University of Wisconsin–Madison

Wisconsin Geospatial News

Redesign of Wisconsin County Coordinate System now complete

The Wisconsin Land Information Association (WLIA) Coordinate Systems Task Force recently completed a fundamental redesign of the Wisconsin County Coordinate System (WCCS). The redesigned system carries a new name – Wisconsin Coordinate Reference Systems (WISCRS), pronounced “whiskers.”

A little more than a year ago, the Task Force decided to proceed with the redesign. About the same time, the Wisconsin Land Information Board allocated $35,000 in a strategic initiative grant for the redesign work. Jackson County, the grant recipient, subsequently contracted with Al Vonderohe, a professor of civil engineering at UW-Madison, to complete the redesign.

WCCS dates back to early ’90s
The WCCS was originally published in 1995 by the State Cartographer’s Office. It was based on work developed several years earlier by the Wisconsin Department of Transportation. The WCCS has been widely adopted by state and local governments across Wisconsin for use in GIS/LIS, and infrastructure design. Its popularity is based on the fact that distances measured on the ground are, for most applications, minimally different from distances on the corresponding coordinate grid. The WCCS design is based on a “raised reference surface.” This design characteristic, although mathematically sound, caused many problems and confusion among WCCS users.

WISCRS was designed to produce negligible coordinate differences when compared to the WCCS. This was a design requirement so legacy GIS databases and other spatial data could be merged with newly acquired data without the need for transformation. That is, map data referenced to either WCCS or WISCRS can be used together without concern for coordinate value differences. The largest differences in coordinate values between the two systems are between 4 and 5 millimeters (approximately ¼-inch) and this difference occurs in only four counties. In most other counties the differences are less than 3 millimeters.

Final report available
The final report on the WISCRS design is available for download from the State Cartographer’s Office website. The report contains a short introductory discussion about coordinate systems, the redesign process, and comparisons between the two systems. Individual county pages that include the redesign parameters for each county, plus a pair of diagrams showing the coordinate shifts in two directions between WCCS and WISCRS, are provided. The final section of the report contains a listing of mathematical transformations for the two projection systems used – Transverse Mercator and Lambert Conformal Conic. 

Material from this final report will be incorporated into a new spatial reference systems handbook to be published by the State Cartographer’s office later this year.