Flight Path Deviation

Use the Flight Path Deviation option (geogxnet.dll(Geosoft.GX.AirborneQC.FlightPathDeviation;Run)*) from the Airborne QC menu to carry out quality control on airplane flight path.

Flight Path Deviation dialog options

Input database file	Select the database from which you wish to calculate the flight path deviations. This field is auto-populated with the name of the active database.
Ideal flight path database	Select the database containing the ideal flight path. See the Application Notes below for further details. Script Parameter: QCPATH.GDB
Maximum deviation	Specify the maximum deviation from the flight path. See the Application Notes bellow for details on the specification tests and results. Script Parameter: QCPATH.MAXDEV
Allowed deviation over a distance	Allowed deviation Specify the deviation tolerance from the ideal flight path for a given distance (see below). Script Parameter: QCPATH.ALLDEV Over a distance of Input the distance over which the flight path deviation tests are carried out. See the Application Notes bellow for details on the specification tests and results. Script Parameter: QCPATH.DIST At least one of the two specifications, maximum deviation or allowed deviation over a distance, must be defined.
Plot results	Specify if the outcome (flight lines, flagged locations, legend) should be plotted 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), 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. In order to visualize multiple QC test results on the same map, flag symbols signifying data that are outside of specifications are plotted using a unique colour and offset for each QC test. Script Parameter: QCPATH.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: QCPATH.MAP_FILE
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Flag Attributes	Ideal path colour Select a colour for plotting the ideal line path; by default, this is set to dark grey. Script Parameter: QCPATH.FLAG_COLOR Colour Readings exceeding the specified tolerance are indicated by colour-coded symbols along the survey path. Select a colour for plotting these symbols. By default, this is set to dark red. Script Parameter: QCPATH.FLAG_COLOR Thickness Specify the symbol size in mm. By default, it is set to 0.2. Script Parameter: QCPATH.FLAG_THICKNESS Offset Specify the symbol offset (the distance from the survey line) in mm. By default, it is set to 0.1. A negative value will plot the symbols to the left of the survey line; a positive value will plot the symbols to the right of the survey line. Set the offset to 0 to plot the symbols on top-of-the-line path. Script Parameter: QCPATH.FLAG_OFFSET
Line Attributes	Colour Readings exceeding the permissible deviation are indicated by colour-coded symbols along the survey path. Select a colour for plotting the line path. By default, the colour is set to black. Script Parameter: QCPATH.LINE_COLOR Thickness Specify the line thickness in mm. By default, it is set to 0.15. Script Parameter: QCPATH.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: QCPATH.LINE_LABEL_LOCATION Label size Specify the label size in mm. The default is 2.5. Script Parameter: QCPATH.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: QCPATH.LINE_BREAK_ON_GAPS

Application Notes

This GX assumes that the current database is the one containing the actual survey data. The database is called the survey database. If you wish to process a different database, you may browse to add it to the project or select one from the workspace list.

The "Ideal Line Path Database''

This is the database created when a proposal is made during planning stage; it contains the ideal flight path. If you used the Airborne QC extension option, Create a Survey Plan, to create the proposed survey plan, you should have such a database available. Otherwise, you need to prepare an XYZ file containing the proposed survey plan data and then import the file into a new database.

The exception to the above rule is for "re-flights". The line number of re-flights is generally labelled using the number of the original line plus 1. Subsequent re-flights on the same line will be incremented by one, to a maximum of nine. For example, the first re-flight for line 11230 is labelled 11231, the 2nd re-flight is labelled 11232. The re-flight line numbers do not need to exist in the ideal line path database. As in the previous example, re-flights 11231 and 11232 will be tested against the line number 11230 in the ideal line path database.

Ideal lines are straight lines defined by two separate points. Therefore, this GX uses only the first and second set of (X, Y) coordinates to define the straight line. If there are dummy values in those two pairs of coordinates, a straight line cannot be defined, and the quality control test will not be carried out. The warning message displayed, if this occurs, will report the line number.

You can use the Edit Line tool to change the line numbers (type, number and version) in the ideal line path database. You can also use the Create Line tool to insert a new re-flight line into the ideal line path database.

Quality Control Specifications and Indicators

This GX allows for two separate specifications to be tested to determine whether the airplane flight line paths are acceptable or not:

1)	At each reading location, the deviation of the flight lines from the ideal flight path must be less than the maximum deviation specified.
2)	The deviation of the flight lines from the ideal flight path may be greater than the allowed deviation for a distance less than the specified distance.

You can apply one or both of these specification tests. To disable a test, leave the field(s) blank.

The GX creates a flag channel called Flag_Path in the current database. This channel contains numbers from -3 to 3 inclusive to indicate the result of the quality control test in terms of the flight line path.

Indicator Definition

Flag	Description
0	Flight path is acceptable. The flight path passes the test(s) applied.
±1	Flight path fails the maximum deviation test.
±2	Flight path fails the test on the allowed deviation over a given distance.
±3	Both tests were run, and the flight path fails both tests.

Positive and negative values indicate the different direction the actual survey deviates from the ideal flight line path.

Distance Calculation

When the specification of deviation over a specified distance is tested, the cumulative distance along the actual survey locations is used instead of the distance along the ideal line path.