[vtkusers] Fwd: Clipping STL only clips part of the object

[Dieter Rosch]

Hi all,

I have just started experimenting with VTK via the ActiViz.NET wrapper. The
examples are a very useful introduction, and I am really enjoying the
toolkit so far.

As an exercise, I have taken the regular BoxWidget example, and replaced
the mace object with an STL I have. However I am running into a slight
problem:

When I move the BoxWidget to clip the STL image, it only seems to clip the
front of the STL.
An example of what I mean is visible here: <<http://imgur.com/Yalu91C>>

I am pretty sure it is something small I am missing, it's as if the
clipping algorithm does not see the not clipped part as an outside surface,
perhaps a normal problem. Can anyone perhaps shed some light on this for me?

.NET Code below for critique:

using Kitware.VTK;
using System;

/// <summary>
/// Class containing main method
/// </summary>
public class Demo
{


    public static vtkWindowedSincPolyDataFilter GetBoneSTL()
    {
        string path =
"C:\\Data\\sandbox\\python\\dicom\\example_images\\Shoulder";
        var reader = new vtkDICOMImageReader();
        reader.SetDirectoryName(path);

        var threshold = new vtkImageThreshold();
        threshold.SetInputConnection(reader.GetOutputPort());
        threshold.ThresholdByLower(350);// remove all soft tissue
        threshold.ReplaceInOn();
        threshold.SetInValue(0);        //set all values below 400 to 0
        threshold.ReplaceOutOn();
        threshold.SetOutValue(1);       //set all values above 400 to 1


        //Discrete Marching Cubes algorithm
        var dmc = new vtkDiscreteMarchingCubes();
        dmc.SetInputConnection(threshold.GetOutputPort());
        dmc.GenerateValues(1, 1, 1);

        //Clean the mesh
        var connect = new vtkPolyDataConnectivityFilter();
        connect.SetInputConnection(dmc.GetOutputPort());
        connect.SetExtractionModeToLargestRegion();

        var clean = new vtkCleanPolyData();
        clean.SetInputConnection(connect.GetOutputPort());
        //clean.SetInputConnection(dmc.GetOutputPort());

        //Smooth
        var smooth = new vtkWindowedSincPolyDataFilter();
        smooth.SetNumberOfIterations(25);
        smooth.SetInputConnection(clean.GetOutputPort());


        return smooth;
    }



    public static void Main(String[] argv)
    {


        boneSTL = Demo.GetBoneSTL();

        glyph = vtkGlyph3D.New();

        glyph.SetInputConnection(boneSTL.GetOutputPort());
        glyph.SetVectorModeToUseNormal();
        glyph.SetScaleModeToScaleByVector();
        glyph.SetScaleFactor(0.25);

        boneMapper = vtkPolyDataMapper.New();
        boneMapper.SetInputConnection(boneSTL.GetOutputPort());

        boneActor = vtkLODActor.New();
        boneActor.SetMapper(boneMapper);

        boneActor.VisibilityOn();

        // This portion of the code clips the mace with the vtkPlanes
implicit function.
        // The clipped region is colored green.
        planes = vtkPlanes.New();
        clipper = vtkClipPolyData.New();

        clipper.SetInputConnection(boneSTL.GetOutputPort());
        clipper.SetClipFunction(planes);
        clipper.InsideOutOn();

        selectMapper = vtkPolyDataMapper.New();
        selectMapper.SetInputConnection(clipper.GetOutputPort());
        selectMapper.ScalarVisibilityOff();

        selectActor = vtkLODActor.New();
        selectActor.SetMapper(selectMapper);
        selectActor.GetProperty().SetColor(0, 1, 0);
        selectActor.VisibilityOff();
        selectActor.SetScale(1.01, 1.01, 1.01);

        // Create the RenderWindow, Renderer and both Actors
        ren1 = vtkRenderer.New();
        renWin = vtkRenderWindow.New();
        renWin.AddRenderer(ren1);
        iren = vtkRenderWindowInteractor.New();
        iren.SetRenderWindow(renWin);

        // The SetInteractor method is how 3D widgets are associated with
the render
        // window interactor. Internally, SetInteractor sets up a bunch of
callbacks
        // using the Command/Observer mechanism (AddObserver()).
        boxWidget = vtkBoxWidget.New();
        boxWidget.SetInteractor(iren);
        boxWidget.SetPlaceFactor(1.25);
        ren1.AddActor(boneActor);
        ren1.AddActor(selectActor);

        // Add the actors to the renderer, set the background and size
        ren1.SetBackground(0.1, 0.2, 0.4);
        renWin.SetSize(600, 600);

        // Place the interactor initially. The input to a 3D widget is used
to
        // initially position and scale the widget. The EndInteractionEvent
is
        // observed which invokes the SelectPolygons callback.
        boxWidget.SetInput(glyph.GetOutput());
        boxWidget.PlaceWidget();
        boxWidget.EndInteractionEvt += new
vtkObject.vtkObjectEventHandler(SelectPolygons);

        // render the image
        iren.Initialize();
        iren.Start();
        //Clean up
        deleteAllVTKObjects();
    }

    static vtkPolyDataAlgorithm boneSTL;
    static vtkGlyph3D glyph;
    static vtkAppendPolyData apd;
    static vtkPolyDataMapper boneMapper;
    static vtkLODActor boneActor;
    static vtkPlanes planes;
    static vtkClipPolyData clipper;
    static vtkPolyDataMapper selectMapper;
    static vtkLODActor selectActor;
    static vtkRenderer ren1;
    static vtkRenderWindow renWin;
    static vtkRenderWindowInteractor iren;
    static vtkBoxWidget boxWidget;

    /// <summary>
    /// Callback function for boxWidget.EndInteractionEvt
    /// </summary>
    public static void SelectPolygons(vtkObject sender, vtkObjectEventArgs
e)
    {
        boxWidget.GetPlanes(planes);
        selectActor.VisibilityOn();
    }

    ///<summary>
    ///Deletes all static objects created
    ///</summary>
    public static void deleteAllVTKObjects()
    {
        //clean up vtk objects
        if (boneSTL != null) { boneSTL.Dispose(); }
        //if (cone != null) { cone.Dispose(); }
        if (glyph != null) { glyph.Dispose(); }
        //if (apd != null) { apd.Dispose(); }
        if (boneMapper != null) { boneMapper.Dispose(); }
        if (boneActor != null) { boneActor.Dispose(); }
        if (planes != null) { planes.Dispose(); }
        if (clipper != null) { clipper.Dispose(); }
        if (selectMapper != null) { selectMapper.Dispose(); }
        if (selectActor != null) { selectActor.Dispose(); }
        if (ren1 != null) { ren1.Dispose(); }
        if (renWin != null) { renWin.Dispose(); }
        if (iren != null) { iren.Dispose(); }
        if (boxWidget != null) { boxWidget.Dispose(); }
    }
}




Regards,
Dieter
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