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/TC
287, Geographic Information, in accordance with the Agreement on technical cooperation between ISO
and CEN (Vienna Agreement), and in collaboration with the Open Geospatial Consortium (OGC).
This first edition cancels and replaces the first edition (ISO 19123:2005), which has been technically
revised.
The main changes are as follows:
— the document has been renamed as “Part 1: Fundamentals”, since a new “Part 2: Coverage
Implementation Schema” has been published;
— the text has been simplified for better understanding;
— concepts, while in principle unchanged, have been defined more rigorously and some errors have
been corrected;
— the approach to standardization taken in this document has been changed. This edition of the
document defines a high-level, generic concept of coverages with an interface definition from which
many different (not necessarily interoperable) implementation structures can be derived. The
previous edition of this document, ISO 19123, defined a single generic data structure for coverages.
This remains valid as one of the many possible data structures that can implement the ISO 19123-1
interface. This data structure, which is defined in Annex D, allows for backward compatibility in
the sense that standardization targets that referenced ISO 19123 can continue referencing these
same classes, although new realizations are not encouraged to do so. It is noted, however, that the
coverage definition terms in Clause 3 which are owned by other documents have been updated to
refer to newer editions of the documents (including their definitions) where such newer editions are
in place.
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ISO/FDIS 19123-1:2023(E)
1)
— all operations except evaluate() have been removed, for simplification purposes. ISO 19123-3:— is
to take over the operations part;
— the Scope has been extended to include Mesh;
— the concept of discrete and continuous coverages has been generalized to achieve an improved
conceptual basis and to allow for coverages which are discrete along some domain axes and
continuous along other domain axes. This is achieved by using the coordinate reference system axes
as the basis for the definitions so that any axis individually can be discrete or continuous. Since this
is a generalization of the previous concept it is backward compatible. As a side effect, this reworking
has greatly simplified the structure of this document;
— updates in ISO 19103 have been reflected, and corresponding adjustments have been made where
necessary; the informative Annex on “UML notation” has been deleted since this is now described
in ISO 19103.
— all coordinate-related definitions are based on ISO 19111, and corresponding adjustments have
been made in all places necessary;
— the definition of image CRS has been moved from ISO 19111 to this document;
— the definition of interpolation is now based on the interpolation definition of ISO 19107 in order to
avoid duplicate and diverging definitions;
— the UML diagrams have been redrawn for clarity, in order to correct errors, and to follow the new
conventions established in ISO/TC 211.
— the bibliography has been revised to include additional references and has been reformatted.
A list of all parts in the ISO 19123 series can be found on the ISO website.
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.
1) Under preparation. Stage at the time of publication: ISO/FDIS 19123-3:2023.
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ISO/FDIS 19123-1:2023(E)
Introduction
This document defines, at a high, implementation-independent level, the notion of coverages as digital
representations of space-time varying phenomena, corresponding to the notion of a field in physics.
Such coverages can be discrete or continuous.
Historically, geographic information has been treated in terms of two fundamental types called "vector
data" and "raster data".
Vector data deals with discrete phenomena, each of which is conceived of as a feature. The spatial
characteristics of a discrete real-world phenomenon are represented by a set of one or more geometric
primitives (points, curves, surfaces or solids). Other characteristics of the phenomenon are recorded as
feature attributes. Usually, a single feature is associated with a single set of attribute values. ISO 19107
provides a schema for describing features in terms of geometric and topological primitives.
Raster data, on the other hand, deals with phenomena that vary over space and time, mathematically
described by “fields”. It contains a set of values, each associated with one of the elements in an array of
points or cells. It is often associated with a method for interpolating values at spatial positions between
the points or within the cells.
The coverage concept, originally adopted from the Abstract Specification of the Open Geospatial
[15]
Consortium (OGC), generalizes these and further data structures, such as point clouds, into a model
for representing phenomena that vary continuously over space and time, and possibly over further
dimensions such as spectral bands. Formally, a coverage is a function from a spatial (such as horizontal
x and y and vertical height or depth), temporal, other (in ISO 19111 nomenclature: parametric) domain
or any combination thereof to values of some data type.
A coverage consists of a set of spatio-temporally extended geometric (often geographic) objects,
each with associated attribute values. The spatio-temporal locations with which attribute values are
associated are called “direct positions”.
Formally, a coverage itself is a subtype of feature as defined in ISO 19101-1. This feature is a set of
features all sharing some key properties, such as the same attribute definition and coordinate reference
system.
NOTE Direct positions can be of different dimensions. For example, in a raster image modelled as a coverage,
the direct positions will be the grid points; in a multi-solid coverage a direct position is given by the interior of a
3D solid.
In practice, coverages encompass regular and irregular grids, point clouds and general meshes.
Examples include raster data, point clouds, meshes such as triangulated irregular networks and
polygon sets. Coverages are multi-dimensional, including examples like 1D sensor timeseries, 2D
satellite images, 3D x/y/t image timeseries and x/y/z geophysical voxel data, and 4D x/y/z/t climate
and ocean data. Coordinate axes of such coverages can have spatial, temporal, or any other meaning,
and they can be combined freely for n-dimensional coverages.
EXAMPLE The electromagnetic spectrum is an example of an axis with neither spatial nor temporal
semantics. Such a spectral axis can be defined as a “parametric CRS” as established in ISO 19111.
A coverage which provides values only at the direct positions is called “a discrete coverage”; if
interpolation information is added so that values can be obtained also between the coverage’s direct
positions, such a coverage is called “a continuous coverage”.
Just as the concepts of discrete and continuous phenomena are not mutually exclusive, their
representations as discrete coverages are not mutually exclusive. The same phenomenon can be
represented as either a discrete feature or a coverage, depending on the particular context and
requirements. A city can be viewed as a discrete coverage that returns a single value for each attribute,
such as its name, area and total population, but it can also be represented as a coverage that returns
values such as population density, land value or air quality index for each location in the city.
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ISO/FDIS 19123-1:2023(E)
A coverage, moreover, can be derived by bundling a collection of discrete features sharing a common
attribute definition, the values of the coverage at each position being the values of the attributes of
the feature located at that position. Conversely, a collection of discrete features can be derived from a
coverage by extracting all direct positions with their associated attribute values.
The previous edition of this document, ISO 19123:2005, addressed coverage modelling on both a
conceptual and (to some extent) an implementation level, effectively mixing both. Coverage modelling
has now been split into two separate, but connected documents: ISO 19123-1 (this document),
which establishes an abstract, high-level coverage model, and ISO 19123-2, which establishes an
implementation-level model ensuring interoperability, based on the concepts of ISO 19123-1. A
corresponding high-level processing model for coverages is defined in ISO 19123-3.
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 19123-1:2023(E)
Geographic information — Schema for coverage geometry
and functions —
Part 1:
Fundamentals
1 Scope
This document defines a conceptual schema for coverages. A coverage is a mapping from a spatial,
temporal or spatio-temporal domain to attribute values sharing the same attribute type. A coverage
domain consists of a collection of direct positions in a coordinate space that can be defined in terms
of spatial and/or temporal dimensions, as well as non-spatio-temporal (in ISO 19111: “parametric”)
dimensions. Examples of coverages include point clouds, grids, meshes, triangulated irregular networks,
and polygon sets. Coverages are the prevailing data structures in a number of application areas, such
as remote sensing, meteorology and mapping of depth, elevation, soil and vegetation. This document
defines the coverage concept including the relationship between the domain of a coverage and its
associated attribute range. This document defines the characteristics of the domain; the characteristics
of the attribute range are not defined in this document, but left to specific implementation standards.
Consequently, the standardization target of this document consists of implementation standards, not
concrete implementations themselves.
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 19103, Geographic information — Conceptual schema language
ISO 19107, Geographic information — Spatial schema
ISO 19111, Geographic information — Referencing by coordinates
3 Terms, definitions, abbreviated terms and notation
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
analytical coverage
coverage where the mapping function from domain to range is given by an analytical
mathematical function
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ISO/FDIS 19123-1:2023(E)
3.1.2
axis
tuple of axis name, axis abbreviation, axis direction, axis unit and further
information, as specified in ISO 19123-1
Note 1 to entry: This definition is established in accordance with ISO 19111:2019, Table 26 and subclause 10.4.
Note 2 to entry: Inside a coordinate reference system (CRS) containing several axes the axis names are required
to be pairwise different.
Note 3 to entry: The axis unit (of measure) defines the set of values which can be used as a coordinate along this
axis. These can be numbers (such as in Latitude and Longitude) or general strings (such as in timestamps or
special identifiers like “FL100” in aviation).
3.1.3
cell
neighbourhood around a direct position in a coverage grid, not overlapping with any other
direct position neighbourhood in the coverage grid
Note 1 to entry: Coverage cell is synonymous to grid cell.
Note 2 to entry: All cells of a grid coverage together establish a tessellation (i.e. complete, overlap-free cover) of
the grid space.
3.1.4
continuous coverage
coverage that returns values for both direct positions and positions between direct positions
3.1.5
coordinate
one of a sequence of measures designating the position of a point
Note 1 to entry: In a coordinate reference system, the coordinate numbers are usually qualified by units. Some
coordinates may use a unit representation, for example date/time conformant with ISO 8601-1. When coordinates
are an index (ordinal coordinates) they are unitless (which possibly can be r
...
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