Multiple Backsight

Main Menu or Instrument Toolbar | Measure Modes | Setup & Check | Backsight by Multiple Points or Directions

Multiple Backsight routine allows you to use multiple known control points to calculate a more accurate backsight orientation.

Backsight by Multiple Points or Directions

Occupy Point

Your instrument location or Occupy Point can be entered here. Double click the empty will show a drop-down list. You can then select the point from Map, List, or create a New point.

Instrument Height

Enter the height of your instrument set up, it will be used in the calculation.

Control Points Table

You can click the "Add" button to select backsight points, a minimum of 2 points are required for calculation.

You can use the second column to select a desired backsight point, unchecked backsight points will be used to improve the accuracy of the selected one.

Multiple Backsight Results

After taking measurements for each control points entered, Multiple Backsight results screen will show up to display calculated results and allow you to refine Azimuth Offset base on Offset Residual values.

Control Points Table

• "Point" column - shows the Point ID for each control points measured
• "Use" column - allows you to toggle if the selected control point will be used in the calculation or not.
• "Azimuth Offset" column - shows individual azimuth offset value for each control point.
• "Offset Residual" column - shows individual offset residual value, this value can be used to access the accuracy of each control point.
• "HA Observed" column - shows the measured horizontal angle.
• "HD Observed" column - shows the measured horizontal distance.
• "HD Difference" column - shows the difference in horizontal distance.

Observe Again

This button allows you to re-measure the selected control point if the residual offset value is greater than expected.

Azimuth Offset

This is calculated Azimuth for your improved backsight direction. You can adjust this value by selecting desired control points from the above table. The Offset Residual column can be used to assess the quality of each control point.

RMS

This is Root Mean Square (RMS) value for all selected Offset Residuals.

 

Once you are satisfied with the result, click 'OK' to Backsight Summary