Columbus supports several keywords that are only applicable to the Adjust From File page. If present, these keywords are ignored when importing a Columbus file. All Adjust From File keywords begin with the text "_ADJUST_". ---------- _ADJUST_1D_HGT 1D vertical adjustment _ADJUST_2D_LOCAL 2D local north and east adjustment at mean or known height _ADJUST_2D_GRID 2D grid north and east adjustment at mean or known height _ADJUST_2D_LATLON 2D geodetic lat and lon adjustment at mean or known height _ADJUST_3D_LOCAL 3D local north, east, height adjustment (orthometric or ellipsoidal) _ADJUST_3D_GRID 3D grid north, east, height adjustment (orthometric or ellipsoidal) _ADJUST_3D_LATLONHGT 3D geodetic lat, lon, height adjustment (orthometric or ellipsoidal) You must declare one of these keywords in you file to indicate the type of adjustment to perform. DEFAULT IF NOT PROVIDED - NONE. A slection must be provided ---------- _ADJUST_CREATE_MISSING_STATION Use this keyword to automatically create stations (referenced by observations in the file) that have not been defined using the _STA_COORD keyword. This can be both a great convenience and a potential problem. Many users prefer to only identify control stations using the _STA_COORD record. After all, control station coordinate components need to be defined anyway. What happens, then, if you mistakenly reference a station CCc in one of your observations? If that station is not defined by a _STA_COORD record, it will be automatically created. In most cases this is what you want. However, if the correct station name is CCC, you could then end up with two station names representing the same location on the ground (CCC and CCc) - assuming some other observation that correctly references station CCC or CCC is defined using the _STA_COORD keyword. These stations only exist during the life of the adjustment. They are not added to your project without your permission (from within the UI Adjusted Coord grid using the Keep option). DEFAULT IF NOT PROVIDED - OFF ---------- _ADJUST_USE_ELLIPHGT This keyword tells the network adjustment engine to use the ellipsoidal height field for applicable stations instead of the orthometric field. It applies to fixed height stations for 1D and 3D adjustments. It also applies when performing 2D adjustments based on an approximate or known height for each station. DEFAULT IF NOT PROVIDED - Use orthometric height ---------- _ADJUST_2D_KNOWN_HGT This is used when performing a 2D adjustment in which you can approximate the height of all stations in the project. Often, 2D adjustments are performed at some mean height for the project area (provided by the surveyor). However, if the terrain varies considerably in the project, it may be better to estimate the height of each station (using the _STA_COORD record) prior to adjustment. Estimating station heights to within 1 to 50 meters may produce better results than using one mean project height. DEFAULT IF NOT PROVIDED - Mean project height ---------- _ADJUST_MEAN_2DHGT; 2000 This is used when performing a 2D adjustment in which you want to use a project-wide average height to define the vertical. In the example above, the average project height is 2000.0 linear units (meters, U.S. feet, etc.), depending on the active linear unit when reading the file. DEFAULT IF NOT PROVIDED - 0.0 ---------- _ADJUST_APPROX_GHGT; 20.0 When performing an adjustment based on orthometric height (elevation), you should consider providing an approximate geoid height for the project area. The approximate geoid height is added to the orthometric height (for each station fixed in 1D or 3D) to obtain an approximate ellipsoid height. This will minimize distance scaling issues on medium to large projects. In the example above, the approximate geoid height is 20.0 linear units (meters, U.S. feet, etc.), depending on the active linear unit when reading the file. All adjustment computations in Columbus are based on an ellipsoidal height based model. Therefore, approximating ellipsoidal height will produce more accurate results. For projects covering a small area, this improvement may be negligible. DEFAULT IF NOT PROVIDED - 0.0 ---------- _ADJUST_APPROX_LAT_LON; 45.0; -120.0 The approximate latitude is used in 1D trigonometric and 2D/3D Local North, East, Elev (NEE) networks. It is used to correct for curvature and rotate average bearings to true azimuths. For these corrections, enter a latitude good to within a few minutes. The approximate longitude (and latitude) is required to convert 3D GPS vectors into a 2D Local Horizon north and east components for 2D adjustments. They are also required when using GPS in 3D Local NEE networks. Always enter latitude and longitude in DD.MMSSsss format. N 37-41-58.12345 is entered as 37.415812345 S 37-41-58.12345 is entered as -37.415812345 E 120-30-40.12345 is entered as 120.304012345 W 120-30-40.12345 is entered as -120.304012345 When using GPS vectors in 2D or 3D Local NEE networks, be sure to provide the best possible approx latitude and longitude, based on one of your 2D or 3D fixed stations. DEFAULT IF NOT PROVIDED - 45.0, -120.0 ---------- _ADJUST_MAX_ITER; 20 This keyword defines the maximum number of iterations to be performed during the nonlinear adjustment process. Ten is usually an adequate maximum for most projects. There is no penalty for making this number larger; it will just take longer for a diverging network to abort. Most well-defined networks converge within one to four iterations. DEFAULT IF NOT PROVIDED - 10 ---------- _ADJUST_CONVERGE_CRITERIA; 0.001 This is the convergence level that signals the adjustment is done. When the change in coordinates from the previous and current iteration differ by less than this value, the solution is said to have converged. In the example above, the convergence criteria is 0.001 linear units (meters, U.S. feet, etc.), depending on the active linear unit when reading the file. DEFAULT IF NOT PROVIDED - 0.001 meters ---------- _ADJUST_CONFIDENCE_LEVEL; 0.95 This is the confidence level upon which the statistics are based. The closer to 1.0, the greater the confidence intervals (or regions for 2D and 3D) must become. The most common setting is 0.95 (95% confidence). Standard deviations are based on a 68.3% confidence level (0.683). DEFAULT IF NOT PROVIDED - 0.95 ---------- _ADJUST_STANRES_THRESHOLD; 2.5 Set this value to zero (the default) to use the Tau Statistic to evaluate whether the observation standardized residual is a possible outlier. Set to a non-zero value to directly control which observation standardized residuals will be flagged. In this example, the threshold is set to 2.5. If any observation standardized residual (its absolute value) is greater than 2.5, the observation will be flagged as a possible outlier. DEFAULT IF NOT PROVIDED - 0.0 ---------- _ADJUST_IGNORE_APOST_VARIANCE Include this keyword if you don't want statistical results to be based on the A Posteriori Variance Factor. In most cases, you will not want this keyword set. DEFAULT IF NOT PROVIDED - False ---------- _ADJUST_APRIORI_FACTOR; 2.2 Use this keyword to scale all observation variances prior to computing the weights (during network adjustment). The default is 1.0 when this keyword is not set. In this example, all observation variances will be scaled by 2.2 before adjustment. Observation variance (standard deviation squared) is used to weight each observation in an adjustment. Changing this value will not change the adjusted coordinates, because this value is applied to all observation variances equally. It will change the adjustment statistics if the keyword _ADJUST_IGNORE_APOST_VARIANCE is set. DEFAULT IF NOT PROVIDED - 1.0 ---------- _ADJUST_IGNORE_FULL_GPS_COVAR Use this keyword to turn off the usage of the full GPS vector covariance matrix (3x3 matrix). Only the diagonal elements will be used. Normally, you will not set this keyword. However, if you are comparing results against an adjustment where only the diagonal elements were used, then you should set this keyword to ensure the two adjustments are compatible. DEFAULT IF NOT PROVIDED - False ---------- _ADJUST_1D_WGT; 2 Use this keyword to specify the weight method for 1D Leveling networks using Height Difference observations. 0 - Weight the network by the number of setups between points 1 - Weight the network by the distance between points (in km, miles, etc.) 2 - Weight the network by each observation standard deviation The method you choose must be reflected in the Height Difference observation standard deviation field (the _OBS_HGTDIFF record). Examples: AT TO HgtDiff SD _OBS_HGTDIFF; AAA; BBB; 2.56916; ## If _ADJUST_1D_WGT is set to 0, replace ## with the number of setups from AAA to BBB (e.g., 5.0) If _ADJUST_1D_WGT is set to 1, replace ## with the approx distance from AAA to BBB (e.g., 37.0) It does not matter what units the distance are in. It's just a relative number, relative to all the other observation distances (the same is true with num setups - it's just a relative number). However, there is a maximum value that can be entered, so you may need to enter a value in terms of miles instead of U.S. feet or enter a value in kilometers instead of meters, etc. If _ADJUST_1D_WGT is set to 2, replace ## with the estimated standard deviation of the observation (e.g., 0.002 for 2 millimeters if the linear units are meters). Based on the selection above, the observation weight is then computed as follows: _ADJUST_1D_WGT = 0 or 1, weight = 1.0 / num setups or 1.0 / distance _ADJUST_1D_WGT = 2, weight = 1.0 / 0.002 squared or 1.0 / 0.000004 DEFAULT IF NOT PROVIDED - 2, weight by standard deviation ---------- _ADJUST_GPS_SCALE Set this keyword to scale GPS vectors (if applicable) during adjustment to better fit the existing control in the project. Requires a minimum of two 2D control stations to perform scaling (or one 3D and one 2D, etc.). DEFAULT IF NOT PROVIDED - False ---------- _ADJUST_GPS_ROT_N _ADJUST_GPS_ROT_E _ADJUST_GPS_ROT_U Set these keywords to rotate GPS vectors (if applicable) during adjustment to better fit the existing control in the project. Requires a minimum of three control stations fixed in height and two control stations fixed in 2D. Some possible ways to satisfy: 1) Three 1D stations fixed and two 2D stations fixed 2) Three 3D stations fixed 3) Two 3D stations fixed and one 1D station fixed DEFAULT IF NOT PROVIDED - False ---------- _ADJUST_ALTA_FIXED; 0.02134 Set this keyword to alter the fixed component for ALTA testing. In this example we have set the new value to the built-in default value (in meters), where 0.02134 meters equals 0.07 U.S. feet. DEFAULT IF NOT PROVIDED - 0.02134 meters (or 0.07 U.S. feet) ---------- _ADJUST_ALTA_PPM; 50 Set this keyword to alter the ppm components for ALTA testing. In this example, we have set the new value to the built-in default value (50 parts per million). DEFAULT IF NOT PROVIDED - 50 ---------- _ADJUST_ROT_AVG_BEAR_TO_AZ Set this value when you are using average bearings in your network. An average bearing is described as: Bearing from AAA --> BBB is NE 89.3040 (89-30-40) Bearing from BBB --> AAA is SW 89.3020 (89-30-30) Mean: NE 89.3035 Average bearings need to be rotated back to true bearings (or azimuths) during adjustment. When _ADJUST_ROT_AVG_BEAR_TO_AZ is set, all entered bearings are assumed to be average bearings, and they will automatically be rotated back to true bearings during adjustment. The rotation computation is based on the latitude of the project area. Be sure to set _ADJUST_APPROX_LAT_LON with a latitude approximation within several minutes of latitude. Public Land Survey System (PLSS) records are usually recorded with average bearing between corners. To incorporate these PLSS bearings in an adjustment (e.g., 2D), they should be rotated back to true bearings by enabling this keyword. DEFAULT IF NOT PROVIDED - False ---------- _ADJUST_GRID; COLORADO,S,0503,L2 Set this keyword to define the Grid Zone (State Plane Zone) to be used during adjustment in Geodetic or Grid networks. The zone name (i.e., COLORADO,S,0503,L2) and all zones Columubus supports can be found at http://www.bestfit.com/keywords/GridZones_Keywords.txt. DEFAULT IF NOT PROVIDED - COLORADO,S,0503,L2 ---------- Use these generic grid keywords to set up any of the following grid types: LAMBERT SINGLE PARALLEL GRID _ADJUST_GRID_L1_PARMS; SP; SF; CM; FE; FN LAMBERT TWIN PARALLEL GRID _ADJUST_GRID_L2_PARMS; SP1; SP2; CM; CP; FE; FN TRANSVERSE MERCATOR GRID _ADJUST_GRID_TM_PARMS; CM; SF; CP; FE; FN AZIMUTH EQUIDISTANT GRID _ADJUST_GRID_AE_PARMS; CM; CP; FE; FN Where: SP = Standard Parallel SP1 = First Standard Parallel SP2 = Second Standard Parallel CM = Central Meridian CP = Central Parallel SF = Scale Factor FE = False Easting FN = False Northing All latitude and longitudes must be entered in DD.MMSSsssss format: N 37-30-40.12345 is entered as 37.304012345. Northern latitudes are positive. Southern are negative. Eastern longitudes are positive. Western are negative. ------------------------------------------------------------------------------- REPORT GENERATION All applicable reports are created by default. Use keywords below to turn OFF report generation. ---------- _ADJUST_REPORT_COORD_SD Remove the adjusted coordinates and their standard deviations from the generated report. Applies to all networks. ---------- _ADJUST_REPORT_COORD_COVAR Remove the adjusted coordinates and their covariance matrices from the generated report. Applies to geodetic networks. ---------- _ADJUST_REPORT_COORD_GRID Remove the adjusted grid coordinates and their standard deviations from the generated report. Applies to grid and geodetic networks. ---------- _ADJUST_REPORT_OBS Remove the adjusted observations from the generated report. Applies to all networks. ---------- _ADJUST_REPORT_OUTLIER_OBS Remove the outlier observations (if any) from the generated report. Applies to all networks. ---------- _ADJUST_REPORT_NOCHECK_OBS Remove the no check observations (if any) from the generated report. No check observations are those which have residuals of zero; in other words, they received no adjustment. These are usually associated with "fly-lined" or "sideshot" stations. Applies to all networks. ---------- _ADJUST_REPORT_GPS_RESID Remove the GPS North, East, Up residuals from the generated report. GPS vector residuals (dx, dy, dz) are usually not helpful when looking for errors in a North, East, Up 3D coordinate system. Applies to 3D networks with GPS observations. ---------- _ADJUST_REPORT_GRIDINVERSE Remove the Grid inverses from the generated report. Applies to 2D/3D Grid and Geodetic networks. ---------- _ADJUST_REPORT_GPSINVERSE Remove the GPS inverses from the generated report. Applies to 3D Grid and Geodetic networks. ---------- _ADJUST_REPORT_ASTROINVERSE Remove the Astro Geodetic inverses from the generated report. Applies to 3D networks. ---------- _ADJUST_REPORT_ALTA Remove ALTA results from the generated report. Applies to 2D and 3D networks. ---------- _ADJUST_REPORT_DISTANCE_ERR Remove Distance Error results from the generated report. Applies to 2D and 3D networks. ---------- _ADJUST_REPORT_HGT_ERR Remove Height Error results from the generated report. Applies to 1D and 3D networks. ---------- _ADJUST_REPORT_REL_HGT_ERR Remove Relative Height Error results (between station pairs) from the generated report. Applies to 1D and 3D networks. ---------- _ADJUST_REPORT_ELLIPSE Remove Station Error Ellipse results from the generated report. Applies to 2D and 3D networks. ---------- _ADJUST_REPORT_REL_ELLIPSE Remove Relative Error Ellipse results (between station pairs) from the generated report. Applies to 2D and 3D networks. ---------- _ADJUST_REPORT_ELLIPSOID Remove Station Error Ellipsoid results from the generated report. Applies to 3D networks. ---------- _ADJUST_REPORT_REL_ELLIPSOID Remove Relative Error Ellipsoid results (between station pairs) from the generated report. Applies to 3D networks.