XML and Geodesy: A SOPAC Perspective

XML and Geodesy: A SOPAC Perspective

Paul Jamason, Scripps Orbit and Permanent Array Center

IGS Analysis Center Conference, Miami, June 2008


SOPAC Participants

Director: Yehuda BockGPS Analysts:

Peng FangLinette Prawirodirdjo

Programmers:Ruey-Juin ChangPaul JamasonIan MacLeodMelinda Squibb

System Administrator: George Wadsworth


XML: An Overview

XML: eXtensible Markup Language

Framework for sharing structured data Hierarchical tree-like structure Extensible: users define their own elements and documents by

extending base types

Encode data via element names/attributes (self-describing format)

XML schemas Validation: reduce publication of errors

Translate XML documents (instances) to a variety of formats via stylesheets


XML Example: siteOffsets.xml

<siteOffsets xsi:schemaLocation="http://sopac.ucsd.edu/geodesy http://sopac.ucsd.edu/ns/geodesy/1.0.2/reason/procInput/offsets/siteOffsets.xsd><offset>

<fourCharacterID>ldes</fourCharacterID> <geod:sopacSiteID>ldes0000</geod:sopacSiteID> <geod:date>1999-10-16T00:00:00</geod:date> <geod:cause>co-seismic</geod:cause> <comments>Hector Mine EQ</comments>

<offsetComponentMagnitude> <geod:directionalComponent>north</geod:directionalComponent> <geod:magnitude uom="mm">178.287</geod:magnitude> <geod:sigma uom="mm">2.361</geod:sigma> </offsetComponentMagnitude> -- SNIP -- </offset></siteOffsets>

http://garner.ucsd.edu/pub/gamit/setup/siteOffsets.xml


XSD Example: siteOffsets.xsd<?xml version="1.0"?>

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://sopac.ucsd.edu/geodesy" xmlns:geod="http://sopac.ucsd.edu/geodesy" xmlns:gen="http://sopac.ucsd.edu/general" elementFormDefault="qualified" version="1.0.2" xml:lang="en"> <xsd:include schemaLocation="includes.xsd"/> <xsd:import namespace="http://sopac.ucsd.edu/general" schemaLocation="http://sopac.ucsd.edu/ns/general/1.0.0/descriptors/spatialDescriptors.xsd"/>--SNIP--<xsd:complexType name="offsetType"> <xsd:sequence minOccurs="1" maxOccurs="1"> <xsd:element name="fourCharacterID" type="geod:gpsSiteFourCharacterID" minOccurs="1" maxOccurs="1"/> <xsd:element name="date" type="geod:gpsDateType" minOccurs="1" maxOccurs="1"/> <xsd:element name="cause" type="geod:offsetCauseType" minOccurs="1" maxOccurs="1"/>  <xsd:element name="offsetComponentMagnitude" type="geod:offsetComponentMagnitudeType" minOccurs="1" maxOccurs="3"/> </xsd:sequence> </xsd:complexType> <xsd:simpleType name="offsetCauseType"> <xsd:restriction base="xsd:string"> <xsd:enumeration value="co-seismic"/> <xsd:enumeration value="equipment change"/> <xsd:enumeration value="environmental change"/> <xsd:enumeration value="creep event"/> <xsd:enumeration value="monument disruption"/> <xsd:enumeration value="metadata correction"/> <xsd:enumeration value="processing software change"/> <xsd:enumeration value="unknown"/> </xsd:restriction></xsd:schema>


XML: (Dis)Advantages

Advantages Set of standards for

representing data; speak a common data language

Validation reduces publication of errors

Field formatting Limit valid entries (e.g.,

receiver/antenna types) Existing software:

XML schema creation XML instance validation XSLT transformation

Disadvantages Size Speed (validation) Additional work Difficult to visually

interpret XML Schema creation

can be unpleasant Not for large data files


XML and Geodesy: Relevant Standards

Open Geospatial Community (OGC): Geographic Markup Language (GML) http://www.opengeospatial.org/standards Observation Collections Filter Encoding

Dublin Core Metadata Initiative (DCMI) Document-related Classify dates/files/services/creators

Geodesy Standard? Define a set of xml schemas with core spatial,

temporal, nominal parameters, and extend them


Geodesy XML Candidates

Metadata-orientedIGS site logsProcessing setup files

Processing software front-ends (e.g., GAMIT)Bluebooking - NGS geodetic data

submissionOrbitML (GMV) - spacecraft flight

parametersRINEX, SINEX headers


XML: Supporting Software

XML parsers/transformation software available in variety of languagesJavaPerl - Xerces FORTRAN - xmlf90; xmlfortran

XML schema generation software oxygenML for Eclipse

Java class generation XMLBeans


XML and Geodesy at SOPAC: IGS Site Logs

Overview: http://sopac.ucsd.edu/projects/xml

Sample XML IGS Site Log

<igsSiteLog xmlns="http://sopac.ucsd.edu/ns/geodesy/doc/igsSiteLog/2004" xmlns:mi="http://sopac.ucsd.edu/ns/geodesy/doc/igsSiteLog/monumentInfo/2004" xmlns:equip="http://sopac.ucsd.edu/ns/geodesy/doc/igsSiteLog/equipment/2004" xsi:schemaLocation="http://sopac.ucsd.edu/ns/geodesy/doc/igsSiteLog/2004 http://sopac.ucsd.edu/ns/geodesy/doc/igsSiteLog/2004/igsSiteLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

<siteIdentification> <mi:siteName>Scripps 5 - Mt. Soledad</mi:siteName> <mi:fourCharacterID>SIO5</mi:fourCharacterID> <mi:iersDOMESNumber>40460M006</mi:iersDOMESNumber> </siteIdentification>

<siteLocation> <mi:city>La Jolla</mi:city> <mi:state>California</mi:state> <mi:country>USA</mi:country> <mi:approximatePositionITRF> <mi:xCoordinateInMeters>-2456115.13</mi:xCoordinateInMeters> <mi:yCoordinateInMeters>-4768905.79</mi:yCoordinateInMeters> <mi:zCoordinateInMeters>3439232.44</mi:zCoordinateInMeters> <mi:latitude-North>+325024.00</mi:latitude-North> <mi:longitude-East>-1171500.00</mi:longitude-East> <mi:elevation-m_ellips.>185.53</mi:elevation-m_ellips.> </mi:approximatePositionITRF> </siteLocation>

<gnssReceiver> <equip:receiverType>ASHTECH Z-XII3</equip:receiverType> <equip:satelliteSystem>GPS</equip:satelliteSystem> <equip:serialNumber>LP02814</equip:serialNumber> <equip:firmwareVersion>CD00</equip:firmwareVersion> <equip:dateInstalled>2002-05-15T00:00Z</equip:dateInstalled> <equip:dateRemoved>2003-01-09T00:00Z</equip:dateRemoved> </gnssReceiver>

<gnssAntenna> <equip:antennaType>ASH701945B_M</equip:antennaType> <equip:serialNumber>CR519991867</equip:serialNumber> <equip:antennaReferencePoint>BPA</equip:antennaReferencePoint> <equip:marker-arpUpEcc.>0.0083</equip:marker-arpUpEcc.> <equip:dateInstalled>2002-05-15T00:00Z</equip:dateInstalled> <equip:dateRemoved>2004-09-29T00:00Z</equip:dateRemoved> <equip:notes></equip:notes> </gnssAntenna>


XML and Geodesy at SOPAC

Time Series PlottingGPS analysis input

Historical equipment informationSite motion model terms - apriori coordsPhase center information

GPS coordinate data submission/queryingGML Observation CollectionsGML Filter Encoding

GPS time series offsets


XML and Geodesy: Conclusion

SOPAC: support IGS/INDIGO via XML site log implementation

Widely used in other fields

Encapsulate, control, validate metadata

Appeal to IT staffs

Documents

XML and Geodesy: A SOPAC Perspective