[Insight-users] rigid2D registration fails to rotate images

[Luis Ibanez]

Darren,


Thanks for posting all the source code and images that
reproduce the problem that you are observing.


As Richard pointed out, the registration process must be
initialized properly.


It is very unlikely that an optimization process will manage
to register two images that are 140 degrees off, as the ones
that you kindly posted.


So you should:

1)  Initialize the Transform with an angle close to 140 degrees.

2)  Use the Rigid2DTransform instead of the
     CenteredRigid2DTransform (this later one is deprecated)

3)  Remove all the Change image filters that you have in your
     code. They shouldn't be necessary.


Please find attached a simplified variation of the example:

    Insight/Examples/Registration/
                            ImageRegistration6.cxx

With this attached .cxx file,
I manage to register your two images with the following output:

 Angle (radians) 2.45657
 Angle (degrees) 140.751
 Translation X = 1.67046
 Translation Y = -0.480926
 Iterations    = 92
 Metric value  = 6.19969e+07


I ran it with the following set of command line arguments:

ImageRegistration6

     section0004_w1.tif section0005_w1.tif 150.0 output.tiff


Where "150.0" is the initial angle to set in the Transform.


Please give it a try at this attached code and let us
know if you find any problems.


     Thanks


            Luis


--------------------------------------------------------------------------------------
On Fri, Mar 5, 2010 at 7:56 PM, Richard Beare <richard.beare at gmail.com> wrote:
> Good initialization is essential for all registration, with the
> rotation component often the most critical. If the rotation is greater
> than 15 degrees then you're probably going to have trouble.
>
> If you're trying to build an automated process rather than a one off,
> then here are some options.
>
> Moments based initialization as a first step. This is good if the
> scene is reasonably simple, or you have masks defining the regions of
> interest. You can check how similar the major moments are. If they are
> sufficiently dissimilar then the initialization is likely to be
> accurate along the major axis, but potentially flipped. In this case
> you need to try both options and select the one that gives the best
> resulting cost. If the moments are similar then the initialization
> will be unreliable and sensitive to small changes, so you need to try
> a series of angles covering the entire 360 degrees and select the best
> result as defined by your cost metric.
>
> On Sat, Mar 6, 2010 at 11:45 AM, Darren Weber
> <darren.weber.lists at gmail.com> wrote:
>>
>> I've got a couple of images that clearly need nearly 180 degree rotation for
>> registration, see:
>> ftp://anonymous@ftp.buckinstitute.org/dweber/section0004_w1.tif
>> ftp://anonymous@ftp.buckinstitute.org/dweber/section0005_w1.tif
>> The registration fails to rotate the images into alignment.  I'm using:
>> // Registration components
>> #include "itkImageRegistrationMethod.h"
>> #include "itkMeanSquaresImageToImageMetric.h"
>> #include "itkLinearInterpolateImageFunction.h"
>> #include "itkRegularStepGradientDescentOptimizer.h"
>> // Transforms
>> #include "itkCenteredRigid2DTransform.h"
>> #include "itkCenteredTransformInitializer.h"
>>
>> What can I do about it?  Have I selected the wrong transform for rotations?
>> I've prepared a package of my test program and data for download here:
>> ftp://anonymous@ftp.buckinstitute.org/dweber/itkRegistrationTest.tar.gz
>> The program is built against ITK 3.16 (and it uses Boost).
>> TIA,
>> Darren
>>
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