How To Re-Orientate a Total Station

A total station may need to be removed from its tribrach and then returned or replaced.  On these occasions the instrument will no longer have the same orientation and the system needs to be updated so that the measurement commands point it in the co

The procedure for re-orientating a total station is described below.

1. Ensure the instrument is level.
2. Make a note of the most recent horizontal angle measured for one of the observations (from before the instrument was removed).  See below for details.
3. Open the Live Control dialog for the total station and use the 'Request Manual Control' button to acquire manual control of the instrument.
4. Physically aim the total station at the observation whose measured horizontal angle you noted in Step 2.
5. In Live Control select the Advanced button on the Actions Page.  Note that the Advanced button does not appear until you have manual control. 
6. Enter the horizontal circle (angle) noted in Step 2. 
7. Click on the tick box next to the horizontal circle input box.

Finding a Previously Measured Horizontal Angle

The most recent measured horizontal angles may be displayed using the Sensor List or a Systems View of the sensors.  However, if the most recent measurement failed then the value may not be displayed.  If this is the case then simply create a time-series graph of the measured horizontal angle values and read the value that is revealed when you hover the cursor over a data point.

From <https://geoexplorer61.helpdocsonline.com/how-to-re-orientate-a-total-station>

Finding a horizontal angle from raw coordinates data

We can calculate the horizontal angle to each control point using the coordinates of the controls and the AMTS. We can use the law of cosines using the below formula

Angle in radians = acos((P122 + P132 - P232) / (2 * P12 * P13))

Where p12 = sqrt((P1x - P2x)2 + (P1y - P2y)2)

P1 will be our total station

P2 will be our target prism

And P3 will be a theoretical point due North of the Total Station.

Use the below spreadsheet as a template for doing these calculations

<<All Prisms Coordinates.xlsx>>