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Above: A vast amount of spatial information can be reviewed and analyzed by integrating data from multiple sources. Right: Consistent standards should be created for the collection of spatial data, including property survey information. Photos: R.A. Smith & Associates Inc.

An example of this is the integration of GIS data and survey data from different sources. GIS should not only make analysis easier, but it should also increase confidence in the outcome. The ALTA/ACSM Standards (developed by the American Land Title Association and American Congress on Surveying and Mapping) for land title surveys allow for a degree of uncertainty due to random measurement errors that equate to a 95% confidence level. However, when integrating data from various sources that may use different standards and confidence levels, the resulting validity of any analysis is diminished to the confidence level of the least accurate dataset. In some instances confidence levels may be reduced to the point where any derived results would be suspect. To remedy this, all suspect data that falls significantly outside the desired confidence level should be recaptured and digitized to the defined standards of the organization. Having properly defined standards in place and upfront serves to avoid this duplication of effort and the pitfalls that come from managing data across vastly differing confidence levels.

Standards Organizations

The Open Geospatial Consortium consists of companies, government agencies, and universities that collaboratively develop publicly available interface specifications for the Web, wireless and location-based services, and mainstream information technology.

International Organization for Standardization Technical Committee 211 “Geographic information/Geomatics” develops and maintains standards for information concerning objects or phenomena that are directly or indirectly associated with a location relative to the earth.

The Federal Geographic Data Committee pulls together the different formats used throughout the United States to maintain proper national standards for spatial data. One such standard is the Utilities Geospatial Data Content Standard, which supports any system that captures or uses spatial data about utility systems. Public works departments can apply this standard for support planning, design, construction, and facilities management initiatives.

Public agencies have a responsibility to produce and maintain consistent data based on accredited standards and best practices. A common set of standards helps provide reliable spatial data and enables successful integration with other data sources and systems.

— Aaron Ford, GISP, is GIS technical manager with Brookfield, Wis.-based R.A. Smith & Associates Inc.