[Insight-users] element order of vector image and vectorImage

[Hsieh]

Hi all,

 

I tried to load two vector images, one using itk::Image<
itk::SymmetricSecondRankTensor< double, 3> > and the other using
itk::VectorImage< double, 3 >. I got the voxel values using
itk::ImageRegionIterator::Get() function. However, very strange thing
occurred to me. The order of the vector elements the iterators read
behaves not in a way I create the phamton vector images. The vector I
created is [0 1 2 3 4 5] for the symmetric tensor and [0 1 2 3 4 5 6 7
8] for the VectorImage. The voxel I got from the iterators are [0 1 3 2
4 5] and [0 1 3 6 2 4 7 5 8]. Why is that? Is there anything to do with
the image headers? I'm using nifti .nii. 

 

The header file for the symmetric tensor image is as below. The header
of VectorImage differs only in the dimension, which is dim: [5 20 20 20
1 9 1 1].

 

       sizeof_hdr: 348

        data_type: ''

          db_name: ''

          extents: 0

    session_error: 0

          regular: 'r'

         dim_info: 0

 

               dim: [5 20 20 20 1 6 1 1]

         intent_p1: 0

         intent_p2: 0

         intent_p3: 0

       intent_code: 1005

          datatype: 16

            bitpix: 32

       slice_start: 0

            pixdim: [-1 0.8984 0.8984 3 1 1 1 1]

        vox_offset: 352

         scl_slope: 1

         scl_inter: 0

         slice_end: 0

        slice_code: 0

        xyzt_units: 2

           cal_max: 0.0017

           cal_min: 0

    slice_duration: 0

           toffset: 0

             glmax: 0.0017

             glmin: 0

 

        descrip: 'FSL4.0'

       aux_file: ''

     qform_code: 1

     sform_code: 1

      quatern_b: 0.0066

      quatern_c: 0.9946

      quatern_d: -0.0764

      qoffset_x: 110.0322

      qoffset_y: -113.4360

      qoffset_z: 28.6710

         srow_x: [-0.8895 0.0214 -0.4165 110.0322]

         srow_y: [0.0021 0.8879 0.4586 -113.4360]

         srow_z: [-0.1265 -0.1357 2.9353 28.6710]

    intent_name: ''

          magic: 'n+1'

 

 

Best regards,

Meng-Kang Hsieh (Michael)

OpSciTech, Erasmus Mundus

Delft University of Technology

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