Real Estate

Departments » Real Estate » Geographic Information System

Summary of the Franklin County Auditor's Geographic Information System:

The Franklin County Auditor's Geographic Information System was launched in February 1987. A Geographic Information System (GIS) is a computer graphic system that allows the input, query, manipulation, display and output of geographically referenced information. The goal of the project was to create a single source of digital data containing graphic and non graphic real estate appraisal information captured on an accurate planimetric base map foundation.

Within the Auditor's Real Estate Division, one of the many duties performed by the Auditor's Office is the important and time-consuming task of appraising and reappraising each of the 433,000 plus parcels of real estate within the county. This ongoing process demands extensive information management capabilities now being provided by the GIS.

The GIS enhances the appraisal process by greatly increasing the Auditor's information storage, retrieval, inventory and analysis capabilities, ultimately resulting in equalized taxation for the taxpayers of Franklin County.

The initial Franklin County Auditor's GIS, containing records of property characteristics, location, ownership and valuation, consisted of:

  • Aerial photographs at four scales: 1" = 1,320' for developing the ground control network; 1" = 660' for producing the planimetric base map; 1" = 600' for creating orthophotos; and 1" = 800' for periodic updating.
  • First-order Global Positioning System (GPS) satellite control for 96 horizontal survey points, including azimuths: 43 existing monuments, 47 new monuments and 6 additional monuments for photo control.
  • Analytical triangulation, a method for extension or densification of ground control, performed using a fully analytic stereoplotter and state-of-the-art bundle adjustment software with refinements.
  • 2,663 digital orthophotos with 12-inch ground pixel resolution (for use with appraisal mapping)
  • 2,663 planimetric maps photo-compiled at 1" = 100' scale.
  • 2,663 appraisal maps ortho-compiled at 1" = 100' scale for more than 395,000 parcels tied to the planimetric base.
  • 2,663 2-foot contour maps when compiled at 1" = 100' scale, tied to the planimetric and cadastral base.

The Franklin County Auditor's Geographic Information System project is unique because it was developed especially to meet the needs of the Auditor's Office. Appraisal, planimetric and cadastral base map information was captured by the Auditor's Office and the Auditor is maintaining all non-graphic appraisal information along with some elements of the planimetric base map that relate to the appraisal process. The Franklin County Engineer's Office assists in maintaining right-of-way and other cadastral information.