How to disable interpolation (bluring image) in vtkResliceCursorWidget?

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Hello, as I’ve previously written in other topic, I’ve found that piece of code of running Multi Planar Reconstruction via vtkResliceCursorWidget and I wanted to run it, but it shows images blurred (can’t see raw pixels). I wanted to disable interpolation, but it seems not working, I mean I tried to use SetResliceInterpolateToNearestNeighbour function for vtkResliceCursorLineRepresentation class, which is connected to vtkResliceCursorWidget, but it seems had no effect. Any idea how to disable blurring?

from vtk import *

# Reslice cursor callback
def ResliceCursorCallback(obj,event):
    for i in range(0,3):
        ps = planeWidgetArray[i].GetPolyDataAlgorithm();
        origin = resliceCursorWidgetArray[i].GetResliceCursorRepresentation().GetPlaneSource().GetOrigin();
        ps.SetOrigin(origin);
        point1 = resliceCursorWidgetArray[i].GetResliceCursorRepresentation().GetPlaneSource().GetPoint1();
        ps.SetPoint1(point1);
        point2 = resliceCursorWidgetArray[i].GetResliceCursorRepresentation().GetPlaneSource().GetPoint2();
        ps.SetPoint2(point2);
        planeWidgetArray[i].UpdatePlacement();

# DICOM reader
reader = vtkDICOMImageReader();
reader.SetDirectoryName("CT");
reader.Update();
imageDims = reader.GetOutput().GetDimensions();

# // Bounding box
outline = vtkOutlineFilter();
outline.SetInputConnection(reader.GetOutputPort());

outlineMapper = vtkPolyDataMapper();
outlineMapper.SetInputConnection(outline.GetOutputPort());

outlineActor = vtkActor();
outlineActor.SetMapper(outlineMapper);
outlineActor.GetProperty().SetColor(1,1,0);

# // Mapper and actors for volume
volumeMapper = vtkPolyDataMapper();
volumeMapper.SetInputConnection(reader.GetOutputPort());

volumeActor = vtkActor();
volumeActor.SetMapper(volumeMapper);

# // Renderers
renWin = vtkRenderWindow();
RendererArray = [None]*4;
for i in range(0,4):
    RendererArray[i] = vtkRenderer();
    renWin.AddRenderer(RendererArray[i]);
renWin.SetMultiSamples(0);

# // Render window interactor
iren = vtkRenderWindowInteractor();
renWin.SetInteractor(iren);

# // Picker
picker = vtkCellPicker();
picker.SetTolerance(0.005);

# // Properties
ipwProp = vtkProperty();

# // 3D plane widgets
planeWidgetArray = [None]*3;
for i in range(0,3):
    planeWidgetArray[i] = vtkImagePlaneWidget();
    planeWidgetArray[i].SetInteractor(iren);
    planeWidgetArray[i].SetPicker(picker);
    planeWidgetArray[i].RestrictPlaneToVolumeOn();
    color = [0, 0, 0 ];
    color[i] = 1;
    planeWidgetArray[i].GetPlaneProperty().SetColor(color);
    planeWidgetArray[i].SetTexturePlaneProperty(ipwProp);
    planeWidgetArray[i].TextureInterpolateOff();
    planeWidgetArray[i].SetResliceInterpolateToLinear();
    planeWidgetArray[i].SetInputConnection(reader.GetOutputPort());
    planeWidgetArray[i].SetPlaneOrientation(i);
    planeWidgetArray[i].SetSliceIndex(int(imageDims[i] / 2));
    planeWidgetArray[i].DisplayTextOn();
    planeWidgetArray[i].SetDefaultRenderer(RendererArray[3]);
    planeWidgetArray[i].SetWindowLevel(1358, -27, 0);
    planeWidgetArray[i].On();
    planeWidgetArray[i].InteractionOff();

planeWidgetArray[1].SetLookupTable(planeWidgetArray[0].GetLookupTable()); 
planeWidgetArray[2].SetLookupTable(planeWidgetArray[0].GetLookupTable());

# // ResliceCursor
resliceCursor = vtkResliceCursor();
center = reader.GetOutput().GetCenter();
resliceCursor.SetCenter(center[0], center[1], center[2]);
resliceCursor.SetThickMode(0);
resliceCursor.SetThickness(10, 10, 10);
resliceCursor.SetHole(0);
resliceCursor.SetImage(reader.GetOutput());

# // 2D Reslice cursor widgets
resliceCursorRepArray = [None]*3;
resliceCursorWidgetArray = [None]*3;
viewUp = [[0, 0, -1],[0, 0, -1],[0, 1, 0]];
for i in range(0,3):
    resliceCursorWidgetArray[i] = vtkResliceCursorWidget();
    resliceCursorRepArray[i] = vtkResliceCursorLineRepresentation();
    resliceCursorWidgetArray[i].SetInteractor(iren);
    resliceCursorWidgetArray[i].SetRepresentation(resliceCursorRepArray[i]);
    resliceCursorRepArray[i].GetResliceCursorActor().GetCursorAlgorithm().SetResliceCursor(resliceCursor);
    resliceCursorRepArray[i].GetResliceCursorActor().GetCursorAlgorithm().SetReslicePlaneNormal(i);
    minVal = reader.GetOutput().GetScalarRange()[0];
    reslice = resliceCursorRepArray[i].GetReslice();
    reslice.SetInputConnection(reader.GetOutputPort());
    reslice.SetBackgroundColor(minVal, minVal, minVal, minVal);
    reslice.AutoCropOutputOn();
    reslice.Update();
    resliceCursorWidgetArray[i].SetDefaultRenderer(RendererArray[i]);
    resliceCursorWidgetArray[i].SetEnabled(1);
    RendererArray[i].GetActiveCamera().SetFocalPoint(0, 0, 0);
    camPos = [0, 0, 0];
    camPos[i] = 1;
    RendererArray[i].GetActiveCamera().SetPosition(camPos[0], camPos[1], camPos[2]);
    RendererArray[i].GetActiveCamera().ParallelProjectionOn();
    RendererArray[i].GetActiveCamera().SetViewUp(viewUp[i][0], viewUp[i][1], viewUp[i][2]);
    RendererArray[i].ResetCamera();
    resliceCursorWidgetArray[i].AddObserver('InteractionEvent',ResliceCursorCallback)
    range_color = reader.GetOutput().GetScalarRange();
    resliceCursorRepArray[i].SetWindowLevel(range_color[1] - range_color[0], (range_color[0] + range_color[1]) / 2.0, 0);
    planeWidgetArray[i].SetWindowLevel(range_color[1] - range_color[0], (range_color[0] + range_color[1]) / 2.0, 0);
    resliceCursorRepArray[i].SetLookupTable(resliceCursorRepArray[0].GetLookupTable());
    planeWidgetArray[i].GetColorMap().SetLookupTable(resliceCursorRepArray[0].GetLookupTable());
    
# // Background
RendererArray[0].SetBackground(0.3, 0.1, 0.1);
RendererArray[1].SetBackground(0.1, 0.3, 0.1);
RendererArray[2].SetBackground(0.1, 0.1, 0.3);
RendererArray[3].AddActor(volumeActor);
RendererArray[3].AddActor(outlineActor);
RendererArray[3].SetBackground(0.1, 0.1, 0.1);
renWin.SetSize(600, 600);

# // Render
RendererArray[0].SetViewport(0, 0, 0.5, 0.5);
RendererArray[1].SetViewport(0.5, 0, 1, 0.5);
RendererArray[2].SetViewport(0, 0.5, 0.5, 1);
RendererArray[3].SetViewport(0.5, 0.5, 1, 1);
renWin.Render();

# // Camera in 3D view
RendererArray[3].GetActiveCamera().Elevation(110);
RendererArray[3].GetActiveCamera().SetViewUp(0, 0, -1);
RendererArray[3].GetActiveCamera().Azimuth(45);
RendererArray[3].GetActiveCamera().Dolly(1.15);
RendererArray[3].ResetCameraClippingRange();

iren.Initialize()
iren.Start()
2

I’ve never used these widgets, so I cannot help with disabling interpolation.

I would just note that interpolation is not some arbitrary or optional operation and if it is done well then interpolation does not blur the image, but it reconstructs the original continuous signal from discrete samples. Voxels edges that becomes visible when you use inaccurate interpolation (e.g., nearest neighbor) are artifacts that hinder correct interpretation of the image.

If you want visualize the voxel edges (which might be useful in some rare cases) then you can display a grid over the image (using an additional polydata actor). This has many advantages over relying on interpolation artifacts; most importantly that you can see the edges even if neighbor voxels have similar intensity.