GIS S TANDARDS

1. GIS STANDARDS Introduction Reasons for standards Organizations Types of standards Implementing standards

2. INTRODUCTION • 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

3. REASONS FOR STANDARDS • portability of applications • data networks • common environments • cost of program development

4. STANDARDS ORGANIZATIONS • 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

5. TYPES OF STANDARDS • 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:

6. DATA EXCHANGE FORMATS • DEM – Digital Elevation Models • allows a single attribute per cell

7. DLG Roads DATA 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

8. DATA EXCHANGE FORMATS • GBF/DIME – Geographic Base File/Dual Independent Map Encoding • allows both coordinate and attribute data

9. DATA EXCHANGE FORMATS • TIGER – Topologically Integrated Geographic Encoding and Referencing • 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

10. DATA EXCHANGE FORMATS • 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.

11. IMPLEMENTING STANDARDS • 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)

12. IMPLEMENTING 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

13. IMPLEMENTING 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

14. 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

15. STANDARDS • 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