Process / Validate Measurements Report

Description

Report on measurements and coordinates after validating or processing the selected measurements.
Access

Measurements / Process / Validate measurements
Measurements / Process / Process Measurements

Requirements
  • Adjust module (to perform Least Squares adjustments)
  • Measurements imported via an appropriate Data Import or entered via manual input.
Report

The report is divided into the following sections:
Summary

The following table describes items in the 'Summary' section.

Summary Description
General General project information.
Units Angular and linear units.
Adjustment Method Type of adjustment applied.
Summary A summary of the adjustment results, including if the measurement adjustment was successful, the number of errors and the number of coordinates that will be updated.
Adjustment

The following table describes results in the 'Adjustment' section.

General Description
Solution The number of iterations taken for the solution to converge.
Note:
  • The solution will fail to converge if the number of iterations exceeds the maximum number of iterations.
Type Geodetic or Local adjustment.
Note:
  • A defined coordinate systems is required for a Geodetic adjustment.
Number of Unknown Parameters The number of parameters to be estimated by the least squares adjustment.
Number of Measurements The number of measurement components used in the adjustment.
Note:
  • Each GNSS baseline is considered to have 3 measurement components (x,y,z).
Number of Potential Outliers The number of measurements that statistically do not fit with the remaining measurements in the adjustment.
Note:
  • In the Adjusted Measurements section, the potential outliers are marked with a dot in the outliers column.
  • An erroneous measurement can cause other reliable measurements to be considered potential outliers.
  • It is important to distinguish the true outliers and remove them from the adjustment. See notes below.
Degrees of Freedom The number of redundant measurements in the adjustment. (The number of observations minus the number of unknowns).
Chi Squared Used to determine the upper and lower limits in the Chi Squared Test. (Calculated from the a-priori measurement precisions and the least squares measurement residuals).
Rigorous Sigma Zero The estimated variance factor, used to test the least squares solution.
Note:
  • A value close to 1 indicates the estimated errors correspond well to the observation errors.
  • If the value is too low, it may indicate the error estimates for the instrument are too pessimistic.
  • If the value is too high the error estimates may be too optimistic.
Global (Pelzer) Reliability An indication of the reliability of all measurements in the network. A value close to 1 is ideal.
Chi Squared Test (95%) A goodness of fit test:
Passed - The estimations can be considered statistically reliable as the Rigorous Sigma Zero value falls within the upper and lower limits of the 95% confidence interval.
Failed - The Rigorous Sigma Zero has exceeded the confidence interval upper limit. This indicates that a number of measurement corrections have failed.
Warning - The Rigorous Sigma Zero is less than the confidence interval lower limit. This can indicate that the measurements were more precise than the errors given.
Note:
  • This statistical test should be considered in conjunction with individual measurements tests.
Measurements Description
Directions The number of measured angles between stations.
Zenith Distances The number of measured vertical angles to stations.
Distances The number of measured distances to stations.
GNSS Baselines The number of measured GNSS baselines between stations.
Error Factors Description
Angles The computed error factor for Angular measurements. (∑ Adjusted Standard Deviation/∑ Measured Standard Deviation)
Distances The computed error factor for distance measurements. (∑ Adjusted Standard Deviation/∑ Measured Standard Deviation)
Zenith Distances The computed error factor for vertical angles. (∑ Adjusted Standard Deviation/∑ Measured Standard Deviation)
Fixed Coordinates Description
Point Name Name of the stations constrained in the adjustment.
Coordinates Easting, Northing and Orthometric Height of the constrained station.
Constrained The coordinate components that are constrained.
Constraints Description
From From station
To To station
Type The type of the constraint (Plane Bearing, Grid Bearing, Azimuth)
Constraint The value of the constraint between the From and To stations.
Levelling

The following table describe items in the 'Levelling' section.

Processing Data Description
Apply Staff Correction Specifies if the measurements were corrected for thermal expansion or contraction of the staff.
Allowable Misclosure Allowable misclosure for the level run as specified in the processing options.
Allowable Adjustment per Setup Allowable adjustment to each measured height difference as specified in the processing options.
Allowable distance balance The maximum allowable total distance balance between backsight and foresight as specified in the processing options.
Apply Staff Correction Specifies if the measurements were corrected for thermal expansion or contraction of the staff.
Level Run Description
Profile Graph Profile graph of points in the level run points.
Note:
  • Heights and distances are in the current linear units
  • Benchmarks and change points are plotted on the graph
  • Heights are determined from field measurements.
General Description.
Description Level run description.
Date Date of observation
Field Party Persons who completed the survey
Instrument Instrument used to collect the measurements
Start Point Start Point of the level run.
End Point End Point of the level run.
Method The order in which observations were measured.
Number of Setups Number of level setups in the level run.
Number of Observations Number of observations in the level run, including observations to intermediate points.
Results Description
Height Difference The height difference between the start and end point.
Length The sum of backsight and foresight distances for the entire level run.
Total Distance Balance The total distance balance between backsight and foresight distances.
Error per Setup The misclosure in the level run per instrument setup.
Note:
Level Sheet Description
Point Point name or vertex unique identifier.
Backsight Observations to backsights as measured in the field.
Intermediate Observations to intermediate sights as measured in the field.
Foresight Observations to foresights as measured in the field.
Height Difference Observed height difference between points.
Distance Combined measured distances from the instrument setup to the backsight and foresight points.
Height Height computed from unadjusted observations.
Note:
  • Heights are computed from the first control point encountered. If there are not any control points the height of the Start Point is used as a starting height.
Observations Description
Point At From Point
Point To To Point
Observed Height Difference The height difference between points as computed from the field measurements.
Computed Height Difference The height difference between points as computed from the adjusted measurements.
Difference Difference between the computed and the observed height difference.
Note:
Updated Coordinates

The 'Updated Coordinates' section displays the resultant coordinates, compared with the values prior to processing.

Updated Coordinates Description
Point Name Name of Point with adjusted coordinates.
Coordinate Class Coordinate class given to the Point.
Estimates The number of solutions that are averaged to determine the resultant adopted coordinates for the point. See Averaged Measurement.
Original Initial estimate of the easting, northing and orthometric height.
Updated Resultant easting, northing and orthometric height.
Difference Difference between the initial estimate and the resultant adjusted coordinates.
Standard Deviation Standard deviation computed for the estimated coordinates.

Use the 'Average Measurement' table in conjunction with the 'Checked Coordinates' table to view the coordinate solutions that have been averaged.

Averaged Measurements Description
Point Name Name of the point or the vertices unique identifier.
Setup Id Name of the point or the vertices unique identifier.
Measurement Id Measurements unique identifier.
Estimate Coordinate solution for the point determined from a single observation.
Difference The difference between the resultant coordinate determined for the point and the solution determined from the single observation.
  • The updated coordinate table does not display when the coordinates have not changed.
Checked Coordinates

The 'Checked Coordinates' section displays when there is multiple coordinate solutions for an point that can not be included in an average as the resultant solution has already been determined. For example an observation to a control point or a check measurement to a reference station or a traverse station.

Checked Coordinates Description
Point Name Name of the Point or the vertex unique identifier.
Coordinate Class Coordinate class assigned to the point. The coordinate class reflects how the points resultant coordinates were determined.
Estimates The number of solutions for the points coordinates.
Updated The resultant easting, northing and orthometric height adopted for the point.
Checked The easting, northing and orthometric height determined from the check measurement to the point.
Difference Difference between the resultant adopted coordinates and the coordinates determined from the check observations.
Standard Deviation Standard deviation computed for the point based on all the solutions.
  • The checked coordinate table does not display when a network adjustment is performed as all measurements are used to determine the solution.
Standard Deviations

The following table describes results in the Station 'Standard Deviations' section.

Station Standard Deviations Description
Point Name Name of the unconstrained control point.
Vertex ID Unique ID of the control points vertex.
Coordinate Class Coordinate class given to the station.
Coordinate Adjusted coordinates for the station.
Standard Deviation Standard deviations computed for the estimated coordinates.
Station Uncertainty

The following table describes results in the 'Station Uncertainty' section.

Station Uncertainty Description
Point Name Name of the station.
Vertex ID Unique ID of the stations vertex.
Coordinate Class Coordinate class given to the station.
Coordinate Adjusted coordinates for the station.
Position Uncertainty An indication of the coordinate quality in the horizontal and vertical plane.
Semi Major The semi major axis of the error ellipse.
Semi Minor The semi minor axis of the error ellipse.
Orientation The orientation of the error ellipse.
Station Corrections

The following table describes results in the 'Station Corrections' section.

Station Corrections Description
Point Name Name of the station.
Vertex ID Unique ID of the stations vertex.
Coordinate Class Coordinate class given to the station.
Difference The difference between the original and updated(adjusted) station coordinates.
Measurement Summary

The following table describes items in the 'Station Measurement' Summary section. Only measurements included in the adjustment appear in the summary.

Station Measurement Summary Description
Point Name Name of the station.
Vertex ID Unique ID of the stations vertex.
Directions The number of directions measured from the station.
Vertical Angles The number of vertical angles measured from the station.
Distances The number of distances measured from the station.
GNSS Baselines The number of GNSS measurements measured from the station.
Height Differences The number of height differences between stations.
Adjusted Measurements

The following table describes results in the 'Adjusted Measurements' section.

Adjusted Measurements Description
From From name (for angles only).
At Station name.
To Target name.
Measured The original measurement. For directions, this value is the original clockwise angle.
Adjusted The adjusted measurement. For directions, this value is the adjusted clockwise angle.
Residual Estimated correction to the measurement
Measured SD Estimated standard deviation of the original measurement.
Adjusted SD Standard deviation of the adjusted measurements.
N-Stat The standardised Normal statistic, calculated relative to the unit Normal distribution.
If the N-stat exceeds the critical value (95% confidence interval) of +/- 1.96 the measurement is marked as an outlier.
This test is suitable when there is a large set of measurements that have reliable estimates of precision.
T-Stat The standardised Student-T statistic calculated relative to the unit Student-T distribution.
The T-stat gives an indication on what the N-stat values would be if the Rigorous Sigma Zero value (variance factor) was used to scale the a–priori standard deviations prior to adjustment.
This test is used to gain a higher level of confidence in the solution when the redundancy in the network is limited and precision estimates are not reliable.
Residual The estimated random error in the original measurement. (Adjusted measurement - Measured measurement)
Pelzer Reliability Pelzer’s measurement reliability criterion. A test to access the reliability of the measurement. A value close to 1 is ideal.
Outlier A dot is displayed if the measurements N-stat or T-stat value exceeds the critical value (95% confidence interval) of +/- 1.96.
All outliers must be investigated.
Measurement Differences

The following table describes items in the 'Total Station Setup Measurement Differences' section. Use this section to detect gross errors in total station data prior to performing a least squares adjustment.

Measurement Differences Description
Point Name Station setup points.
Easting, Northing, Height A comparison between the station coordinates computed from different observations.
Horizontal Angle The directional error computed from the coordinate difference.
Horizontal Distance The distance error computed from the coordinate difference.
Notes
  • Only observations selected in the measurement view are processed.
  • Validating the measurements does not update any coordinates.
  • The azimuth and station constrained in a minimally constrained adjustment is selected by the system.
  • Possible reasons for a Chi-Squared Test failing include:
    - optimistic total station angle and distance accuracy.
    - optimistic GNSS accuracy in the measurement file.
    - erroneous or substandard measurements.
    - errors in field practices, for example, moving a station mark without changing the name or measuring to the wrong mark.
  • Error Factors close to 1 indicate the measured standard deviations are suitable for the observations.
  • If the measurement errors are pessimistic a warning will be given with the Chi Square Test and the precision estimates (error ellipses) may be inaccurate.
  • Coordinates influenced by outlier measurements will have a biased location and quality. Use the N-stat and T-stat values to detect the true outliers.
  • If removing a measurement results in the Chi-Square test passing, and all remaining measurements pass the local Normal distribution and Student-t distribution tests then it is likely there is a blunder in the measurement that was removed.
  • In the Station Correction section, Plane Bearing, Zenith Angle, Slope Distance and Horizontal Distance are the polar components of the coordinate difference.
  • If gross errors are not present in the data, outliers in GNSS measurements could be eliminated by scaling the a-priori standard deviations with the Rigorous Sigma Zero value.
  • Large errors in the Total Station Setup Measurement Differences section indicate a gross error in the field.
  • Print the report using the Print Preview application available from the Quick Access Toolbar.
Possible errors

Error or Warning Description
Operation Failed. Layer 'Layer Name' is locked. Processing requires modifications to a locked layer. No changes have been made. Unlock the layer and re-process.
Measurement to 'Target Station' from setup at 'Instrument Station' has suspect target height 'Target Height'. The target height is outside the range specified in the measurement processing options.
Setup at 'Instrument Station' has suspect instrument height 'Instrument Height'. The instrument height is outside the range specified in the measurement processing options .
Differences are excessive. The adjustment to height differences exceeds the tolerance setting for Allowable error per setup..
Layer 'Layer Name' not found. New layer created. A new code has been detected during code processing. A new layer with the name 'code name' has been created.
Insufficient measurements with code 'code name' to form object type." The intended use for the layer 'code name' requires an object to be created that requires more vertices than there are measurements with the code.
Invalid layer name 'Layer name' sanitised to 'new layer name'. A new code was added for the measurement that is invalid as a layer name. The object created has been placed on the specified layer.
Related topics

Top of page TOP OF PAGE