UNIT 69 - GIS STANDARDS

• Reasons for standards
• Standards organizations related to GIS

• Operating system standards
• User interface standards
• Networking standards
• Database query standards
• Display and plotting standards
• Data exchange standards

• Start-up costs
• Management support
• Technical tradeoffs
• Potential for security risks
• Innovation

UNIT 69 - GIS STANDARDS

A. INTRODUCTION

• this unit is based largely on information from Exler (1990) and Tom (1990)

• standards are needed as GIS users attempt to integrate their operations with other hardware, GISs and data sources

• challenge is to get industry, government and users to implement and promote the use of standards

• many standards are set simply through common use, though major attempts are currently being made to develop broad ranging national and international standards

1. Portability of applications
• need the ability to move developed applications to new hardware platforms in order that development efforts are not duplicated and can be shared

2. Data networks
• need ability to access digital data which is distributed through various offices, agencies, states and even countries

3. Common environments
• if applications use similar operating environments, learning curves are reduced and productivity is increased

3. Cost of program development
• standards are important to software developers as they reduce the need to develop interfaces for many different data formats, operating systems, plotters, etc.

overhead - Standards Organizations
• the following is from Exler (1990)

  ANSI - American National Standards Institute

  • approves standards for US industrial and commercial sectors

  DCDSTF - Digital Cartographic Data Standards Task Force
  • combines FICCDC-SWG and NCDCDS for digital cartographic standards

  FICCDC-SWG - Federal Coordinating Committee on Digital Cartography - Standards Working Group
  • formed by the Interagency Coordinating Committee - Office of Management and Budget to serve as a focal point for the coordination of digital cartographic activities

  FIPS - Federal Information Processing Standards
  • official source of information processing standards for federal departments and agencies

  IEEE - Institute of Electrical Electronics Engineers
  • develop standards for a broad range of subjects, including information processing

  ISO - International Standards Organization
  • approves standards for the international community through national standards bodies such as ANSI

  NCDCDS - National Committee for Digital Cartographic Data Standards
  • formed by ACSM (American Congress on Surveying and Mapping) and funded by USGS

  NIST - National Institute of Standards and Technology
  • formerly the National Bureau of Standards
  • oversees standards activities for the government
  • recently opened a GIS laboratory

  OSF - Open Software Foundation
  • a vendor consortium of IBM and Digital Equipment Corporation

  UNIX International - a vendor consortium of AT&T and SUN

  X/Open - a nonprofit independent consortium of 19 computer manufacturers representing 160 software developers from 17 countries attempting to define standards for a complete computing environment

Operating system standards

• for micro-computers, most GIS use the DOS operating system, though applications are being written for OS/2 and Macintosh

• UNIX appears to be the current popular operating system for the powerful workstations and mainframe computers, though there are several other well accepted and newly developing options

• affect the "look and feel" of GIS programs

• windowing is becoming popular as a standard in GIS and as well as most other applications

• at the micro-computer level:
  • for PC computers, Presentation Manager available under the OS/2 operating system and as Microsoft Windows in DOS is becoming the standard

  • Macintosh operating system has always been a windowing environment

• X-Windows is the de facto windowing standard for UNIX and other mainframe and workstation operating systems
  • this allows different vendor's hardware to support a common interface in a networked environment

• are critical to allow communications between remote computers
  • networked environments are increasingly popular for GIS as the technology and data becomes widely used within organizations

• SQL (standard query language) is emerging as a standard across the data processing spectrum, though in its current form it is limited in its ability to handle spatial queries

• several standards have emerged in this area simply as a result of the popularity of specific hardware devices

• these include:
  • CalComp and HPGL - line plotter formats
  • Postscript - raster, page oriented graphics

• the largest standardization effort is currently being directed at this area

• US Federal government has recognized the need to exchange data between different agencies (see Unit 68) and has formed committees to examine aspects of this
  • note work done by NCDCDS, FICCDC and DCDSTF
  • current efforts are directed towards the development of the Spatial Data Transfer Specification (SDTS) (see Tom (1990) for more details on SDTS)
  • the Defence Mapping Agency's digital cartographic data standard DIGEST is part of an effort to establish standards within the international defense community, e.g. NATO

• however, there are several common data exchange formats currently in use (see GIS World, 1989)

• these include: overhead - Spatial data exchange formats

  USGS DEM- Digital Elevation Model

  • format used by the USGS since early 1980s for gridded elevation data
  • allows a single attribute per cell

  USGS DLG - Digital Line Graph
  • all features of the USGS quadrangle map series are supported by this format
  • is the most widely used format for exchange of digital cartographic data
  • used primarily for coordinate information though it does support alphanumeric attributes

  GBF/DIME - Geographic Base File/Dual Independent Map Encoding (Census Bureau)
  • original Census Bureau digital files developed in early 1970s
  • allows both coordinate and attribute data

  TIGER - Topologically Integrated Geographic Encoding and Referencing (see Units 8 and 29)

  IGES - Initial Graphic Exchange Specifications (National Bureau of Standards)

  • used extensively for the exchange of CAD and CAM data
  • only one attribute per feature

  SDDEF - Standard Digital Data Exchange Format (NOAA)
  • primarily used to exchange data between NOAA, Defense Mapping Agency and the Federal Aviation Administration
  • only supports point data

  SIF - Standard Interchange Format (Intergraph)
  • developed to support exchange of data between Intergraph and other systems
  • popular data exchange format for many GIS packages

  MOSS - Map Overlay and Statistical System (US Fish and Wildlife)
  • originally developed as part of the MOSS GIS
  • a non-topological format for vector data with translators to several common spatial data formats
  • now used by several federal and local government agencies

  DXF - Digital eXchange Format (Autodesk)
  • developed by Autodesk, Inc. for AutoCAD
  • like SIF is a popular data exchange format for many GIS packages

• several issues are related to the implementation of GIS standards

• implementation of a standard can incur substantial costs in terms of money and time

• will be major short-term costs related to user training and reprogramming of software

• management needs to recognize the positive impacts of standards on productivity and system costs and be willing to commit short-term resources for retraining and reprogramming

• adopting of standards require tradeoffs between functionality and performance

• standards provide for broad functionality
  • e.g. adopting software that uses a standard data exchange format allows access to a broad range of data sources
  • e.g. adopting a standard operating system provides access to a large library of existing applications

• however, standards by their very nature, do not allow fine tuning to specific hardware or applications
  • e.g. plotter standards may not make the optimum use of the hardwired capability of your plotter

• some de facto standards are neither efficient nor the best available
  • many exist simply due to the original popularity of the hardware or software, even though they may no longer be the state-of-the-art

• wide availability of common operating systems allow for misuse and exploitation
  • e.g. the spread of computer viruses depends on common operating systems

• broadly accepted standards make it very difficult to introduce innovations

• the majority of standards effort in GIS to date has concerned data formats

• standards such as DIGEST provide standard record layouts, coding schemes

• although formats are standardized, these efforts deal primarily with the structure of the data, and not with its meaning

• data may be written into a standard format for transfer, and thus be readable by some other system, but it may still be virtually meaningless without extensive documentation

• the SDTS goes well beyond format standards by defining standard meanings for terms
  • e.g. SDTS attempts to remove the confusion over the use of arc, link, edge, chain, segment in GIS by establishing a standard term for every type of object

• the USFS effort to establish a corporate database may similarly yield standards of meaning, e.g. standardized definitions of GIS layers, at least within this organization

• still missing is a standard of data models that would provide standard ways of representing geographic phenomena
  • e.g. for digital elevation data, should the standard include all of contours, DEMs and TINs?
    • should there be standard resolutions for DEMs?

    • should there be standards of vertical accuracy?

• also missing are standards of data accuracy for GIS
  • map accuracy standards deal only with cartographic features
  • e.g. a GIS standard for digital elevation data might specify the accuracy of elevation for any point in an area, not the accuracy of positioning of a contour

• such standards would provide the GIS user with expectations about the reliability of the database as a window on the world, rather than a window on source documents, or a window on transferred databases

GIS World, 1989. "Spatial data exchange formats", The GIS Sourcebook, GIS World, Fort Collins, CO, pp. 122-23.

Exler, R.D., 1990. "Geographic Information Systems Standards: An Industry Perspective", GIS World Vol 3(2):44-47.

FICCDC, 1988. "The proposed standard for digital cartographic data", The American Cartographer, Vol 15(1).

Thorley, G.A., 1987. "Standards - Why bother?," USGS Open File Reports, 87-314. Abstracts of papers presented at the GIS Symposium.

Tom, H., 1990. "Geographic Information Systems Standards: A Federal Perspective", GIS World Vol 3(2):47-52.

EXAM AND DISCUSSION QUESTIONS

1. Standards can be imposed from above, or emerge through consensus. Discuss the pros and cons of top-down and bottom-up approaches to GIS standardization.

2. How successful do you think DXF can be as a GIS exchange standard? What aspects of information exchange does it standardize?

3. Review the approach taken by SDTS to standardizing the use of the term "chain".

4. "SDTS is a standard for cartography, not GIS" - discuss.

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