GSD 6322: Fundamentals of GIS Lecture Outline
Paul Cote
Harvard Graduate School of Design
excerpted from: http://www.gsd.harvard.edu/~gsd6322/

The Future of Spatial Data Sharing

Acquiring data for use in GIS can be the most costly and important part of GIS application development. If we are lucky, somebody else has already assembled data that we can use. Some consider a major role of government as the compilation and provision of base geographic data for research. Such a "Spatial Data Infrastructure" would be a huge public good. This development is one of the biggest areas for future development in GIS. This development is interesting because is not a technical improvement in GIS as we have been learning about it, but a change in the economic and policy environment that is being brought about. The following points should illustrate the importance of a spatial data sharing, the problems that the NSDI would help to overcome, and the current activities and policies which are helping to bring it about.

The importance of Cooperation (particularly data sharing) in the development of GIS

• The power of integrating disparate data sources is one of the primary features of GIS and relational tools.
• Useful GIS data is so expensive to generate therefore, sharing permits access to a much broader community of researchers.
• Opportunities for researchers in a particualr region working from a common geographic framework (basemap, if you will) will save money and permit huge synergystic benefits.
• Good scholarship and scientific practice requires that source data be made available to critics and competitors. (this is especially important in the area of public policy.)
• References: an executive order from Bill Clinton toard establishing a spatial data infrastructure.

Difficulties in sharing spatial data.

One of the largest areas of difficulty for GIS users today is in learning about and obtaining useful GIS data. Creation of data sources is often cited as being the most expensive part of any GIS effort. Using data that has already been created seems like a natural solution. It is a good solution in many cases, but it is very difficult.

• Institutional Impediments to Making Data Accessible: The primary motive for assembling geographic data is largely single-purpose. The added costs of making data multi-purpose is difficult to justify. Specific added costs anticipated are: 1. Documentation, 2. Transfer, 3. Technical support.
• Difficulty in Discovery of Available Data Sources: If apropriate data for your projecrt did exist, how would you find out about it?
• Difficulty in Assessing the Apropriateness of Data: Documentation is scarce, inadequate, and essential for understanding critical attributes of GIS data: Who made it? When was it made? What time period does it represent? For what purpose was it collected? What is the coordinate System? What do the attributes mean?
• Technical problems in Data Transfer: For years, software vendors have deliberately created obstacles to moving data from one proprietary application to another. Continuing development of communication protocols, storage media and data transfer standards has improved the possibility of improving this situation, but for ther present, we are stuck with a plethora of transfer protocols; software; data, and compression formats; disk and tape media and associated hardware compatibility issues. To be sure, one needs to know a lot of general arcane computer lore to be facile scavengers of GIS data.
• Technical Problems in Conversion: Often, data we recieve must be converted between formats. Sometimes we have to convert data to use it in a substantially different GIS data model (e.g. vector to raster). And more often than that we must convert or reinterpret the meaning of the data attributes to use someone elses data for our own application. Some of these conversion methods involve decisions and compromises.
• References: This hotlist from the US EPA.

For more information on the growing spatial data infrastructure, see The National Spatial Data Infrastructure page at the Federal Geographic Data Comittee Web Site.