[Insight-users] ITK4 ImageToVTKImageFilter improvements?

[Dženan Zukić]

Thanks for suggestions.

I think I will go the resampling way. Since the resampled image will only be
used for visualization (the end of the processing pipeline), the information
loss is not really important.

Regards,
Dženan

2011/4/12 Bill Lorensen <bill.lorensen at gmail.com>

> Dženan,
>
> vtk and itk have different coordinate systems. itk treats images such that
> the first row of pixels on disk is the first row of pixels in memory. This
> is the normal imaging convention. vtk places the last row of pixels on disk
> as the first row of pixels in memory. This is normal graphics convention.
>
> To get the two coordinate systems to agree, use either itkFlipImageFilter
> or vtkImageFlip to flip the y-axis.
>
> vtk does not store the orientation of an image. itk does. If your images
> have a non-identity orientation (direction), then you should resample the
> image before passing it to vtk.
>
> Bill
>
> 2011/4/12 Dženan Zukić <dzenanz at gmail.com>
>
>>  Hi ITK programmers!
>>
>> ITK wiki <http://www.itk.org/Wiki/ITK> states "a beta of ITK4 will be
>> available by the end of March 2011". Could you please update that info
>> (since it is no longer true).
>>
>> And a question: do you plan to fix itk::ImageToVTKImageFilter so it works
>> properly, i.e. physical coordinates in ITK and world coordinates in VTK are
>> equal, if you haven't done so already?
>>
>> Problem example: I load a dataset using ITK readers, apply some filters to
>> it (denoising, rescaling), pass it through ImageToVTKImageFilter and add it
>> into the scene using vtkGPUVolumeRayCastMapper. I also do segmentation using
>> ITK's physical coordinates, create polygonal meshes of segmented objects,
>> also add them to the scene and behold: they are in completely different
>> places (if ITK_IMAGE_BEHAVES_AS_ORIENTED_IMAGE is set to TRUE)!
>>
>> The workaround is to set ITK_IMAGE_BEHAVES_AS_ORIENTED_IMAGE to FALSE, but
>> then real image orientation is lost (I don't need it yet but I plan to use
>> it).
>>
>> This problem would be understandable if ITK and VTK were made by 2
>> different companies (but it is not the case).
>>
>> Regards,
>> Dženan
>>
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