GIS S TANDARDS  Introduction  Reasons for standards  Organizations  Types of standards  Implementing standards

I NTRODUCTION  standards are needed as GIS users attempt to integrate operations with other hardware, GISs and data sources  challenge is to get industry, government and users to implement and promote use of standards  many standards are set simply through common use, major attempts to develop national and international standards

 portability of applications  data networks  common environments  cost of program development R EASONS FOR STANDARDS

 American National Standards Institute  Digital Cartographic Data Standards Task Force  Federal Coordinating Committee on Digital Cartography – Standards Working Group  Institute of Electrical Electronics Engineers  International Standards Organization  Open Software Foundation  X-Open S TANDARDS ORGANIZATIONS

 networking standards – critical to allow communications between remote computers  database query standards – SQL is emerging as the standard  data exchange standards – governments/private companies recognize need to exchange data between different agencies/groups  several common data exchange formats currently in use: T YPES OF STANDARDS

 DEM – Digital Elevation Models  allows a single attribute per cell D ATA EXCHANGE FORMATS

 DLG – Digital Line Graph  most widely used format for exchange of digital cartographic data in vector format  used primarily for coordinate information, though it does support alphanumeric attributes D ATA EXCHANGE FORMATS DLG Roads

 GBF/DIME – Geographic Base File/Dual Independent Map Encoding  allows both coordinate and attribute data D ATA EXCHANGE FORMATS

 TIGER – Topologically Integrated Geographic Encoding and Referencing D ATA EXCHANGE FORMATS  support pre-census geographic and cartographic functions in preparation for the 1990 Census  to assist in the analysis of the data as well as to produce new cartographic products

 SIF – Standard Interchange Format (Intergraph)  popular data exchange format for many GIS packages  DXF – Digital eXchange Format  popular exchange format for many GIS packages to transfer with CAD  specially formatted text file that can be viewed and modified with any text editor  organized into different sections – header, table, block, etc. D ATA EXCHANGE FORMATS

 Start-up Costs  implementation of standard can incur substantial costs (money and time)  major short-term costs related to user training and reprogramming software  Management Support  needs to recognize the positive impacts of standards on productivity and system costs (plus commitment of short-term costs) I MPLEMENTING STANDARDS

 Technical Tradeoffs  tradeoffs between functionality and performance  standards provide for broad functionality  adopting standard operating system provides access to large library of existing applications  standards do not allow fine tuning to specific hardware  some de facto standards are neither efficient nor the best available I MPLEMENTING STANDARDS

 Potential for Security Risks  wide availability of common operating systems allow for misuse and exploitation  spread of computer viruses depends on common operating systems  Innovation  broadly accepted standards make it very difficult to introduce innovations I MPLEMENTING STANDARDS

 majority of standards effort in GIS to date has concerned data formats  missing – standard of data models that would provide standard ways of representing geographic phenomena  should there be standard resolutions for DEM?  should there be standards of vertical accuracy?  missing – standards of data accuracy for GIS  map accuracy standards deal only with cartographic features S TANDARDS

 data may be written into standard format for transfer, but it may still be virtually meaningless without extensive documentation  standards would provide GIS user with expectations about the reliability of the database as a window on the world  rather than on source documents, on transferred databases S TANDARDS