The reweight_observations command

reweight_observations [by_set] factor selection_criteria

reweight_observations offset_error uncertainty selection_criteria

reweight_observations centroid_error uncertainty selection_criteria

The reweight_observations command is used to reweight observations in the adjustment. Observations can be selected based upon observation type, observation date, stations used, and observation classifications.

Reweighting can either specify one of:

• a scale factor factor by which standard errors of the selected observations is multiplied. This is the factor applied to observation uncertainties - the square of this is applied to covariances. If multiple scale factors apply to an observation then they are multiplied together. If "by_set" is specified then the scale factor will apply to the whole set of observations if any of the observations in the set match the critieria.
• an offset error that specifies an error in the location of the equipment relative to the reference point of the mark, for example plumbing errors.
• an centroid error that specifies an error in the centroid of a set of GNSS derived coordinates such as in a SINEX file. This error is applied to the covariance of the set to reflect an uncertainty in the location of the set as a whole relative to the reference frame.

The offset error and centroid are experimental features which attempt to remedy deficiencies in the covariance information resulting from GNSS processing software and are only supported for data types GX (coordinate observations) and GB (baseline observations). Centroid errors do not apply to GB observations. For other data types the offset errors are silently ignored. They can each be specified with horizontal and vertical error components and are applied after scale factors have been applied. They are specified with one of the following formats:

offset_error hv_error m
offset_error h_error v_error m

The format of selection_criteria is described for the reject_observations command.

Examples of reweighting observations are:

reweight_observations 1.5 @data_type=HA/AZ

reweight_observations 2.0 before 2000-01-01 using_stations inside NZGD2000 affected_area.wkt

reweight_observations offset_error 0.01 m @data_type=GX

Observations can also be rejected or ignored based on selection criteria. Rejected observations are not used to calculate coordinates but do still have residuals calculated, whereas ignored observations are not included in the adjustment at all.