Least Squares Adjustment Editor

(This functionality is available with the Adjustment module)

The Least Squares Adjustment Editor is displayed after selecting the Field Transfer/Resolve/Least Squares Adjustment command. It may also be run from the Adjustment task. It is used to create, edit and adjust least squares control file observations, and create points in the data base with adjusted co-ordinates. The adjustment technique is Least Squares.

The colours used in the Least Squares Adjustment Editor to signify whether co-ordinates and observations are locked (fixed) or floating (to be adjusted) are set using the Utilities/Configure/Colours/Table command.

Item Used to
Cells: Display the data in the currently open least squares adjustment control file and to select the active cell enabling its value to be edited.
The currently active cell is highlighted with a border.
The currently active cell is selected by clicking the required cell with the mouse, or by using the arrow or Tab keys to move the border to the required cell.
Stations Window Display the Fixed (locked) and Approximate (floating) co-ordinates.
Fixed co-ordinates are held during the adjustment process. There must be at least one fixed co-ordinate record.
All points in the network that do not have fixed co-ordinates must have approximate co-ordinates before a least squares adjustment may proceed.
Stn. Column Display the station record number and to select an entire station record for editing.
Select a record number with the mouse to select the entire record.
Pt. Column Display or edit the station point identifiers.
Entering a point identifier that exists in the currently open data base will automatically extract the co-ordinates from the data base and enter them in the appropriate cells.
East, North & Elevation Columns Display the station co-ordinates.
Code Display the feature code.
Description Display the description.
Observations Window Display the observations contained in the least squares adjustment control file.
Obs. Column Display the observation record number and to select an entire observation record for editing.
Select a record number with the mouse to select the entire record.
From Column Display the station point identifier from which an angle observation was observed. It must be empty for all observations other than angles.
At Column Display the station point identifier at which the observation was observed. This column contains the instrument set up point identifier. It must contain an identifier for each observation record.
To Column Display the point identifier to which the observation was observed. It must contain an identifier for each observation record.
Angular Display the angular measurements.
These may be:
  • Angles measured clockwise between the From and To points. The From, At and To cells must contain point identifiers.
  • Directions from the At point to the To point. The From cell must be empty; the At and To cells must contain point identifiers.
    Note that a direction must be preceded or followed by at least one other direction record with the same At point identifier.
  • Bearings from the At point to the To point. The From cell must be empty; the At and To cells must have point identifiers.
    Note that a bearing is an orientated direction.
Note that a direction can toggled to a bearing (and vice versa) by using the Edit/Bearing command.
For any one least squares adjustment control file, the angles, directions and bearings must be all of the same type in relation to the geodetic corrections that have been applied. That is they must all be:
  • -Azimuths (uncorrected for grid convergence and arc to chord correction), or
  • -Grid (corrected for grid convergence only), or
  • -Plane (corrected for grid convergence and arc to chord correction).
This is set in the Horizontal/Corrections command.
Distance Display the distance measurements.
The distance is considered by the adjustment process to have been already reduced for slope.
For any one least squares adjustment control file the distances must be all of the same type in relation to the geodetic corrections that have been applied. That is they must all be:
  • -Ground distances (uncorrected for mean sea level, geoidal separation and scale factor), or
  • -Ellipsoidal distances (corrected for mean sea level and geoidal separation), or
  • -Grid distances (corrected for mean sea level, geoidal separation and scale factor).
The distance type is set in the Horizontal/Corrections command.
Diff. Elev. Display an observed height difference.
SD Ang/Dir, SD Dist & SD Elev Columns Display the standard deviations of the Angle/Direction, Distance and Elevation observations.
The default standard deviations computed by the system for single distance, angle/direction or slope/elevation observations are based on the settings in the Field Transfer/Settings/Instrument Settings dialog. Note however that the standard deviations shown for means of sets are the (non zero) sample standard deviations computed for the sets, as per the rounds report produced when File/Extract is used. If the rounds report standard deviation is zero, the standard deviation reverts to the value in the Instrument Settings dialog divided by the square root of the number of rounds.
Tool Bar The following special tools are available in the Least Squares Adjustment Editor.
Tool Used to
New File File/New Create a new untitled least squares adjustment control file.
Open File File/Open Open an existing least squares adjustment control file.
Extract File File/Extract Extract control observations from a field file.
Import XML File/Import XML Imports data from an XML file compliant with the LISCADXML-ADJHZ or LISCADXML-ADJEL Schemas.
Save File File/Save Save the currently open file to disk.
Cut Edit/Cut Row Cut the selected row to the clipboard.
Copy Edit/Copy Row Copy the selected row to the clipboard.
Paste Edit/Paste Row Paste a row from the clipboard to the editor.
Retrieve Coords Edit/Retrieve Co-ordinates Retrieve co-ordinates from the currently open database and place them in the Least Squares Adjustment Editor
Set Reference Edit/Set Reference Toggle whether a direction is a reference direction. A reference direction is underlined and is the start of a set of directions which were measured in relation to the reference direction.
Set Bearing Edit/Set Bearing Toggle whether a direction is orientated. That is, whether it is a direction or a bearing. A bearing is shown in italic.
Lock Edit/Fix Toggle whether a co-ordinate, angle, bearing or distance is to be held fixed (locked).
Exclude Observation Edit/Exclude Observation Toggle whether an observation is to be excluded from the adjustment computation.
Display Observations Edit/Modify Standard Deviations Automatically sets the standard deviations of the observations.
Display Stations Options/Station Toggle the display of the Stations window on or off.
Display Observations Options/Observation Toggle the display of the Observations window on or off.