[Insight-users] Building Unit Vector Field

[Luis Ibanez]

Hi Abayiz,

Since you declared the image type to be:

  typedef itk::Image<VectorType, Dimension> VectorImageType;

where "VectorType" is the pixel type of the image,

Then SetPixel() method of the image is expecting
that you pass to it the parameters of type

  image->SetPixel( IndexType, VectorType );


But in your code,
you are passing a VariableLenghtVector type
as second argument.

So, what you need to do is
to replace that for loop with simply:

    VectorType  unitVector;
    unitVector[0] = 1.0;
    unitVector[1] = 0.0;
    unitVector[2] = 0.0;

    image->FillBuffer( unitVector );


BTW, just for the record, the call

   image->SetPixel( index, unitVector );

should also work, once you use the right
type for the unitVector variable.



   Luis



-----------------------------------------------
On Thu, May 17, 2012 at 3:22 PM, Abayiz <abayiz at yahoo.com> wrote:

> Hello,
>
> I am trying to build a unit vector field, my code is as follows:
>
> ************************************
>   typedef itk::Vector<float, Dimension >
> VectorType;
>   typedef itk::Image<VectorType,Dimension>
> VectorImageType;
>   typedef itk::ImageRegionConstIterator< VectorImageType >
> NeighborhoodIterator;
>
>   VectorImageType::Pointer image = VectorImageType::New();
>   image->SetRegions(vec_region);
>   image->SetSpacing(vec_spacing_image);
>   image->SetOrigin(vector_origin_image);
>   image->SetDirection(vec_direction_image);
>   image->SetNumberOfComponentsPerPixel(3);
>   image->Allocate();
>
>   VectorImageType::IndexType vec_start;
>   vec_start[0] =   0;
>   vec_start[1] =   0;
>   vec_start[2] =   0;
>
>   typedef itk::VariableLengthVector<double> VariableVectorType;
>   VariableVectorType variableLengthVector;
>   variableLengthVector.SetSize(2);
>   variableLengthVector[0] = 1.0;
>   variableLengthVector[1] = 0.0;
>   variableLengthVector[2] = 0.0;
>
>   NeighborhoodIterator vec_it(image, image->GetLargestPossibleRegion());
>
>   for (vec_it_i.GoToBegin();  !vec_it_i.IsAtEnd();  ++vec_it_i)
>   {
>
>    image->SetPixel(vec_start, variableLengthVector);
>
>   }
>
> ************************************
> Then I got an error, saying that "image" does not have a function for
> "SetPixel". Is there some one can help me?? How should I build a unit
> vector?
> Thanks in advance.
>
> Regards
> Abayiz
>
>
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