Hi all, Hi Peter Neher,
We are trying to see the tensor direction, like you do in MITK Diffusion
in the "Tensors" plugin in "Start Tensor Principal Direction
Extraction". Thanks to you, the work is all done :) This being said, we
have one problem. It works perfectly on an image without rotation
(translation and scaling is ok), but we have trouble with rotated
images. http://imgur.com/UR9JnKO
- We can see the lower and/or upper slice
- The tensors are not "in" the voxel, but floating in its neighborhood.
It can be impossible to say which voxel a tensor belongs to.
- The crosshair is not in the center of a voxel. (Not a bug I guess
because the image is rotated)
- The image navigator (not shown in screenshot) and step size are wrong.
(Idem???)
I'm pretty sure I understand what's going on. On
http://imgur.com/gaJhm7U, I printed many tensors per voxel but only on
one slice. The image is rotated but the axes aren't, so we end up
crossing a lot of slices. Since we are not exactly in the center of a
layer, we can see the end of a tensor on slice i and the start of a
tensor on slice i + 1.
I tried fixing the problem by rotating the axes as best as I can so they
"follow" the image. http://imgur.com/yVLKj5c If you place the crosshair
on the right voxel, it centers some tensors. It's hard to find the
"right" pixel and we still have the layer problem. I'm not sure how MITK
works on the inside, but it seems that we are stuck with interpolation
and bad step size if the image is rotated, even if you try to rotate the
axes so it fits.
What are your thoughts on this? Is tensor visualization on rotated
images an impossible idea in MITK? Is the only way to succeed is to
remove the rotation in the transformation matrix? Thanks for your time.
--
Logo Imeka <http://imeka.ca/> Nil Goyette, M.Sc.
www.imeka.ca <http://imeka.ca/>
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