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Observations, Features, Coverages, SOS

Simon Cox

CSIRO Exploration and Mining

9 September 2006

Observations, Features and Coverages 2 of 27

ISO/OGC Feature Model

Features have properties

A feature-type is characterized by a specific set of properties


ISO 19101, 19109 General Feature Model

Properties include

attributes

associations between objects

value of a property may be a complex object

operations

Metaclass diagram


Conceptual object model: features

Digital objects correspond with identifiable, typed, objects in the real world

mountain, road, specimen, event, tract, catchment, wetland, farm, bore, reach, property, license-area, station

Feature-type is characterised by a specific set of properties

Specimen

ID (name)

description

mass

processing details

sampling location

sampling time

related observation

material

…


Assignment of property values

Each property value is either

i. asserted

name, owner, price, boundary (cadastral feature types)

ii. estimated

colour, mass, shape (natural feature types)

i.e. error in the value is of interest


Observations and Features

An estimated value is determined through observation

i.e. by application of an observation procedure


«FeatureType»Observ ation

+ quality: DQ_Element [0..1]+ responsible: CI_ResponsibleParty [0..1]+ result: Any

«FeatureType»Event

+ eventParameter: TypedValue [0..*]+ time: TM_Object

«DataType»TypedValue

+ property: ScopedName+ value: Any

«Union»Procedure

+ procedureType: ProcedureSystem+ procedureUse: ProcedureEvent

AnyIdentifiableObject

«FeatureType»AnyIdentifiableFeature

AnyDefinition

«ObjectType»Phenomenon

+followingEvent 0..*+precedingEvent 0..*

+generatedObservation

0..*

+procedure 1

+observedProperty1{Definition must be of aphenomenon that is a propertyof the featureOfInterest}

+propertyValueProvider

0..*

+featureOfInterest

1

Observation model – Value-capture-centric view

An Observation is an Event whose result is an estimate of the value of some Property of the Feature-of-interest, obtained using a specified Procedure


Feature of interest

may be any feature type from any domain-model …

observations provide values for properties whose values are not asserted

i.e. the application-domain supplies the feature types


Some feature types only exist to support observations

Station

+ elevation: DirectPosition [0..1]+ position: GM_Point

SamplingFeature

+ responsible: CI_ResponsibleParty [0..1]

Trav erse

Flightline

Profile

+ begin: GM_Point+ end: GM_Point+ length: RelativeMeasure [0..1]

Shape3D

SurfaceOfInterest

+ area: RelativeMeasure [0..1]

Interv al

Shape2D

SolidOfInterest

+ volume: RelativeMeasure [0..1]

Shape1D

SamplingFeatureCollection

constraints{count(member)>=1}

Swath

Section

Surv eyProcedure

Sounding

LidarCloud

Specimen

+ currentLocation: Location [0..1]+ mass: Measure+ material: CV_Coverage

+shape 1+shape 1+shape 1

+member 0..*

+surveyDetails

0..1


Observation model

Generic Observation has dynamically typed result

«FeatureType»Observ ation

+ quality: DQ_Element [0..1]+ responsible: CI_ResponsibleParty [0..1]+ result: Any

«FeatureType»Event

+ eventParameter: TypedValue [0..*]+ time: TM_Object

«DataType»TypedValue

+ property: ScopedName+ value: Any

«Union»Procedure

+ procedureType: ProcedureSystem+ procedureUse: ProcedureEvent

AnyIdentifiableObject

«FeatureType»AnyIdentifiableFeature

AnyDefinition

«ObjectType»Phenomenon

+followingEvent 0..*+precedingEvent 0..*

+generatedObservation

0..*

+procedure 1

+observedProperty1{Definition must be of aphenomenon that is a propertyof the featureOfInterest}


0..*

+featureOfInterest

1


Observation specializations

Override result type


More on property values

Each property value is either constant on the feature instance

e.g. name, identifier

non-constant

colour of a Scene or Swath varies with position

shape of a Glacier varies with time

temperature at a Station varies with time

rock density varies along a Borehole

Variable values may be described as a Coverage over some axis of the feature


Observations and coverages

If the property value is not constant across the feature-of-interest

varies by location, in time

the corresponding observation result is a coverage

individual samples must be tied to the location within the domain, so result is set of e.g.

time-value

position-value

(stationID-value ?)

Time-series observations are a particularly common use-case


«DataType»CV_GeometryValuePair

+ geometry: CV_DomainObject+ value: Record

CV_Coverage

CV_DiscreteCov erage

«DataType»CV_PointValuePair

+ geometry: GM_Point

CV_DiscretePointCov erage

+element 1..*

+collection 0..*

+collection 0..*

+element 1..*



CV_Coverage




CV_DiscretePointCov erage CV_DiscreteTimeInstantCov erage

«DataType»CV_TimeInstantValuePair

+ geometry: TM_Instant

+element 1..*

+collection 0..*

+collection 0..*

+element 1..* +element 1..*

+collection 0..*



CV_Coverage




CV_DiscretePointCov erage CV_DiscreteTimeInstantCov erage

«DataType»CV_TimeInstantValuePair

+ geometry: TM_Instant

CV_DiscreteElementCov erage

«DataType»CV_ElementValuePair

+ geometry: AnyIdentifiableObject+ value: Record

+element 1..*

+collection 0..*

+collection 0..*

+element 1..* +element 1..*

+collection 0..*

+element 1..*

+collection 0..*

Discrete coverage model



CV_Coverage


+element 1..*

+collection 0..*


Observation specializations

Override result type

Primary use-case for “CommonObservation” matches “CoverageObservation”

N.B. CommonObservation is an implementation


SamplingFeature

Specimen


SamplingFeature

Specimen


Observation

Measurement

+ result: RelativeMeasure

Observation

Cov erageObserv ation

+ result: CV_DiscreteCoverage

Mass :Phenomenon

Material :Phenomenon

+observedProperty


+featureOfInterest

+observedProperty


+featureOfInterest

Observations support property assignment

These must match if the observation is coherent with the feature property

N.B. Each “Phenomenon” definition reifies a (Feature) property definition


Invariant property values: cross-sections through collections

Specimen Au (ppm) Cu-a (%) Cu-b (%) As (ppm) Sb (ppm)

ABC-123 1.23 3.45 4.23 0.5 0.34 A Row gives properties of one feature

A Column = variation of a single property across a domain (i.e. set of features)

A Cell describes the value of a single property on a feature, often obtained by observation or measurement


Features, Coverages & Observations (1)


An observation provides an estimate of a property value for the feature-of-interest

Features and Coverages (1)

The values of the same property from a set of features constitutes a discrete coverage over a domain defined by the set of features

Observations and Coverages (1)

A set of observations of the same property on different features provides an estimate of the range-values of a discrete coverage whose domain is defined by the set of features-of-interest

feature-of-interest is lots of little features – property value constant on each one


Variable property values

Some property values are not constant

colour of a Scene or Swath varies with position

shape of a Glacier varies with time

temperature at a Station varies with time

rock density varies along a Borehole


Features, Coverages & Observations (2)


An observation provides an estimate of a property value for the feature-of-interest

Features and Coverages (2)

The value of a property that varies on a feature defines a coverage whose domain is the feature

if this is sampled at discrete times/positions on the feature, the property value may be described as a discrete coverage

Observations and Coverages (2)

An observation of a property sampled at different times/positions on a feature-of-interest estimates a discrete coverage whose domain is the Observation feature-of-interest

feature-of-interest is one big feature – property value varies within it


SamplingFeature

Specimen


Material :Phenomenon

Mass :Phenomenon

Observation

Cov erageObserv ation

+ result: CV_DiscreteCoverage

Observation

Measurement

+ result: RelativeMeasure

Scales :Observ ationProcedure

MicroProbe :Observ ationProcedure


+featureOfInterest

+observedProperty


+featureOfInterest

+observedProperty

+procedure

+procedure

SamplingFeature

Specimen


Observations support property assignment


premises:

O&M is the high-level information model

SOS is the primary information-access interface

SOS can serve:

an Observation (Feature)

getObservation == “getFeature” (WFS/Obs) operation

a feature of interest (Feature)

getFeatureOfInterest == getFeature (WFS) operation

or Observation/result (often a time-series == discrete Coverage)

getResult == “getCoverage” (WCS) operation

or Sensor == Observation/procedure (SensorML document)

describeSensor == “getFeature” (WFS) or “getRecord” (CSW) operation

Sensor service

optional – probably required for dynamic sensor use-cases


SOS vs WFS, WCS, CS/W?

WFS/Obs

getFeature, type=Observation

WCS

getCoverage

getCoverage(result)

Sensor Registry

getRecord

SOS

getObservation

getResult

describeSensor

getFeatureOfInterest

WFSgetFeature

SOS interface is effectively a composition of (specialised) WFS+WCS+CS/W operations

e.g. SOS::getResult == “convenience” interface for WCS

www.csiro.au

Thank You

CSIRO Exploration and Mining

Name Simon Cox

Title Research Scientist

Phone +61 8 6436 8639

Email [email protected]

Web www.seegrid.csiro.au

Contact CSIRO

Phone 1300 363 400

+61 3 9545 2176

Email [email protected]

Web www.csiro.au

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