[vtkusers] image moved afer an orientation change

[David Gobbi]

The slicing and the panning are both controlled via the camera's focal
point.  So slicing through the axial images causes the camera's
FocalPoint to move in and out along the Z axis.  Then, when you switch
to a new orientation, this "Z" position is centered in the window.

If you want to avoid this, you should save the FocalPoint for each
view orientation.  Then, you can restore the focal point before you
call SetImageOrientation, e.g.

camera.SetFocalPoint(focal_point_for_axial_view)
camera.SetImageOrientation(orientation_for_axial_view)

 - David

On Wed, Dec 12, 2012 at 5:24 AM, José M. Rodriguez Bacallao
<jmrbcu at gmail.com> wrote:
> no one please, is this normal?
>
>
> On Tue, Dec 11, 2012 at 9:45 AM, José M. Rodriguez Bacallao
> <jmrbcu at gmail.com> wrote:
>>
>> hi folks, I am trying to implement a MPR viewer, so far so good. I am
>> using the new image classes, this is test code:
>>
>> #!/usr/bin/env python
>>
>> import os
>> import gdcm, vtkgdcm, vtk
>>
>>
>> def key_press(sender, event):
>>     key = interactor.GetKeySym()
>>     style.SetCurrentRenderer(renderer)
>>     if key == 'a':
>>         print 'axial'
>>         style.SetImageOrientation(
>>             style.GetZViewRightVector(),
>>             style.GetZViewUpVector()
>>         )
>>     elif key == 'c':
>>         print 'coronal'
>>         style.SetImageOrientation(
>>             style.GetYViewRightVector(),
>>             style.GetYViewUpVector()
>>         )
>>     elif key == 's':
>>         print 'axial'
>>         style.SetImageOrientation(
>>             style.GetXViewRightVector(),
>>             style.GetXViewUpVector()
>>         )
>>     render_window.Render()
>>
>>
>>
>> interactor = vtk.vtkRenderWindowInteractor()
>> render_window = vtk.vtkRenderWindow()
>> render_window.SetSize(400, 400)
>> interactor.SetRenderWindow(render_window)
>>
>> style = vtk.vtkInteractorStyleImage()
>> style.SetInteractionModeToImageSlicing()
>> interactor.SetInteractorStyle(style)
>> style.AddObserver('CharEvent', key_press)
>>
>> print 'sorting files...'
>> path = '/home/jmrbcu/pictures/workpictures/dicom/BRAIN/'
>> files = [os.path.join(path, x) for x in os.listdir(path)]
>>
>> ipp = gdcm.IPPSorter()
>> ipp.SetComputeZSpacing(True)
>> ipp.SetZSpacingTolerance(1e-3)
>> result = ipp.Sort(files)
>>
>> sorted_files, zspacing = files, 0
>> if result:
>>     sorted_files = ipp.GetFilenames()
>>     zspacing = ipp.GetZSpacing()
>>     print 'files sorted, z spacing is: %s' % zspacing
>> else:
>>     print 'cannot sort files, this is not a valid volume'
>>
>> vtk_files = vtk.vtkStringArray()
>> map(vtk_files.InsertNextValue, sorted_files)
>>
>> reader = vtkgdcm.vtkGDCMImageReader()
>> reader.FileLowerLeftOn()
>> reader.SetFileNames(vtk_files)
>> reader.Update()
>>
>> spacing = reader.GetOutput().GetSpacing()
>> change = vtk.vtkImageChangeInformation()
>> change.SetInputConnection(reader.GetOutputPort())
>> change.SetOutputSpacing(spacing[0], spacing[1], zspacing)
>>
>> im = vtk.vtkImageResliceMapper()
>> im.SetInputConnection(change.GetOutputPort())
>> im.SliceFacesCameraOn()
>> im.SliceAtFocalPointOn()
>> im.BorderOff()
>>
>> ip = vtk.vtkImageProperty()
>> ip.SetColorWindow(255)
>> ip.SetColorLevel(128)
>> ip.SetAmbient(0.0)
>> ip.SetDiffuse(1.0)
>> ip.SetOpacity(1.0)
>> ip.SetInterpolationTypeToLinear()
>>
>> ia = vtk.vtkImageSlice()
>> ia.SetMapper(im)
>> ia.SetProperty(ip)
>>
>> renderer = vtk.vtkRenderer()
>> renderer.AddViewProp(ia)
>> renderer.SetBackground(0 , 0, 0)
>> render_window.AddRenderer(renderer)
>>
>> style.SetCurrentRenderer(renderer)
>> style.SetZViewRightVector((1, 0, 0))
>> style.SetZViewUpVector((0, -1, 0))
>>
>> style.SetXViewRightVector((0, 1, 0))
>> style.SetXViewUpVector((0, 0, 1))
>>
>> style.SetYViewRightVector((1, 0, 0))
>> style.SetYViewUpVector((0, 0, 1))
>> style.SetImageOrientation(style.GetZViewRightVector(),
>> style.GetZViewUpVector())
>>
>> # render the image
>> renderer.ResetCamera()
>> renderer.GetActiveCamera().ParallelProjectionOn()
>> renderer.ResetCameraClippingRange()
>> render_window.Render()
>>
>> interactor.Initialize()
>> interactor.Start()
>>
>> the problems arise in this sequence:
>>
>> 1-  initially display the image: ok
>> 2-  slice the image to a different slice with ctrl + mosue left: ok
>> 3-  change the orientation to a different one (sagital or coronal, doesn't
>> matter): this is the problem, orientation of the image is changed fine to
>> the new one but the image is panned to a different position in the render
>> window/renderer, not the center of it and in a different slice (the middle
>> slice of the whole image)
>>
>> how can I avoid this, I mean, keep the image centered in the render
>> window/renderer when the image orientation is changed and in the correct
>> slice location?