[ITK Community] [Insight-users] [Community] Demons Deformable Registration and Paraview

[Tim Bhatnagar]

Hey Matt,

Sorry to re-visit this specific email... in your message, you said:

"The displacement fields output of ITK's deformable image registration
represent the displacement of a point in the FixedImage to a point in
the MovingImage.  Therefore overlaying the displacement field vector
glyphs on the FixedImage should give the correct visualization.  The
start of the arrow sits on its location in the input FixedImage, and
the tip of the arrow glyphs are directed towards where a given pixel
in the FixedImage will move to in the MovingImage."

However, in the Demons examples that are built with the ITK package, an
'output' image from the registration is produced by passing the
*movingImage* into the WarpImageFilter, and utilizing the newly created
deformation field. This makes it seem like the deformation field actually
takes the movingImage form into the fixedImage form, not the other way
around.

I really appreciate all your help thus far.. could you comment on this
aspect of the non-rigid methods?

Thanks again,

Tim


On Mon, Nov 4, 2013 at 11:14 PM, Matt McCormick
<matt.mccormick at kitware.com>wrote:

> Hi Tim,
>
> The displacement fields output of ITK's deformable image registration
> represent the displacement of a point in the FixedImage to a point in
> the MovingImage.  Therefore overlaying the displacement field vector
> glyphs on the FixedImage should give the correct visualization.  The
> start of the arrow sits on its location in the input FixedImage, and
> the tip of the arrow glyphs are directed towards where a given pixel
> in the FixedImage will move to in the MovingImage.
>
> Hope this helps,
> Matt
>
> On Mon, Oct 21, 2013 at 6:39 PM, Tim Bhatnagar <tim.bhatnagar at gmail.com>
> wrote:
> > Hello all,
> >
> > Has anyone used Paraview to visualize Deformable Registration
> Displacement
> > fields in Paraview? I am having trouble verifying what exactly paraview
> is
> > showing me. A point (x,y,z) where I know a large y-deformation occurs
> does
> > not exhibit that vector magnitude in Paraview, but it DOES seem to exist
> at
> > a spatial coordinate that corresponds to where the large deformation ENDS
> > (ie where the (x,y,z) point is located AFTER registration).
> >
> > Between this, and 'flipping' the x- and y- components of the vectors in
> the
> > displacement field, I have managed to become very confused about the
> proper
> > way to visualize the data.
> >
> > Note that after using WarpImageFilter with my registration-produced
> > displacement field, I get the registered output I was looking for (yay!).
> > It's just visualizing the proper deformation field for visual/qualitative
> > figures is completely eluding me.
> >
> > Any help is greatly appreciated, though I feel like my emails in this
> > user-list not up to par in terms of how I describe my problem, or the
> > information I pass along is not enough to have an experienced ITKer chime
> > in. If this is the case, please tell me what other info you need,as I'm
> > happy to provide it.
> >
> > Alternatively, if it's best I address this to a Paraview-users
> community, I
> > can try that. I just figured anyone who used Demons in ITK would most
> likely
> > also visualize the field..
> >
> > Thanks,
> > --
> > Tim Bhatnagar
> > PhD Candidate
> > Orthopaedic Injury Biomechanics Group
> > Department of Mechanical Engineering
> > University of British Columbia
> >
> > Rm 5000 - 818 West 10th Ave.
> > Vancouver, BC
> > Canada
> > V5Z 1M9
> >
> > Ph: (604) 675-8845
> > Fax: (604) 675-8820
> > Web: oibg.mech.ubc.ca
> >
> > _____________________________________
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> > Visit other Kitware open-source projects at
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>



-- 
Tim Bhatnagar
PhD Candidate
Orthopaedic Injury Biomechanics Group
Department of Mechanical Engineering
University of British Columbia

Rm 5000 - 818 West 10th Ave.
Vancouver, BC
Canada
V5Z 1M9

Ph: (604) 675-8845
Fax: (604) 675-8820
Web: oibg.mech.ubc.ca
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