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خفن خفن خفن - National Land Parcel Data: A Vision for the Future

National Land Parcel Data: A Vision for the Future

شنبه 20 بهمن 1386

property that is often a family's most significant asset. Land parcel information is also the cornerstone of a host of public- and private-sector decision making. For those reasons, the National Research Council (NRC) conducted a study, National Land Parcel Data: A Vision for the Future, that examines the status of land parcel data in the United States and provides a set of recommendations that would foster a national system for land parcel data operated by the public sector. In many ways, this report is an update of the 1980 report The Need for a Multipurpose Cadastre. Clearly, much has happened since 1980. Institutionally, cadastre is considered a foundation layer for the Federal Geographic Data Committee's (FGDC) development of the National Spatial Data Infrastructure (NSDI). The FGDC Cadastral Subcommittee has developed a formal parcel data model and extensive documentation of the best practices and business plans. Technically, new data sources and sophisticated GIS data models have enabled thousands of local governments to capture and manage parcel data. Furthermore, several states now manage parcels as a function of state government. However, even though several federal agencies need parcel-level data to fulfill their missions, there is no federal government initiative to acquire and utilize parcel data.

Unfortunately, while the public sector is questioning whether it is technically and economically feasible to integrate parcel data, several private-sector firms are racing to complete just such a system. The most significant example is the recent acquisition by Nokia of NAVTEQ that places the value of accurate and current renditions of street centerlines and parcel-level street addresses at $8.1 billion. Furthermore, real estate-oriented firms have found parcel-level attribute data to be critical to their business applications. For example, Zillow currently maintains information about more than 70 million parcels that are accessed by two million visitors a month, and Blue Raster has developed an ArcWeb Services parcel Web service. It is also significant that Google utilizes Public Sector Mapping Agencies (PSMA) Australia data to support parcel-level geocoding across the country.

In order to address the needs for a public-sector approach to a national parcel data program, the committee developed a vision and series of findings and recommendations. The committee envisions a system that employs modern distributed database concepts and practices similar to those employed in many local governments or businesses. Each parcel would be a unique entity with feature-level metadata. In other words, parcels would be treated the same way FedEx tracks millions of packages. Ideally, this approach would not disrupt current systems, but it would enforce lines of stewardship and agreements to distribute data. This land parcel data system would include the following organizational characteristics:

  • Built on already existing data systems, the system would link a series of servers maintained by local and state governments. The objective would be to seamlessly assemble accurate parcel information for any part of the nation at a given point in time.
  • A national land parcel coordinator, working with coordinators for federal lands, Indian lands, and each state, would oversee the development and integration of consistent land parcel data.
  • The data would be in the public domain; however, in order to protect privacy and confidentiality, no information would be provided about private ownership, use, or value.
  • Each parcel would be a unique polygon (but not the legal document) with a minimum set of attributes that includes street address, unique identification number, a generalized category of ownership, and feature-level metadata that describes information about the data.
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