USER GUIDE - DATA
The Data page is where you load, import or enter all data for the current project. Each time you import a new file, the data (stations and observations) extracted from that file are added to the current project.
Columbus 4.5 input files can be created manually or within the UI. There are dozens of keywords that describe the data. These files can be very simple or more complex depending on your needs. For example, you can specify one set of centering errors for the entire project or you can declare different centering errors for every setup. For samples on Columbus input files goto Sample Network files.
You can also import Columbus 3.8.x.x files.
Third party file support
Several third-party file formats are supported, including:
- OPUS XML and Text files
- Google KML files containing latitude, longitude and height coordinates
- Star*Net files containing many of the commonly used keywords
- Trimble Data Exchange, SSF, SSK and WAVE
- TDS RW5 files
- Ashtech "O" files
- Leica Ski files containing GPS data
- Topcon XML
- NGS Bluebook "G" Files
After importing data (or without importing data) you can edit, add and delete station and observation data using the Station and Observation grids found in the lower half of the Data page.
When using the Stations grid, there is only one set of North and East coordinate values for each station. If you are working with Grid (State Plane) coordinates, you would enter them in the North and East columns. If you are working with a Local Plane coordinate system, you would use the same columns. Columbus knows how to interpret these coordinates based on the adjustment type setting you select in the Adjust page.
Preferences are all the settings made in Columbus that affect computation results. Preference settings can be stored on disk for future use.
Most preference settings occur on the Preference page. However, additional preference settings are sprinkled throuout the application. For example, when you are on the Adjust page, altering the Adjustment type, Height type, Create Station flag, etc. results in a change to preferences.
There are three ways to manage Preferences. Your choice of usage may depend on your workflow, comfort level or habits learned from using other software.
- Store preferences in every project file. Every time you save your project data to a file using the Save Project To File button, the current preferences can also be saved into the file. When that file is reloaded, the preferences are also loaded. To work this way, you must enable (check) the Include Preferences checkbox.
- Create a library or preference settings. This method allows you to create a new set of preferences for different
types of surveys. For example, you do two types of jobs: control surveys and subdivision surveys. For the control surveys,
you use more accurate equipment. Therefore, you set your default standard deviations to smaller values. There may be several other preference settings that vary between these two job types as well. To create a unique set of Preferences that can be loaded at any time, do the following:
Modify the current preferences to fit the job type. Save the preferences to a unique file (for example: "ControlPreferences.txt") using the Save Preferences To File button on the Data page. This set of preferences can then be retrieved at any time by using the Load Preferences From File button. Because preference settings are saved to a file of your choice, you can create any number of unique preference sets. Although not required, you may want to uncheck the Include Preferences checkbox in order to have less clutter in your project files.
- A combination of method 1 and 2. For some projects you set preferences from your library, while for others you store the preferences in each project file.
Preference settings are stored in XML format. Do not edit the XML directly
Latitude and longitude
Latitude and longitude must always be provided in DMS (degree, minute, second) units. For example:
N 40-10-15.123456 must be entered as: 40.1015123456
S 40-10-15.123456 must be entered as: -40.1015123456 (negative)
E 105-3040111111 must be entered as: 105.3040111111
W 105-3040111111 must be entered as: -105.3040111111 (negative)
Using observation grids
When using the various observation grids, you can enter up to three observations for each row; for example a horizontal angle, zenith angle and slope distance.
If you did not measure one of the observations, simply leave that specific observation cell blank; for example, leave the Slope Dist field blank if
you did not take that measurement.
For Direction sets, assign a unique number (Set Num) to all direction records that are part of the same set. This can be any number between 1 and 999999.
Entering data within the grids
When entering data within the grids, you will receive and error indicator if you make an invalid entry. Be sure to enter linear and angular measurements in the active linear or angular units (as set up in Preferences). The exception to this rule are Latitude and Longitude as described above.
- Azimuth: An astro-geodetic azimuth usually obtained from solar or polaris observations.
- Direction: An alternative to horizontal angles. Minimum of two directions required in every set.
- Bearings: A bearing (derived from an azimuth) or an average bearing (commonly obtained from Public Land Surveying System records within the United States). Set up Preferences to indicate true bearings or average bearings. You cannot mix both types in same network.
- Horizontal Angle (turned to right): An alternative to the use of directions.
- Zenith Angle: Where 90 degrees is equivalent to a vertical angle of zero.
- Chord Distance: The distance from the instrument at the AT station to the target of the TO station (where Instr/Targ heights are measured). If the chord distance is a mark-to-mark distance, then set the Instr/Targ heights to zero.
- Horizontal Distance” The local tangent plane distance (2D) from the AT station to the TO station. This is equivalent to using the corrected zenith angle and slope distance (measured from the AT station) to compute the horizontal distance where HD = sin(zenith angle) * slope distance.
- Height Difference: The height difference between stations.
- Local Delta North: A local north offset (often measured with a tape).
- Local Delta East: A local east offset (often measured with a tape).
- Local Delta Up: A local up offset (often measured with a tape). For projects with limited extent, this would be similar to an elevation change where minimal curvature is applicable.
- GPS X, Y, Z: Vectors determined using GPS equipment.
Coordinate observations are useful when you don’t want to hold a station fixed, but you do want to constrain its movement by specifying its standard deviation or variance.
- Latitude: A coordinate observation used in 2D and 3D geodetic adjustments.
- Longitude: A coordinate observation used in 2D and 3D geodetic adjustments.
- Height: A coordinate observation used in 1D and 3D adjustments.
- North: A coordinate observation used in 2D and 3D Grid or Local Plane adjustments.
- East: A coordinate observation used in 2D and 3D Grid or Local Plane adjustments.
- Geodesic Azimuth: Use when you know the geodesic azimuth between two points. The geodesic azimuth is the direction along the ellipsoidal surface between two points. It is rarely used.
- Geodesic Distance: Use when you know the geodesic distance between two points. The geodesic distance is the distance along the ellipsoidal surface between two points. It is rarely used.
Note: Instrument and Target heights are not used in 2D Adjustments.