Blank a grid file above or below a given Z value via Surfer automation

Updated November 15, 2021 14:25

When analyzing data, there are times when only values above or below a certain threshhold are relevant. For example, when evaluating an area for building sites with acceptable inclines and obstructions. One way to make this process easier is to remove data that doesn't meet your criteria. In the script below, this is done by prompting the user for a cutoff value and direction and then assigning NoData to grid file as directed.

To run this script:

Copy the text below, or download the attached BAS file: BlankByLevel.bas.
In a Windows Explorer window, navigate to C:\Program Files\Golden Software\Surfer.
Double click on Scripter.exe to launch Scripter.
Press Ctrl+A to select all of the existing lines then press Delete.
If you copied this script, press Ctrl+V to paste it into Scripter. If you downloaded it, click File | Open, select the BAS file from your downloads directory, and click Open.
Click Script | Run to run the script.

*********

'BlankByLevel blanks a grid above or below a given Z value,
'and saves the blanked grid to a new grid file.
Sub Main
Debug.Clear
    Dim SurferApp As Object
    Set SurferApp = CreateObject("Surfer.Application")
    SurferApp.Visible = True
    Set Plot = SurferApp.Documents.Add(srfDocPlot)
    Set Shapes = Plot.Shapes
    Set Grid = SurferApp.NewGrid
'Choose a grid file
    gridfilepath = GetFilePath( , "grd",SurferApp.Path+"\samples\","Open Grid File",0)
    Set Grid2 = Grid.LoadFile(gridfilepath,False)
    Debug.Print "Grid Min =";Grid.zMin
    Debug.Print "Grid Max =";Grid.zMax
' Set level cutoff and flag above or below
    Dim level As Double
    Dim below As Boolean
    Begin Dialog UserDialog 270,112 ' %GRID:10,7,1,1
        Text 10,7,90,14,"Z Level value:",.Text0
        TextBox 10,28,180,21,.LevlVal
        OptionGroup .Group1
            OptionButton 20,77,130,14,"Blank Below",.below
            OptionButton 20,56,130,14,"Blank Above",.above
        OKButton 170,70,80,21
    End Dialog
    Dim entervalue As UserDialog
    Dialog entervalue
        level = Val(entervalue.LevlVal$)
        Debug.Print "Z Level Value = ";entervalue.LevlVal$
        If entervalue.Group1 = 0 Then below = True
        If entervalue.Group1 = 1 Then below = False
    Debug.Print "Processing GridRow:"
    For row=1 To Grid.NumRows()
    For col=1 To Grid.NumCols()
        If below = True Then
          If Grid.GetNode(row,col) < level And Grid.IsBlanked(row,col) = False Then Grid.BlankNode(row,col)
        ElseIf below = False Then
          If Grid.GetNode(row,col) > level And Grid.IsBlanked(row,col) = False Then Grid.BlankNode(row,col)
        End If
    Next col
    Debug.Print row;
    If row Mod 20 = 0 Then Debug.Print
    Next row
'Saves the grid to a new name
    gridfilepath = Left(gridfilepath,InStrRev(gridfilepath,".")-1) + "_Blanked.grd
    Grid.SaveFile(gridfilepath, srfGridFmtS7)
    Debug.Print "" 'newline
    Debug.Print "" 'newline
    Debug.Print "File saved as ";gridfilepath
'Creates a contour map of new grid
    Shapes.AddContourMap(gridfilepath)
End Sub

Updated November 2021

BlankByLevel.bas
(2 KB)

Comments

4 comments

Felipe Camargo de Almeida
August 08, 2018 06:43

Where do I set the Z value which will blank the values above or below it? This algorithm seems like the normal blanking.

0
Brittany Bodane
August 08, 2018 17:46

Hi Felipe,

Thank you for posting your question! It appears the wrong script was included this article, but the attachment was correct. My apologies for the confusion. I have updated the article so you can copy/paste the correct script should you prefer that to downloading it.

You will now see where to set the Z level on line 39. Please let me know if you have any other questions.

Thank you,

Brittany Bodane

Technical Support

0
Michael Huber
September 24, 2018 16:10 (Edited September 24, 2018 16:34)

I am trying to print Grid Statistics for Z, specifically the 99 percentile. Does anyone know how I can accomplish this?

My code currently displays the zMin & zMax (snip from above) but when I use Debug.Print Grid.Statistics.Percentile99 it returns the 99Percentile of X and I'm not sure how to specify Z.

Alternatively, I would be okay with the entire grid statistics running / opening & saving. Then I could scroll for the specific stats I need and open the statistics document at a later date if required, but I cant seem to find out a code for this either.

I am also confused as to why Debug.Print row; is used at the end, as I get hundreds of numbers printing due to this and it doesn't seem to stop..

Any advice would be greatly appreciated! :)

0
Brittany Bodane
September 24, 2018 18:23

Hi Michael,

Thank you for posting your question. Percentile99 pertains to the Z value by default, so you should be seeing this data for the Z value. You can verify this number by looking at the Grid Report for your grid. If you are still not seeing this in relation to your Z values, please email your script and a data file you are seeing this behavior with to support@goldensoftware.com.

If you would like to have the Grid Report open and save via automation, this can be done during the gridding process. We have a sample script for this you may be interested in: https://support.goldensoftware.com/hc/en-us/articles/227873488-How-can-I-save-a-grid-report-when-using-Surfer-Scripter-.

Regarding your last question about Debug.Print row being used at the end of the this sample script, I believe this is included so you can see the script is working, and which row it is on. However, it is not necessary for the function of the script and you can delete these lines if you choose.

Thanks,

Brittany

Technical Support

Golden Software

1

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