[vtkusers] image moved afer an orientation change

[José M. Rodriguez Bacallao]

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?
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