[vtkusers] Re: Rotation does not happen about the center of the image

[Anja Ende]

Hi,

This is kinda bizarre. I verified that the zooming (scaling in the
transform) happens around the center but the rotation does not...the
rotation happens as if the vtkImageChangeInformation filter has not been
applied at all...

Did anyone else notice this ?? is there something special I have to do for
rotations???

Cheers,
Anja

On 18/09/06, Anja Ende <anja.ende at googlemail.com> wrote:
>
> Hi everyone,
>
> I am unsable to have the rotations at the center of the image.
>
> So, I have a 3D volume and I pass it through the vtkImageChangeInformation
> filter. The CenterImageOn() function si called.
>
> The output of this filter is passed to a vtkImageReslice which has a
> transformation object that does the scaling and rotation. The scaling works
> fine but when I rotate the image I can see the center being shifyted. I
> thought that the vtkTransform should do these operations around the image
> center.
>
> I printed the vtkImageReslice index matrix and the original matrix is:
>
> Elements:
>  1 0 0 0
>  0 1 0 0
>  0 0 1 62
>  0 0 0 1
>
> And after a rotation of one degree:
>
> 0.999848        -0.0174524 0            0.0776696
> 0.0174524       0.999848 0              -4.44969
>   0 0 1 62
>   0 0 0 1
>
> I was hoping that the center would remain stationary....
>
> If anyone can cast some light on how I can manage this, I would be really
> grateful.
>
> Thanks,
> Anja
>
>
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