Transcript Geospatial standards

Geospatial standards
Geog 458: Map Sources and Errors
March 1, 2006
Outlines
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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
– Hardware upgrades
DB
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
organization
Independent standard
bodies
Industry consortia
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
DB
Intermediate Batch Exchange
(e.g. DXF, SDTS)
Transparent Inter-operability
(e.g. SQL, OGIS)
• 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