[vtkusers] Urgent: vtkImageActor not rendering

[Citizen Snips]

I'm currently stuck upon an issue with a deadline in a week and I could
really use some assistance. I implemented, initially in Python now ported to
C++, a program to display two side-by-side renders of a model overlayed on
two webcam feeds. In Python, this was working wonderfully. The video filled
the entire viewport on each side and the models rendered perfectly. However,
now that I'm in C++, the videos do not render and I cannot figure out why.

To first detail my class structure, I have written a vtk3DRender class that
utilizes a vtkCallbackCommand to call a non-member function TimerCallback.
The trigger for this callback is a timer attached to the
vtkRenderWindowInteractor I'm using. All render elements are private members
of the vtk3DRender object. All configuration of render elements is done in
the constructor.

I'm acquiring the video using OpenCV to obtain a cv::Mat in TimerCallback
which I then use as the c array to pass to a vtkImageImport. This
vtkImageImport then passes its output to my vtkImageActor through a
vtkImageFlip. In Python this worked great. However, now I'm just getting
black in the background where there should be my webcam feed.

Here's the relevant code:

TimerCallback function:

void TimerCallback(vtkObject* caller, long unsigned int eventId, void*
clientData, void* callData)
{
        // Set up reference to vtk3DRender object
        vtk3DRender* v3DR       =
reinterpret_cast<vtk3DRender*>(clientData);

        // Configure frame acquisition
        Mat frameL;
        v3DR->webcamL.read(frameL);
        if (frameL.empty())
                return;
        //cvtColor(frameL, frameL, CV_BGR2RGB);

        // Pass frame data to pipeline and set modification flag
        v3DR->imgPort->SetImportVoidPointer(frameL.data);
        v3DR->imgPort->Modified();
        v3DR->imgPort->Update();

        // Set and print output positions of cams
        v3DR->camR->SetPosition(xyz[cur], xyz[cur+1], xyz[cur+2]);
        v3DR->camL->SetPosition(xyz[cur]+40, xyz[cur+1], xyz[cur+2]);
        cur+=3;

        // Rerender
        v3DR->iren->Render();
}


Related code within initializer (Anything with suffix ___BGL is related to
left webcam renderer and ___BGR is to right):
{
        ...
        //Initialize left webcam (Right not yet implemented)
        webcamL = VideoCapture(0);
        Mat tmp;
        webcamL.read(tmp);

        // Initialize image importer for conversion from OpenCV format to
VTK
        imgPort         = vtkSmartPointer<vtkImageImport>::New();
        imgPort->SetDataSpacing(1,1,1);
        imgPort->SetDataOrigin(0,0,0);
        imgPort->SetWholeExtent(0, tmp.size().width-1, 0,
tmp.size().height-1, 0, 0);
        imgPort->SetDataExtentToWholeExtent();
        imgPort->SetDataScalarTypeToUnsignedChar();
        imgPort->SetNumberOfScalarComponents(tmp.channels());
        imgPort->SetImportVoidPointer(tmp.data);
        imgPort->Update();

        // Initialize camera image inverter
        imgFlip         = vtkSmartPointer<vtkImageFlip>::New();
        imgFlip->SetInputData(imgPort->GetOutput());
        imgFlip->SetFilteredAxis(1);

        // Assign updated camera data to background actors
        actorBGL->SetInputData(imgFlip->GetOutput());
        actorBGR->SetInputData(imgFlip->GetOutput());

        // Set image to fill screen
        double* origin  = imgPort->GetOutput()->GetOrigin();
        double* spacing = imgPort->GetOutput()->GetSpacing();
        int* extent     = imgPort->GetOutput()->GetExtent();

        double xc       = origin[0] + 0.5*(extent[0] +
extent[1])*spacing[0];
        double yc       = origin[1] + 0.5*(extent[2] +
extent[3])*spacing[1];
        double xd       = (extent[1] - extent[0] + 1)*spacing[0];
        double yd       = (extent[3] - extent[2] + 1)*spacing[1];
        double d        = camBGL->GetDistance();
        camBGL->SetParallelScale(0.5*yd);
        camBGL->SetFocalPoint(xc,yc,0.0);
        camBGL->SetPosition(xc,yc,d);
        camBGR->SetParallelScale(0.5*yd);
        camBGR->SetFocalPoint(xc,yc,0.0);
        camBGR->SetPosition(xc,yc,d);

        // Begin rendering
        renWin->Render();
        iren->Initialize();

        cbc = vtkSmartPointer<vtkCallbackCommand>::New();
        functiontype func = &TimerCallback;
        cbc->SetCallback(func);
        cbc->SetClientData(this);
        iren->AddObserver(vtkCommand::TimerEvent, cbc);
        iren->CreateRepeatingTimer(50);
        iren->Start();
}


Any ideas? I would be incredibly thankful as this deadline is really pushing
me hard and I've spent a day on this problem already.



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