Slice multiple maps to create a profile of non-adjacent layers (like a coal seam) in Surfer automation

Need to visualize subsurface formations in Surfer? The Profile command works great for continuous or adjacent formations, but what about discontinuous ones—like a coal seam? That’s where the GridSlice method comes in!

The sample script below simplifies the process by using a single BLN file as the profile line in multiple Grid Slice commands. Each formation is generated by combining the top and bottom grid slices into a DAT file, representing a single formation. These formations are then added as base layers under one map frame, creating a clear and accurate discontinuous cross section.

To run the script, you’ll need grid files for the tops and bottoms of your formations, along with a BLN file for the profile line.

To run this script:

1. In a Windows Explorer window, navigate to C:\Program Files\Golden Software\Surfer.
2. Double click on Scripter.exe to launch Scripter.
3. Copy and paste the script below into Scripter's code window (be sure to delete any existing lines first), or simply download the attached BAS file and open it in Scripter.
4. Update the variables under the USER-DEFINED VARIABLES section at the beginning of the script:
   1. The path variable should be the path to the folder with your input BLN and grid files, and it should end with a backslash, "\". 
   2. The numFormations variable represents the number of formations. You must have separate grid files for the top and the bottom of each formation. 
5. Click Script | Run to run the script.
6. You will then encounter several dialogs in which you must first select the BLN file and then the top and bottom grids of each formation.
7. Each grid slice output file will be saved at the location specified in the path variable. 

Sub Main
    
    '===========================================
    ' USER-DEFINED VARIABLES
    '===========================================
    ' Define the path to the input/output directory
    path = "C:\Temp\"

    ' Number of desired slice formations
    numFormations = 2
    '===========================================

    ' Initialize Surfer 
    Dim SurferApp As Object
    Set SurferApp = SurferApplication()
    SurferApp.Visible = True

    ' Create a new plot document
    Dim Plot As Object
    Set Plot = SurferApp.Documents.Add

    ' Prompt user for the BLN file containing the XY coordinates of the cross section line
    BLN$ = GetFilePath( , "bln", path, "BLN for slice")
    If BLN$ = "" Then End

    ' Initialize a map frame and a base layer object
    Dim MapFrame As Object, BaseLayer As Object

    ' Define an interval value that will be used to assign different colors to each formation
    Interval = Int( 255 / numFormations )
    
    ' Loop through number of slice formations
    For i = 1 To numFormations
        
        ' Prompt user for top grid
        top$ = GetFilePath( , "grd;dem;ddf", path, "Formation " + Format(i) + ": Select the top grid")
        If top$ = "" Then End

        ' Prompt user for bottom grid
        bottom$ = GetFilePath( , "grd;dem;ddf", path, "Formation " + Format(i) + ": Select the bottom grid")
        If bottom$ = "" Then End

        ' Define the output grid slice file names
        gridSlice_top = RemoveFileExtension(top$) + " formation" + i + " top" + ".dat"
        gridSlice_bot = RemoveFileExtension(bottom$) + " formation" + i + " bottom" + ".dat"

        ' Slice GRD files
        SurferApp.GridSlice(InGrid:=top$, BlankFile:=BLN$, OutDataFile:= gridSlice_top)
        SurferApp.GridSlice(InGrid:=bottom$, BlankFile:=BLN$, OutDataFile:= gridSlice_bot)

        '===============================================
        'Rearrange the data columns in the top and bottom DAT files
        '===============================================
        Dim Wks_top As Object, Wks_bot As Object
        Set Wks_top = SurferApp.Documents.Open(FileName:=gridSlice_top)
        Set Wks_bot = SurferApp.Documents.Open(FileName:=gridSlice_bot)

        'Cut column C (the Z values) and paste it into column B
        Wks_top.Columns(Col1:=3).Cut
        Wks_top.Columns(Col1:=2).Paste
        Wks_bot.Columns(Col1:=3).Cut
        Wks_bot.Columns(Col1:=2).Paste

        ' Cut column D (the accumulated distance values) and paste it into column A
        Wks_top.Columns(Col1:=4).Cut
        Wks_top.Columns(Col1:=1).Paste
        Wks_bot.Columns(Col1:=4).Cut
        Wks_bot.Columns(Col1:=1).Paste

        '============================================
        ' Combine the top and bottom DAT files into a single BLN
        '============================================

        ' Fill column C in the the 'bottom' dat file with the row number
        Wks_bot.Transform3 (RangeMin:=1, RangeMax:= Wks_bot.UsedRange.ColumnCount, Equation:="C=row()")

        ' Sort the data in descending order by column C to invert the data
        Wks_bot.Columns(Col1:=1, Col2:=3).Sort(Col1:=3, Order1:=wksSortDescending, Header:=False, MatchCase:=False)

        ' Copy and paste all of the 'bottom' data into the worksheet with the 'top' data
        Wks_bot.Cells(Col:=1, LastCol:=2, Row:=1, LastRow:=Wks_bot.UsedRange.LastRow).Copy
        Wks_top.Cells(Col:=1, Row:=Wks_top.UsedRange.LastRow + 1).Paste(ClipToRange:=False)

        ' Copy and paste row 1 into the first empty row to close the polygon
        Wks_top.Rows(Row1:=1).Copy
        Wks_top.Cells(Col:=1, Row:=Wks_top.UsedRange.LastRow + 1).Paste(ClipToRange:=False)

        'Count the number of rows and puts that into an empty row at the top of the file
        'This is the BLN header row
        nrows = Wks_top.UsedRange.RowCount
        Wks_top.Rows(Row1:=1).Insert
        Wks_top.Cells("A1").Value = nrows

        'Save the file and close the worksheet windows
        combinedBLN = path + "Formation" + Str(i) + " combined.bln"
        Wks_top.SaveAs(FileName:=combinedBLN)
        Wks_top.Close(SaveChanges:=srfSaveChangesNo)
        Wks_bot.Close(SaveChanges:=srfSaveChangesNo)

        '============================================
        ' Add the formation as a base layer to the plot documnet
        '============================================       

        ' Check if a map frame already exists 
        If MapFrame Is Nothing Then
            
            ' Create the new base layer under a new map frame
            Set MapFrame = Plot.Shapes.AddBaseMap(ImportFileName:=combinedBLN)
            Set BaseLayer = MapFrame.Overlays(1)

        Else ' Create the new base layer under the existing map frame
            Set BaseLayer = Plot.Shapes.AddVectorBaseLayer(Map:=MapFrame, ImportFileName:=combinedBLN)

        End If

        ' Fill each formation with a different color
        With MapFrame.Overlays(i).Fill
            .Pattern = "Solid"
            .ForeColorRGBA.Red = (i - 1) * Interval
            .ForeColorRGBA.Green = (i - 1) * Interval
            .ForeColorRGBA.Blue = (i - 1) * Interval
        End With

    ' Move on to the next formation
    Next i

' Set the MapFrame limits to the extents of all data
MapFrame.SetLimitsToData

End Sub
Function SurferApplication()
    ' This function returns the current instance of Surfer if one is already running; 
    ' otherwise, it creates a new instance.

   On Error Resume Next
   Set SurferApplication = GetObject( ,"Surfer.Application")
   If Err.Number <> 0 Then
      Set SurferApplication = CreateObject("Surfer.Application")
   End If
   On Error GoTo 0
End Function
Function RemoveFileExtension(fileName As String) As String
    Dim dotPosition As Long

    ' Find the position of the last dot in the file name
    dotPosition = InStrRev(fileName, ".")
    
    ' If a dot is found, remove the extension; otherwise, return the original string
    If dotPosition > 0 Then
        RemoveFileExtension = Left(fileName, dotPosition - 1)
    Else
        RemoveFileExtension = fileName
    End If
End Function

Updated February 2025