Section 2: GPS Survey Accuracy
Anchor: #i1000047Overview
The accuracy of classical triangulation network surveys has been described by a proportional standard, e.g., 1:10,000, which reflected the distance-dependant nature of terrestrial surveying error. The accuracy of GPS surveys, being less distance dependant requires different accuracy standards.
Anchor: #i1000061Federal Geographic Data Committee Methodology
The use of multiple standards creates difficulty in comparing the accuracy of coordinate values obtained by different survey methods. In recognition of these difficulties, the Federal Geographic Data Committee (FGDC) has changed its methodology for reporting the accuracy of horizontal and vertical coordinate values. Defining the new reporting standard is the two sigma (2σ) confidence intervals: a circle for horizontal uncertainty, and a linear value for vertical uncertainty.
Figure 3-1. 3-D Accuracy