<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman, new york, times, serif;font-size:12pt"><DIV>Hello Luis,</DIV>
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<DIV>Thanks for the reply. It was quite informative. I really appreciate it.</DIV>
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<DIV>We would like to consider the second option, but one thing is not clear to me. I suppose you are suggesting us to use the Similarity3DTransform. </DIV>
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<DIV>But as i understand Similarity3DTransform is designed for homogenous scaling ( isotropic scaling ) along three xyz axial directions. </DIV>
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<DIV>But for our purpose we need the scaling to be anisotropic ----> by this i mean the scaling should be different along each of the x,y,z axis.</DIV>
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<DIV>Is this possible with the trick you are mentioning ?????</DIV>
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<DIV>Also can you describe the trick with a small example (C++ code). Specifically how to set the optimizer scales so that the rotations about and X and Y axis are constrained.</DIV>
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<DIV>And also how should i set the optimizer scales, to make the scaling anisotropic ---> if it is possible.</DIV>
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<DIV>Please Help !!!!!!!!!</DIV>
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<DIV>Eagerly waiting for your reply.</DIV>
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<DIV>Regards,</DIV>
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<DIV>Deepak</DIV>
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<DIV><EM>Hi Deepak,<BR><BR><BR>Here are three options that you may want to consider:<BR><BR><BR>1) Write your own transform<BR><BR> You could do this by creating a variant of the SimilarityTransform<BR><BR></EM><A href="http://www.itk.org/Insight/Doxygen/html/classitk_1_1Similarity3DTransform.html"><FONT color=#0000ff><EM>http://www.itk.org/Insight/Doxygen/html/classitk_1_1Similarity3DTransform.html</EM></FONT></A><BR><BR><BR><BR><EM>2) Use the SimilarityTransform and<BR><BR> trick the optimizer by setting the array of parameters scaling in<BR> such a way that rotations around X and Y will be hardly done.<BR><BR> This is probably the simplest method. It doesn't require you to<BR> write any code. You just need to set the scalings that correspond<BR> to rotationX and rotationY to be extreme values.<BR><BR> For details on the meaning of the parameters
scaling on the<BR> Image Registration framework, please read the Image Registration<BR> chapter of the ITK Software Guide<BR><BR> </EM><A href="http://www.itk.org/ItkSoftwareGuide.pdf"><FONT color=#800080><EM>http://www.itk.org/ItkSoftwareGuide.pdf</EM></FONT></A><BR><BR><BR><BR><EM>3) Use a sequence of three transform.<BR><BR> 3.1) First, perform a registration using<BR> only the TranslationTransform<BR><BR> 3.2) With the result perform a registration<BR> using only the rotation transform (but still using<BR> the parameter-scalin for penalizing rotations on<BR> X and Y.<BR><BR> 3.3) Finish with a
ScaleTransform<BR><BR> You will find descriptions of each one of these transform<BR> in the Image Registration chapter of the ITK Software Guide.<BR><BR><BR><BR><BR>Regards,<BR><BR><BR> Luis<BR></EM><BR><BR><BR>------------------<BR>Deepak Roy wrote:<BR>><I> Hello,<BR></I>><I> <BR></I>><I> I want to do registeration of two image volumes ...<BR></I>><I> <BR></I>><I> each of them have different spacing but the same dimension and voxel type.<BR></I>><I> <BR></I>><I> Also both of them are from the same modality.<BR></I>><I> <BR></I>><I> But i want the registration to use only the following set of <BR></I>><I> transformations:<BR></I>><I> <BR></I>><I> >>> Translation along x,y,z axis<BR></I>><I> <BR></I>><I> >>> Rotation along z-axis onlye<BR></I>><I> <BR></I>><I> >>> Anisotropic
scaling along x,y,z.<BR></I>><I> <BR></I>><I> None of the transforms available seem to allow me to implement this <BR></I>><I> combination.<BR></I>><I> <BR></I>><I> >>> AffineTransform includes shearing which i dont want.<BR></I>><I> <BR></I>><I> >>> Similarity3DTransform implements homogenous scaling, but i want <BR></I>><I> anisotropic scaling.<BR></I>><I> <BR></I>><I> Also i dont know how to restrict the rotations to happen around the <BR></I>><I> z-axis only.<BR></I>><I> <BR></I>><I> Is this possible with one of the existing transform classes or do i have <BR></I>><I> to write a custom transform class ???<BR></I>><I> <BR></I>><I> Please Help !!!!!!<BR></I>><I> <BR></I>><I> Thanks in advance !!!!!<BR></I>><I> <BR></I>><I> Eagerly waiting for your reply !!!</I></DIV></div><br></body></html>