[vtkusers] actor not showing

[johnsonjonaris]

Dear All
I made a pipeline which visualize a set of shapes from a vtkImageData volume
with integral data (integer values). The pipeline executes but the output is
not rendered in the rendering window, although I can save the output and
load it in PARAVIEW.
Moreover, I know that the actors I create are there since I can probe their
color property later. 
Please help

the code is:

    vtkSmartPointer<vtkImageThreshold> threshold =
vtkSmartPointer<vtkImageThreshold>::New();;
    threshold->SetOutValue(0);
    threshold->SetInput(brain3D);
    threshold->ReleaseDataFlagOn();
    vtkSmartPointer<vtkImageToStructuredPoints> imgToStrPnts =
vtkSmartPointer<vtkImageToStructuredPoints>::New();
    imgToStrPnts->SetInputConnection(threshold->GetOutputPort());
    imgToStrPnts->ReleaseDataFlagOn();
    // create an isosurface, note that vtkMarchingCubes is better than
    // vtkContourFilter
    vtkSmartPointer<vtkMarchingCubes> mcubes =
vtkSmartPointer<vtkMarchingCubes>::New();
    mcubes->SetInputConnection(imgToStrPnts->GetOutputPort());
    mcubes->ComputeNormalsOff();
    mcubes->ComputeGradientsOff();
    mcubes->ComputeScalarsOff();
    mcubes->GetOutput()->ReleaseDataFlagOn();
    // try to reduce the number of triangles
    vtkSmartPointer<vtkDecimatePro> decimator =
vtkSmartPointer<vtkDecimatePro>::New();
    decimator->SetInputConnection(mcubes->GetOutputPort());
    decimator->SetFeatureAngle(60);
    decimator->SetMaximumError(1);
    decimator->SplittingOff();
    decimator->PreserveTopologyOn();
    decimator->SetTargetReduction(0.5);
    decimator->ReleaseDataFlagOn();
    // smooth the result of the iso vtkMarchingCubes
    vtkSmartPointer<vtkWindowedSincPolyDataFilter> smoother =
vtkSmartPointer<vtkWindowedSincPolyDataFilter>::New();
    smoother->SetInputConnection(decimator->GetOutputPort());
    smoother->SetNumberOfIterations(10);
    smoother->BoundarySmoothingOff();
    smoother->FeatureEdgeSmoothingOff();
    smoother->SetPassBand(0.1);
    smoother->GetOutput()->ReleaseDataFlagOn();
    // compute normals and point normals
    vtkSmartPointer<vtkPolyDataNormals> normals =
vtkSmartPointer<vtkPolyDataNormals>::New();
    normals->SetInputConnection(smoother->GetOutputPort());
    normals->ComputePointNormalsOn();
    normals->SetFeatureAngle(60);
    normals->SetSplitting(true);
    normals->ReleaseDataFlagOn();
    // stripper: create triangle out of polygons
    vtkSmartPointer<vtkStripper> stripper = vtkSmartPointer< vtkStripper
>::New();
    stripper->SetInputConnection(normals->GetOutputPort());
    stripper->GetOutput()->ReleaseDataFlagOn();
    // map smoothed data
    vtkSmartPointer<vtkPolyDataMapper> isoMapper =
vtkSmartPointer<vtkPolyDataMapper>::New();
    isoMapper->SetInputConnection(stripper->GetOutputPort());
    isoMapper->ScalarVisibilityOff();   // utilize actor's property I set

    // render isosurfaces
    for (uint i = 0;i <20;i++) {
        // update the threshold according to the new label
        threshold->ThresholdBetween(lblValues(i),lblValues(i)); // lblValues
contain the values of the labels
        mcubes->SetValue(0,lblValues(i));
        stripper->GetOutput()->Update();
        // create actor
        vtkSmartPointer<vtkActor> isoActor =
vtkSmartPointer<vtkActor>::New();
        isoActor->SetMapper(isoMapper);
        isoMapper->Update();
        QColor c = ctable.at(lblValues(i));
       
isoActor->GetProperty()->SetColor(c.red()/255.0,c.green()/255.0,c.blue()/255.0);
        lblsActors.append(isoActor);
        MainRenderer->AddActor(isoActor);
        vtkWidget->GetRenderWindow()->Render();
    }


Regards
Johnson



-----
Johnson Jonaris 
PhD Candidate
Electrical & Computer Eng 
University of IL at Chicago
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