Measuring a new control point with GNSS

There are several reasons why you may need to measure a new control point during a project and then add the measured position to the Control Point file for the project. Typical cases include:

• When operating the project with a mixture of GNSS and total station equipment; total stations require more control points around the project because of their line-of-sight dependence. Control points can be established very rapidly using GNSS and can be used later by total station crews to establish their position and orientation.

• When operating a site, a base station often needs to be moved closer to the current working location to provide better radio coverage. The base station must be relocated to a known point in the local coordinate system, unless BaseAnywhere is used. Using the Measure control point option ensures that the point is created in the correct location, with the correct coordinates, and guarantees that the project calibration remains valid after the base station is moved.

• When carrying out topographic measurements on a new site before control for the project is established, you may set the base station up in an arbitrary and convenient location and then carry out a single-point calibration. Once completed, measuring three or more control points around the project provides a common set of reference points that can be used later to transform the data measured using the single-point calibration, to the project coordinate system once it is established.

1. From the Home menu, tap Measure / Measure Control Point.

2. Create the control point location using a stake, a hub, or a road nail as required and then mark the stake with the name for the control point, for example, CP3.

3. Set up the GNSS rod over the point and hold it steady using a bipod. The software displays the current GNSS position on the map.

4. When you are ready to take the measurement, tap the Measure icon. The measurement process takes approximately 15 seconds to complete. Measuring for 15 seconds takes an average position that increases the accuracy of the computed control point. It is possible to change the amount of time that the static point is measured.

When each control point is measured, the software stores the control point data position in the control point (Control.field.csv) file for the site, and also records the measurement data into the record and report files for the work order.