[Insight-users] CenteredEuler3DTransform

Karthik Krishnan Karthik.Krishnan at kitware.com
Thu Aug 4 10:08:08 EDT 2005


The paramters returned are 6, The following post should have a few answers.


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.


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)?
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