Illinois Height Modernization Program Begins

A comparison of commonly available DEM (left) with the quality of DEM we plan to  acquire under this program.Every engineering project and many land-use planning efforts require accurate height measurement, which, in turn, requires a datum-consistent vertical and horizontal statewide network of survey benchmarks and a statewide high-resolution digital elevation model (DEM) of the Earth's surface. Unfortunately, Illinois currently falls far short of both goals and is ranked in the bottom ten in the quality of its elevation data. The National Geodetic Survey (NGS), part of the National Oceanic and Atmospheric Administration, provides funding to states through the Height Modernization program to improve the quality of elevation data using global positioning satellites (GPS) technology in conjunction with traditional leveling, gravity, and modern remote sensing. Thanks to an earmark through Representative Timothy Johnson's office, Illinois joined this program in July 2008.

The long-term goal of the Illinois Height Modernization Program is to establish (1) a datum-consistent vertical and horizontal statewide network of survey benchmarks, and (2) a statewide high-resolution digital elevation model (DEM) of the Earth's surface based upon the updated network of survey benchmarks. During the first year of this multi-year project, the program will plan the long-term work, establish an infrastructure for data distribution, begin to recover existing benchmarks and establish new benchmarks, search out and begin to acquire existing DEM data sets from county or other governmental units, and initiate project outreach. The plan for future years, if funded, is to continue to establish benchmarks and to partner with other units of government to acquire new DEM data.