USER GUIDE - PREFERENCES

The Preferences page is where you define various settings for computations for the current project. Preferences are saved to disk with the current project.


Datum / Units tab

Use to select the datum you wish to be active, or define a new datum by selecting the User Defined Datum and supplying the Semi-Major and Flattening parameters.You can also define the Linear and Angular units for Data Input and Reports. Latitude and Longitudes must always be entered in DD.MMSSsssss (Degrees, Minutes, Seconds).

Grid Projection tab

Use to select any of the predefined grid zones or set up a user-defined zone by selecting one of the first four zones, then providing the grid parameters.The first four zones in the list are:

  • User-Defined Lambert Single Parallel
  • User-Defined Lambert Double Parallel
  • User-Defined Transverse Mercator
  • User-Defined Azimuth Equidistant
  • User-Defined Steriographic Double

To create a UTM or 3TM zone, select the User-Defined Transverse Mercator zone and enter the applicable parameters in the Transverse Mercator column.


ALTA tab

Use to modify the default American Land Title Association (ALTA) settings used in many states. To return to the default settings, click the Set Defaults button. ALTA statistics can be computed during a 2D or 3D network adjustment.


Outlier tab

Use to specify the threshold at which an observation standardized residual is tagged as a possible outlier.
The standardized residual is:

If the Standardized Residual threshold value is set to zero, Columbus will calculate a threshold value based on the Tau statistic. The Tau statistic thresholdis a function of the number of observations, the degrees of freedom and the confidence level set up for the network.


Overrides tab

Standard Deviations tab

Use to set a default standard deviation (SD) for any supported observation type.Any positive non-zero value will replace all observation-specific standard deviations during adjustment and traversing. For example, you have three azimuth measurements in your network:

  • Azimuth one SD set to 3.0 seconds
  • Azimuth two SD set to 10.0 seconds
  • Azimuth three SD set to 8.5 seconds

If you enter a non-zero value (for example, 2.0 seconds) in the Azimuth edit box, during adjustment each of these three individual azimuth SDs will be replaced with an SD of 2.0 seconds. Set the Azimuth edit box back to zero to use the observation-specific SDs during adjustment (3.0, 10.0 and 8.5, respectively).


Centering / PPM tab

Use to set the default centering standard deviations and PPM values for supported observation sets. Values defined here will override individual observation set values during adjustment and traversing. Set the centering standard deviations and PPM values back to zero to use the observation set-specific values.


Distance Scalers tab

Use to set a scaler to be applied to applicable observations during adjustment and traversing. Set the values back to 1.0 to apply no scaler.


Standard Deviation Scalers tab

Use to set a scaler to be applied to applicable observation standard deviations (SD)during adjustment and traversing.For example, if you have three azimuth measurements in your network:

  • Azimuth one SD set to 1.0 seconds
  • Azimuth two SD set to 2.0 seconds
  • Azimuth three SD set to 3.0 seconds

If you enter a scaler of 1.5 in the Azimuth edit box, during adjustment each of these three individual azimuth SDs will be replaced with a SD of 1.5, 3.0 and 4.5 seconds, respectively. Set the Azimuth edit box back to 1.0 to use the original observation SDs during adjustment (1.0, 2.0 and 3.0, respectively).


Others tab

Use to override the current Zenith Angle refraction coefficient for all Zenith angles and Deflection of The Verticalvalues for all stations.Deflection of Vertical settings allow Columbus to correct astro geodetic (field) observations leveled in the direction of gravity to geodetic observations leveled in the direction of the ellipsoidal normal. This correction is often applied to high-accuracy networks. To set the Deflection of the Verticalto zero for all stations, enter a small non-zero value, such as 0.00001 seconds for N-S and E-W.The Zenith Angle coefficient is used to apply a zenith angle refraction correction. The correction is computed as follows:

ZA corrected = ZA measured + (K * D) / (2 x R)K = Zenith angle coefficient (range 0 to 0.5)D = Slope (chord) distance between the AT and TO station

R = Radius of earth + Ellipsoidal Height at the AT station.

Note: To turn all settings off in this tab, set each field to Zero.


Advanced tab

Use to apply additional options and settings to both network adjustment and traversing.Traversing uses the same adjustment engine as is used for network adjustments. The difference is that when traversing, no stations along a traverse are adjusted; they are simply computed using the known observations and their standard deviations, to weight the observations. This allows you to include more than the minimum-required observations between each station in a traverse.


Reports tab

Use to select all reports you want to generate during network adjustment. Some reports may not be applicable to the adjustment you are currently performing; for example, Error Ellipsoids will not be generated when performing a 1D or 2D adjustment.


About tab

Information about releases.