[Insight-users] 3D rigid registration

[Grace Chen]

Hi Karthik,

The reason I want to do that is because the registered moving image is still
3 or 4 pixels off the fixed image....So, I thought I should center the
images to get better result.

Thanx!

Grace

----- Original Message ----- 
From: "Karthik Krishnan" <Karthik.Krishnan at kitware.com>
To: "Grace Chen" <Grace.Chen at swri.ca>
Cc: <insight-users at itk.org>
Sent: Monday, June 05, 2006 6:14 PM
Subject: Re: [Insight-users] 3D rigid registration


> Grace Chen wrote:
>
> >Hi Karthik,
> >
> >By centering the image, I mean to make coordinate (0,0,0) to the center
of
> >the image.
> >
> >
> >
> Why are you doing this ?
>
> >If I do that on one of the input images, then I need to shift the other
> >image by the same amount in the same direction (by reseting the origin).
> >
> >
> It is always a bad idea to shift the origin of your image. The right
> thing to do is to compute a transform that will overlay the images
> according to your needs and leave the origins of the images intact.
>
> >Don't we need to center the images for the center transform to work well?
> >
> >
> No. The CenteredTransformInitializer does that for you as detailed in
> the earlier email. " It computes the transform, which when applied to
> the moving image would align the two images via their geometric centers.
> It is one way of starting the registration from an initial transform.".
>
> Please refer to the examples first.
>
> -karthik
>
> >Grace
> >
> >----- Original Message ----- 
> >From: "Karthik Krishnan" <Karthik.Krishnan at kitware.com>
> >To: "Grace Chen" <Grace.Chen at swri.ca>
> >Cc: <insight-users at itk.org>
> >Sent: Monday, June 05, 2006 5:14 PM
> >Subject: Re: [Insight-users] 3D rigid registration
> >
> >
> >
> >
> >>Grace Chen wrote:
> >>
> >>
> >>
> >>>Hi,
> >>>
> >>>If I center just one image and shift another image....
> >>>
> >>>
> >>>
> >>What do you imply when you say :
> >>"If I center just one image and shift another image" ?
> >>
> >>  A minimal example might help
> >>
> >>
> >>
> >>>The result is quite
> >>>different (slice shift 2 slices forward) from if I don't center any
input
> >>>images....
> >>>
> >>>Can some ITK people please tell me if I should center input images at
> >>>
> >>>
> >all??
> >
> >
> >>>
> >>>
> >>If you have datasets of the same anotomical region, acquired in the same
> >>manner, it is sometimes useful them via their geometrical centers:
> >>
> >>
> >>
>
>http://www.itk.org/Insight/Doxygen/html/classitk_1_1CenteredTransformInitia
lizer.html
> >
> >
> >>You will need to look at the datasets to see if aligning them via their
> >>geometrical centers makes sense. There is no hard and fast rule here.
> >>
> >>There are several examples that you can refer to on using this class:
> >>
> >>./Registration/ImageRegistration12.cxx
> >>./Registration/ImageRegistration13.cxx
> >>./Registration/ImageRegistration14.cxx
> >>./Registration/ImageRegistration6o.cxx
> >>./Registration/ImageRegistration7o.cxx
> >>./Registration/ImageRegistration6.cxx
> >>./Registration/ImageRegistration7.cxx
> >>./Registration/ImageRegistration8.cxx
> >>./Registration/ImageRegistration9.cxx
> >>
> >>
> >>
> >>>
> >>>
> >>>>Hi there,
> >>>>
> >>>>To use VersorRigid3DTransform for 3D rigid registration, should we
> >>>>
> >>>>
> >center
> >
> >
> >>>>both of the input imgaes?  It seems wrong to center both images.....If
> >>>>
> >>>>
> >we
> >
> >
> >>>>need to center just one image, which one, the fixed image or the
moving
> >>>>image??
> >>>>
> >>>>
> >>>>
> >>>>
> >>To clarify:  When you "center images", you are computing the transform,
> >>which when applied to the moving image would align the two images via
> >>their geometric centers. It is one way of starting the registration from
> >>an initial transform.  I suppose, you have a different notion of "center
> >>images prior to registration".
> >>
> >>
> >>
> >>>>Please help!  This part of using ITK can't seem to be found
anywhere....
> >>>>Thanx!
> >>>>
> >>>>Grace
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>_______________________________________________
> >>>Insight-users mailing list
> >>>Insight-users at itk.org
> >>>http://www.itk.org/mailman/listinfo/insight-users
> >>>
> >>>
> >>>
> >>>
> >>>
> >
> >
> >
> >
>