Flight/Tie Intersection Difference

Use the Flight/Tie Intersection Difference option (geogxnet.dll(Geosoft.GX.AirborneQC.IntersectionDifference;Run)*) from the Airborne QC menu to carry out quality control on data values measured at the intersection of flight and tie lines.

Flight/Tie Intersection Difference dialog options

Input database file

Select the database from which you wish to calculate the flight/tie intersection differences. This field is auto-populated with the name of the active database.

Data channel

Select the input data channel from which the intersection differences will be calculated. This could be, for instance, a radar altimeter channel to QC altitudes.

Script Parameter: QCINTERSECT.CHAN

Maximum difference

Enter a maximum difference value. Locations where the altitude at the intersection point differ by more than this amount will be marked (flagged).

Script Parameter: QCINTERSECT.ALLDEV

Plot results

Specify if the outcome (flight lines, flagged locations, legend) should be displayed on the current map, on a new map, or not at all:

  • Existing map: this is the default option. If the legend group already exists on the map ('LEGEND_QC_<database>' in the Base view), new legend items will be added to it. If this group already exists and contains a survey path ('PATH_<database>' group in the Data view), then the path will not be replotted, and the Line Attributes tab in the expanded section will not be active. The Flag Attributes tab will allow you to customize the colour, thickness and offset from the survey path of the flagged locations.
  • New map: the Line Attributes tab in the expanded section is active and prompts for the label size and position, as well as the colour, thickness, and break on gaps of the survey path.
  • Do not plot: the output plot will not be generated. The two Attributes tabs are hidden.

Script Parameter: QCINTERSECT.MAP [0 – Display on current map (default), 1 – Display on a new map, 2 – Do not plot]

Map name

Specify the name of a new or existing map on which to plot the results. The map will open in the foreground. If the map is new, you will be prompted to interactively specify the location of the legend. New information will be added to the map; the legend will indicate the line path colour as well as the colour of the flagged locations and the percentage of the survey that is not within the specifications.

When a new map is generated, the map is scaled to the input database extents, and the map projection is set to the projection of the database.

Script Parameter: QCINTERSECT.MAP_FILE
[More]

Flag Attributes

Colour table

At the intersections where the specified separation is exceeded, colour-coded symbols will be plotted based on the current colour table file (scheme). To modify the selection, click on the colour scheme, and in the selection dialog navigate through the colour scheme categories.

Mouse over the Colour table entry to see the name of the current colour table file.

Script Parameter: QCINTERSECT.FLAG_COLOR_TABLE

Colour method

Select the colour method to be used with the selected colour scheme above: 

  • As last displayed
    This will display the symbols as they were displayed last time, and the colour table will be ignored.
  • Default
  • Histogram equalization
  • Normal distribution (default)
  • Linear
  • Log-linear

Script Parameter: QCINTERSECT.FLAG_COLOR_METHOD [0 – Default (set in the global setting); 1 – Linear; 2 – Normal distribution; 3 – Histogram equalization; 5 – Log-linear; 6 – As last displayed]

Symbol

Select the symbol shape. By default, the out-of-specification locations are plotted as circular symbols to the map.

Script Parameter: QCINTERSECT.FLAG_SYMBOL

Symbol size

Specify the symbol size in mm. By default, it is set to 2.

Script Parameter: QCINTERSECT.FLAG_SYMBOL_SIZE

Legend X location

Specify (in units of millimetres) the location, in the X-axis, of the centre of the colour bar from the lower-left corner of the map.

Script Parameter: QCINTERSECT.FLAG_LEGEND_LOCATION_X

Legend Y location

Specify (in units of millimetres) the location, in the Y-axis, of the centre of the colour bar from the lower-left corner of the map.

Script Parameter: QCINTERSECT.FLAG_LEGEND_LOCATION_Y

[Locate]

Click the Locate button to interactively position the colour bar on the map.

The Legend X/Y location fields will be updated automatically with the new X and Y location of the colour bar.

Legend height

Specify the height of the legend colour bar. If the field is empty, the legend bar height is calculated automatically and produces a height to accommodate all the zones in the selected colour ramp.

Script Parameter: QCINTERSECT.FLAG_LEGEND_HEIGHT

Line Attributes

Colour

Select a colour for plotting the line path. By default, the colour is set to black.

Script Parameter: QCINTERSECT.LINE_COLOR

Thickness

Specify the line thickness in mm. By default, it is set to 0.15.

Script Parameter: QCINTERSECT.LINE_THICKNESS

Label location

Select the label position relative to the ends of the lines: 

  • End (default): the labels are displayed centered off the ends of the line.
  • Above: the labels are displayed above the ends of the lines.
  • Below: the labels are displayed below the ends of the lines.
  • None: the line labels are not plotted.

Script Parameter: QCINTERSECT.LINE_LABEL_LOCATION

Label size

Specify the label size in mm. The default is 2.5.

Script Parameter: QCINTERSECT.LINE_LABEL_SIZE

Break on gaps>

Specify the maximum gap (in units of distance) before breaking the line. The default is 0 (no gap).

Script Parameter: QCINTERSECT.LINE_BREAK_ON_GAPS

Application Notes

This GX assumes that the current database contains data with both normal flight lines and tie lines.

Quality Control Specification and Indicators

The GX first determines the intersection points between flight lines (e.g., L100) and tie lines (e.g., T50) in a database.

Two channels are created and automatically displayed in the active database:

  1. IntDiff: this channel holds the difference between the intersecting lines. The difference between the data values recorded in the input channel at the intersection points are written to this channel at the rows for which the fiducial is the closest to the actual intersection. The symbols plotted on the map are coloured using this channel and the colour table and method specified in the Flag Attributes tab.
  2. Flag_Int: this channel contains a value of 1.0 anywhere the difference in the intersection value is outside the specification. All other points, both intersection and non-intersection, are given a value of 0.0.

As the discretely recorded data points are not necessarily exactly at the intersect points, the symbols themselves may not be plotted exactly at the intersections points, but at the point on the flight line closest to the intersection.

*The GX tool will search in the "...\Geosoft\Desktop Applications \gx" folder. The GX.Net tools, however, are embedded in the geogxnet.dll located in the "...\Geosoft\Desktop Applications \bin" folder. If running this GX interactively, bypassing the menu, first change the folder to point to the "bin" folder, then supply the GX.Net tool in the specified format.