[ITK-users] [ITK] Evaluate results of registration

[Matias Montroull]

Thanks all for your answers, much appreciated, I will follow your
suggestions and learn in the process, thanks again.

Matias.

On Fri, Feb 13, 2015 at 6:41 PM, Andras Lasso <lasso at queensu.ca> wrote:

> Hi Matias,
>
> Checkerboard pattern image is easy to generate but conveys very limited
> information while taking up a lot of space. The main issue is that you can
> only see displacement (residual registration error) along gridlines, but
> only at those points where a linear image feature (for example, an organ
> contour) crosses a gridline. So, in an entire image you can estimate the
> displacement only at a couple of relevant points. Using a more dense grid
> does not help much, because it makes image features harder to recognize.
>
> I would suggest the following representation instead:
>
> 1. Show only the fixed image with the following information overlaid (in
> one or more images)
> - contours segmented on the moving image with/without registration: this
> allows evaluation of displacement along the entire segmented contour, not
> just at a few points; the segmentation can be also used for quantitative
> evaluation (e.g., Hausdorff distance)
> - vector field of the registration transform (shown as arrows, distorted
> grid, etc.): this is important because very often registration at the
> contours look perfect but in areas where the image gradients are smaller
> the registration transform may become very irregular
>
> 2. Visualize the vector field of the transformation (with arrows or
> distorted grid) in 3D: this allows the evaluation of how realistic the
> computed displacements are
>
> These visual representations have not been very easy to generate in the
> past but since we added full support of real-time visualization of
> non-linear transforms to 3D Slicer, this should not be a problem anymore.
> Slicer can read ITK transforms (even composite transforms), concatenate
> them, invert them, and apply them to any 3D volume, surface mesh, point
> cloud, etc. and visualize them in 2D and 3D. See some example
> visualizations here:
> http://www.slicer.org/slicerWiki/index.php/Documentation/Nightly/Modules/Transforms
> .
>
> Andras
>
> -----Original Message-----
> From: Community [mailto:community-bounces at itk.org] On Behalf Of Matt
> McCormick
> Sent: Friday, February 13, 2015 3:31 PM
> To: Matias Montroull
> Cc: insight-users at itk.org Users
> Subject: Re: [ITK] [ITK-users] Evaluate results of registration
>
> Hi Matias,
>
> Yes, it is possible to get the intensities on similar scales with the
> RescaleIntensityImageFilter [1] or the IntensityWindowingImageFilter [2]
> before passing into the CheckerBoardImageFilter.
>
> HTH,
> Matt
>
> [1]
> http://www.itk.org/Doxygen/html/classitk_1_1RescaleIntensityImageFilter.html
>
> [2]
> http://www.itk.org/Doxygen316/html/classitk_1_1RescaleIntensityImageFilter.htmlhttp://www.itk.org/Doxygen316/html/classitk_1_1RescaleIntensityImageFilter.html
>
> On Fri, Feb 13, 2015 at 7:33 AM, Matias Montroull <matimontg at gmail.com>
> wrote:
> > Hi,
> >
> > I'm using a check-board output (CheckerBoardImageFilter) to evaluate
> > the results of a CT/RM registration, now I would like to write
> > something where I could change the WL WC of the 2 images independently
> > to really make sure the registration is right; I guess is not possible
> > with ITK itself and I need to write some code for visualizing the CT
> > and the RM and then change window levels independently, am I right?
> >
> > Thank you,
> >
> > Matias.
> >
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