[vtkusers] Unwrap a cylinder of data using vtkCylindricalTransform and vtkImageReslice

[David Gobbi]

On Thu, Dec 11, 2014 at 10:45 AM, Vincent32160 <vsh at magellium.fr> wrote:

> I wanted to talk about the data display but I was wrong, the transformation
> is applied in a complex way (cf picture below).
> On the right, a vtkImageReslice with the original data and on the left, a
> vtkImageReslice with the original data and a cylindrical transformation
> applied.
> Am I right if I say that I am supposed to get a pyramid instead of a
> rectangular prism (as seen on the picture)?
> Thanks
>
> <http://vtk.1045678.n5.nabble.com/file/n5729805/2reslices.png>
>

No, it shouldn't give a pyramid.  The circumferencial coordinate "theta"
is measured in radians, so it has a range of [0,2*pi] regardless of whether
you are at the center or whether you are at the surface.

It would be a pyramid if the circumferencial coordinate was measured in
distance units (e.g. in millimeters).  But it's not, because by definition a
cylindrical transform uses an angular measure.

 - David
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