Shape as primitive with representations.

[CresitelloDittmar, Mark]

All,

I have been thinking on the discussion we had at the running meeting
yesterday, about modeling Shape as a primitive (ala 'datetime') with
multiple Representations.

Mainly, I'm looking to see what the end-point would be, what does this look
like in an annotated VOTable?
Below is a pseudo element from the Field-of-View prototype which simply
connects an Object with a Shape, I've shown the mango:Ellipse
representation for the shape.
   1) Is the MIVOT serialization of the elements as modeled elements
   2) possible annotation for a Primitive type with different
representations.
         a) an XML  representation (wanted something that would allow
reference to VOTable FIELD
         b) as the shape portion of an STC-S string

Outside of 'datetime', we have one example of this in the current modeling.
  * Quantity:  The IVOA base model describes Quantity type, and there is a
single representation defined in the model (sort of).
        "allows mapping of these structured DataType-s directly to single
FIELDs or PARAMs.  Here, the unit specified on those VOTable elements is
assumed to be mapped to the unit on the Quantity ATTRIBUTE."

For Shape, we would need more formal representation(s)
   * simple string representation(s) such as STC-S string (part), or DALI
   * something that allows reference to VOTable FIELD/PARAM, either in
VOTable or MIVOT or both

Questions:
   * Where would these representations live? in the Shape standard?
   * How would we indicate the representation being used?  I used a 'rep'
node with vo-dml ID style notation.

Mark

==================================================================================

  # Using modeled DataTypes.

  <INSTANCE dmid="_spacesys_icrs" dmrole="" dmtype="coords:SpaceSys">

    <INSTANCE dmid=“_spaceframe_icrs”
dmrole="coords:PhysicalCoordSys.frame" dmtype="coords:SpaceFrame">

      <ATTRIBUTE dmrole="coords:SpaceFrame.spaceRefFrame"
dmtype="ivoa:string" value="ICRS" />

        <INSTANCE dmrole="coords:SpaceFrame.refPosition"
dmtype="coords:StdRefLocation">

          <ATTRIBUTE dmrole="coords:StdRefLocation.position"
dmtype="ivoa:string" value="BARYCENTER"/>

        </INSTANCE>

    </INSTANCE>

  </INSTANCE>

  <INSTANCE dmtype=“fov:FoV”>

    <ATTRIBUTE dmrole=“fov:FoV.name” dmtype="ivoa:string” value=“Instrument
FOV”/>

    <REFERENCE dmref="_spaceframe_icrs" dmrole=“fov:Shape.frame” />

    <COLLECTION dmrole=“fov:FoV.shape”>

      <INSTANCE dmtype=“shape:Ellipse”>

        <INSTANCE dmrole=“shape:Ellipse.center” dmtype=shape:SkyPoint>

            <ATTRIBUTE dmrole=“shape:SkyPoint.lon"
dmtype="ivoa:RealQuantity" ref="RA_ICRS" unit="deg"/>

            <ATTRIBUTE dmrole=“shape:SkyPoint.lat"
dmtype="ivoa:RealQuantity" ref="DE_ICRS" unit="deg"/>

        </INSTANCE>

        <ATTRIBUTE dmrole=“shape:Ellipse.semiMajorAxis”
dmtype=“ivoa:RealQuantity” ref=“FOV_SemiMajor” unit=“arcsec”/>

        <ATTRIBUTE dmrole=“shape:Ellipse.semiMinorAxis”
dmtype=“ivoa:RealQuantity” ref=“FOV_SemiMinor” unit=“arcsec”/>

        <ATTRIBUTE dmrole=“shape:Ellipse.angle” dmtype=“ivoa:RealQuantity”
ref=“FOV_RotAngle” unit=“deg”/>

      </INSTANCE>

    </COLLECTION>

  </INSTANCE>


  # Using Representations defined in a referenceable standard.

  #   * Here I show the Shape model defining the Primitive type with
packages defining the representation in different formats.

  # XML representation

  <INSTANCE dmtype=“fov:FoV”>

    <ATTRIBUTE dmrole=“fov:FoV.name” dmtype="ivoa:string” value=“Instrument
FOV”/>

    <REFERENCE dmref="_spaceframe_icrs" dmrole=“fov:Shape.frame” />

    <COLLECTION dmrole=“fov:FoV.shape”>

      <PRIMITIVE dmtype=“shape:Ellipse” rep=“shape:rep.xml.SkyEllipse”>

        <VALUE>

          <SKYELLIPSE>

            <CENTER>

              <LONGITUDE ref="RA_ICRS" unit="deg”/>

              <LATITUDE ref="DE_ICRS" unit="deg"/>

            </CENTER>

            <SEMI_MAJOR ref=“FOV_SemiMajor” unit=“arcsec”/>

            <SEMI_MINOR ref=“FOV_SemiMinor” unit=“arcsec”/>

            <ANGLE ref=“FOV_RotAngle” unit=“deg”/>

          <SKYELLIPSE>

        </VALUE>

      </PRIMITIVE>

    </COLLECTION>

  </INSTANCE>



  # STC-S-ish Representation

  <INSTANCE dmtype=“fov:FoV”>

    <ATTRIBUTE dmrole=“fov:FoV.name” dmtype="ivoa:string” value=“Instrument
FOV”/>

    <REFERENCE dmref="_spaceframe_icrs" dmrole=“fov:Shape.frame” />

    <COLLECTION dmrole=“fov:FoV.shape”>

      <PRIMITIVE dmtype=“shape:Ellipse” rep=“shape:rep.stc-s.Ellipse”>

        <VALUE>Ellipse 154.32 -11.38 23 18 43.710</VALUE>

      </PRIMITIVE>

    </COLLECTION>

  </INSTANCE>
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