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					Geospatial standards

Geog 458: Map Sources and Errors
         March 1, 2006
                  Outlines

•   Roles of geospatial standards
•   Categories of geospatial standards
•   Developers of geospatial standards
•   Areas of geospatial standards
    Why bother with standards?
• Consensus is good, it avoids confusions, and it allows
  systematic managements of geospatial data
• Documenting data characteristics with no agreement on
  which should be included would have too much room for
  interpretation → FGDC’s metadata content standards
• Converting file formats between different computer
  systems will end up losing details if proprietary formats
  are not compatible with other formats → SDTS
• Integrating data with different classification schemes will
  cause trouble in processing values properly →
  standardized code set (e.g. occupation code, land use
  type code, road class, FIPS code for locality name)
           Value of standards
• Wisely-designed standards provide the
  foundation to help make information systems
  and databases easier to use and maintain
• Standards solve particular problems also, such
  as how to represent data efficiently or manage a
  communications system
  – In the sense standards reflect best practices in
    particular areas
• Saves money and time (also stress?)
Values of geospatial standards can
   be reflected in three themes:
• Portability
   – Ability to use and move data and custom applications
     among multiple computers and operating systems
     environments without re-tooling or reformatting
• Inter-operability
   – Ability to connect and retrieve information from
     multiple systems
• Maintainability
   – Ability to promote long-term and efficient updating,
     upgrading, and the effective use of computer systems
     and databases
                Roles of standards
• Portability
   – Data transfer
   – Software


• Interoperability
   – Data access
   – Software functions


• Maintainability
   – Data update
   – Software revisions              DB
   – Hardware upgrades
      What is a good standard?
• So you would say that having standards is good
• Sometimes, better question is not whether
  standards should be adopted, but rather to
  choose suitable standards.
• In essence, standards cannot be quite flexible in
  the sense that we have to conform to them and
  things keep changing
   – Think about CSDGM; you spend some time in
     learning about it, but how would you feel if it is not
     considered standard anymore?
• It is hard to satisfy different needs with one good
  super-hero kinds of standards
     Quality of a good standard
• Should reflect what’s best now, also should be
  flexible enough to be accommodated into future
  development
• How do you know what’s best?
   – Agreement given knowledgeability in particular areas?
• What do you think of CSDGM with these regards?
  Is it really flexible? Isn’t there any assumption on
  data structure and so on? Standards shouldn’t
  be something that defers progress
        Categories of standards
• Geospatial standards may be broadly categorized as
  ‘independent’ standards or ‘de facto’ standards
• Independent (consensus, or formal) standards: formally
  approved by a recognized body through a well-defined
  consensus settings
   – e.g. FGDC CSDGM, USGS SDTS, ANSI ASCII
• De facto standards: those that become accepted
  because of their broad popularity and use, but are not
  necessarily accompanied by any formal approval by an
  independent standards organization
   – e.g. Microsoft ODBC, ESRI Shapefile? thanks to either their
     sufficient market share or their seemingly good performance
        Developers of standards
• National government organizations
   – National government agencies in all industrialized nations with specific
     responsibility for approval of information system standards (e.g. NIST,
     FGDC in the U.S.)
• Independent standards bodies
   – Formal standards bodies work in a consensus building process to adopt
     and promote formal standards; include representation from government
     agencies, professional organizations, and private companies; open
     policies for membership (e.g. ANSI, IEEE, CEN, ISO)
• Industry consortia and trade associations
   – Formal or informal associations with missions for joint definition,
     development, and promotion of standard-based products for their
     customer base; created to address specific market niches (e.g. OMG,
     OGC)
• Professional organizations
   – Group of professionals with missions for education, interaction between
     members, and review of proposed standards (e.g. URISA, IAAO, ACM)
Developers of geospatial standards




National government   Independent standard   Industry consortia
organization          bodies
  Areas of geospatial standards
• Standards of importance to geospatial information users
  may be broadly categorized into low-level and high-level
  categories
• Low-level standards
   – Covers technical concerns in hardware, network (e.g. Ethernet,
     TCP/IP), and operating system (UNIX, NT)
   – Important issue for interoperability
   – Domain of computer industry
• High-level standards
   – Deals with database design, data exchange and presentation
     topics
   – User interface, data format/exchange, programming and
     application development, and user design
   – Developers of GIS have influence over these standards
         Software standards
• Operating systems: running applications
  without modification on multiple platforms
  – UNIX by Open Group
  – Windows NT, XP by Microsoft
• Object management architectures:
  standards and compliant projects for
  object management and communication
  – CORBA by OMG
  – DCOM by Microsoft
Three strategies for geospatial data
   exchange and interoperability
     DB              DB

  Direct Batch Translation



            DB




                       DB       Transparent Inter-operability
   DB                                (e.g. SQL, OGIS)

  Intermediate Batch Exchange
        (e.g. DXF, SDTS)
• Direct batch translation
   – Requires specific programs to translate formats directly from one
     proprietary structure to another
• Intermediate batch exchange
   – Most appropriate when data must be exchanged between
     several different software formats
   – Industry standards include DXF (AutoCAD)
   – Government agencies developed SDTS (neutral exchange
     formats that encompass comprehensive GIS database content
     and format information; it also includes attributes associated with
     map graphics, complex map feature structures, map symbology,
     and metadata)
   – Raster file format make use of some type of data compression
     (e.g. JPEG)
• Transparent interoperability
   – Establishes interactive session between two or more databases
     to allow a GIS application or user query to automatically and
     transparently access the “external” data
   – Two standards facilitate this
       • SQL: structured query language accepted by ANSI; standard
         dialogue to access data, perform queries, and select records from a
         relational DB
       • ODBC: industry standard developed by Microsoft; transparent
         access among disparate databases
   – Isn’t this attribute data exchange standards? Any geospatial
     standards?
       • Spatial extensions to SQL
       • Open GIS Specification in progress
    Programming and application
       development standards
• GIS had been developed through proprietary
  languages (called macro language)
  – AML: procedural language
  – Avenue: transition to object-oriented language
• Increasingly ‘open’ development environments
  (e.g. Visual Basic, Visual C++, Delphi, Java,
  Python)
• ArcObject is a set of GIS functions to be
  accessed directly by industry standard
  programming languages
  – Can be written by any object-oriented languages
            Why ‘openness’?
• Maximize the efficiency of staff resources in
  application development
  – You don’t have to write the code from scratch
• Application can be inherently more portable
  – The same code can be reused
• Increase opportunities to integrate data from
  multiple systems and databases
  – Different program languages can understand data
    without changing the format into its proprietary one
     What is a good standard?
• A wisely crafted set of standards will promote
  portability, interoperability, and maintainability
• Developing standards takes time and diligence
  to ensure that standards are adhered to as a
  GIS matures
• A well-designed set of standards will take into
  account the specific needs of an organization
  within a broader community of users

				
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