Edward E Carlson’s scientific contributions

In November 1997, guidelines were developed by the National Geodetic Survey (NGS) for performing Global Positioning System (GPS) surveys that are intended to achieve ellipsoid height network accuracies of 5 cm at the 95 percent confidence level, as well as ellipsoid height local accuracies of 2 cm and 5 cm, also at the 95 percent confidence level (Zilkoski et al. 1997). See Appendix A for information about local and relative ellipsoid height accuracies and Appendix B for information on the basic requirements for 2-cm ellipsoid height standards. The following guidelines were developed by NGS for performing GPS surveys that are intended to achieve orthometric height network accuracies of 5 cm at the 95 percent confidence level, as well as orthometric height local accuracies of 2 cm and 5 cm, also at the 95 percent confidence level. These guidelines were developed in partnership with Federal, state, and local government agencies, academia, and private surveyors. We are confident that these guidelines, if followed, will result in achieving the intended accuracy. Additional analysis may show that some of these guidelines can be relaxed in the future. These guidelines are intended for establishing vertical control networks.