[Insight-users] Multi Modality Multi Resolution Doubt

[Luis Ibanez]

Hi Arash,

The 20 to 30 degrees that a registration method can correct for
are assumed to be *after* you provide an initialization.

If you have images with a relative rotations that is larger than
30 degrees, but you can provide an initialization by for example
using landmarks, then the actual rotation that the registration
method has to correct is only the residual rotation error left after
the initialization.

The problem of reconstructing a panorama is very similar
to the problem of constructing mosaics in teledetection or
stitching images in microscopy.  They can be solved with
the current registration framework in ITK.

You will find usefult to take advantage of the masking
capabilities that have been added to some metrics.

The extra dificulty in mosaic is that you don't only need
to register two images but a set of N images in subsets.
Therefore you may have to iterate among the pairs of
neighbor images and redistribute the geometric transform
over the entire set of images.


Regards,


     Luis




----------------------------
Arash Jahangir wrote:

>Hi Luis,
>Would this range of 20-30 degrees be still the limiting factor if I had some
>user input that could roughly identify matching regions between the images
>as a starting point?  To put this question in perspective, let me explain
>what I am after.
>
>I have a set of photos that form a "panorama" with some overlap.  Because
>the subject was relatively close to the camera, the rotational distortion in
>the overlapping region is quite obvious (as compared to say a panorama of
>the Rocky Mountains).  I am trying to write a program that would merge all
>these photos with each other.  Do you have any suggestions for how I should
>go about this?
>
>thanks,
>Arash
>
>----- Original Message ----- 
>From: "Luis Ibanez" <luis.ibanez at kitware.com>
>To: "CSPL" <hyd2_affable at sancharnet.in>
>Cc: <insight-users at itk.org>
>Sent: Saturday, February 28, 2004 10:55 AM
>Subject: Re: [Insight-users] Multi Modality Multi Resolution Doubt
>
>
>  
>
>>Hi Abdul,
>>
>>A reasonable registration proces will correct for
>>rotations of about 20 to 30 degrees.  Expecting
>>it to correct for image orientation (axial, coronal
>>saggital) is unrealistic and actually dangerous.
>>
>>Registration is an optimization problem that is solved
>>with a cost function with multiple extrema. There is
>>no magic here, if you don't initialize the registration
>>close to the optimal region, you can end up anywhere,...
>>and don't have to much right to complain.
>>
>>
>>There are filters in ITK for correcting Flipping and
>>orienting images:
>>
>>http://www.itk.org/Insight/Doxygen/html/classitk_1_1OrientImageFilter.html
>>http://www.itk.org/Insight/Doxygen/html/classitk_1_1FlipImageFilter.html
>>
>>    
>>
>http://www.itk.org/Insight/Doxygen/html/classitk_1_1ReflectImageFilter.html
>  
>
>>This is something that has to be done very carfully since
>>you could easily switch left-right on the patient image
>>and lead a surgeon to operate on the wrong side.
>>
>>
>>So, to answer your questions explicitly:
>>
>>1) Yes, you must set the orientation to be the same
>>2) No,  ITK will not do that for you.
>>3) Yes, you need to supply parameters.
>>
>>
>>
>>Regards,
>>
>>
>>    Luis
>>
>>
>>-----------------
>>CSPL wrote:
>>
>>    
>>
>>>Hi,
>>>
>>> I need to do some registration of SPECT[brain] with MRI[segmented
>>>brain]. So i have choosen Multi Modality Multi Resolution Registration
>>>and stuck with some problems. I am not getting the final results upto
>>>the mark. Later i found that my MRI is in Coronal View and the SPECT is
>>>in Transverse View. I want you to clarify in this point that
>>>
>>>1. Do we need to set the orientation of both the volumes same? or
>>>2. Does ITK will itself look for this and REGISTER? or
>>>3. Do we need to supply any parameters to get REGISTRATION even in this
>>>situation?
>>>
>>> Please reply.
>>>
>>>Thanks in Advance
>>>S. Abdul Rahim
>>>      
>>>
>>
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>>
>>
>>    
>>
>
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>