[Insight-users] affine transform without scaling?

[Darren Weber]

On Sat, Oct 24, 2009 at 7:58 PM, Darren Weber
<darren.weber.lists at gmail.com>wrote:

>
> Is there an easy way to turn off the scaling component of an affine
> transform?
>
> Is there a method in itkAffineTransform to set the scale component to a
> constant?
>
> Would you manually pull out the matrix, etc., modify it and then reset it
> in the itkAffineTransform?
>
> TIA,
> Darren
>
>
PS,  Maybe a geometric problem can help (or obscure) the problem.  Imagine a
series of conic sections, starting at the tip of a cone and working down
toward the base.  Each of these 2D conic sections needs to be registered
into a 3D volume to recreate the cone.  If each section were a "pure"
section taken along the axis from the tip to the center of the base, this
would be fairly trivial as a rigid-body registration (probably no
registration at all is required, just a known sequence of slices).  However,
assume each section has an unknown deformation (but the series of sections
is given in a known order).  If the affine registration starts at the tip
(img001) and propagates all the way to the base (img100), the final diameter
of the base section will be decreased to about the same diameter as the tip.

The real problem is a series of microscopy images for a worm, which has a
smaller diameter at the head and tail than in the body.
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