You can calculate the volume or area between contours by using a script to automate the process.
For performing these steps in the user interface, see: Calculate area and volume between contour levels in Surfer
Using Automation
The attached contarea2.bas script calculates the area between evenly spaced contour levels automatically.
To run this script:
- Copy the script below, or download the attached BAS file: contarea2.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.
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'========================================================================== 'CONTAREA2.BAS ' 'This script demonstrates the following: ' ' Calculates the volume and area between contours ' Extracts area and volume information from calculations ' Prints extracted area and volume to the Immediate Window ' and to output file '========================================================================== Sub Main 'Declare the variable that will reference the application Dim SurferApp As Object 'Creates an instance of the Surfer Application object ' and assigns it to the variable named "SurferApp" Set SurferApp = CreateObject("Surfer.Application") Debug.Print SurferApp.Version 'Makes Surfer visible SurferApp.Visible = False path1 = SurferApp.Path+"\samples\" path2 = "d:\incoming\" path3 = "d:\program files\golden software\surfer\samples\" 'Input upper surface for volume calculations 'Upper$ = InputBox$("Enter path and grid filename for Upper Surface") Upper$ = GetFilePath( , "grd;dem;ddf",path1, "Upper Surface") If Upper$ ="" Then End 'Creates a volume report to get zMin, zMax, xMin, xMax, yMin, yMax Dim Results() As Double SurferApp.GridVolume(Upper:=Upper$,Lower:=0, _ pResults:= Results, ShowReport:=False) 'Set ZMin and ZMax Dim Grid As Object Set Grid = SurferApp.NewGrid Grid.LoadFile (Upper$, False) ZMin=Grid.zMin ZMax=Grid.zMax XMin=Grid.xMin XMax=Grid.xMax YMin=Grid.yMin YMax=Grid.yMax 'Obtain user defined min, max, and interval cMin= Val(InputBox$("Enter minimum Z contour value", "ZMin", ZMin)) cMax=Val(InputBox$("Enter maximum Z contour value", "ZMax", ZMax)) cInterval=Val(InputBox$("Enter Contour Interval", "CI", "5")) If cInterval = 0 Then End 'Create output file 'OutFile=InputBox$("Enter output path and filename for the area report") Outfile = Left(Upper$,Len(Upper$)-4) + "Report.dat" Open OutFile For Output As #1 'Reports the planar areas between contours to Immediate Window and to File 'Calculates planar area, volumes, and surface areas PrevArea = 0 PrevNegArea = 0 PrevSurf = 0 PrevNegSurf = 0 PrevVol = 0 PrevNegVol = 0 PrevCVal = 0 For CValue=cMin To cMax Step cInterval SurferApp.GridVolume(Upper:=Upper$,Lower:=cValue, pResults:= Results, _ ShowReport:=False) PosVol = Results(srfGVPosVol) NegVol = Results(srfGVNegVol) PosPlanArea = Results(srfGVPosPlanarArea) NegPlanArea = Results(srfGVNegPlanarArea) BlankedPlanArea = Results(srfGVBlankedArea) PosSurfArea = Results(srfGVPosArea) NegSurfArea = Results(srfGVNegArea) If cValue = cMin Then Debug.Print"==============================================================================" Debug.Print " Planar Planar Planar Surface Surface Surface" Debug.Print " Area Area Area Area Area Area Volume Volume Volume" Debug.Print "Contour Above Below Between Above Below Between Above Below Between" Debug.Print "Value Contour Contour Contour Contour Contour Contour Contour Contour Contour" Debug.Print "------------------------------------------------------------------------------" Print #1, " Planar Planar Planar Surface Surface Surface" Print #1, " Area Area Area Area Area Area Volume Volume Volume" Print #1, "Contour Above Below Between Above Below Between Above Below Between" Print #1, "Value Contour Contour Contour Contour Contour Contour Contour Contour Contour" Print #1, "-----------------------------------------------------------------------------" Else 'Debug.Print PrevArea-PosPlanArea 'Print #1, PrevArea-PosPlanArea string1=" " + PrevCVal + " " + PrevArea + " " + PrevNegArea + " " string2=" " + PrevSurf + " " + PrevNegSurf + " " string3=" "+ PrevVol + " " + PrevNegVol + " " Debug.Print string1; PrevArea-PosPlanArea ;string2; PrevSurf-PosSurfArea; string3; PrevVol-PosVol Print#1, string1; PrevArea-PosPlanArea; string2; PrevSurf-PosSurfArea; string3; PrevVol-PosVol End If PrevArea=PosPlanArea PrevNegArea=NegPlanArea PrevSurf=PosSurfArea PrevNegSurf=NegSurfArea PrevVol=PosVol PrevNegVol=NegVol PrevCVal=CValue If CValue = CMax Then Debug.Print " ";CValue;" ";PosPlanArea;" ";NegPlanArea;" ";PosPlanArea;" ";PosSurfArea;" ";NegSurfArea;" ";PosSurfArea;" ";PosVol;" ";NegVol;" ";PosVol Print #1, " ";CValue;" ";PosPlanArea;" ";NegPlanArea;" ";PosPlanArea;" ";PosSurfArea;" ";NegSurfArea;" ";PosSurfArea;" ";PosVol;" ";NegVol;" ";PosVol End If Next MsgBox outfile+" created." End Sub
Updated November 2021
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