Background Location Validation Test

Use the Background Location Validation Test option, (Geosoft.uxo.gxnet.dll(Geosoft.GX.UXO.UxaBackgroundValidationTest;Run)*), to determine whether a specific field location is suitable for background measurements.

ClosedExpand to see the locations (menus) where this option is available.

UX-Analyze extension:

  • AGC Static Data > Sensor Tests and QC Tools
  • AGC Expert User > Static Data Prep and QC

Background Location Validation Test dialog options

Raw Background Validation Data

Database prefix

Select the prefix for the background locations databases that contain the raw background location validation measurements (SBR).

Script Parameter:UXANALYZE.BKGTEST_RECONPREFIX

Group name

Select the group name.

Script Parameter:UXANALYZE.BKGTEST_RECONGROUP

Mask channel

Select the mask channel.

Script Parameter:UXANALYZE.BKGTEST_TARGETMASK

TOI Reference Data

Database prefix

Select the prefix for the databases containing the data for the TOI reference item.

Script Parameter:UXANALYZE.BKGTEST_TOIPREFIX

Group name

Select the group name.

  • If the list is empty, the source database for the TOI Reference data does not exist. Run Invert for Sources (Static) to create the database*.

    • Script Parameter:UXANALYZE.BKGTEST_TOIGROUP

    ID channel

    Select the ID channel.

  • If the list is empty, the source database for the TOI Reference data does not exist. Run Invert for Sources (Static) to create the database*.

    • Script Parameter:UXANALYZE.BKGTEST_IDCHANNEL

    TOI description channel

    Select the channel that contains description of the TOI.

  • If the list is empty, the source database for the TOI Reference data does not exist. Run Invert for Sources (Static) to create the database*.

    • Script Parameter:UXANALYZE.BKGTEST_DESCRCHANNEL

    Selected TOI

    Pick the TOI to use for the test. The list is populated from the values in Description channel.

    Script Parameter:UXANALYZE.BKGTEST_SELE…DTOI

    Response data channel

    Select the channel that contains the TOI response data.

    Script Parameter:UXANALYZE.BKGTEST_DATACHANNEL

    [More]

    Background cluster distance (m)

    Specify the search distance that is used to identify clusters of measurements for test location.

    Default value is 1.5 times the cart width (see the SBR Target database, UXA_Cart). The factor is defined in the configuration file, clusterWidthvalueMultiplier.

    Script Parameter:UXANALYZE.BKGTEST_SENSORWIDTH

    Min. reference to surrounding measurement (m)

    Specify the minimum distance from the reference background (centre) to the surrounding measurements.

    Default value is 0.25 times the cart width (see the SBR Target database, UXA_Cart). The factor is defined in the configuration file, clusterWidthminMultiplier.

    Script Parameter:UXANALYZE.BKGTEST_MINDIST

    Max. reference to surrounding measurement (m)

    Specify the maximum distance from the reference background (centre) to the surrounding measurements.

    Default value is 1.0 times the cart width (see the SBR Target database, UXA_Cart). The factor is defined in the configuration file, clusterWidthmaxMultiplier.

    Script Parameter:UXANALYZE.BKGTEST_MAXDIST

    Sum of TOI to background amplitude threshold (m3/s)

    Specify the sum of TOI to background amplitude threshold.

    Default value is 2.5.

    Script Parameter:UXANALYZE.BKGTEST_SUMOFAMPLITUDETHRESHOLD

    Minimum polarization amplitude (mV)

    Specify the minimum beta value.

    Default value is 0.001.

    Script Parameter:UXANALYZE.BKGTEST_MINBETA

    TOI match metric

    Specify the minimum combined match metric between the background measurements and the TOI. This threshold should define a high confidence TOI classification.

    Default value is 0.85.

    Script Parameter:UXANALYZE.BKGTEST_MATCHTHRESH

    Background difference window start gate

    Select the start gate to be used to calculate the sum of absolute differences between the reference background and the surrounding measurements.

    Default value is the first valid time gate (determined from UXA_GateFirstValidTime).

    Script Parameters:UXANALYZE.BKGTEST_STARTGATE

    Background difference window end gate

    Select the end gate to be used to calculate the sum of absolute differences between the reference background and the surrounding measurements.

    Default value is the first valid time gate plus two gates. Defined in the configuration file, windowGatesNumber.

    Script Parameter:UXANALYZE.BKGTEST_ENDGATE

    Background location ID

    The background location (cluster) ID can be generated automatically if Auto generate is selected. The starting number is 1.

    The current flag ID can also be used as the location, if the Use flag ID is selected.

    Default value is Auto generate.

    Script Parameter:UXANALYZE.BKGTEST_LOCATIONID_METHOD

    Application Notes

    *The Invert for Sources (Static) option is located under the AGC Expert User > Invert Data menu.

    At the start of your project, establish background measurement locations to remove the effects of instrument drift and geology on the survey measurements. Additional locations can be defined as needed throughout the project.

    To ensure a location is suitable for background measurements, confirm the following:

    • The area is "clean", i.e., free from metallic objects in the vicinity.
    • A TOI (Target of Interest) is detectable above the background noise level.

    The background test involves a static measurement at a central (reference) location, along with at least four surrounding measurements. These surrounding measurements should be placed at a distance of ½ sensor width from the initial reference location and distributed evenly.

    For example:

      1 2
      0
      2 4

    You'll also need to provide a reference TOI representing the worst-case scenario—specifically, the smallest TOI at the maximum required detection depth—to demonstrate detectability above background noise.

    TOI data can be generated using either of the following methods:

    • Calculation: Use library data to calculate the item's response — see Calculate Forward Model.

    • Data Collection: Gather and process data from an item on a test stand (Import, Level, and Invert).

    Process

    The Background Location Validation Test tool performs the following steps:

    1. Manage the Data
      • Group or cluster the measurements to identify background locations.
        • Determine which measurements fall within the background cluster distance of each other.
        • Assign a sequential Background ID to each valid background test location.
        • Label each measurement with the associated Background ID.
      • Determine which measurement is the centre (reference) background location ID.
      • Label measurements - assign Location IDs as follows:
        • Centre location is labeled 0.
        • Surrounding measurements are labeled 1 to n, based on heading (i.e., ordered clockwise from North).
    2. Check Location
      • Calculate the distance and heading of each surrounding measurement relative to centre (reference location).
      • Identify measurements that are:
        • Too close (Min. reference to surrounding measurement) from the centre/reference location.
        • Too far (Max. reference to surrounding measurement) from the centre/reference location.
      • Identify measurements that are not evenly distributed around the centre/reference location:
        • Ensure no more than ~120° of angular separation between any two consecutive surrounding measurements.
      • Subtract the centre (reference) measurement from each surrounding measurement (levelling the data to reference location).
      • Identify surrounding measurements where the difference of the sum of absolute value for the response (between the Background difference window start and end) is greater than the Sum of TOI to background amplitude threshold.
      • Identify background locations with fewer than four valid surrounding measurements–as defined by surroundingMeasTolerance in the configuration file.
    3. Check Noise and TOI Detectability
      • Add the TOI response data to the surrounding measurements:
        • Invert the surrounding measurements to solve for a single object.
        • Determine a combined library match with the TOI item. The combined match metric is the average of 111, 110, 011, and 100 match metrics.
      • Identify background locations with fewer than four valid surrounding measurements.

    Output

    • Static Background Validated (SBV) Databases
      Two types of databases will be generated as part of the output:
      • Target database – contains measurement metrics for each surrounding location as array channels. There will be two groups of background measurements:
        • Validated: background locations that can be used for subsequent survey background QC checks and levelling.
        • Failed: background locations that did not pass validation criteria.
      • Data database – stores measurement data only for the valid background locations.
    • Summary Report/Table (CSV Format)
      A tabular report will be generated with the following columns:
      • Location ID
      • Pass/Fail
      • X
      • Y
      • Combined metric match for each surrounding location (1 to n)
      • Difference in sum of absolute response values Window start to Window end for each surrounding location (1 to n)
    • Map and Summary Plot:
      • Generate a map that shows all the background locations with labels - clearly mark the background locations that fail, along with the date/time.
      • Generate a plot for each background location that shows:
        • The locations of all the measurements with labels - for failed surrounding measurements, the symbols are highlighted in red.
        • Polarization plots – show the polarization curves for each surrounding measurement (see below). For failed surrounding measurements, the plot title is highlighted in red.
          • TOI response in blue
          • TOI reference item in red.
        • Amplitude plot - displays for each surrounding measurement the sum of absolute response value for each gate, along with that of the TOI reference item.
        • A table listing the surrounding measurement statistics. Failed measurements are indicated with an asterisk (*):
          • Surround measurement location ID
          • The distance from surrounding measurement to reference measurement
          • The azimuth in degrees to surrounding measurements
          • Sum of the response over Window start to Window end
          • Combined match metric to the TOI Reference Item
          • Sensor ID
          • Low gate
          • High gate
          • Minimum beta (polarization) amplitude

    Duplicate Identifiers

    When writing to an existing output database, the GX performs a validation step:

    • It checks whether any input flag IDs already exist in the output database.

    • If a duplicate ID is detected, the system will issue a warning and prompt the user with two options:

      • Manual Correction: Edit the input data and manually assign a new, unique flag ID to all records within the flagged cluster.
      • Auto-Generate Option: Select Auto generate to create a new background location ID, calculated as: max(existing background location ID) + 1

    *The GX tool will search in the gx folder. The GX.Net tools, however, are embedded within the Geosoft.uxo.gxnet.dll located in the bin directory. If running this tool interactively, bypassing the menu, change the folder to point to the bin directory, then ensure the GX.Net tool is supplied in the correct format when called directly.

    See Also: