[Insight-users] what is the meaning of deformation field?

[xianjun.sun.ext_CRC]

I try some cases in Examples\Registration, and outputs of them can give explicit deformation field, I am not sure the meaning of deformation field.

In source code of the cases, there are often existing two lines as follows

 typedef itk::Vector< float, ImageDimension >      VectorType;
  typedef itk::Image< VectorType, ImageDimension >  DisplacementFieldType;

I review ItkSoftwareGuide in which it is explained as "write the deformation field as an image of vectors. " and "Note that the file format used for writing the deformation field must be capable of representing multiple components per pixel. This is the case for the MetaImage and VTK file formats for example." In page No. 447.

Each pixel in deformation field has a vector of d dimensional components, whether the components store the displacements such as a pixel(i,j) under 2D image coordinates system has 2 components representing the pixel's position translation?

Which the suffix of deformation field file should be if I want the deformation field?  With the case of DeformableRegistration4.cxx, I get a .mha deformationField output file, and find that it is not a 2DX3 image, but a 2D only.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.itk.org/pipermail/insight-users/attachments/20121106/ba49c846/attachment.htm>