# To review observation residuals and setup results

Use the observation residual information shown after a station setup plus or resection to review the quality of the observations and remove poor observations. A residual is the difference between the known position and the observed position of the backsight point(s).

- During a station setup plus or resection, no observations are stored to the job until you store the station setup.
- A foresight point that does not yet exist in the database has null residuals in the Residuals screen.

To view the standard deviations of the observations for each point, tap Std Dev. The Std Dev softkey is available only after all rounds are complete.

Station setup and resection results

To view the station setup results, tap Results.

To store the station setup, tap Results and then tap Store.

To view the details of an observation, select it and then tap Details.

To observe more points, tap + Point.

To navigate to a point, tap + Point and then tap Navigate.

In a conventional only survey, when one measurement is completed, the Trimble Access software can provide navigation information for further points, and a Navigate softkey is available. Tap Navigate to navigate to another point. If connected to a GNSS receiver or using a controller with internal GPS, the Trimble Access software can provide navigation information for any point, and a Navigate softkey is available. Tap Navigate to navigate to another point.

Point residuals

To view the mean observed position and the individual observations for a point in the Point residuals screen, tap the point.

If the residuals for an observation are high, it may be better to disable the observation from the round.

To disable an observation, highlight it and then tap Use. Whenever you make a change in the Point residuals screen, the mean observations, residuals, and standard deviations are recalculated. If you have measured face 1 and face 2 observations to a point, when you disable the observation for one face, the corresponding observation on the opposite face is automatically disabled.

If you turn off some (but not all) of the observations to a backsight point in a resection, the solution for the resection is biased and there is different number of observations to each backsight point.

If the current station setup has a single backsight only, the Use softkey is not available for observations to the backsight. Observations to the backsight are used to orientate observations and cannot be deleted.

If you remove observations, the icon appears. If you skipped observations in a round, no icon appears.

Point details

The Point details screen shows the mean observation to the point.

If required, you can change the target height and prism constant for all observations to that point.

if you are viewing the residuals for a resection, you can change the components that are used for the resection calculation if you:

- selected the compute station elevation option
- the observed point has a 3D grid position

To do this, tap Used for and select:

- H (2D) to use only the horizontal values for that point in the calculation
- V (1D) to use only the vertical values for that point in the calculation
- H,V (3D) to use the horizontal and vertical values for that point in the calculation