Perform a least-squares network adjustment on GNSS, total station, and/or digital level data that has been imported into your project to achieve the following benefits:

• Random errors can be estimated and removed.
• A single solution is provided when there is redundant data.
• Corrections made to observations are minimized.
• Blunders and large errors can be detected.
• Information for analysis can be generated, including estimates of precision.

Note: The Adjust Network command allows you to perform a network adjustment that includes two or more subnetworks (networks with unconnected observations) within your project. You can specify adjustment parameters for each subnetwork individually as necessary as shown here before all subnetworks are adjusted together. An individual adjustment report is generated for each subnetwork.

Following are the basic steps for this workflow. For more detailed instructions, see Adjust a Network.

Steps:

Commands:

1.

Before performing a network adjustment, ensure your project is configured correctly in the Network Adjustment section of the Project Settings dialog.

For example, you can specify whether observations that make up mean angles are used individually or as a mean. You can also specify covariance display and transformation settings

Project Settings

2.

Display the Adjust Network pane to begin the network adjustment process.

To evaluate the internal consistency of the survey network, you should first perform a minimally constrained network adjustment, which uses the minimum number of constraints required to define the coordinate system.

Adjust Network (requires adjustable network data)

3.

If applicable, select the subnetwork for which you want to set adjustment parameters in the Subnetwork name drop-down list.

The parameters you specify in the next several steps pertain only to the select subnetwork. You can repeat them for each subsequent subnetwork to be included in the overall adjustment.

4.

On the Fixed Coordinates tab, select the minimum number of constraints required. Then click the Adjust button.

View a summary of the adjustment results on the Results tab.

5.

In the Adjust Network pane, click the Report icon to view the Network Adjustment Report. Observations with standardized residuals that fail the Tau criteria are displayed in red. These observations are outliers and can be disabled.

Click any underlined observation in the report to select the related observation in the project.

6.

If necessary, disable any observations by opening the Properties pane for the observation and selecting Disabled for the Status. Then click the Adjust button to re-adjust the network.

Properties

7.

If the Chi Square test fails, use the Weighting tab to apply a weighting strategy to the processed vectors to improve the initial a priori error estimates for the observations. Then click the Adjust button to re-adjust the network.

Repeat these steps until the Chi Square test passes, indicating the initial a priori error estimates agree with the adjusted errors for the network vectors.

You are now ready to perform a constrained network adjustment in which... the remaining control points are held (fixed) to the coordinates from the imported data sheets. The object is to compute adjusted coordinates for the measured points in the survey network, relative to the existing control stations. Assign standard error values to each control point based on its quality using previously adjusted values from past surveys or error estimates from CORS or national network reference station adjustments if available. When you assign a standard error to a control point, you enable the network adjustment to adjust the coordinate value of the control point based on the quality of the observations and the other control points.

8.

In the Adjust Network pane, select the Fixed Coordinates tab. Then click the Use assigned weighting icon at the top of the pane.

On the Constrained Coordinates tab, enter error values and select the "fix" checkboxes for each point you want to constrain.

Then click the Adjust button to re-adjust the network starting with the 2D points and heights to derive an acceptable horizontal solution.

Apply scalars to the observations and re-adjust if necessary.

Once a satisfactory horizontal adjustment has been made, uncheck the height control points and start checking the elevation control in an iterative approach.