[vtkusers] Why ITK re-implements VTK?

[Luis Ibanez]

Hi Ali,


Yes, there is some duplication of code between ITK and VTK.

As you pointed out this is the consequence of maintaining both
toolkits independent of each other.

There is also a lot of code in ITK that was taken from VTK
mostly because the data pipeline architecture of ITK was
inherited from the VTK design.


However, there shouldn't be any confusion when using both
toolkits together. ITK classes uses the "itk" namespace,
and vtk uses the "vtk" prefix. So, all class names are
independent.

The case of the Import filters is probably the one that
should produce the less confusion of all. In one case you
import a buffer to a vtkImageData, in the other case you
import a buffer to an itkImage class.

There is nothing superior or inferior in each filter,
they are doing different things and therefore they are
not comparable.


    Regards,



       Luis


-------------
Ali - wrote:
> Hi,
> 
> I understand that ITK does not fully cover VTK, eg ITK does not provide 
> visualisation facilities. In this way, ITK and VTK 'complete' each 
> other, they also 'overlap' to some great extent. Many classes in VTK  
> are re-implemented in ITK. One can say the reason behind this is because 
> of the fact that ITK it template-based and it is specifically designed 
> for medical image analysis. Even so, VTK could have been implemented in 
> the same way, ie template-based. This leads to these problems:
> 
> (1) With the current design, a program that is based on VTK+ITK draggs a 
> lot of duplicated resources, each implemented in a different approach.
> 
> (2) The overlapping classes cause confusion for developers. For example, 
> if one wants to use/extend an image import class, why (and why not) the 
> VTK (or ITK) approach should be superior.
> 
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