Between February 2011 and April 2012, the National Geodetic Survey (NGS) executed one of the most comprehensive geodetic surveys in its history: the Geoid Slope Validation Survey of 2011 (GSVS11).
The survey was performed to quantify the accuracy of differential geoid modeling based on NGS' airborne Gravity for the Redefinition of the American Vertical Datum (GRAV-D) surveys. During the GSVS11, geodetic data was collected on over 200 control marks, including leveling, long-session GPS, short-session GPS,
Real Time Network (RTN) GPS, absolute gravity, relative gravity, and deflections of the vertical. Airborne Light Detection and Ranging (LiDAR) imagery collection augmented the effort.
The initial release of the raw data, as well as the coordinates computed by processing the data, is now freely available for download from the NGS website. To find the data and its documentation, please visit: http://geodesy.noaa.gov/GEOID/GSVS11/data/