[Insight-users] CenteredEuler3DTransform

[Karthik Krishnan]

typo in the reply !
"The Centered3DTransform has 9 parameters"

sorry for the noise..
karthik

Karthik Krishnan wrote:

> Dennis,
>
> The paramters returned are 6, The following post should have a few 
> answers.
>
> http://public.kitware.com/pipermail/insight-users/2005-July/013868.html
>
> The center for centered transforms (deriving from 
> MatrixOffsetTransformBase is stored seperately in the base class ).
>
> On a related note, there is little sense in optimizing both the 
> translation and the center. The Centered3DTransform has 5 parameters, 
> [3 for rotation, Tx, Ty, Tz and the 3 for center ]. Really, you could 
> represent rotation about any center Cx, Cy, Cz with an equivalent 
> transform that is rotated about the origin [0, 0], the value of the 
> translation calculated accordingly. See above post or the SW guide. 
> You are just increasing the work of the optimzier by optimizing both 
> center and translation.
>
> -karthik
>
> wenzeld at att.net wrote:
>
>> My understanding from the documentation and from looking at the 
>> header file for this class is that this transform has 9 parameters 
>> for which it tries to solve in the case of using it with an 
>> optimizer.  These parameters are the three for rotation, the three 
>> for the centered offset, and the three for the translation.  After 
>> running an optimization using this transform, I got only 6 parameters 
>> returned instead of 9 and upon inspecting the transform instance in 
>> the debugger, I noticed that the centered offset was zero.  Is this 
>> because the centered offset was incorporated into the translation 
>> component?  Is the center of rotation really being solved for in the 
>> optimzer as I did not see it as part of the jacobian calculation 
>> (there is none defined in this class)?
>>
>> Thanks...
>>
>> Dennis
>> _______________________________________________
>> Insight-users mailing list
>> Insight-users at itk.org
>> http://www.itk.org/mailman/listinfo/insight-users
>>
>>  
>>
> _______________________________________________
> Insight-users mailing list
> Insight-users at itk.org
> http://www.itk.org/mailman/listinfo/insight-users
>