[Auscope-geosciml] An issue with ISO DataQuality and UnitsOfMeasure schema [SEC=UNCLASSIFIED]

Mon Oct 12 04:49:52 EDT 2009

Ollie - Its all OK. 

You have to distinguish between the abstract model and the implementation. 

Sometimes they are related by a rule (e.g. the 19136 Annex E, or 19139
encoding rule), but sometimes they are just related by a 'mapping',
particularly if there is a pre-existing implementation that captures the
semantics. 
Thats what has happened in this case. 

It is also explained in Annex D of ISO 19136 (GML) where the GML
implementations of classes from ISO 19103 are explained. 

Simon

--------------------------------------------------------
Simon Cox

European Commission, Joint Research Centre 
Institute for Environment and Sustainability 
Spatial Data Infrastructures Unit, TP 262 
Via E. Fermi, 2749, I-21027 Ispra (VA), Italy 
Tel: +39 0332 78 3652 
Fax: +39 0332 78 6325 
 <mailto:simon.cox at jrc.ec.europa.eu> mailto:simon.cox at jrc.ec.europa.eu 
 <http://ies.jrc.ec.europa.eu/simon-cox>
http://ies.jrc.ec.europa.eu/simon-cox 

SDI Unit:  <http://sdi.jrc.ec.europa.eu/> http://sdi.jrc.ec.europa.eu/ 
IES Institute:  <http://ies.jrc.ec.europa.eu/> http://ies.jrc.ec.europa.eu/ 
JRC:  <http://www.jrc.ec.europa.eu/> http://www.jrc.ec.europa.eu/

--------------------------------------------------------

  _____  

From: auscope-geosciml-bounces at lists.arcs.org.au
[mailto:auscope-geosciml-bounces at lists.arcs.org.au] On Behalf Of
Oliver.Raymond at ga.gov.au
Sent: Monday, 12 October 2009 08:53
To: auscope-geosciml at lists.arcs.org.au
Subject: [Auscope-geosciml] An issue with ISO DataQuality and UnitsOfMeasure
schema [SEC=UNCLASSIFIED]

Hi all,

I have discovered a quirk/bug in the ISO DataQuality UML model and schemas
that we should be aware of, but should not be a show-stopper for us using
ISO DataQuality.

According to the ISO19115 UML model (see diagram below),
gmd:DQ_QuantitativeAttributeAccuracy/result/DQ_QuantitativeResult/valueUnit
is of type gco:UnitOfMeasure (imported from ISO 19103).

However, contrary to the above UML diagram, the ISO19139 XML schema
implementation (gco/basicTypes.xsd) actually imports UnitOfMeasure from GML
(ISO 19136), not from ISO 19103.  As a result, the attributes of
DQ_QuantitativeResult/valueUnit that appear in the XML schema are quite
different to those shown in the ISO 19115 UML diagram.

Snippet from gml/units.xsd....

  <element name="unitOfMeasure" type="gml:UnitOfMeasureType">

    <annotation>

      <documentation>The element gml:unitOfMeasure is a property element to
refer to a unit of measure. This is an empty element which carries a
reference to a unit of measure definition.</documentation>

    </annotation>

  </element>

  <complexType name="UnitOfMeasureType">

    <sequence/>

    <attribute name="uom" type="gml:UomIdentifier" use="required"/>

  </complexType>

  <element name="UnitDefinition" type="gml:UnitDefinitionType"
substitutionGroup="gml:Definition">

    <annotation>

      <documentation>A gml:UnitDefinition is a general definition of a unit
of measure. This generic element is used only for units for which no
relationship with other units or units systems is known.

The content model of gml:UnitDefinition adds three additional properties to
gml:Definition, gml:quantityType, gml:quantityTypeReference and
gml:catalogSymbol.  

The gml:catalogSymbol property optionally gives the short symbol used for
this unit. This element is usually used when the relationship of this unit
to other units or units systems is unknown.</documentation>

    </annotation>

  </element>

  <complexType name="UnitDefinitionType">

    <complexContent>

      <extension base="gml:DefinitionType">

        <sequence>

          <element ref="gml:quantityType" minOccurs="0"/>

          <element ref="gml:quantityTypeReference" minOccurs="0"/>

          <element ref="gml:catalogSymbol" minOccurs="0"/>

        </sequence>

      </extension>

    </complexContent>

  </complexType>

 UML diagram of the GML UnitDefinition class from ISO 19136:

My colleague John Hockaday is contacting the lead author of ISO 19139 to
find out why the schema and the ISO 19115 UML don't match.

Cheers,

Ollie

----------------------------------------------------------------------------
--------------------

Ollie Raymond
National Advice,  Maps and Standards Project

Geoscience Australia

Address: GPO Box 378, Canberra, ACT, 2601, Australia | ABN: 80 091 799 039

Ph: (02) 62499575 | Fax: (02) 62499992 | Email: Oliver.Raymond at ga.gov.au 

Web:
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http://www.ga.gov.au/minerals/research/national/nat_maps/nat_geol_maps.jsp
<http://www.ga.gov.au/geoscience/national> 

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