[vtkusers] vtkImagePlaneWidget and vtkLookupTable being used partially?

[Bruno Oliveira]

Hi everyone,

I’ve looked at other emails from the mailing list but have not found
anything which explains the problem I’m having.

I have a vtkImageData object with scalars set as a vtkUnsignedCharArray
ranging from 0 to 1. This volume represents rock porosity, with 0 meaning
solid rock and 1 meaning a pore.

I’m using 3 vtkImagePlaneWidget instances, each along one axis, to show 3
plane cuts of the rock.

I’m trying to use a vtkLookupTable to show solid rock as black, and pore as
white:

lookup_table = vtk.vtkLookupTable()
lookup_table.SetNumberOfTableValues(2)
lookup_table.SetTableValue(0, (0., 0., 0., 1.0))
lookup_table.SetTableValue(1, (1., 1., 1., 1.0))

Unfortunately the planes appear as completely black. Changing the color
values to other colors (say, first entry red and second entry blue) has no
effect on the image. If I change the first table entry’s alpha value to
zero though, I can then see the pores of the image as black, which shows
that the data is correct and that the lookup table is being used. It seems
that it is not using the RGB part of the lookup table somehow.

Here’s the relevant part of the code:

self._plane_widgets = []

lookup_table = vtk.vtkLookupTable()
lookup_table.SetNumberOfTableValues(2)
lookup_table.SetTableValue(0, (0., 0., 0., 1.0))
lookup_table.SetTableValue(1, (1., 0., 1., 1.0))
lookup_table.SetTableRange(0., 1.)
for plane_name in ['XY', 'XZ', 'YZ']:
    orientation = vtk_reslice_details.GetVtkPlaneIndexValue(plane_name)
    slice_data = mpr_representation.slices_data[orientation]

    plane_widget = vtk.vtkImagePlaneWidget()
    plane_widget.SetInteractor(vizu.GetInteractor())

    plane_widget.GetPlaneProperty().SetColor(slice_data.norm_color)
    plane_widget.TextureInterpolateOff()
    plane_widget.TextureVisibilityOn()
    plane_widget.SetInputData(vtk_image)
    plane_widget.SetPlaneOrientation(orientation)
    plane_widget.SetSliceIndex(slice_data.slice_index)
    plane_widget.UserControlledLookupTableOn()
    plane_widget.SetLookupTable(lookup_table)

    plane_widget.SetMiddleButtonAction(vtk.vtkImagePlaneWidget.VTK_CURSOR_ACTION)
    plane_widget.SetRightButtonAction(vtk.vtkImagePlaneWidget.VTK_CURSOR_ACTION)
    plane_widget.On()
    plane_widget.InteractionOn()
    plane_widget.DisplayTextOn()

    self._plane_widgets.append(plane_widget)

Any helps or tips are greatly appreciated.

Cheers,
Bruno.
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