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Features for sampling: Sites and Specimens


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A key aspect of the process of Observation and Measurement is the sampling regime. In the ObservationsAndMeasurements model, this often features as the featureOfInterest.

Since observations may be made on more-or-less any real-world object, the feature of interest may be defined in any application schema, which will generally be domain-specific. Nevertheless, there is a set of feature-types that exist primarily to support observations. These include stations, profiles, sections, area-of-interest, etc, and physical specimens.

Site Model

Schema: XmmlSVN:trunk/sampling/0.1.0

  • Basic Site model and concept, showing relationships with Observations, Specimens, etc

  • More detail of Sites hierarchy, showing some key properties of different site-types:
    More detail of Sites hierarchy, showing some key properties of different site-types


A Site is an identifiable location which may be occupied once, continuously, or re-occupied periodically, for various purposes, particularly making observations or collecting specimens. The generic Site is modelled as an extension (specialisation) of Feature, having
  • an optional surveyDetails property.
  • a set of relatedObservation properties
  • a set of associatedSpecimen properties
  • an optional set of ordered member Sites, such as Stations on a Traverse, Profiles across a Section, Sections through a SolidOfInterest.

Four specializations of Site are defined:

Station - a 0-D site having
  • position - the Point location
  • elevation - the elevation may be given separately if the CRS used forthe position is only 2-D

Profile - a 1-D site having
  • shape - a description of a 1-D geometry
  • explicit begin and end points
  • length - the 1-D size of the feature
  • a set of log properties whose values are Coverages, which may include a CurveSurvey which is specialized coverage recording a set of position-direction observations

Several specializations of Profile are defined:

SurfaceOfInterest - a 2-D site having
  • shape - a description of a 2-D geometry
  • area - the 2-D size of the feature

Several specializations of SurfaceOfInterest are defined:
  • Swath
  • Section

SolidOfInterest - a 3-D site having
  • shape - a description of a 3-D geometry
  • volume - the 3-D size of the feature

Specimen Model



A generic Specimen is modelled as an extension (specialisation) of Feature, adding
  • a location property, to record the location relevant when analysing results of observations on the Specimen (i.e. its original location, not where it is currently stored)
  • a locationMethod property, to record the method used to obtain the location (map, GPS, guess, etc)
  • the sampleTime when the specimen was retrieved
  • a material property, whose value is some text like "rock", "pulp", "calcrete" - the classification schema or vocabulary is indicated using the codeSpace attribute
  • a mass property
  • a (optional) set of processingStep properties, used to record collection, sampling and preparation events associated with the specimen
  • a (optional) set of relatedObservation properties, used to record ObservationsAndMeasurements associated with the specimen
  • a (optional) sampledOn property, which links the specimen to the Site from where it was obtained

We tested the O&M model with a sampling curation project we have and could not deal with this use case "Geologist A take a sample of basalt from Unit X at this site". The specimen has a material property but is missing a 'sampledFeature' property to identify from which feature this specimen has been taken from. Site and Unit X are two different features that plays a different role.

-- EricBoisvert - 09 Jul 2006 - 08:50 (modif from 03 Jul)

I'm currently revising both the O&M model and sampling features as part of OWS-4. The new schema should accommodate this requirement. Specimen is now a specialization of SamplingFeature, so inherits associations with SamplingFeatureRelation class. However, it also has a "sampledFeature" association with AnyFeature (UML version of gml:AbstractFeature).

I will update the TWiki pages as soon as I have completed the main revision of the spec (i.e. within a week or so).

-- SimonCox - 11 Jul 2006

  • I saw that this has been added to the new UML. Regarding SamplingFeature, we already saw this structure, and honestly, we all liked the Station being a Site rather than a SamplingFeature. This said, I think I understand why you organised all these entities under SamplingFeature, but virtually anything could be can be use to support sampling, many thing would need to be migrated under SamplingFeature. Wouldn't it be wiser to isolate Speciment in such a way that any other domain can reuse Samples/Specimen without creating a sub-class of SamplingFeature ? -- EricBoisvert - 12 Jul 2006 - 00:41
Topic attachments
I Attachment Action Size Date Who Comment
site.PNGPNG site.PNG manage 24.2 K 04 Jan 2006 - 19:36 SimonCox Top level site model
siteHierarchy.PNGPNG siteHierarchy.PNG manage 33.0 K 04 Jan 2006 - 19:24 SimonCox Specialized site types
siteTop.PNGPNG siteTop.PNG manage 8.6 K 10 Nov 2005 - 18:14 SimonCox Top level site model
specimen.PNGPNG specimen.PNG manage 27.8 K 05 Jan 2006 - 08:31 SimonCox Basic Specimen model
Topic revision: r26 - 15 Oct 2010, UnknownUser

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