Wide area coverage parcel data allow for much more accurate geocoding. They are also a good mechanism for disseminating public data, which in turn increase the usefulness of computer generated maps. Mapping at the parcel level offers more accurate maps which do a better job of portraying the geography. NAVTEQs literature offers a list of uses for parcel boundaries, shown below.
Another example not listed above is public safety parcel data better define the location of incidents and the surrounding areas. In this example, you can see the parcel concentrations and even estimate land use, residential, commercial and industrial, by the location and size of the parcels. The image of Teton, WY, shows an example of the database.
Because the data are provided by NAVTEQ, a commercial vendor, the which format issue goes away; NAVTEQ provides the data in whatever format the user needs. As a result, the database has the advantage of greater interoperability among government entities as well as businesses.
The scope of creating this product is far from trivial, both in terms of coverage and assembly. To give you an appreciation of the range currently available, here is what I gleaned from NAVTEQ literature.
Coverage: The product was first released in October 2006 has approximately 55 million parcels the most comprehensive packaged parcel database available today, according to NAVTEQ, representing over 50% of the U.S. population.
Standardization: NAVTEQ parcels are acquired from at least 4,100 tax mapping authorities, each with disparate format, projection, data model, and highly varied usage/distribution policies. NAVTEQ has built a standard format, structure and projection into which the company has standardized the data. Parcels are checked for accuracy, street alignment, projection, etc.
Product Growth: NAVTEQ has a team dedicated to enhancing the parcel boundaries product. The team is adding parcel coverage each month and is surveying the market to determine the priority for adding attributes.
I am wondering what attributes will be added, beyond ownership, area and the nature of what exists on a parcel. Will there be demographics? Is so, what about privacy issues? NAVTEQ has already addressed the adding attributes issue by using the common identifier, the Assessors Parcel Number (commonly known as APN), in the data model so that there can be links (joins) with other attribute sources. Certainly, ownership, value and structure size would be obvious data additions.
One of the interesting things about changing technologies is how quickly they are adopted and how quickly we forget they are new. Parcel boundaries will no doubt be absorbed quickly by the business community, especially as they can solve a number of challenges and improve overall quality.