DirectionVectorType DirectionDescriptionType Change Requests | OGC

Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. 193 A gml:compassPoint is specified by a simple enumeration string type that is declared as follows: simpleType name=CompassPointEnumeration restriction base=string enumeration value=N enumeration value=NNE enumeration value=NE enumeration value=ENE enumeration value=E enumeration value=ESE enumeration value=SE enumeration value=SSE enumeration value=S enumeration value=SSW enumeration value=SW enumeration value=WSW enumeration value=W enumeration value=WNW enumeration value=NW enumeration value=NNW restriction simpleType These directions are necessarily approximate, giving direction with a precision of 22.5°. It is thus generally unnecessary to specify the reference frame, though this may be detailed in the definition of a GML application language. EXAMPLE 1 This form may appear in a data instance as follows: gml:direction gml:DirectionDescription gml:compassPointWNWgml:compassPoint gml:DirectionDescription gml:direction In addition, the elements to contain text-based descriptions of direction are provided. If the direction is specified using a term from a list, gml:keyword should be used, and the list indicated using the value of the codeSpace attribute. EXAMPLE 2 This form may appear in a data instance as follows: gml:direction gml:DirectionDescription gml:keyword codeSpace=http:my.big.orgtermsdirectiononshoregml:keyword gml:DirectionDescription gml:direction If the direction is described in prose, gml:direction or gml:reference should be used, allowing the value to be included inline or by reference. EXAMPLE 3 This form may appear in a data instance as follows: gml:direction gml:DirectionDescription gml:directionTowards the lighthousegml:direction gml:DirectionDescription gml:direction 194 Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. gml:direction gml:DirectionDescription gml:reference xlink:href=http:my.big.orglogbook20021127paragraph6 gml:DirectionDescription gml:direction 18 GML schema — Observations

18.1 Observations

A GML observation models the act of observing, often with a camera, a person or some form of instrument. An observation feature describes the ―metadata‖ associated with an information capture event, together with a value for the result of the observation. This covers a broad range of cases, including tourist photos not the photo but the act of taking the photo. NOTE This schema is primarily intended to serve for simple observations. Schemas for scientific, technical and engineering observations and measurements will typically require the development of a GML application schema for such observations. See, for example, the Observations and Measurements specification from the Open Geospatial Consortium.

18.2 Observation schema

18.2.1 Overview

This clause describes two kinds of observations, gml:Observation and gml:DirectedObservation. NOTE Observations are described in the schema document observations.xsd. The schema is identified by the following location-independent name using URN syntax: urn:x-ogc:specification:gml:schema-xsd:observation:3.2.1

18.2.2 Observation

The gml:Observation element is declared in the schema as follows: element name=Observation type=gml:ObservationType substitutionGroup=gml:AbstractFeature complexType name=ObservationType complexContent extension base=gml:AbstractFeatureType sequence element ref=gml:validTime element ref=gml:using minOccurs=0 element ref=gml:target minOccurs=0 element ref=gml:resultOf sequence extension complexContent complexType The content model is a straightforward extension of gml:AbstractFeatureType; it automatically has the gml:identifier, gml:description, gml:descriptionReference, gml:name, and gml:boundedBy properties. Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. 195 The gml:validTime element is declared in 14.2.1.3. In this context it describes the time of the observation. Note that this may be a time instant or a time period. EXAMPLE Some examples of simple observations are as follows: gml:Observation gml:validTime gml:TimeInstant gml:timePosition2002-11-12T09:12:00gml:timePosition gml:TimeInstant gml:validTime gml:using xlink:href=http:www.my.orgsensorsthermometer4 gml:target xlink:href=http:www.environment.orgstationsl456 gml:resultOf gml:Quantity uom=C18.4gml:Quantity gml:resultOf gml:Observation gml:Observation gml:validTime gml:TimeInstant gml:timePosition2002-11-12T09:12:00gml:timePosition gml:TimeInstant gml:validTime gml:using xlink:href=http:www.my.orgcamerasleica2 gml:subject xlink:href=http:www.tourist.orgsightsmountain3 gml:resultOf xlink:href=http:www.my.orgphotoslandscape1.jpg gml:Observation gml:Observation gml:validTime gml:TimeInstant gml:timePosition2002-10-25T11:37:25gml:timePosition gml:TimeInstant gml:validTime gml:subject xlink:href=http:www.people.orgkidsabby gml:resultOf xlink:href=myDaughtersPortrait.jpg gml:Observation

18.2.3 using

The gml:using property contains or references a description of a procedure such as a camera used for the observation. It is declared as follows: element name=using type=gml: ProcedurePropertyType complexType name=ProcedurePropertyType sequence minOccurs=0 element ref=gml:AbstractFeature sequence attributeGroup ref=gml:OwnershipAttributeGroup attributeGroup ref=gml:AssociationAttributeGroup complexType

18.2.4 target

The gml:target property contains or references the specimen, region or station which is the object of the observation. This property element is declared in the schema as follows: