[Insight-users] Plotting BSpline controlpoints/deformation vectors?

[motes motes]

I am looking for a more basic approach. I have tried to update the pixel
values manually:


  void updatePixel(){
    std::string input  = image_dir + "2D/deform/lena.png";
    std::string output = image_dir + "2D/deform/lena_updated_pixel.png";

    fixedImageReader = ImageReaderType::New();
        WriterType::Pointer writer =  WriterType::New();
        CastFilterType::Pointer caster = CastFilterType::New();

    // Read the input image.
    fixedImageReader->SetFileName(input);
    fixedImageReader->Update(); // make sure this is called before accessing
the image.

    // Modify the input image.
    ImageType::Pointer fixedImage = fixedImageReader->GetOutput();
    ImageType::IndexType pixelIndex;
    pixelIndex[0] = 10;
    pixelIndex[1] = 10;
    ImageType::PixelType pixelValue;
    pixelValue = fixedImage->GetPixel(pixelIndex);
    std::cout << "pixelValue = " << pixelValue << std::endl;


    fixedImage->SetPixel(pixelIndex, 255);
    // Write the output image.
    writer->SetFileName(output);
        caster->SetInput(fixedImageReader->GetOutput());
        writer->SetInput(caster->GetOutput());
        try {
            writer->Update();
        }
        catch(itk::ExceptionObject & err) {
            std::cerr << "ExceptionObject caught !" << std::endl;
            std::cerr << err << std::endl;

    }
    std::cout << "Updated image: " << output << " stored!\n";

  }


But this not visible unless I update a range of pixels and further it will
not work in white areas. Unless there are some "markers" (crosses,
triangles, squares - in color) in ITK that can be written to an image I
think I will try to do it in gnuplot after the image has been processed.







On Sun, Aug 16, 2009 at 2:46 AM, Luis Ibanez <luis.ibanez at kitware.com>wrote:

> Hi Motes,
>
> Something that comes to mind is that you could mark the closest
> pixels to your control points in the image that you are saving.
>
> E.g. if you are using a CT image, you could use values around
> 2000 to highlight the closest pixel to every control point.
>
> A second option is that you could create an itkMesh with these
> points, save it as a vtkPolyData in a .vtk legacy file by  using the
> itkVTKPolyDataWriter, and load it into Paraview, along with your
> 2D image, then use the Glyph filter on the loaded vtkPolyData.
>
> You may also find useful this paper from the Insight Journal:
>
> "Gridding Graphic Graticules"
> by Tustison N., Avants B., Gee J.
> http://www.insight-journal.org/browse/publication/140
> http://hdl.handle.net/1926/475
>
>
>      Regards,
>
>
>           Luis
>
>
> --------------------------------------------------------------
> On Wed, Aug 12, 2009 at 8:02 AM, motes motes <mort.motes at gmail.com> wrote:
>
>>
>> On Tue, Aug 11, 2009 at 1:41 PM, motes motes <mort.motes at gmail.com>wrote:
>>
>>> I am using one of the basic BSplineDeformableTransform examples on some
>>> 2D CT images of a brain.
>>>
>>> Now for each 5 or 10 iteration I would like to view the currently
>>> registered image and the corresponding BSpline controlpoints (deformation
>>> vectors).
>>>
>>> Are there any functionality in ITK that deals with this kind of
>>> visualization of registered images in progress and the corresponding
>>> controlpoints (deformation vectors)?
>>>
>>
>>
>>
>>
>>
>>
>>
>> Ok I have now written some code that writes the registered image to disk
>> after a sequence of N iterations.
>>
>> In the future I hope to  enable movement of control points in my
>> application. Therefore I would also like to plot the current position of the
>> control points on the current registered image.
>>
>> I am working on the following idea. When I store the current registered
>> image, I write the position of the control points to a file.
>>
>> Later I can (hopefully) in eg. gnuplot load the image and read in the
>> corresponding control points and plot them on top of the image.
>>
>> If anyone know of a better/easier way (maybe ITK already has examples
>> showing this?) they are most welcome to give suggestions!
>>
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