(The Adjustment module is required for this procedure.)
This procedure is used to create and edit a Control file, and carry out any of the following adjustments:
Horizontal Least Squares Adjustment
Vertical Least Squares Adjustment
The resulting adjusted co-ordinates or elevations may then be transferred to the currently open data base.
- Ensure that there is a data base open.
Refer to the procedures for creating or opening a data base. - Use the Utilities/Configure/Earth Constants commend to check that the Earth Constants settings
are correct. Refer to the procedure for Configuring Earth
Constants.
These values will be used if curvature & refraction correction or mean sea level correction are applied during the extraction or adjustment process. - Select the Field Transfer task.
- Select the Settings/Instrument command and use the Instrument dialog box to ensure that the theodolite vertical circle type is correctly set to match the theodolite used, and also to set the default standard deviations for the observations. These default standard deviations will be used when the control file observations are generated.
- Select the Settings/Tolerances command and use the Tolerances dialog box to set the tolerances used by the system to generate warnings in the adjustment report if the adjustments to observations are outside the maximum standard deviation tolerance set. This dialog box is also used to set the Maximum number of iterations that the adjustment process will attempt before the adjustment is aborted.
- Select the Resolve/Adjustment command to display the Control File Editor. An empty control file will automatically be opened in the control file editor.
- Use the Options Menu to govern what is displayed and whether point identifiers and standard deviations are to be automatically generated when entering data in the Control File Editor. The Options may be changed at any time.
- If desired, use the File/New command to create and
open a different control file.
Alternatively, you may wish to use the File/Open command to open a different control file that you had already created and done some work on. - If there is a Field File containing control observations
that you wish to adjust, use the File/Extract command
to extract the control observations from the selected field file into the currently open control
file. Ensure that the currently open control file is a blank file before carrying out the extraction
process.
The Field file may have been created manually using one of the following Field Transfer/Input/Manual Entry commands:- Stadia
- Slope Distance
- Horiz. Distance
- Resection
- Intersection
- Alternatively, it may have been created automatically from a Raw file using the Resolve/Create Field File command.
- Observations to an Instrument setup point;
- Observations to a point of fixed co-ordinates;
- Multiple observations to the same point.
- Fixed co-ordinates in the Field file are also extracted.
- You may use the Edit Menu at any time to insert,
delete, clear, cut, copy or paste rows in the editor. First, highlight the appropriate record by
clicking the row number in the Stations window or the Observations window.
- Use the Control File Editor to add to, delete, or edit the control file stations and observations.
Refer to the Control File Editor topic for details
on editing control file data.
Co-ordinates, elevations, angles, bearings and distances may be toggled between fixed and variable by selecting the appropriate cell in the stations window and using the Edit/Fix command, or the appropriate tool. Fixed co-ordinates and observations are treated as constraints on the adjustment and are held to their fixed values.
Directions may be toggled between oriented and non-oriented by selecting the appropriate Angular cell in the observations window and using the Edit/Set Bearing command or the appropriate tool.
You can also select that a direction is the start of a set of directions using the Edit/Set Reference command or the appropriate tool.
Note that it is advisable to use the File/Save command at regular periods when entering data to minimise possible loss of data in the event of hardware or power failure. When editing is complete, you should again use the File/Save command, and you may wish to also use the File/Print command to send the contents of the control file to the Windows Print Manager. - Carrying out the Adjustment
If you are going to perform a horizontal least squares adjustment:
First, ensure that there are sufficient Fixed Co-ordinates entered in the Stations Window to fix and orientate the network.
Use the Horizontal/Corrections command to control the corrections that will be applied in the adjustment.
Next, use the Horizontal/Approximate Co-ordinates command to generate approximate co-ordinates in the Stations window for the unknown points. If the system cannot compute an approximate co-ordinate, you are warned, and you must compute and add it manually before repeating this command.
When all the required approximate co-ordinates are in the stations window, use the Horizontal/Check command to identify and report on any problems with the data. Such problems must be fixed before continuing with an adjustment.
After a successful check process, use the Horizontal/Adjustment command to carry out the adjustment. If the data cannot be adjusted, you are informed and appropriate editing of the control file must be carried out before repeating step 12.
When the Adjustment is successfully completed, an appropriate report is produced and you have the opportunity to update the control file with the adjusted co-ordinates. Refer to step 13.
If you are going to perform a vertical least squares adjustment:
First, ensure that there is at least one Fixed Elevation entered in the Stations Window to fix the elevation datum.
Next, use the Elevation/Approximate Elevations command to generate approximate elevations in the Stations window for the unknown points. If the system cannot compute an approximate elevation, you are warned, and you must compute and add it manually before repeating this command.
When all the required approximate elevations are in the stations window, use the Vertical/Check command to identify and report on any problems with the data. Such problems must be fixed before continuing with an adjustment.
After a successful check process, use the Elevation/Adjust command to carry out the adjustment. If the data cannot be adjusted, you are informed and appropriate editing of the control file must be carried out before repeating step 12.
When the Adjustment is successfully completed, an appropriate report is viewed and you have the opportunity to update the control file with the adjusted elevations. Refer to step 13. - Updating the Data Base.
After an adjustment is successfully carried out, the appropriate Report is displayed. Note that you may send the adjustment report to the Windows Print Manager, or save the report to a text file.
When exiting the report screen, you have the option of saving the adjusted co-ordinates or elevations in the Stations window. If you are satisfied with the adjustment, then select yes when prompted with "Update Co-ordinates into spreadsheet".
Once you have done this update of the spreadsheet, you are in a position to update the database. Use the Horizontal/Update command or the Vertical/Update command as appropriate to update the co-ordinates or elevations in the database with the values in the stations window.