Pick Target Locations from Grids

Use the Pick Target Locations from Grids option (Geosoft.uxo.gxnet.dll(Geosoft.GX.UXO.UxaPickTargetLocations;Run)*) to pick the peak locations from the Coherence Anomaly and/or Amplitude grids using the Blakely peak picking method. The threshold for Model Coherence grid is established using the Determine Coherence Anomaly Threshold tool. The results will be saved into the target database.

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

UX-Analyze extension:

  • AGC Dynamic Data
  • AGC Expert User > Dynamic Data Target Picking

Pick Target Locations from Grids from dialog options

Database prefix

Select the sensor (data) database prefix.

Script Parameter: UXANALYZE.DYN_PICK_DBPREFIX

Anomaly Grids

Model coherence

Select the model coherence grid name.

  • Model coherence grid should be entered if Amplitude grid is blank.

    • Script Parameter: UXANALYZE.DYN_PICK_COH_GRID

    Threshold

    Specify a grid value below which you want peaks to be removed from the list.

    You can determine a reasonable threshold by using Determining Coherence Threshold tool.

    Script Parameter: UXANALYZE.DYN_PICK_COH_THRESHOLD

    Amplitude

    Select the amplitude grid name.

  • Amplitude grid should be entered if Model coherence grid is blank.

    • Script Parameter: UXANALYZE.DYN_PICK_AMP_GRID

    Threshold

    Specify a grid value below which you want peaks to be removed from the list.

    Script Parameter: UXANALYZE.DYN_PICK_AMP_THRESHOLD

    Survey Target Database

    Name

    Displays the name of the target database, which will be created if it doesn't exist.

    Group

    Specify the target group name. The group will be created if it doesn't exist.

    Script Parameter: UXANALYZE.TARGETGROUP

    Id channel

    Specify the target id channel name. The channel will be created if it doesn't exist.

    Script Parameter: UXANALYZE.TARGETID

    Mask channel

    Specify the target mask channel name. The channel will be created if it doesn't exist.

    Script Parameter: UXANALYZE.TARGETMASK

    [More]

    Anomaly merge distance (m)

    Specify the anomaly merge distance. If a Model coherence pick is within this distance from an Amplitude pick, discard the Amplitude pick, set the UXA_PeakType channel to "Both".

    Default value is 0.2.

    Script Parameter: UXANALYZE.DYN_PICK_MERGE_DISTANCE

    No of passes of smoothing filter

    Specify the number of passes of smoothing (Hanning) filter to apply to the grid so that low amplitude, high frequency ‘noise’ targets will not be picked. The grid will not be smoothed if you enter 0 (zero) or leave the entry blank. More filter passes tend to reduce the number of peaks found. The default is 0.

    The system applies 9-point (3x3) Hanning smoothing filter to the grid, if smoothing is desired. The coefficients of the filter are:

    0.06 0.10 0.06

    0.10 0.36 0.10

    0.06 0.10 0.06

    Script Parameter:

    • UXANALYZE.DYN_PICK_COH_NPASSES
    • UXANALYZE.DYN_PICK_AMP_NPASSES

    Level of peak detection

    The Blakely method is used to find peaks in a grid. For each grid cell, the GX compares its value with the values of its eight (8) nearest grid cells in four directions (along the row, along the column, and along both diagonals). There are four sensitivity levels which may be used to determine whether a grid cell will be selected as a peak:

    Normal (4) - grid values in all of the nearest grid cells are lower

    More peaks (3) - grid values in any three directions are lower

    Even more peaks (2) - grid values in any two directions are lower

    All ridge peaks (1) - grid values in one direction are lower

    Selecting Normal (4) (default) finds fewer peaks. To find all ridges, use All ridge peaks (1) option.

    Script Parameter:

    • UXANALYZE.DYN_PICK_COH_LEVEL
    • UXANALYZE.DYN_PICK_AMP_LEVEL

    Application Notes

    The output channels saved into the target database are: UXA_Flag_X, UXA_Flag_Y, UXA_Target_Id, UXA_Mask, UXA_Mask_All, UXA_ModCoh_Value, UXA_Amp_Value, UXA_PeakType and UXASensorHeight.

    UXA_PeakType channel is an indicator to identify the source grid, and can be one of these values: "ModCoh", "Amp", or "Both".

    *The GX tool will search in the "gx" folder. The GX.Net tools, however, are embedded in the Geosoft.uxo.gxnet.dll located in the 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.