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Managing different views of data

This presentation discusses the management of different views of data using OGC/ISO meta-models for information objects, features, coverages, and observations. It explores the concept of digital objects corresponding to identifiable, typed objects in the real world and how they are represented in conceptual object models. The presentation also covers the variation of property values across domains of interest and the estimation of property values through observation processes.

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Managing different views of data

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  1. Managing different views of data Simon Cox CSIRO Exploration and Mining 29 November 2006

  2. Outline • OGC/ISO meta-models for information objects • Features and coverages • Property estimation events • Observations • Transforming viewpoints Observations, Features and Coverages

  3. 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 … Conceptual object model: features Observations, Features and Coverages

  4. ISO 19101, 19109 General Feature Model • Properties include • attributes • associations between objects • value may be object with identity • operations • Metaclass diagram Observations, Features and Coverages

  5. Geology domain model - feature type catalogue Borehole • collar location • shape • collar diameter • length • operator • logs • related observations • … • Conceptual classification • Multiple geometries Fault • shape • surface trace • displacement • age • … License area • issuer • holder • interestedParty • shape(t) • right(t) • … Ore-body • commodity • deposit type • host formation • shape • resource estimate • … Geologic Unit • classification • shape • sampling frame • age • dominant lithology • … Observations, Features and Coverages

  6. Water resources feature type catalogue • Aquifer • Storage • Stream • Well • Entitlement • Observation • … Observations, Features and Coverages

  7. Meteorology feature type catalogue • Front • Jetstream • Tropical cyclone • Lightning strike • Pressure field • Rainfall distribution • … • Bottom two are a different kind of feature Observations, Features and Coverages

  8. Variation of a property across the domain of interest For each element in a spatio-temporal domain, a value from the range can be determined Used to analyse patterns and anomalies, i.e. to detect features (e.g. storms, fronts, jetstreams) Discrete or continuous domain Domain is often a grid Time-series are coverages over time (x2,y2) Spatial function: coverage (x1,y1) Observations, Features and Coverages

  9. ISO 19123 Coverage model Observations, Features and Coverages

  10. Discrete coverage model Observations, Features and Coverages

  11. Features vs Coverages • Feature • object-centric • heterogeneous collection of properties • “summary-view” • Coverage • property-centric • variation of homogeneous property • patterns & anomalies • Both needed; transformations required Observations, Features and Coverages

  12. A Row gives properties of one feature • A Column = variation of a single property across a domain (i.e. set of locations) “Cross-sections” through collections Observations, Features and Coverages

  13. Assignment of property values • For each property of a feature, the value is either • asserted • name, owner, price, boundary (cadastral feature types) • estimated • colour, mass, shape (natural feature types) • i.e. error in the value is of interest Observations, Features and Coverages

  14. Value estimation process: observation • An Observation is a kind of “Event Feature type”, whose result is a value estimate, • and whose other properties provide metadata concerning the estimation process Observations, Features and Coverages

  15. Observation model – Value-capture-centric view • An Observation is an Event whose result is an estimate of the valueof some Propertyof theFeature-of-interest,obtained using a specified Procedure Observations, Features and Coverages

  16. A Cell describes the value of a single property on a feature, often obtained by observation or measurement • A Row gives properties of one feature • A Column = variation of a single property across a domain (i.e. set of features) “Cross-sections” through collections Observations, Features and Coverages

  17. 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 Observations, Features and Coverages

  18. These must match if the observation is coherent with the feature property Some properties have interesting types … Observations support property assignment Observations, Features and Coverages

  19. 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 • Variable values may be described as a Coverage over some axis of the feature Observations, Features and Coverages

  20. 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 Observations, Features and Coverages

  21. Observations, features and coverages Same property onmultiple samplesis a another kindof coverage Multiple observations different features, one property:coverage evidence A property-valuemay be a coverage Multiple observations one feature, different properties:feature summary evidence Feature summary Property-valueevidence Observations, Features and Coverages

  22. Features, Coverages & Observations (1) • Observations and Features • An observation provides evidence for estimation of a property value for the feature-of-interest • Features and Coverages (1) • The value of a property that varies on a feature defines a coverage whose domain is the feature • Observations and Coverages (1) • An observation of a property sampled at different times/positions on a feature-of-interest estimates a discrete coverage whose domain is the feature-of-interest • feature-of-interest is one big feature – property value varies within it Observations, Features and Coverages

  23. Features, Coverages & Observations (2) • Observations and Features • An observation provides evidence for estimation of a property value for the feature-of-interest • Features and Coverages (2) • 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 (2) • 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 Observations, Features and Coverages

  24. Conclusions • Feature and coverage viewpoints used for different purposes • Summary vs. analysis • Some values are determined by observation • Sometimes the description of the estimation process is necessary • Transformation between feature and coverage views depends on the “feature-type” • Management of observation evidence depends on feature-of-interest-type • One big feature, with internal variation, vs • Aggregation of many small features Observations, Features and Coverages

  25. Thank You Contact CSIRO Phone 1300 363 400 +61 3 9545 2176 Email enquiries@csiro.au Web www.csiro.au CSIRO Exploration and Mining Name Simon Cox Title Research Scientist Phone +61 8 6436 8639 Email Simon.Cox@csiro.au Web www.seegrid.csiro.au

  26. Sensor service • 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 optional – probably required for dynamic sensor use-cases Observations, Features and Coverages

  27. getFeature, type=Observation WFS/Obs SOS getObservation getCoverage(result) getCoverage getResult WCS describeSensor getFeatureOfInterest Sensor Registry getRecord WFS getFeature SOS vs WFS, WCS, CS/W? SOS interface is effectively a composition of (specialised) WFS+WCS+CS/W operations e.g. SOS::getResult == “convenience” interface for WCS Observations, Features and Coverages

  28. Some feature types only exist to support observations Observations, Features and Coverages

  29. Observation model • Generic Observation has dynamically typed result Observations, Features and Coverages

  30. Observation specializations • Override result type Observations, Features and Coverages

  31. Observation specializations • Override result type • Primary use-case for “CommonObservation” matches “CoverageObservation” • N.B. CommonObservation is an implementation Observations, Features and Coverages

  32. Observations and Features • An estimated value is determined through observation • i.e. by application of an observation procedure Observations, Features and Coverages

  33. A Cell describes the value of a single property on a feature, often obtained by observation or measurement • A Row gives properties of one feature • A Column = variation of a single property across a domain (i.e. set of features) Invariant property values: cross-sections through collections Observations, Features and Coverages

  34. Variable 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, Features and Coverages

  35. Observations support property assignment Observations, Features and Coverages

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