[vtkusers] Volume Rendering problem

[Anton Majourine]

Hello vtkusers,

I am a beginner with VTK.
I use VTK volume rendering, but the frame rate is very slow.
VolView 1.3 operates with my dataset appr. 10 times faster.

Can anybody help?

System: Win2K, Radeon 8500 65K, MSVC++ 60

The code is:

        CSize sz(366, 428);
        int nFrames = 150;

        vtkStructuredPoints* Points = vtkStructuredPoints::New();

        // fill StructuredPoints
        Points->SetDimensions(sz.cx, sz.cy, nFrames);
        vtkUnsignedShortArray* scalars = vtkUnsignedShortArray::New();
        scalars->Allocate(sz.cx * sz.cy * nFrames);
        for(int k = 0; k < nFrames; k++)
        {
                int z = k * sz.cx * sz.cy;
                for(int j = 0; j < sz.cy; j++)
                {
                        int y = z + sz.cx * j;
                        for(int i = 0; i < sz.cx; i++)
                        {
                                scalars->InsertValue(y + i, ...);
                        }
                }
        }
        Points->GetPointData()->SetScalars(scalars);
        scalars->Delete();

        //Create transfer mapping scalar value to opacity
        vtkPiecewiseFunction* opacityTransferFunction = vtkPiecewiseFunction::New();
        opacityTransferFunction->AddPoint(20, 0.0);
        opacityTransferFunction->AddPoint(255, 0.2);

        // Create transfer mapping scalar value to color
        vtkColorTransferFunction* colorTransferFunction = vtkColorTransferFunction::New();
        colorTransferFunction->AddRGBPoint(0.0, 0.0, 0.0, 0.0);
        colorTransferFunction->AddRGBPoint(64.0, 1.0, 0.0, 0.0);
        colorTransferFunction->AddRGBPoint(128.0, 0.0, 0.0, 1.0);
        colorTransferFunction->AddRGBPoint(192.0, 0.0, 1.0, 0.0);
        colorTransferFunction->AddRGBPoint(255.0, 0.0, 0.2, 0.0);

        // The property describes how the data will look
        vtkVolumeProperty * volumeProperty = vtkVolumeProperty::New();
        volumeProperty->SetColor(colorTransferFunction);
        volumeProperty->SetScalarOpacity(opacityTransferFunction);
        volumeProperty->SetInterpolationTypeToNearest();

        // The mapper / ray cast function know how to render the data
        vtkVolumeRayCastCompositeFunction* compositeFunction = vtkVolumeRayCastCompositeFunction::New();
        vtkOpenGLVolumeRayCastMapper* volumeMapper = vtkOpenGLVolumeRayCastMapper::New();
        volumeMapper->SetVolumeRayCastFunction(compositeFunction);
        volumeMapper->SetInput(Points);

        // create VolRen
        vtkVolume* Vol = vtkVolume::New();
        Vol->SetMapper(volumeMapper);
        Vol->SetProperty(volumeProperty);

        vtkRenderer *ren1= vtkRenderer::New();
        ren1->SetBackground( 0.0, 0.0, 0.0 );

        // set VolRen
        ren1->AddVolume(Vol);

        vtkRenderWindow *renWin = vtkRenderWindow::New();
        renWin->DoubleBufferOff();
        renWin->AddRenderer( ren1 );
        renWin->SetSize( 500, 500 );
        renWin->StereoRenderOff();

        vtkRenderWindowInteractor *Interactor = renWin->MakeRenderWindowInteractor();

        renWin->Render();

        Interactor->Start();

Best regards,
Anton