[vtkusers] Flipping an image with vtkCamera

[Amy Squillacote]

Hi Jesús,

Why not directly manipulate the camera's position (SetPosition method) 
and view up vector (SetViewUp method)?

- Amy

Jesús Spí­nola wrote:
> Hi,
>
> I'm using vtkImageViewer for a 2D medical image viewer and I want to 
> put flipping functionality. My purpose is to flip, either horizontally 
> or verticaly, the image in axial, sagital or coronal view. I know 
> about vtkImageFlip filter but I want to avoid it because I think I can 
> do the same, manipulating directly the camera and it would be faster.
>
> My question is that I don't know exactly which is the proper method to 
> achieve the flipping with vtkCamera. For rotations on the image I used 
> the SetRoll method, it seems I'll need one of this ones Yaw, Azimuth, 
> Elevation, Pitch, etc to flip, but I don't obtain the results that i 
> like.
> If I'm on the axial view, Yaw(180) is ok for horizontal flip, but with 
> sagital or coronal view it doesn't behave well.
>
> Did someone achieved correct flippings manipulating vtkCamera?
>
> Her are some code snippets that tell what I'm doing in each situation:
>
> To change to axial view
>
> m_imageViewer->SetSliceOrientationToXY();
> // this is because the vtk default axial orientation is not as the 
> medical axial orientation
> camera->SetFocalPoint(0,0,0);               
> camera->SetViewUp(0,-1,0);
> camera->SetPosition(0,0,-1);
> renderer->ResetCamera();
> cam->SetRoll( -m_rotateFactor*90. + 180. ); // apply the rotation of 
> the camera, it will be always 0,90,180 or 270 degrees
>
>
> To change to sagital view
>
> m_imageViewer->SetSliceOrientationToYZ();
> camera->SetRoll( -m_rotateFactor*90. -90. );
>
>
> To change to coronal view
>
> m_imageViewer->SetSliceOrientationToYZ();
> camera->SetRoll( -m_rotateFactor*90.  );
>
> When i update the camera to apply a flip:
>
> if( m_applyFlip )
> {                   
>     camera->OrthogonalizeViewUp();
>     camera->Yaw(180);
>     renderer()->ResetCamera();
> }
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