Short description of the O&M standard

The OGC Observations and Measurements (O & M) standard specifies a conceptual model and exchange format for observations, and for features involved in sampling when making observations. Such observations are typically the result of measurements utilizing different kinds of sensors. Observations which are queried from a Sensor Observation Service (SOS) are typically encoded using the O&M data model and format.

The Role of O&M in SDDI

Currently, the Sensor Observation Service is in use in the SSD district London QEOP. The SOS facades has been set up for the following two sensors:

  • Weather stations - The weather stations are set up and operated by Intel UK and measure in total 15 properties in the park including temperature, humidity, wind speed etc. The observations are recorded every minute.
  • Smart Meters - The "fake" smart meters for 3 buildings have been set up by TUM, which measure electricity and gas consumption for the buildings every 30 minutes.

Information about observations can be queried using a Sensor Observation Service (SOS) with the help of the GetObservation operation. This operation is designed to query the service for observation data structured according to the O&M specification.

More details about the implementations can be found here.

O&M components

A valid O&M data comprise of the following properties:

  • feature of interest - a feature (so a representation of a real-world object) that carries the property which is observed
  • phenomenon time – time when the observation's result applies
  • result time – time when the observation's result has been created.
  • valid time – the period during which the result may be used.
  • procedure – instance of a process which has performed the observation. This is usually a physical sensor (or sensor system) (e.g., thermometer "t_234") but can also be for example a computation, post-processing step or simulation
  • observed property - description of the property which is observed (e.g. temperature, humidity, wind speed etc.)
  • result - the result value of the observation (e.g. 23 m/s). Can be a scalar value or a complex multi-dimensional array
  • Unit of Measure (uom) - allows the interpretation of the result value.

The different components of an O&M document have been described as follows:

The header information defines the schema and namespaces for the response of GetObservation operation. Followed by the header, sos:observationData defines individual observations encoded according to the O&M standards.

GetObservation Response 
<sos:GetObservationResponse 
    xmlns:sos="http://www.opengis.net/sos/2.0" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:om="http://www.opengis.net/om/2.0" 
    xmlns:gml="http://www.opengis.net/gml/3.2" 
    xmlns:xlink="http://www.w3.org/1999/xlink" 
    xsi:schemaLocation="http://www.opengis.net/sos/2.0 
                        http://schemas.opengis.net/sos/2.0/sosGetObservation.xsd 
                        http://www.opengis.net/om/2.0 
                        http://schemas.opengis.net/om/2.0/observation.xsd 
                        http://www.opengis.net/gml/3.2 
                        http://schemas.opengis.net/gml/3.2.1/gml.xsd">
<sos:observationData>...</sos:observationData>
<sos:observationData>...</sos:observationData>
<sos:observationData>...</sos:observationData>
        ................
        ................
</sos:GetObservationResponse>
Observation Data (in the O&M format) 
<sos:observationData>
    <om:OM_Observation gml:id="o_0252AFD612DB221A86071EFA5180D94772717274">
        <om:type xlink:href="http://www.opengis.net/def/observationType/OGC-OM/2.0/OM_Measurement"/>
        <om:phenomenonTime>
            <gml:TimeInstant gml:id="phenomenonTime_322330">
                <gml:timePosition>2017-06-13T00:30:00.000Z</gml:timePosition>
            </gml:TimeInstant>
        </om:phenomenonTime>
        <om:resultTime xlink:href="#phenomenonTime_322330"/>
        <om:procedure xlink:href="DHT22_Sensor" xlink:title="DHT22_Sensor"/>
        <om:observedProperty xlink:href="Temperature_DHT22" xlink:title="Temperature_DHT22"/>
        <om:featureOfInterest xlink:href="DHT22_Sensor_Munich" xlink:title="DHT22_Sensor_Munich"/>
        <om:result xmlns:ns="http://www.opengis.net/gml/3.2" uom="Celsius" xsi:type="ns:MeasureType">16.8</om:result>
    </om:OM_Observation>
</sos:observationData>


Standard Specification

Specification documents: http://www.opengeospatial.org/standards/om

Implementations / Products

The following selection of products was made by the SDDI team and includes those implementations which are (or likely will be) used in the SSD project and from which we know that they are compatible with the requirements of the Smart Sustainable Data Infrastructure. Please note that the list is not a complete list of available or suitable O&M implementations. The Open Geospatial Consortium provides a catalog of implementations of their standards which can be found at http://www.opengeospatial.org/resource. Note that also the OGC list is not complete and not necessarily completely up-to-date.

  • Name, Type (commercial, Open Source), Link, Short Description, used in which districts?

Additional Information

to be provided

  • Keine Stichwörter