Observations and Measurements
Encyclopedia
Observations and Measurements (O&M) is an International Standard which defines a conceptual schema encoding for observations, and for features involved in sampling when making observations. While the O&M standard was developed in the context of geographic information system
s, the model is derived from generic patterns proposed by Fowler and Odell, and is not limited to spatial information. O&M is one of the core standards in the OGC Sensor Web Enablement suite, providing the response model for Sensor Observation Service (SOS).
O&M defines a core set of properties for an observation:
The key to the model is the division of the observation and its feature of interest, separating the concerns so that the appropriate information associated with the description of each object. This allows a unified treatment of in situ, ex-situ, and remote-sensed observations. The observation schema may also be understood as a corollary of the General Feature Model from ISO 19101, providing metadata associated with the estimation of the value of a feature property. The Observation model takes a user-centric viewpoint, emphasizing the semantics of the feature-of-interest and its properties. This contrasts with sensor oriented models such as SensorML
, which take a process- and thus provider-centric viewpoint.
Many observations are made to detect the variation of some property in the natural environment, expressed as a spatial function or field, also known as a coverage (ISO 19123:2005). The relationship between observations, features and coverages is explained, in the context of ocean observations an modeling, in a report for GEOSS Architecture Implementation Pilot 3.
The core properties of sampling features are:
encoding (GML Application Schema) is provided for transfer of data:
An experimental OWL
representation of O&M is available: O&M in OWL.
Abstract Specification . The XML
implementation of O&M is published as an Open Geospatial Consortium implementation standard.
The previous version of O&M (Version 1) factored the model into two documents: Part 1 described the Observation Schema, and Part 2 described Sampling Features.
Geographic Information System
A geographic information system, geographical information science, or geospatial information studies is a system designed to capture, store, manipulate, analyze, manage, and present all types of geographically referenced data...
s, the model is derived from generic patterns proposed by Fowler and Odell, and is not limited to spatial information. O&M is one of the core standards in the OGC Sensor Web Enablement suite, providing the response model for Sensor Observation Service (SOS).
Observation Schema
The core of the standard provides the Observation schema. An observation is an act that results in the estimation of the value of a feature property, and 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. Use of a common model for observation metadata allows data to be combined unambiguously, across discipline boundaries. Observation details are also important for data discovery and for data quality estimation. An observation is defined in terms of the set of properties that support these applications.O&M defines a core set of properties for an observation:
- feature of interest
- observed property
- result
- procedure - the instrument, algorithm or process used (which may be described using SensorMLSensorMLSensorML is an approved Open Geospatial Consortium standard. SensorML provides standard models and an XML encoding for describing sensors and measurement processes...
) - phenomenon time - the real-world time associated with the result
- result time - the time when the result was generated
- valid time - the period during which the result may be used
The key to the model is the division of the observation and its feature of interest, separating the concerns so that the appropriate information associated with the description of each object. This allows a unified treatment of in situ, ex-situ, and remote-sensed observations. The observation schema may also be understood as a corollary of the General Feature Model from ISO 19101, providing metadata associated with the estimation of the value of a feature property. The Observation model takes a user-centric viewpoint, emphasizing the semantics of the feature-of-interest and its properties. This contrasts with sensor oriented models such as SensorML
SensorML
SensorML is an approved Open Geospatial Consortium standard. SensorML provides standard models and an XML encoding for describing sensors and measurement processes...
, which take a process- and thus provider-centric viewpoint.
Many observations are made to detect the variation of some property in the natural environment, expressed as a spatial function or field, also known as a coverage (ISO 19123:2005). The relationship between observations, features and coverages is explained, in the context of ocean observations an modeling, in a report for GEOSS Architecture Implementation Pilot 3.
Sampling Features
The standard also provides a schema for Sampling Features. Observations commonly involve sampling of the ultimate feature of interest. Specific sampling features, such as station, specimen, transect, section, are used in many application domains, and common processing and visualization tools are used. The standard defines a common set of sampling feature types classified primarily by spatial dimension, as well as samples for ex-situ observations. The schema includes relationships between sampling features (sub-sampling, derived samples).The core properties of sampling features are:
- sampled feature - which links the sampling artefact with the real-world feature of interest
- related observation
- related sampling feature - linking sampling features into complexes
Data transfer
An XMLXML
Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....
encoding (GML Application Schema) is provided for transfer of data:
An experimental OWL
Web Ontology Language
The Web Ontology Language is a family of knowledge representation languages for authoring ontologies.The languages are characterised by formal semantics and RDF/XML-based serializations for the Semantic Web...
representation of O&M is available: O&M in OWL.
Related documents
O&M is also published as a topic of the Open Geospatial ConsortiumOpen Geospatial Consortium
The Open Geospatial Consortium , an international voluntary consensus standards organization, originated in 1994. In the OGC, more than 400 commercial, governmental, nonprofit and research organizations worldwide collaborate in a consensus process encouraging development and implementation of open...
Abstract Specification . The XML
XML
Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....
implementation of O&M is published as an Open Geospatial Consortium implementation standard.
The previous version of O&M (Version 1) factored the model into two documents: Part 1 described the Observation Schema, and Part 2 described Sampling Features.
External links
- Observations and Sampling Wiki page @ SEEGrid with examples from environmental sciences (no login required)