Surveying. Introduction - MDT26

Introduction

It is advisable to explain some essential concepts to take full advantage of the possibilities offered by the Surveying Module. Many of these aspects are related to the program's configuration, which can be accessed through the Utilities > Configuration command in the drop-down menu or by clicking the Configuration button in the Station Calculation section (see Customization Manual).

Units

The program allows one to choose between meters and feet as distance measurement units, and among centesimal degrees, sexagesimal degrees and radians for angles. Check what mode the system is configured with in order to avoid confusion or incorrect results.

Stations

Stations are identified by a name comprised of up to eight numerical or alphabetic characters, their X, Y and Z coordinates, a scale or optional anamorphosis, and a code of up to fourteen characters.

Occupation Points

Occupation points are used to initiate the station or point observations. They consist of the station name, the instrument's height, horizontal correction or disorientation, and the horizontal and vertical angle corrections arising from instrument inaccuracies. These are assigned automatically by the program if the angular correction option is on.

They also include the point information obtained from their observations.

Observations

The information making up an observation depends on the current configuration:

If the program is configured in total station mode, the components also depend on its configuration: horizontal angle, reduced or geometric distance, vertical angle or elevation difference, and stake or target height.

If it is in tachymeter mode, each observation consists of horizontal angle, vertical angle, thread 1 and thread 2.

Station observations are identified by their station of origin, instrument height (in other words, occupation point) and name of their target station. On the other hand, point observations are identified by their point number.

Double Observations

A double observation consists of a direct circle observation and an inverse circle observation associated to the same station or point.

Observations

Observations consist of each of the measurements making up an observation. They are used to generate observation equations, which are processed by the least squares method in the traverse and network compensation, the resection and direct intersection, and the levelling options.

In essence, they all consist of an observed value, a calculated value and a residual amount left over from the difference between the two. They also include a standard deviation, or estimated error of these observations, calculated from the equipment's accuracy factor set in the configuration. Consult to the Least Squares section for further details

The program handles four types of observations:

Distance observations, containing the following information: origin and observed stations, observed distance, standard deviation and residual.

Azimuth observations, containing the same information as distance observations, but also including a horizontal correction of its respective occupation point.

Angle observations, arising from differences between two observations from consecutive stations.

Vertical observations, indicating the difference between the observed vertical distance and the calculated vertical distance.