Departments » Real Estate » Geographic Information System

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

The Franklin County Auditor's Geographic Information System (GIS) launched in February 1987. A 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 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 Franklin County Auditor's Office annually processes between 12,000 and 18,000 property transactions with valid sale deeds. Since 2011, the county has seen a more than 50 percent increase in property transactions.

The quarterly sales trend report of property transactions in Franklin County is a distribution analysis and quarterly comparison of transactions from 2014 to 2015.

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 six 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 Office Geographic Information System project is unique because it was developed 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.