[vtkusers] Volume rendering of vtkRectilinearGrid using vtkImageData grid and vtkProbeFilter (ERROR: "vtkStreamingDemandDrivenPipeline,... update extent.... outside whole extent")

[SKoch at trinityconsultants.com]

Help

I've spent enough hours trying to stop VtkOutputWindow from popping up 
with this error:

ERROR: In ..\..\vtk\Filtering\vtkStreamingDemandDrivenPipeline.cxx, line 
628
vtkStreamingDemandDrivenPipeline (061A8E28): The update extent specified 
in the information for output port 0 on algorithm 
vtkTrivialProducer(061AE298) is 0 31 0 31 0 31, which is outside the whole 
extent 0 32 0 27 0 9.

Our volume rendering is working fine!  But this error message won't go 
away.  Our data is loaded into a vtkRectilinearGrid (any resolution - 
32x27x9 is just one of many possibilities).  To do volume rendering we 
create a 32x32x32 vtkImageData grid and resample the vtkRectilinearGrid 
data using vtkProbeFilter (see code below).  Like I said, everything works 
great.  The volume rendering appears and behaves very well.  The only 
problem is that this error message pops up with the VtkOutputWindow.  I 
looks like the vtkImageData object (32x32x32) has inherited the "whole 
extent" of the original vtkRectilinearGrid (33x28x10)?  This doesn't make 
sense.... somebody please help....


Note:  Code is in Visual Basic (We are using Andrew Dolgert's ".NET 
Wrappers for VTK 5" - works great!)


    Private Sub LoadVolumeActor()

        'Create a rectilinear grid (any resolution and spacing in X, Y, 
and Z)
        Dim vtkGrid3D as vtk.vtkRectilinearGrid = Me.LoadRectilinearGrid()

        'Create the image data grid
        Dim ImageGrid As New vtk.vtkImageData
        Dim nx As Integer = 32
        ImageGrid.SetDimensions(nx, nx, nx)
        ImageGrid.SetOrigin(m_sngGridMinX, m_sngGridMinY, m_sngGridMinZ)
        ImageGrid.SetSpacing((m_sngGridMaxX - m_sngGridMinX) / (nx - 1), _
                             (m_sngGridMaxY - m_sngGridMinY) / (nx - 1), _
                             (m_sngGridMaxZ - m_sngGridMinZ) / (nx - 1))

        'Use probe filter to get scalar values for image data grid
        Dim Probe As New vtk.vtkProbeFilter
        Probe.SetInput(ImageGrid)
        Probe.SetSource(m_vtkGrid3D)

        'Convert the image data grid scalars from float to unsigned 
character
        Dim ScalarMin, ScalarMax As Double
        Me.GetScalarMinMax(vtkGrid3D, ScalarMin, ScalarMax)
        Dim Shift As Double = -ScalarMin
        Dim Scale As Double = 255.0 / (ScalarMax - ScalarMin)
        Dim ShiftScale As New vtk.vtkImageShiftScale
        ShiftScale.SetShift(Shift)
        ShiftScale.SetScale(Scale)
        ShiftScale.SetOutputScalarTypeToUnsignedChar()
        ShiftScale.SetInput(Probe.GetImageDataOutput)

        'Volume function
        Dim VolumeFunction As New vtk.vtkVolumeRayCastMIPFunction
        VolumeFunction.SetMaximizeMethodToScalarValue()  'Default method
        'VolumeFunction.SetMaximizeMethodToOpacity()     'Alternate method

        'Volume mapper
        Dim VolumeMapper As New vtk.vtkVolumeRayCastMapper
        VolumeMapper.SetVolumeRayCastFunction(VolumeFunction)
        VolumeMapper.SetSampleDistance((m_sngGridMaxX - m_sngGridMinX) / 
((nx - 1) * 3))
        VolumeMapper.SetInput(ShiftScale.GetOutput)

        'Opacity transfer function
        Dim OpacityTransferFunction As New vtk.vtkPiecewiseFunction
        OpacityTransferFunction.AddPoint(0.0, 0.7)
        OpacityTransferFunction.AddPoint(255.0, 0.7)

        'Volume property
        Dim VolumeProperty As New vtk.vtkVolumeProperty
        'VolumeProperty.SetInterpolationTypeToNearest()   'Default - 
faster, course image
        VolumeProperty.SetInterpolationTypeToLinear()   'Smoother - 
slower, smooth image
        VolumeProperty.SetScalarOpacity(OpacityTransferFunction)
        VolumeProperty.SetColor(Me.CreateLookupTable(ActorIndex, 
SetLutOptions.NewLUT, Shift, Scale))

        'Volume actor
        Dim Volume As New vtk.vtkVolume
        Volume.SetMapper(VolumeMapper)
        Volume.SetProperty(VolumeProperty)

        m_vtkRen1.AddVolume(Volume)
        m_vtkRenWin.Render()

    End Sub

Steve Koch
Applications Developer

Trinity Consultants, Inc.
skoch at trinityconsultants.com
phone: 972-661-8881 x1332
fax: +214-615-7425
breeze-software.com
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