[vtkusers] problem with blending

[David Gobbi]

Hi Amit,

Here is a general suggestion that I've given to others in the past:
Whenever you use vtkImageReslice, you should always specify
 the OutputExtent
 the OutputOrigin
 the OutputSpacing

Specifically, if you are registering one image to another you should
set these to the Extent, Origin, and Spacing of the data set you are
registering to.  Then vtkImageBlend will work nicely.

This has come up on the list often enough that I'm convinced that
my original scheme for setting the default OutputExtent,
OutputOrigin, and OutputSpacing was wrong.  Really, by default
these parameters should be simply copied from the input (even
better, there should be an option to automatically copy them from
another vtkImageData set).

The OutputAlwaysCenteredOnInput flag aggravates the problem.
If you are trying to register data sets, this flag should
almost certainly _never_ be set.  Unless people can convince
me that this flag is really useful, I'll get rid of it.

 - David

--
  David Gobbi, MSc                    dgobbi at irus.rri.on.ca
  Advanced Imaging Research Group
  Robarts Research Institute, University of Western Ontario

On Mon, 15 Jan 2001, amit saxena wrote:

> Hi,
>    I am trying to register two 3D data sets dataset1 and dataset2. After
> registering I
>        1) transform dataset2 using vtkImageReslice
>        2) blend the images using vtkImageBlend
>        3) display the data using imageViewer.
>        4) display the 3D data of the blended image.
>
>    Now after scaling the size of dataset1 and transformed dataset2 is
> not same. Hence when I blend the images, the images donot overlap.
> Instead the dataset2 starts from the lower left corner in the window.
> Using vtkReslice I tried to tried to bring the images in place, but this
> time I get the original image instead of the transformed one.Further a
> 3D view of the images is much worse. Can somebody please help me out.
> The pipeline is as follows :
>
> void Reader::display() {
>
> vtkTransform *transO1 = vtkTransform::New();
>
> transO1->Translate(15,-5,0);
>
> vtkTransform *transO2 = vtkTransform::New();
>
> transO2->Translate(width/2,height/2,0);
>
> vtkTransform *trans1 = vtkTransform::New();
>
> trans1->Scale(0.9,0.9,1);
>
> trans1->Translate(0,10,2);
>
> vtkTransform *trans = vtkTransform::New();
>
> trans->Concatenate(transform);
>
> vtkVolume16Reader *reader1 = vtkVolume16Reader::New();
>
> reader1->SetFilePrefix(fileName1[0]);
>
> reader1->SetHeaderSize(header[0]);
>
> if (byteSwap)
>
> reader1->SwapBytesOn();
>
> reader1->SetImageRange(range[0][0],range[0][1]);
>
> reader1->SetDataSpacing(space[0][0], space[0][1], space[0][2]);
>
> reader1->SetDataDimensions(height, width);
>
> vtkImageReslice *reslice1 = vtkImageReslice::New();
>
> reslice1->SetInput(reader1->GetOutput());
>
> reslice1->InterpolateOn();
>
> reslice1->SetInterpolationModeToCubic();
>
> reslice1->OutputAlwaysCenteredOnInputOn() ;
>
> vtkImageViewer *viewer1 = vtkImageViewer::New();
>
> viewer1->SetInput(reslice1->GetOutput());
>
> viewer1->SetColorLevel(1000);
>
> viewer1->SetZSlice(0);
>
> viewer1->Render();
>
> reader1->Delete();
>
> char a;
>
> cin>>a;
>
> vtkVolume16Reader *reader2 = vtkVolume16Reader::New();
>
> reader2->SetFilePrefix(fileName1[1]);
>
> reader2->SetHeaderSize(header[1]);
>
> if (byteSwap)
>
> reader2->SwapBytesOn();
>
> reader2->SetImageRange(range[1][0],range[1][1]);
>
> reader2->SetDataSpacing(space[1][0], space[1][1], space[1][2]);
>
> reader2->SetDataDimensions(height, width);
>
> reslice->SetInput(reader2->GetOutput());
>
> reader2->Delete();
>
> reslice->SetOutputSpacing(1,1,1);
>
> reslice->InterpolateOn();
>
> reslice->SetInterpolationModeToCubic();
>
> reslice->OutputAlwaysCenteredOnInputOn() ;
>
> reslice->SetResliceTransform(trans);
>
> vtkImageTranslateExtent *extTrans = vtkImageTranslateExtent::New();
>
> extTrans->SetInput(reslice->GetOutput());
>
> extTrans->SetTranslation(width*0.0,height*0.0,0);
>
> vtkImageReslice *reslice2 = vtkImageReslice::New();
>
> reslice2->SetInput(extTrans->GetOutput());
>
> vtkImageViewer *viewer2 = vtkImageViewer::New();
>
> viewer2->SetInput(reslice->GetOutput());
>
> viewer2->SetColorLevel(1000);
>
> viewer2->SetZSlice(0);
>
> viewer2->Render();
>
> cin>>a;
>
> vtkImageBlend *blend = vtkImageBlend::New();
>
> blend->SetInput(0,reslice1->GetOutput());
>
> blend->SetInput(1,reslice->GetOutput());
>
> blend->SetOpacity(1,0.5);
>
> vtkImageViewer *viewerB = vtkImageViewer::New();
>
> viewerB->SetInput(blend->GetOutput());
>
> viewerB->SetColorWindow(255.0);
>
> viewerB->SetColorLevel(127.5);
>
> viewerB->Render();
>
> cin>>a;
>
> vtkRenderWindow *win = vtkRenderWindow::New();
>
> vtkRenderer *ren = vtkRenderer::New();
>
> win->AddRenderer(ren);
>
> vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
>
> iren->SetRenderWindow(win);
>
> vtkImageToStructuredPoints *iToStruct =
> vtkImageToStructuredPoints::New();
>
> iToStruct->SetInput(blend->GetOutput());
>
> vtkMarchingCubes *march = vtkMarchingCubes::New();
>
> march->SetInput(iToStruct->GetOutput());
>
> march->ComputeScalarsOff();
>
> march->ComputeGradientsOff();
>
> march->ComputeNormalsOff();
>
> march->SetValue(0,150);
>
> vtkSmoothPolyDataFilter *smoother = vtkSmoothPolyDataFilter::New();
>
> smoother->SetInput(march->GetOutput());
>
> smoother->SetNumberOfIterations(6);
>
> smoother->SetRelaxationFactor(0.1);
>
> smoother->SetFeatureAngle(10);
>
> smoother->FeatureEdgeSmoothingOff();
>
> smoother->BoundarySmoothingOff();
>
> smoother->SetConvergence(0);
>
> vtkPolyDataNormals *normals = vtkPolyDataNormals::New();
>
> normals->SetInput(smoother->GetOutput());
>
> normals->SetFeatureAngle(10);
>
> vtkStripper *stripper = vtkStripper::New();
>
> stripper->SetInput(normals->GetOutput());
>
> vtkPolyDataMapper *mapper = vtkPolyDataMapper::New();
>
> mapper->SetInput(stripper->GetOutput());
>
> vtkActor *actor = vtkActor::New();
>
> actor->SetMapper(mapper);
>
> ren->AddActor(actor);
>
> win->Render();
>
> iren->Start();
>
> }
>
>
>
> AMIT
>
>
>