This GML application schema defines a JSON encoding of the the OMSF implementation model compliant with the GeoJSON Feature model defined in RFC 7946.
The GeoJSON specification explicitly forbids 'extending' the GeoJSON types, including the Feature, but at the same time it is allowed to use additional properties (called foreign members) in GeoJSON documents. The way this requirement is interpreted in this project, is that you cannot require additional foreign members to be included in a GeoJSON Feature, or change any aspect of the Feature properties defined in the specification. So to be compliant with the GeoJSON specification and thus improve interoperability with existing client software, the decision has been made to use the GeoJSON Feature type as-is, and to leverage the 'properties' JSON object for encoding the O&M properties. Requiring the use of particular JSON content inside the 'properties' is not interpreted as extending the Feature type, as this 'properties' is allowed to contain any JSON object. In addition to the OMSF properties, any additional properties are also allowed inside the 'properties' of OMSF GeoJSON Features. Also, attention has been paid to ensure that the OMSF properties are simple enough to be interpreted correctly by typical existing client software.
Example of a omsf:MeasureObservation encoded in GeoJSON:
{
"type": "Feature",
"id": "f-1",
"geometry": {
"type": "Point",
"coordinates": [
24.96131,
60.20307
]
},
"properties": {
"featureType": "MeasureObservation",
"phenomenonTime": "2017-08-17T12:00:00Z",
"resultTime": "2017-08-17T12:01:25Z",
"procedureName": "Meteorological surface observations",
"procedureReference": "http://xml.fmi.fi/process/met-surface-observations",
"observedPropertyTitle": "Air temperature",
"observedProperty": "http://vocab.nerc.ac.uk/collection/P07/current/CFSN0023/",
"observerName": "Vaisala AWS310",
"platformName": "Helsinki Kumpula weather observation station",
"ultimateFeatureOfInterestName": "Helsinki Kumpula",
"ultimateFeatureOfInterestReference": "http://sws.geonames.org/843429/about.rdf",
"result": 10.1,
"unitOfMeasureTitle": "Degree Celsius",
"unitOfMeasure": "http://www.opengis.net/def/uom/UCUM/degC"
}
}
MeasureTimeseriesObservation example:
{
"type" : "Feature",
"id": "f-1",
"geometry": {
"type": "Point",
"coordinates": [ 24.96131, 60.20307 ]
},
"properties": {
"featureType": "MeasureTimeseriesObservation",
"phenomenonTimeStart": "2017-08-17T12:00:00Z",
"phenomenonTimeEnd": "2017-08-17T18:00:00Z",
"resultTime": "2017-08-17T12:11:20Z",
"procedureName": "Meteorological surface observations",
"procedureReference": "http://xml.fmi.fi/process/met-surface-observations",
"observedPropertyTitle": "Air temperature",
"observedProperty": "http://vocab.nerc.ac.uk/collection/P07/current/CFSN0023/",
"observerName": "Vaisala AWS310",
"platformName": "Helsinki Kumpula weather observation station",
"ultimateFeatureOfInterestName": "Helsinki Kumpula",
"ultimateFeatureOfInterestReference": "http://sws.geonames.org/843429/about.rdf",
"timeStep": [
"2017-08-17T12:00:00Z",
"2017-08-17T13:00:00Z",
"2017-08-17T14:00:00Z",
"2017-08-17T15:00:00Z",
"2017-08-17T16:00:00Z",
"2017-08-17T17:00:00Z",
"2017-08-17T18:00:00Z"
],
"unitOfMeasureTitle": "Degree Celsius",
"unitOfMeasure": "http://www.opengis.net/def/uom/UCUM/degC",
"result": [12.5, 12.0, 11.0, 13.2, 13.5, 14.1, 14.1]
}
}The work versions of validation rules for each observation type have been defined using JSON Schema in feature.json.
The geometry property of the OMSF GeoJSON Feature is the geometry of the proximate feature of interest of the the observation, or if
no proximate feature of interest is available, a representative geometry of the ultimate feature of interest.
Unless stated otherwise, all property names linking to externally referenced resources end with
Reference. The display names for those resources have otherwise identical property names but end with Name. In cases where there is no externally referenceable object to link to the Name property alone without the Reference may be sufficient to convey the required information. There is a notable exception to this rule: the observedProperty and the unitOfMeasure properties do not end with Reference. Both contain identifiers, which typically point to values in an external code list. Both are also accompanied by "display name" properties observedPropertyTitle and unitOfMeasureTitle, but these title properties are never meant to be used without the corresponding code list property.
Other OMSF properties expected to be used in each of the observation type are given in the tables below.
These properties are defined for all the Observation types:
| OMSF Property name | JSON property name | Condition | Type | Value |
|---|---|---|---|---|
| phenomenonTime | phenomenonTime | required if the phenomenon time is a time instant | string (date-time) | |
| phenomenonTime | phenomenonTimeStart | required if the phenomenon time is a time range | string (date-time) | |
| phenomenonTime | phenomenonTimeEnd | required if the phenomenon time is a time range | string (date-time) | |
| resultTime | resultTime | required | string (date-time) | |
| stimulusTime | stimulusTime | optional | string (date-time) | |
| validTime | validTimeStart | optional | string (date-time) | |
| validTime | validTimeEnd | optional | string (date-time) | |
| observer | observerName | optional | string | |
| observer | observerReference | optional | string (URI) | link to Observer feature |
| platform | platformName | optional | string | |
| platform | platformReference | optional | string (URI) | link to Platform feature |
| procedure | procedureName | optional | string | |
| procedure | procedureReference | optional | string (URI) | link to Procedure feature |
| observedProperty | observedPropertyTitle | optional | string | |
| observedProperty | observedProperty | required | string (URI) | external reference to a code list |
| proximateFeatureOfInterest | proximateFeatureOfInterestName | optional | string | |
| proximateFeatureOfInterest | proximateFeatureOfInterestReference | optional | string (URI) | external reference |
| ultimateFeatureOfInterest | ultimateFeatureOfInterestName | optional | string | |
| ultimateFeatureOfInterest | ultimateFeatureOfInterestReference | optional | string (URI) | external reference |
| metadata | metadataReference | optional | string (URI) | external reference |
In addition to the common properties listed above, GenericObservation has the following properties:
| OMSF Property name | JSON property name | Condition | Type | Value |
|---|---|---|---|---|
| n/a (feature type) | featureType | required | string | fixed 'GenericObservation' |
| result | resultReference | required | string (URI) | external reference |
In addition to the common properties listed above, MeasureObservation has the following properties:
| OMSF Property name | JSON property name | Condition | Type | Value |
|---|---|---|---|---|
| n/a (feature type) | featureType | required | string | fixed 'MeasureObservation' |
| result | result | required | number | |
| result | unitOfMeasureTitle | optional | string | Name of the UoM |
| result | unitOfMeasure | optional | string (uri) | an URI pointing to the remote definition of the UoM |
In addition to the common properties listed above, CategoryObservation has the following properties:
| OMSF Property name | JSON property name | Condition | Type | Value |
|---|---|---|---|---|
| n/a (feature type) | featureType | required | string | fixed 'CategoryObservation' |
| result | result | required | string | URI reference recommended indicating both the codelist and the value |
In addition to the common properties listed above, TruthObservation has the following properties:
| OMSF Property name | JSON property name | Condition | Type | Value |
|---|---|---|---|---|
| n/a (feature type) | featureType | required | string | fixed 'TruthObservation' |
| result | result | required | boolean |
In addition to the common properties listed above, CountObservation has the following properties:
| OMSF Property name | JSON property name | Condition | Type | Value |
|---|---|---|---|---|
| n/a (feature type) | featureType | required | string | fixed 'CountObservation' |
| result | result | required | integer |
In addition to the common properties listed above, MeasureTimeseriesObservation has the following properties:
| OMSF Property name | JSON property name | Condition | Type | Value |
|---|---|---|---|---|
| n/a (feature type) | featureType | required | string | fixed 'MeasureTimeseriesObservation' |
| timeStep | timeStep | required | array of string (date-time) | |
| result | unitOfMeasureTitle | optional | string | Name of the UoM |
| result | unitOfMeasure | optional | string (uri) | an URI pointing to the remote definition of the UoM |
| result | result | required | array of number |