Edit Theodolite/Tape Values¶

Use this dialog to enter calibration data for the combination of tape and theodolite used, as well as the estimated standard deviation for observed directions, distances, and zenith distances. This information is used to correct measured distances and weight the observations.

Where to Find the Dialog¶

Select the icon for Gemini Terrain Settings..., then choose Land Surveying: Instruments under Common Settings.

Number¶

Internal numbering system for the tape and theodolite.

If you need to enter the tape number using the Replace function in the list window, use the format 5/1, 5/2, ..., 5/9.

Name¶

Designation of the instrument combination.

Standard Deviation¶

Estimated observation accuracy when using the instrument combination. There are three types of observations: direction measurement, zenith distance, and distance measurement.

The standard deviation for each observation type consists of three parts:

Constant part: Distance-independent standard deviation, specified in gon or meters.
Distance-dependent part: Distance-dependent standard deviation, specified in meters/km or gon/km.
Centering: Estimated centering accuracy, specified in meters.

Calibration¶

Elasticity modulus: Tape elasticity.

Weight: Tape weight (kg/m).

Cross-section: Tape cross-section (mm²).

Tension: Comparison pressure for calibration data (kg).

Reference temperature: Comparison temperature for calibration data (Celsius).

Total Standard Deviation (Std)¶

Std² = (StdC + D × StdA)² + (StdS)² for distance.

Std² = (StdC + D × StdA)² + (StdS/D)² for direction.

Std² = StdC² + (D × StdA)² + (StdS/D)² for zenith distance.

Here, StdC and StdA are the constant and distance-dependent parts of the observation, respectively, StdS is the centering accuracy, and D is the distance. This total standard deviation is transferred to the observation unless you have entered other values or requested an updated standard deviation.

Note

If you use the formulas to calculate the standard deviation for a given observation, pay attention to the units.

Alternative 1: Convert gon to radians (PI/200) before entering the values in the formula, i.e., for the constant and distance-dependent parameters. Finally, convert the result back from radians to gon (200/PI).

Alternative 2: Convert the centering part (StdS/D) to gon (200/PI). Then all terms will have the unit gon. This gives the same result as alternative 1.

Example

Values for standard deviation calculation:

Observation Type	Constant Part	Distance-Dependent Part	Centering
Direction Measurement	0.0005 gon	0.0000 gon/km	0.003 m
Zenith Distance	0.0005 gon	0.0025 gon/km	0.003 m
Distance Measurement	0.001 m	0.010 m/km	0.001 m