How to create a file raster dataset

Sub CreateFileRasterDataset()
    
    'open a raster workspace
    Dim pWs As IRasterWorkspace2
    Set pWs = OpenRasterWorkspace("c:\temp")
    
    'set the origin, width and height of the raster dataset
    Dim pOrigin As IPoint
    Dim Width As Long
    Dim Height As Long
    
    Set pOrigin = New Point
    pOrigin.PutCoords 15, 15
    Width = 100
    Height = 100
    
    'Create the raster dataset
    Dim pRasterDs As IRasterDataset
    Set pRasterDs = pWs.CreateRasterDataset("myimage1.img", "IMAGINE Image", pOrigin, Width, Height, 30, 30, 3, PT_UCHAR, New UnknownCoordinateSystem, True)
    
    Dim pProp As IRasterProps
    Dim pBands As IRasterBandCollection
    Dim nBands As Integer
    Dim pBand As IRasterBand
    
    'Set NoData if necessary
    Set pBands = pRasterDs
    nBands = pBands.Count
    For k = 0 To nBands - 1
        Set pBand = pBands.Item(k)
        Set pProp = pBand
        pProp.NoDataValue = 255
    Next k
    
    'Create a Raster from the raster dataset
    Dim pRaster As IRaster
    Set pRaster = pRasterDs.CreateDefaultRaster
    
    'Create a pixel block for the pixels that need to write
    Dim pPB As IPixelBlock3
    Dim pPnt As IPnt
    Set pPnt = New Pnt
    pPnt.SetCoords Width, Height
    Set pPB = pRaster.CreatePixelBlock(pPnt)
    
    Dim v As Variant
    For k = 0 To nBands - 1
        v = pPB.PixelData(k)
        For i = 0 To Width - 1
            For j = 0 To Height - 1
                If i = j Then v(i, j) = 255 Else v(i, j) = (i + j) / 8 'set some values that are in 8 bit range
            Next j
        Next i
        pPB.PixelData(k) = v
        Set v = Nothing
    Next k
    
    'Write the pixel block with a (0,0) offset of the upper left corner
    Dim pRasterEdit As IRasterEdit
    Set pRasterEdit = pRaster
    pPnt.SetCoords 0, 0
    pRasterEdit.Write pPnt, pPB
    
    'clean up
    Set pRasterEdit = Nothing
    Set pRaster = Nothing
    Set pProp = Nothing
    Set pPB = Nothing
    Set pBand = Nothing
    Set pBands = Nothing
    Set pRasterDs = Nothing
    Set pWs = Nothing
End Sub


Public Function OpenRasterWorkspace(sPath As String) As IRasterWorkspace2
    ' Create RasterWorkspace
    
    Dim pWsFact As IWorkspaceFactory
    Set pWsFact = New RasterWorkspaceFactory
    
    If pWsFact.IsWorkspace(sPath) Then
        Set OpenRasterWorkspace = pWsFact.OpenFromFile(sPath, 0)
    End If
    
    Set pWsFact = Nothing
    
End Function