What is the Chi-Square?

The Chi-Square, also frequently referred to as disorientation, is the angular value that represents the difference between the theoretical azimuth of a sight line (calculated from coordinates) and the raw Observations horizontal reading taken with the instrument from a Stationo.

Its main characteristics and functions within MDT are as follows:

• Purpose: Its essential function is to orient the horizontal circle of the total station with respect to the Manual coordinate system of the project. By applying this value to all angular observations of a station, the software can transform field measurements into geographic or Projected coordinates (X, Y).

• Calculation: It is usually determined in the process of Station Calculation (or Orientation). To obtain it, sights are taken to one or more points with known coordinates (Reference bases). MDT calculates the angular Difference for each Reference and allows the user to accept a single value or an average of the observed disorientations to improve accuracy.

• Use in Azimuth Observations: As mentioned in Survey management, Azimuth Observations in the Topography module explicitly incorporate this correction to define the positioning of the station in the global network adjustment.

• Visualization: In the survey station Scale reports, this value appears as an Owner attribute of each station, allowing you to Verify at a glance whether the equipment was oriented correctly in the field or if the orientation was calculated afterwards in the office.

This correction is a critical step before proceeding to the adjustment of traverses or networks, as it ensures that all tacheometric observations are referred to a common angle origin.