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SensorThings Entity | Description | Example: NMBGMR Aquifer Monitoring Well | |||
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Metadata | Location | A unique coordinate or area on the surface of the earth | Location in latitude and longitude or UTM easting and Northing (UTM Zone 13, NAD83) | Street Address (possibly with associated latitude and longitude). (e.g. 3960 PRINCE ST) | Location in easting and northing (UTM NAD83 in meters) |
Thing | Some real-world thing with which one or more Sensors are associated | Well Point ID WL-0150 | Sample Pt RT236I | Point of Diversion POD Number A 00008 AS | |
Datastream | A collection of Observations about an ObservedProperty produced by a Sensor associated with a Thing | Time series, Hydrograph | Sample Results | Meter Readings (Quarterly) | |
Datastream/observationType | The type of observation, codified in the Observations and Measurements data standard. Types include Categorical (defined text), Count (integer), Measurement (continuous number), Observation (free text), and TruthObservation (True/False) | Measurement | Categorical or TruthObservation | Measurement | |
Datastream/unitOfMeasurement | A three-item definition of the unit of measurement, including its name, symbol, and link to the definition (preferably to one provided in an established ontology such as http://unitsofmeasure.org/ucum.html or http://qudt.org/) | feet (e.g. http://qudt.org/vocab/unit/FT) | TCR Result | Acre-Feet (e.g. http://qudt.org/vocab/unit/AC-FT) | |
Sensor | The procedure used to provide a Datastream. Can be a particular data recording device model, or a defined procedure followed by a human observer. If applicable, a specific instance (e.g. a sensor model and serial number) | Steel-tape measurement; Continuous acoustic sounder | 9223B-PA (https://www.standardmethods.org/doi/10.2105/SMWW.2882.194) | MCCROMETER Diversion Meter-Meter Number 17147 | |
ObservedProperty | The raw or processed phenomenon (quantitative or qualitative) being measured for the Datastream. Preferably including a link to a definition provided by an established ontology or controlled vocabulary such as the ODM2 Controlled Vocabularies or http://qudt.org/) | Depth to Water Below Ground Surface (BGS) | Analyte (e.g. Coliform (TCR) (3100)) | Mtr Amount | |
OPTIONAL: FeatureOfInterest | The real-world feature that the Observations are about. This may be different from the Thing on which the Sensor is mounted. Can include a JSON-formatted point location or a polygon or collections thereof. | Formation (e.g. https://maps.nmt.edu/maps/data/hydrograph/formation_lu) | Public Water System (head office location or service area boundary) (e.g. Albuquerque Water System PWSID NM3510701) | Water Right (set of relevant points of diversion) | |
Data | Observation | A single measurement value including the result, time values, and other metadata. Information on the ObservedProperty that was measured by what Sensor is provided by the Datastream these observations are in. Features of Interest are linked for each observation as well. Observations are linked to (collected in) Datastreams | Depth Measurement | Sample (e.g. 763391) | Meter Reading |
Observation/result | The actual measured value, with valid values defined in observationType and units defined in unitsOfMeasurement, both provided by Datastream | Depth (e.g. 337.08) | Sample Result (P (Positive/ Coliform found) A (Negative/ Coliform not found)) | Mtr Amount (e.g. 107.948) | |
Observation/phenomenonTime | The date+time (or interval) in ISO 8601 format (YYYY-MM-DDT:HH:MM:SS-Z) when the observation occured | 2019-01-31 00:00:00 | MP (Monitoring Period) (e.g. 01-01-2020 to 01-31-2020) | 1/20/2017-04/05/2017 (Quarterly period for which volume was measured) | |
OPTIONAL: Observation/resultTime | The date+time that the result was generated. May be the same as phenomenonTime | Date (e.g 01-06-2020) | 04/05/2017 (date of meter reading) | ||
OPTIONAL: Observation/validTime | The date+time interval during which the Observation can be used (often used for provisional values that are replaced by QA/QC’d observations) | ||||
OPTIONAL: Observation/resultQuality | A description of the result Quality. Will vary according to agency practice. Can use ODM2 controlled vocabulary for data quality types as a guide. | Precision (e.g. “within two hundredths of a foot”) |
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There are several fully-featured versions of SensorThings that can be hosted:
SensorUp, is the reference implementation of STA. It is a private -sector Canadian company offering with a license + subscription model with customer support and an integrated dashboard and visualization suite. SensorUp is lead by Dr. Steve Liang, who was the lead developer of SensorThings API.
FROST-Server, a free and open-source server written in Java designed for deployment in a Tomcat Java Servlet with a PostGIS database. FROST is developed by the Fraunhofer Society, the main government-supported applied research organization of Germany.
52 North STA, a different free and open-source server written in Java designed as a Spring Boot service with a PostGIS database. 52 North is a non-profit geospatial IT research entity associated with German and EU universities and research consortia that develops open source software as well as provides professional IT consulting.
Geodan GOST, a free and open-source server written in Go designed as a platform-independent Go service connected to a PostGIS database and a basic graphical user interface. Geodan is a private Dutch firm specializing in geospatial business analytics.
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