Geoida Help

Illegal values computing Standard Deviations

Question: The message 'Illegal values when computing Standard Deviations for points - data errors suspected. Check GPS Vector variances & co-variances for incorrect sign ...' is displayed during a minimally-constrained least squares network adjustment containing GNSS baseline vector observations. What does it mean and how can it be resolved?

Answer: Normally this message would indicate incorrect signs have been applied to the baseline vector observation variance-covariance values. However in the current case it may be the result of insufficient constrained (fixed) points for the minimally-constrained adjustment - if the network consists of multiple areas unconnected by observations then EACH area requires at least one fixed point