Surveying adjustment datum and relative deformation accuracy analysis

The adjustment datum was firstly discussed and defined as datum equations.Then an adjustment method based on datum equation and least square was presented.This method is a generic method,not only suiting for the case in ordinary datum but also in gravity center datum or quasi datum,and easy to analyze the problem.Based on this method,the transformation between different datum was derived.The calculation results,deformation and positional accuracy under one kind of datum are relative and generic.A case study was further given and tested.Based on the case study,the conclusions were reached that relative positional root mean square error of each point becomes more as distance between the point and datum point becomes more.And the relative deformation offsets under different kinds of datum are helpful for deformation analysis.