Write pixel values of a raster layer to text file with ArcObjects

Summary

Instructions provided explain how to write the pixel value for each pixel of each band of a multi-band raster layer to a text file using Visual Basic for Applications (VBA) code. The text file will be located in C:\Temp folder.

Warning:
This process may take a long time to complete depending on the number of bands and resolution of the raster image.

Procedure

1. Start ArcMap.
2. Create a new UIButtonControl.
   
   
   A. Select Tools > Customize to open the Customize dialog box.
   B. Select the Commands tab.
   C. Select [UIControls] from the Categories list box.
   D. Select Untitled from the Save In drop-down list to save the button to this map document. Select Normal to save the button to all ArcMap documents on the machine.
   E. Click New UIControl.
   F. Select UIButtonControl and click Create.
   G. Drag the new UIButtonControl to the toolbar of choice.
   H. Close the Customize dialog box.
   
   
   
   

   Note:
    For more information on creating a UIControl, see the ArcGIS Desktop Help topic 'Creating custom commands with VBA and UI Controls.'

   
   
3. With the Customize dialog box still open, Right-click the UIButtonControl and select View Source.
4. Copy this code into the UIButtonControl's click event.
   

   Code:
   'Notes:
   'The following code sample will write the pixel values to a text file
   'for the top layer, first band of the raster.
   
       Dim pMxDoc As IMxDocument
       Set pMxDoc = ThisDocument
       Dim pLayer As ILayer
       Set pLayer = pMxDoc.FocusMap.Layer(0)
   
       ' Check if layer is a raster layer
       If TypeOf pLayer Is IRasterLayer Then
           Dim pRasterLayer As IRasterLayer
           Set pRasterLayer = pLayer
           Dim pRaster As IRaster
           Set pRaster = pRasterLayer.Raster
           Dim pRasterBandCol As IRasterBandCollection
           Set pRasterBandCol = pRaster
           Dim pRawpixel As IRawPixels
           
           Dim pRasterProps As IRasterProps
           Dim pPnt As IPnt
           Dim pSize As IPnt
           Dim pPixelBlock As IPixelBlock3
           Dim pPixelData
           Dim lPixelValue As Long
           Dim sTxtFile As String
           Dim objFSO
           Dim objTextStream
           sTxtFile = "C:\temp\" & pRasterLayer.Name & ".txt"
           
           'Create text file with layer name as filename
           Set objFSO = CreateObject("Scripting.FileSystemObject")
           objFSO.CreateTextFile sTxtFile, True
   
           'Open text file
           Set objTextStream = objFSO.OpenTextFile(sTxtFile, 2, True)
           Dim h As Integer, i As Long, j As Long
   
           For h = 0 To pRasterBandCol.Count - 1
   
               Set pRawpixel = pRasterBandCol.Item(h)
               Set pRasterProps = pRawpixel
               Set pPnt = New DblPnt
               pPnt.SetCoords 0, 0
               Set pSize = New DblPnt
               pSize.SetCoords pRasterProps.Width, pRasterProps.Height
               Set pPixelBlock = pRawpixel.CreatePixelBlock(pSize)
       
               ' Read pixelblock
               pRawpixel.Read pPnt, pPixelBlock
       
               ' Get pixeldata array
               pPixelData = pPixelBlock.PixelDataByRef(0)
       
               ' Write band heading information for each band
               objTextStream.WriteLine "All the pixel values for band index " & h & " from " & pRasterLayer.Name
               objTextStream.WriteLine "(X, Y) = Value"
               objTextStream.WriteLine ""
   
               'Go through each pixel and write its value to text file.
               'Starting with top left corner location (0, 0)
               For i = 0 To pRasterProps.Width - 1
                   For j = 0 To pRasterProps.Height - 1
                       pRawpixel.Read pPnt, pPixelBlock
                       lPixelValue = pPixelBlock.GetVal(0, i, j)
                       objTextStream.WriteLine "(" & i & ", " & j & ") = " & lPixelValue
                   Next j
               Next i
   
               objTextStream.WriteLine ""
               objTextStream.WriteLine "-------------------------------------------------------"
   
           Next h
   
           'Close the file and clean up
           objTextStream.Close
           Set objTextStream = Nothing
           Set objFSO = Nothing
       Else
           MsgBox "Top layer is not a raster layer." & vbNewLine & _
           "Text file was not created.", vbExclamation, "Error"
           Exit Sub
       End If
   
   

   
   
5. Run the code.