EN ISO 19156:2013

SLOVENSKI STANDARD
01-oktober-2013
Geografske informacije - Opazovanja in meritve (ISO 19156:2011)
Geographic information - Observations and measurements (ISO 19156:2011)
Geoinformation - Erdbeobachtung und Erdmessung (ISO 19156:2011)
Information géographique - Observations et mesures (ISO 19156:2011)
Ta slovenski standard je istoveten z: EN ISO 19156:2013
ICS:
07.040 Astronomija. Geodezija. Astronomy. Geodesy.
Geografija Geography
35.240.70 Uporabniške rešitve IT v IT applications in science
znanosti
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 19156
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2013
ICS 35.240.70
English Version
Geographic information - Observations and measurements (ISO
19156:2011)
Information géographique - Observations et mesures (ISO Geoinformation - Erdbeobachtung und Erdmessung (ISO
19156:2011) 19156:2011)
This European Standard was approved by CEN on 27 July 2012.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2013 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 19156:2013: E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
The text of ISO 19156:2011 has been prepared by Technical Committee ISO/TC 211 “Geographic
information/Geomatics” of the International Organization for Standardization (ISO) and has been taken over
as EN ISO 19156:2013 by Technical Committee CEN/TC 287 “Geographic Information” the secretariat of
which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by January 2014, and conflicting national standards shall be withdrawn at
the latest by January 2014.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 19156:2011 has been approved by CEN as EN ISO 19156:2013 without any modification.

INTERNATIONAL ISO
STANDARD 19156
First edition
2011-12-15
Geographic information — Observations
and measurements
Information géographique — Observations et mesures
Reference number
ISO 19156:2011(E)
©
ISO 2011
ISO 19156:2011(E)
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO’s
member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2011 – All rights reserved

ISO 19156:2011(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Conformance . 1
2.1 Overview . 1
2.2 Conformance classes related to Application Schemas including Observations and
Measurements . 1
3 Normative references . 2
4 Terms and definitions . 3
5 Abbreviated terms and notation . 5
5.1 Abbreviated terms . 5
5.2 Schema language . 5
5.3 Model element names . 6
6 Dependencies . 6
7 Fundamental characteristics of observations . 6
7.1 The context for observations . 6
7.2 Observation schema . 8
7.3 Use of the observation model .15
8 Specialized observations .15
8.1 Classification of observation by result type .15
8.2 Observations whose result is constant .16
8.3 Observations whose result varies .17
9 Fundamental characteristics of sampling features .19
9.1 The context for sampling .19
9.2 Sampling Schema .20
10 Spatial sampling features .24
10.1 The context for spatial sampling features .24
10.2 Spatial sampling feature schema .24
10.3 Decomposition of extensive sampling features for observations .26
10.4 Common names for sampling features (informative) .26
11 Specimens .27
11.1 The context for specimens .27
11.2 Specimen schema .27
Annex A (normative) Abstract Test Suite .30
Annex B (informative) Mapping O&M terminology to common usage .35
Annex C (normative) Utility classes .38
Annex D (informative) Best practices in use of the observation and sampling models .40
Bibliography .46
ISO 19156:2011(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 19156 was prepared by Technical Committee ISO/TC 211, Geographic information/Geomatics, in
collaboration with the Open Geospatial Consortium, Inc. (OGC).
iv © ISO 2011 – All rights reserved

ISO 19156:2011(E)
Introduction
This International Standard arises from work originally undertaken through the Open Geospatial Consortium’s
Sensor Web Enablement (SWE) activity. SWE is concerned with establishing interfaces and protocols that will
enable a “Sensor Web” through which applications and services will be able to access sensors of all types, and
observations generated by them, over the Web. SWE has defined, prototyped and tested several components
needed for a Sensor Web, namely:
— Sensor Model Language (SensorML).
— Observations & Measurements (O&M).
— Sensor Observation Service (SOS).
— Sensor Planning Service (SPS).
— Sensor Alert Service (SAS).
This International Standard specifies the Observations and Measurements schema, including a schema for
sampling features.
The content presented here derives from an earlier version published by Open Geospatial Consortium as
OGC 07-022r1, Observations and Measurements — Part 1 — Observation schema and OGC 07-002r3,
Observations and Measurements — Part 2 — Sampling Features. A technical note describing the changes
from the earlier version is available from the Open Geospatial Consortium (see http://www.opengeospatial.
org/standards/om).
INTERNATIONAL STANDARD ISO 19156:2011(E)
Geographic information — Observations and measurements
1 Scope
This International Standard defines a conceptual schema for observations, and for features involved in sampling
when making observations. These provide models for the exchange of information describing observation acts
and their results, both within and between different scientific and technical communities.
Observations commonly involve sampling of an ultimate feature-of-interest. This International Standard defines
a common set of sampling feature types classified primarily by topological dimension, as well as samples for
ex-situ observations. The schema includes relationships between sampling features (sub-sampling, derived
samples).
This International Standard concerns only externally visible interfaces and places no restriction on the underlying
implementations other than what is needed to satisfy the interface specifications in the actual situation.
2 Conformance
2.1 Overview
Clauses 7 to 11 of this International Standard use the Unified Modeling Language (UML) to present conceptual
schemas for describing Observations. These schemas define conceptual classes that
a) may be considered to comprise a cross-domain application schema, or
b) may be used in application schemas, profiles and implementation specifications.
This flexibility is controlled by a set of UML types that can be implemented in a variety of manners. Use of
alternative names that are more familiar in a particular application is acceptable, provided that there is a one-
to-one mapping to classes and properties in this International Standard.
The UML model in this International Standard defines conceptual classes; various software systems define
implementation classes or data structures. All of these reference the same information content. The same
name may be used in implementations as in the model, so that types defined in the UML model may be used
directly in application schemas.
Annex A defines a set of conformance tests that will support applications whose requirements range from the
minimum necessary to define data structures to full object implementation.
2.2 Conformance classes related to Application Schemas including Observations and
Measurements
The conformance rules for Application Schemas in general are described in ISO 19109:2005. Application
Schemas also claiming conformance to this International Standard shall also conform to the rules specified in
Clauses 7 to 11 and pass all relevant test cases of the Abstract Test Suite in Annex A.
Depending on the characteristics of an Application Schema, 18 conformance classes are distinguished. Table 1
lists these classes and the corresponding subclause of the Abstract Test Suite.
ISO 19156:2011(E)
Table 1 — Conformance classes related to Application Schemas including Observations
and Measurements
Conformance class Subclause
Generic observation interchange A.1.1
Measurement interchange A.1.1, A.1.2
Category observation interchange A.1.1, A.1.3
Count observation interchange A.1.1, A.1.4
Truth observation interchange A.1.1, A.1.5
Temporal observation interchange A.1.1, A.1.6
Geometry observation interchange A.1.1, A.1.7
Complex observation interchange A.1.1, A.1.8
Discrete coverage observation interchange A.1.1, A.1.9
Point coverage observation interchange A.1.1, A.1.10
Time series observation interchange A.1.1, A.1.11
Sampling feature interchange A.2.1, A.2.2
Spatial sampling feature interchange A.2.1 to A.2.3
Sampling point interchange A.2.1 to A.2.4
Sampling curve interchange A.2.1 to A.2.3, A.2.5
Sampling surface interchange A.2.1 to A.2.3, A.2.6
Sampling solid interchange A.2.1 to A.2.3, A.2.7
Specimen interchange A.2.1 to A.2.3, A.2.8
3 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced document
(including any amendments) applies.
ISO 19101:2002, Geographic information — Reference model
ISO/TS 19103:2005, Geographic information — Conceptual schema language
ISO 19107:2003, Geographic information — Spatial schema
ISO 19108:2002, Geographic information — Temporal schema
ISO 19109:2005, Geographic information — Rules for application schema
ISO 19111:2007, Geographic information — Spatial referencing by coordinates
ISO 19115:2003, Geographic information — Metadata
ISO 19115:2003/Cor.1:2006, Geographic information — Metadata — Technical Corrigendum 1
ISO 19123:2005, Geographic information — Schema for coverage geometry and functions
ISO 19136:2007, Geographic information — Geography Markup Language (GML)
ISO/IEC 19501:2005, Information technology — Open Distributed Processing — Unified Modeling Language
(UML) Version 1.4.2
1)
ISO 19157:— , Geographic information — Data quality
1) To be published.
2 © ISO 2011 – All rights reserved

ISO 19156:2011(E)
4 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
4.1
application schema
conceptual schema for data required by one or more applications
[ISO 19101:2002, definition 4.2]
4.2
coverage
feature that acts as a function to return values from its range for any direct position within its spatial, temporal
or spatiotemporal domain
[ISO 19123:2005, definition 4.17]
4.3
data type
specification of a value domain with operations allowed on values in this domain
[ISO/TS 19103:2005, definition 4.1.5]
EXAMPLE Integer, Real, Boolean, String, Date (conversion of a date into a series of codes).
NOTE Data types include primitive predefined types and user-definable types. All instances of a data type lack
identity.
4.4
domain feature
feature of a type defined within a particular application domain
NOTE This may be contrasted with observations and sampling features, which are features of types defined for
cross-domain purposes.
4.5
ex-situ
referring to the study, maintenance or conservation of a specimen or population away from its natural
surroundings
NOTE Opposite of in-situ.
4.6
feature
abstraction of real-world phenomena
[ISO 19101:2002, definition 4.11]
NOTE A feature may occur as a type or an instance. In this International Standard, feature instance is meant unless
otherwise specified.
4.7
feature type
class of features having common characteristics
4.8
measurand
particular quantity subject to measurement
[ISO/TS 19138:2006, definition 4.5]
NOTE Specialization of observable property type.
ISO 19156:2011(E)
4.9
measure
value described using a numeric amount with a scale or using a scalar reference system
[ISO 19136:2007, definition 4.1.41]
4.10
measurement
set of operations having the object of determining the value of a quantity
[ISO/TS 19101-2:2008, definition 4.20]
4.11
observation
act of measuring or otherwise determining the value of a property
4.12
observation procedure
method, algorithm or instrument, or system of these, which may be used in making an observation
4.13
observation protocol
combination of a sampling strategy and an observation procedure used in making an observation
4.14
observation result
estimate of the value of a property determined through a known observation procedure
4.15
property
facet or attribute of an object referenced by a name
[ISO 19143:2010, definition 4.21]
EXAMPLE Abby’s car has the colour red, where “colour red” is a property of the car.
4.16
property type
characteristic of a feature type
EXAMPLE Cars (a feature type) all have a characteristic colour, where “colour” is a property type.
NOTE 1 The value for an instance of an observable property type can be estimated through an act of observation.
NOTE 2 In chemistry-related applications, the term “determinand” or “analyte” is often used.
NOTE 3 Adapted from ISO 19109:2005.
4.17
sampling feature
feature which is involved in making observations concerning a domain feature
EXAMPLE Station, transect, section or specimen.
NOTE A sampling feature is an artefact of the observational strategy, and has no significance independent of the
observational campaign.
4 © ISO 2011 – All rights reserved

ISO 19156:2011(E)
4.18
value
element of a type domain
[ISO/IEC 19501:2005]
NOTE 1 A value considers a possible state of an object within a class or type (domain).
NOTE 2 A data value is an instance of a datatype, a value without identity.
NOTE 3 A value can use one of a variety of scales including nominal, ordinal, ratio and interval, spatial and temporal.
Primitive datatypes can be combined to form aggregate datatypes with aggregate values, including vectors, tensors and
images.
5 Abbreviated terms and notation
5.1 Abbreviated terms
GFM General Feature Model
GML Geography Markup Language
O&M Observations and Measurements
OGC Open Geospatial Consortium
SensorML Sensor Model Language
SOS Sensor Observation Service
SWE Sensor Web Enablement
UML Unified Modeling Language
XML Extensible Markup Language
1-D One Dimensional
2-D Two Dimensional
3-D Three Dimensional
5.2 Schema language
The conceptual schema specified in this International Standard is in accordance with the Unified Modelling
Language (UML) ISO/IEC 19501, following the guidance of ISO/TS 19103.
The UML is conformant with the profile described in ISO 19136:2007, Annex E. Use of this restricted idiom
supports direct transformation into a GML Application Schema. ISO 19136 introduces some additional
stereotypes. In particular «FeatureType» implies that a class is an instance of the «metaclass» GF_FeatureType
(ISO 19109), and therefore represents a feature type.
The prose explanation of the model uses the term “property” to refer to both class attributes and association
roles. This is consistent with the General Feature Model described in ISO 19109. In the context of properties,
the term “value” refers to either a literal (for attributes whose type is simple), or to an instance of the class
providing the type of the attribute or target of the association. Within the explanation, the property names
(property types) are sometimes used as natural language words where this assists in constructing a readable
text.
ISO 19156:2011(E)
5.3 Model element names
This International Standard specifies a model for observations using terminology that is based on current
practice in a variety of scientific and technical disciplines. It is designed to apply across disciplines, so the
best or “most neutral” term has been used in naming the classes, attributes and associations provided. The
terminology does not, however, correspond precisely with any single discipline. As an aid to implementors,
a mapping from the element names specified in this International Standard to common terminology in some
application domains is provided in Annex B.
6 Dependencies
Some model elements used in the schema described in Clauses 7 to 11 are defined in other International
Standards. By convention within ISO/TC 211, names of UML classes, with the exception of basic data type
classes, include a two or three letter prefix that identifies the International Standard and the UML package
in which the class is defined. Table 2 lists the standards and packages in which UML classes used in this
International Standard have been defined. UML classes defined in this International Standard have the prefix of
CVT, GFI, OM and SF. The prefix GFI is used for classes defined in this International Standard, but which are
associated with the GF package in ISO 19109. The prefix CVT is used for classes defined in this International
Standard, but which are associated with the CV package in ISO 19123:2005.
Table 2 — Sources of UML classes
Prefix International Standard Package
CVT This International Standard (Annex C) Temporal coverage
CV ISO 19123:2005 Coverage
GFI This International Standard (Annex C) General Feature Model general instance
DQ ISO 19115:2003 Data Quality
GF ISO 19109:2005 General Feature Model
GM ISO 19107:2003 Geometry
LI ISO 19115:2003, ISO 19115:2003/Cor.1:2006 Data Quality
MD ISO 19115:2003/Cor.1:2006 Metadata Entity
OM This International Standard Observations and Measurements
SC ISO 19111:2007 Coordinate reference systems
SF This International Standard Sampling features
TM ISO 19108:2002 Temporal Schema
7 Fundamental characteristics of observations
7.1 The context for observations
7.1.1 Property evaluation
Properties of a feature fall into two basic categories:
a) Value (e.g. name, price, legal boundary) assigned by some authority. These are exact.
b) Value (e.g. height, classification, colour) determined by application of an observation procedure. These
are estimates, with a finite error associated with the value.
The observation error typically has a systematic component, which is similar for all estimates made using
the same procedure, and a random component, associated with the particular application instance of the
observation procedure. If potential errors in a property value are important in the context of a data analysis or
6 © ISO 2011 – All rights reserved

ISO 19156:2011(E)
processing application, then the details of the act of observation which provided the estimate of the value are
required.
7.1.2 Observation
An observation is an act associated with a discrete time instant or period through which a number, term or other
[2]
symbol is assigned to a phenomenon . It involves application of a specified procedure, such as a sensor,
instrument, algorithm or process chain. The procedure may be applied in-situ, remotely, or ex-situ with respect
to the sampling location. The result of an observation is an estimate of the value of a property of some feature.
Use of a common model allows observation data using different procedures to be combined unambiguously.
The observation itself is also a feature, since it has properties and identity.
Observation details are important for data discovery and for data quality estimation.
The observation could be considered to carry “property-level” instance metadata, which complements the
dataset-level and feature-level metadata that have been conventionally considered (e.g. ISO 19115).
NOTE ISO 19115-2:2009 provides MI_Event, which plays a similar role to OM_Observation in the context of image
capture.
7.1.3 Observation properties
An observation results in a value being assigned to a phenomenon. The phenomenon is a property of a
feature, the latter being the feature-of-interest of the observation. The observation uses a procedure, which is
[1][2]
often an instrument or sensor , but may be a process chain, human observer, an algorithm, a computation
or simulator. The key idea is that the observation result is an estimate of the value of some property of the
feature-of-interest, and the other observation properties provide context or metadata to support evaluation,
interpretation and use of the result.
The relationship between the properties of an observation and those of its feature-of-interest is key to the
semantics of the model. This is further elaborated in D.3.
7.1.4 Observation location
The principal location of interest is usually associated with the ultimate feature-of-interest.
However, the location of the feature-of-interest may not be trivially available. For example: in remote sensing
applications, a complex processing chain is required to geolocate the scene or swath; in feature-detection
applications the initial observation may be made on a scene, but the entity to be detected, which is the ultimate
feature-of-interest, occupies some location within it. The distinction between the proximate and ultimate
feature-of-interest is a key consideration in these cases.
Other locations appear in various scenarios. Sub-sampling at locations within the feature-of-interest may occur.
The procedure may involve a sensor located remotely from the ultimate feature-of-interest (e.g. remote sensing;
or where specimens are removed from their sampling location and observations made ex-situ). Furthermore,
the location of the feature-of-interest may be time-dependent.
The model is generic. The geospatial location of the feature-of-interest may be of little or no interest for some
observations (e.g. live specimens, observations made on non-located things like chemical species).
For these reasons, a generic Observation class does not have an inherent location property. Relevant location
information should be provided by the feature-of-interest, or by the observation procedure, according to the
specific scenario.
NOTE In contrast to spatial properties, some temporal properties are associated directly with an observation (7.2.2.2;
7.2.2.3). This is a consequence of the fact that an observation is a kind of ‘event’ so its temporal characteristics are
fundamental, rather than incidental.
ISO 19156:2011(E)
7.1.5 Result types
Observation results may have many datatypes, including primitive types like category or measure, but also
more complex types such as time, location and geometry. Complex results are obtained when the observed
property requires multiple components for its encoding. Furthermore, if the property varies on the feature-of-
interest, then the result is a coverage, whose domain extent is the extent of the feature. In a physical realization,
the result will typically be sampled discretely on the domain, and may be represented as a discrete coverage.
The result type may be used as a basis for defining specialized observation types.
7.1.6 Measurements
[1][5][10][11][19]
In conventional measurement theory (e.g. ) the term “measurement” is used. However, a distinction
[2][12][21]
between measurement and category-observation has been adopted in more recent work so the term
“observation” is used here for the general concept. “Measurement” may be reserved for cases where the result
is a numerical quantity.
7.2 Observation schema
7.2.1 Packaging
The observation schema is organized in one package containing eleven leaf packages corresponding to the
conformance classes defined in 2.2, with dependencies on several other packages from International Standards
covering geographic information, on the General Feature Instance package (C.2) and the Temporal Coverage
package (C.3). The inter-package dependencies are shown in Figure 1. The core observation package is
documented in this subclause. The specialized observations are documented in Clause 8.
8 © ISO 2011 – All rights reserved

ISO 19156:2011(E)
ISO 19115:2003 Metadata (Corrigendum)
ISO 19108:2002 Temporal Schema
ISO 19109 Application Schema
ISO 19107:2003 Spatial Schema
General Feature Instances
ISO 19123:2005 Coverages
ISO/TS 19103:2005 Schema Language
Temporal Coverages
Observation schema
observation
measurement temporalObservation
categoryObservation geometryObservation
countObservation coverageObservation
pointCoverageObservation
truthObservation
timeSeriesObservation
complexObservation
Figure 1 — Package dependencies of the observation schema
7.2.2 OM_Observation
7.2.2.1 General
The class OM_Observation (Figure 2) is an instance of the «metaclass» GF_FeatureType (ISO 19109), which
therefore represents a feature type. OM_Observation shall support five attributes and six associations, and
shall be subject to four constraints.
ISO 19156:2011(E)
« m e ta cl a ss»
« Fe a tu re T yp e »
MD_Metadata
GF_FeatureType OM_Process
1 + p ro ce d u re
0 .1
+ m e ta d a ta
« i n sta n ce O f»
+ th e G F_ Fe a tu re T yp e 1 P ro ce ssUse d
M e ta d a ta
« Fe a tu re T yp e »
GFI_Feature
+ g e n e ra te d O b se rva ti o n 0 .*
+ fe a tu re O fIn te re st « Fe a tu re T yp e »
Do m a i n OM_Observation
+ p a ra m e te r: Na m e d V a l u e [0 .*]
+ p ro p e rtyV a l u e P ro vi d e r + p h e n o m e n o n T i m e : T M _ O b j e ct
+ re su l tQ u a l i ty: DQ _ E l e m e n t [0 .*]
0 .*
+ re su l tT i m e : T M _ In sta n t
+ ca rri e rO fCh a ra cte ri sti cs + va l i d T i m e : T M _ P e ri o d [0 .1 ]
0 .*
P h e n o m e n o n
constraints
+ o b se rve d P ro p e rty {o b se rve d P ro p e rty sh a l l b e a p h e n o m e n o n
« m e ta cl a ss»
GF_PropertyType a sso ci a te d wi th th e fe a tu re O fIn te re st}
{p ro ce d u re sh a l l b e su i ta b l e fo r o b se rve d P ro p e rty}
{ro o t}
{re su l t typ e sh a l l b e su i ta b l e fo r o b se rve d P ro p e rty}
{a p a ra m e te r.n a m e sh a l l n o t a p p e a r m o re th a n
o n ce }
+ re l a te d O b se rva ti o n
0 .*
0 .*
Ra n g e
+ re su l t
« Da ta T yp e »
NamedValue
ObservationContext
« typ e »
+ n a m e : G e n e ri cNa m e Any
+ ro l e : G e n e ri cNa m e
+ va l u e : A n y
{ro o t}
Figure 2 — The basic Observation type
7.2.2.2 phenomenonTime
The attribute phenomenonTime:TM_Object shall describe the time that the result (7.2.2.9) applies to the
property of the feature-of-interest (7.2.2.7). This is often the time of interaction by a sampling procedure (9.1.3)
or observation procedure (7.2.2.10) with a real-world feature.
NOTE The phenomenonTime is the temporal parameter normally used in geospatial analysis of the result.
If the observedProperty of an observation is ‘occurrence time’ then the result should be the same as the
phenomenonTime.
7.2.2.3 resultTime
The attribute resultTime:TM_Instant shall describe the time when the result became available, typically when
the procedure (7.2.2.10) associated with the observation was completed. For some observations, this is
identical to the phenomenonTime. However, there are important cases where they differ.
EXAMPLE 1 Where a measurement is made on a specimen in a laboratory, the phenomenonTime is the time the
specimen was retrieved from its host, while the resultTime is the time the laboratory procedure was applied.
EXAMPLE 2 The resultTime also supports disambiguation of repeat measurements made of the same property of a
feature using the same procedure.
EXAMPLE 3 Where sensor observation results are post-processed, the resultTime is the post-processing time, while
the phenomenonTime is the time of initial interaction with the world.
EXAMPLE 4 Simulations can estimate the values for phenomena in the future or past. The phenomenonTime is the
time that the result applies to, while the resultTime is the time that the simulation was executed.
10 © ISO 2011 – All rights reserved

ISO 19156:2011(E)
7.2.2.4 validTime
If present, the attribute validTime:TM_Period shall describe the time period during which the result is intended
to be used.
NOTE This attribute is commonly required in forecasting applications.
7.2.2.5 parameter
If present, the attributes parameter:NamedValue shall describe an arbitrary event-specific parameter. This
might be an environmental parameter, an instrument setting or input, or an event-specific sampling parameter
that is not tightly bound to either the feature-of-interest (7.2.2.7) or to the observation procedure (7.2.2.10). To
avoid ambiguity, there shall be no more than one parameter with the same name.
NOTE Parameters that are tightly bound to the procedure can be recorded as part of the procedure description.
In some contexts, the Observation::procedure (7.2.2.10) is a generic or standard procedure, rather than an
event-specific process. In this context, parameters bound to the observation act, such as instrument settings,
calibrations or inputs, local position, detection limits, asset identifier, operator, may augment the description of
a standard procedure.
EXAMPLE A time sequence of observations of water quality in a well might be made at variable depths within the
well. While these can be associated with specimens taken from the well at this depth as the features-of-interest, a more
common approach is to identify the well itself as the feature-of-interest, and add a “samplingDepth” parameter to the
observation (Figure 3). The sampling depth is of secondary interest compared to the temporal variation of water quality at
the site.
W e ll BH5 6 7
+ fe a tu re O fIn te re st + fe a tu re O fIn te re st
+ fe a tu re O fIn te re st
W Q -BH5 6 7 -2 0 0 9 -8 -1 :
W Q -BH5 6 7 -2 0 0 9 -8 -2 : W Q -BH5 6 7 -2 0 0 9 -8 -3 :
O M _ O bs e rv a tion
O M _ O bs e rv a tion O M _ O bs e rv a tion
p a ra m e te r = "d e p th = 3 ,5 m "
p a ra m e te r = "d e p th = 5 ,6 m " p a ra m e te r = "d e p th = 7 ,1 m "
Figure 3 — (Example) Observation instances in the same well at different depths,
described using the ‘parameter’ attribute
7.2.2.6 resultQuality
If present, the attributes resultQuality:DQ_Element shall describe the quality of the result (7.2.2.9). This
instance-specific description complements the description of the observation procedure (7.2.2.10), which
provides information concerning the quality of all observations using this procedure. The quality of a result may
be assessed following the procedures in ISO 19157. Multiple measures may be provided.
7.2.2.7 Domain
The association Domain shall link the OM_Observation to the GFI_Feature (C.2.1) that is the subject of the
observation and carries the observed property. This feature has the role featureOfInterest with respect to
the observation. This feature is the real-world object whose properties are under observation, or is a feature
intended to sample the real-world object, as described in Clause 9 of this International Standard. An observation
instance serves as a propertyValueProvider for its feature-of-interest.
ISO 19156:2011(E)
7.2.2.8 Phenomenon
The association Phenomenon shall link the OM_Observation to the GF_PropertyType for which the OM_
Observation:result (7.2.2.9) provides an estimate of its value. The property type has the role observedProperty
with respect to the observation.
The observed property shall be a phenomenon associated with the feature-of-interest.
An observed property may be, but need not be, modelled as a property (in the sense of the General Feature
Model) in a formal application schema that defines the type of the feature-of-interest.
An instance of GF_PropertyType shall describe a property that is either assignable or observable (7.1.2), such
as “temperature”, “height”, “colour”, “material”. A property type may be an operation or function such as a
spatiotemporal coverage. Property-type definitions may be organized into a hierarchy or ontology and managed
in a register and catalogued to support discovery functions. The observed property supports semantic or
thematic classification of observations, which is useful for discovery and data fusion.
NOTE In general, the value of a specific observedProperty can be associated with different feature types in different
observations, thus allowing the results of observations made in different projects or campaigns, and even from different
disciplines, to be combined when required. A property-type register used in observations is most useful if each property
type is not tied to a single feature type, or if equivalence relationships between similar property types from different feature
types are provided.
7.2.2.9 Range
The association Range shall link the OM_Observation to the value generated by the procedure. The value has
the role result with respect to the observation. The type of the result is shown as “Any”, since it may represent
the value of any feature property.
[20]
NOTE 1 OGC SWE Common provides a model suitable for describing many kinds of observation results.
The type of the observation result shall be consistent with the observed property, and the scale or scope for
the value shall be consistent with the quantity or category type. If the observed property (7.2.2.8) is a spatial
operation or function, the type of the result may be a coverage.
NOTE 2 In some contexts, particularly in earth and environmental sciences, the term “observation” is used to refer to
the result itself.
7.2.2.10 ProcessUsed
The association ProcessUsed shall link the OM_Observation to the OM_Process (7.2.3) used to generate the
result. The process has the role procedure with respect to the observation. A process might be responsible for
more than one generatedObservation.
The OM_Process shall be suitable for the observed property. As a corollary, details of the observed property
are constrained by the procedure used.
EXAMPLE Observed radiance wavelength is determined by the response characteristics of the sensor.
A description of the observation procedure provides or implies an indication of the reliability or quality of the
observation result.
7.2.2.11 Metadata
If present, the association Metadata shall link the OM_Observation to descriptive metadata.
7.2.2.12 Constraints — Consistency with domain model
The type of the feature-of-interest is defined in an application schema (ISO 19109). This may be part of a
domain model, or may be from a cross-domain model, such as Sampling Features (Clause 9). The feature type
12 © ISO 2011 – All rights reserved

ISO 19156:2011(E)
defines its set of properties. For consistency, the feature-of-interest shall carry the observed property as part
of the definition of its type (e.g. Figure 4).
EXAMPLE A feature type “Pallet” might be defined as having the attribute “mass
...