XML and Geodesy: A SOPAC Perspective

1
XML and Geodesy A SOPAC Perspective

• Paul Jamason, Scripps Orbit and Permanent Array
  Center
• IGS Analysis Center Conference, Miami, June 2008

2
SOPAC Participants

• Director Yehuda Bock
• GPS Analysts
• Peng Fang
• Linette Prawirodirdjo
• Programmers
• Ruey-Juin Chang
• Paul Jamason
• Ian MacLeod
• Melinda Squibb
• System Administrator George Wadsworth

3
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

4
XML Example siteOffsets.xml

• ltsiteOffsets xsischemaLocation"http//sopac.ucsd
  .edu/geodesy http//sopac.ucsd.edu/ns/geodesy/1.0.
  2/reason/procInput/offsets/siteOffsets.xsdgt
• ltoffsetgt
• ltfourCharacterIDgtldeslt/fourCharacterIDgt
• ltgeodsopacSiteIDgtldes0000lt/geodsopacSit
  eIDgt
• ltgeoddategt1999-10-16T000000lt/geoddate
  gt
• ltgeodcausegtco-seismiclt/geodcausegt
• ltcommentsgtHector Mine EQlt/commentsgt
• ltoffsetComponentMagnitudegt
• ltgeoddirectionalComponentgtnorthlt/geod
  directionalComponentgt
• ltgeodmagnitude uom"mm"gt178.287lt/geod
  magnitudegt
• ltgeodsigma uom"mm"gt2.361lt/geodsigma
  gt
• lt/offsetComponentMagnitudegt
• -- SNIP --
• lt/offsetgt
• lt/siteOffsetsgt

http//garner.ucsd.edu/pub/gamit/setup/siteOffsets
.xml
5
XSD Example siteOffsets.xsd
lt?xml version"1.0"?gt ltxsdschema
xmlnsxsd"http//www.w3.org/2001/XMLSchema"
targetNamespace"http//sopac.ucsd.edu/geodesy"
xmlnsgeod"http//sopac.ucsd.edu/geodesy"
xmlnsgen"http//sopac.ucsd.edu/general"
elementFormDefault"qualified" version"1.0.2"
xmllang"en"gt ltxsdinclude
schemaLocation"includes.xsd"/gt ltxsdimport
namespace"http//sopac.ucsd.edu/general"
schemaLocation"http//sopac.ucsd.edu/ns/general/1
.0.0/descriptors/spatialDescriptors.xsd"/gt --SNIP-
- ltxsdcomplexType name"offsetType"gt
ltxsdsequence minOccurs"1" maxOccurs"1"gt
ltxsdelement name"fourCharacterID"
type"geodgpsSiteFourCharacterID" minOccurs"1"
maxOccurs"1"/gt ltxsdelement
name"date" type"geodgpsDateType" minOccurs"1"
maxOccurs"1"/gt ltxsdelement
name"cause" type"geodoffsetCauseType"
minOccurs"1" maxOccurs"1"/gt lt!-- 1
to 3 of north/east/up components here (and their
mags, sigmas) --gt ltxsdelement
name"offsetComponentMagnitude"
type"geodoffsetComponentMagnitudeType"
minOccurs"1" maxOccurs"3"/gt
lt/xsdsequencegt lt/xsdcomplexTypegt
ltxsdsimpleType name"offsetCauseType"gt
ltxsdrestriction base"xsdstring"gt
ltxsdenumeration value"co-seismic"/gt
ltxsdenumeration value"equipment change"/gt
ltxsdenumeration value"environmental
change"/gt ltxsdenumeration
value"creep event"/gt
ltxsdenumeration value"monument disruption"/gt
ltxsdenumeration value"metadata
correction"/gt ltxsdenumeration
value"processing software change"/gt
ltxsdenumeration value"unknown"/gt
lt/xsdrestrictiongt lt/xsdschemagt
6
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

7
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

8
Geodesy XML Candidates

• Metadata-oriented
• IGS site logs
• Processing setup files
• Processing software front-ends (e.g., GAMIT)
• Bluebooking - NGS geodetic data submission
• OrbitML (GMV) - spacecraft flight parameters
• RINEX, SINEX headers

9
XML Supporting Software

• XML parsers/transformation software available in
  variety of languages
• Java
• Perl - Xerces
• FORTRAN - xmlf90 xmlfortran
• XML schema generation software
• oxygenML for Eclipse
• Java class generation
• XMLBeans

10
XML and Geodesy at SOPAC IGS Site Logs

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

11
Sample XML IGS Site Log
ltigsSiteLog xmlns"http//sopac.ucsd.edu/ns/geod
esy/doc/igsSiteLog/2004" xmlnsmi"http//sopac.
ucsd.edu/ns/geodesy/doc/igsSiteLog/monumentInfo/20
04" xmlnsequip"http//sopac.ucsd.edu/ns/geodes
y/doc/igsSiteLog/equipment/2004"
xsischemaLocation"http//sopac.ucsd.edu/ns/geode
sy/doc/igsSiteLog/2004 http//sopac.ucsd.edu/ns/g
eodesy/doc/igsSiteLog/2004/igsSiteLog.xsd"
xmlnsxsi"http//www.w3.org/2001/XMLSchema-instan
ce"gt ltsiteIdentificationgt
ltmisiteNamegtScripps 5 - Mt. Soledadlt/misiteNamegt
ltmifourCharacterIDgtSIO5lt/mifourCharacterIDgt
ltmiiersDOMESNumbergt40460M006lt/miiersDOMESNu
mbergt lt/siteIdentificationgt ltsiteLocationgt
ltmicitygtLa Jollalt/micitygt
ltmistategtCalifornialt/mistategt
ltmicountrygtUSAlt/micountrygt
ltmiapproximatePositionITRFgt
ltmixCoordinateInMetersgt-2456115.13lt/mixCoordinat
eInMetersgt ltmiyCoordinateInMetersgt-4768905.
79lt/miyCoordinateInMetersgt
ltmizCoordinateInMetersgt3439232.44lt/mizCoordinate
InMetersgt ltmilatitude-Northgt325024.00lt/mi
latitude-Northgt ltmilongitude-Eastgt-1171500.
00lt/milongitude-Eastgt ltmielevation-m_ellip
s.gt185.53lt/mielevation-m_ellips.gt
lt/miapproximatePositionITRFgt lt/siteLocationgt
ltgnssReceivergt ltequipreceiverTypegtASHTECH
Z-XII3lt/equipreceiverTypegt
ltequipsatelliteSystemgtGPSlt/equipsatelliteSystemgt
ltequipserialNumbergtLP02814lt/equipserialNumb
ergt ltequipfirmwareVersiongtCD00lt/equipfirmwar
eVersiongt ltequipdateInstalledgt2002-05-15T000
0Zlt/equipdateInstalledgt ltequipdateRemovedgt20
03-01-09T0000Zlt/equipdateRemovedgt
lt/gnssReceivergt ltgnssAntennagt
ltequipantennaTypegtASH701945B_Mlt/equipantennaType
gt ltequipserialNumbergtCR519991867lt/equipseria
lNumbergt ltequipantennaReferencePointgtBPAlt/equ
ipantennaReferencePointgt ltequipmarker-arpUpE
cc.gt0.0083lt/equipmarker-arpUpEcc.gt
ltequipdateInstalledgt2002-05-15T0000Zlt/equipdate
Installedgt ltequipdateRemovedgt2004-09-29T0000
Zlt/equipdateRemovedgt ltequipnotesgtlt/equipnot
esgt lt/gnssAntennagt
12
XML and Geodesy at SOPAC

• Time Series Plotting
• GPS analysis input
• Historical equipment information
• Site motion model terms - apriori coords
• Phase center information
• GPS coordinate data submission/querying
• GML Observation Collections
• GML Filter Encoding
• GPS time series offsets

13
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