測地リスク計算機

安全係数の理解

In geodetic engineering, a safety factor (Tolerance / Equipment Accuracy) of less than 3.0 is generally considered unacceptable for professional sign-off. This is because GPS/GNSS receiver accuracy is typically stated at the 1-sigma (68%) confidence level.

To guarantee that 99.7% of all measurements stay within your contract tolerance (3-sigma confidence), your equipment must be natively capable of resolving to a dimension three times tighter than your absolute project limit. Furthermore, unmitigated Datum Shifts (such as confusing WGS84 for a local grid) bypass equipment accuracy entirely, injecting a static 1-2 meter bias that guarantees structural failure.