Weights for to the combined adjustment of GPS and terrestrial observations were investigated. The derived weights of terrestrial observations are shown as follows:
Distance σ_S=2.5mm+ (15.9×S) mm P_S=1/σ_S²
Direction σ_D=1.8″+ (0.218/S) ″ P_D=1/σ_D²
Vertical angle σ_V=3.6″+ (0.589/S) ″P_V=1/σ_V²
Leveling σ_L= (σ_LO√S) m P_L=1/σ_L²
σ_LO=0.6 (1^st order), 1.7 (2^nd order), 3.2 (3^rd order), unit in mm/km
where σ: standard error, P: weight, S: approximate observed distance in km.