[Insight-users] affine transform

[Luis Ibanez]

Hi Annelaure,

In order to map your points you can simply use the Transform itself.

Just iterate through the PointSet and for each point invoke the
transform method TransformPoint().

You will find details about the iterators of the PointSet in the
ITK Software Guide


        http://www.itk.org/ItkSoftwareGuide.pdf

in the DataRepresentation chapter.


You *SHOULD NOT* assume that the center of rotation is (0,0,0).
changing the center of rotation induces a translation in the
transformation.


The easy way to map the point is to use the transform that
results from the Iterative Point registration process.



    Regards,


         Luis



-----------------
annelaure wrote:
> Hi,
> I apply the equation 8.11 p440 in the ITK Software Guide in order to obtain
> the final coordinates of my points. I considered that the firt matrix of
> this equation is constituted by the 9 first result parameters and that
> Cx=0,Cy=0 and Cz=0.
> I try to register a theorical rib (95 points)
> www710.univ-lyon1.fr/~adidier/cote8_thpts.txt on a segmentation rib (4280
> points)   www710.univ-lyon1.fr/~adidier/cote8_segpts.txt in using the code
> previously described. I don't obtain good results. I try to proceed to a
> classical icp registration (iterativeclosestpoint2.cxx) first but the
> results are not better. 
> Should I change some optimizer parameters? Should I proceed to a rigid
> registration before in order to bring closer the two ribs?
> Thank you so much for your answer,
> Best regards,
> Anne-Laure
> 
> 
> 
> 
> Luis Ibanez wrote:
> 
>>
>>
>>Hi Annelaure,
>>
>>
>>               No need ot make assumptions
>>
>>
>>Please read the documentation of the AffineTransform class:
>>
>>http://www.itk.org/Insight/Doxygen/html/classitk_1_1AffineTransform.html
>>
>>In particular the GetParameters and SetParameters() methods.
>>
>>
>>You should also read the description of this Transform in the
>>ITK Software Guide:
>>
>>         http://www.itk.org/ItkSoftwareGuide.pdf
>>
>>
>>In section 8.8.16 "Affine Transform" in pdf-pages 439-440.
>>
>>Pay particular attention to Table 8.15 in pdf-page 439.
>>
>>
>>
>>Please note that all the examples are described in detail
>>in the ITK Software Guide.
>>
>>
>>
>>   Regards,
>>
>>
>>
>>       Luis
>>
>>
>>-------------------
>>annelaure wrote:
>>
>>>Hi,
>>>I use Iterative closest point 1 with the affine transform. I obtain 12
>>>numbers : Solution = [0.563524, -0.0204711, -0.0675956, 0.308023,
>>>0.539417,
>>>-0.0100321, -0.0645276, -0.0436415, 0.554475, 83.8441, 81.0703, 139.525].
>>>I
>>>suppose that the 3 last numbers are the translation parameters; but I
>>>don't
>>>know where are the rotation parameters, and the scaling parameters. Thank
>>>you so much for your help,
>>>best regards,
>>>Anne-Laure
>>>
>>
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>>
>>
> 
>