Least Squares Analysis

You can use Least Squares Analysis to make adjustments in Survey Networks.

A surveyor's fundamental job is making measurements, or observations, to determine the relative position of points. In doing this, many surveyors typically make more measurements than are minimally necessary to rule out the possibility of gross errors, or blunders, which might have occurred during the measurement process. As a result, redundant measurements, together with random measurement errors, create a model that is geometrically over-determined. This condition may also be referred to as an over-constrained problem.

You can calculate the most probable value for each observation by adjusting each of the observations simultaneously so that the sum of the squares of the residuals (the difference between measured and adjusted observations) is at a minimum. This is the origin of the term "least squares."

You use the AutoCAD Civil 3D Survey Least Squares commands to perform least squares adjustments of surveys. Traverse loops and networks of distance and angle measurements are evaluated by the observation equation method.

Tutorial Exercise: Performing Least Squares Analysis