[vtkusers] vtkImageActor erases other actors?

[David Gobbi]

Hi Andreas,

Thanks for sending the code along with your question.  The method you want
is AddViewProp(), but it's just a new name for AddActor() and it actually
has the same behavior.

For the image actor, you probably want code like the following.
  vtk_image = vtk.vtkImageData()
   vtk_image.SetDimensions(720, 1280, 1)
   vtk_image.SetSpacing(1.0, 1.0, 1.0)
   vtk_image.SetOrigin(-(720 - 1)/2.0, -(1280 - 1)/2.0, 0.0)

The "Spacing" is the size of each pixel, and the "Origin" is the position
of the first pixel in the image (in this case, I set it so that the center
of the image will be at (0,0,0), I'm not sure if this is what you want but
it is a good place to start).

After creating the image data, it is a good idea to add an assert to ensure
the array is the correct size:
  assert vtk_image.GetNumberOfPoints() == vtk_array.GetNumberOfTuples()

For the following code, I'm not sure what you are trying to do, but the
effect will be to vertically squash the frame so that it is square:
  plane_actor.SetScale(1, 0.5625, 1)

I hope this helps,
  David

On Sun, Nov 18, 2018 at 4:43 AM Andreas Pedroni <anpedroni at gmail.com> wrote:

> Dear list
>
> I would like to display a 3D object in front of a vtkImageActor (using
> Python 3.6 and vtk on Mac OS, see code below). However, the vtkImageActor
> erases the 3D object. I read in the manual that one should use AddProp()
> with the renderer to add a vtkImageActor to a render scene. But there is no
> AddProp() method for the renderer class. I’d be very thankful for any
> suggestions.
>
> Best
> Andreas
>
>
> import vtk
> import cv2
> from vtk.util import numpy_support
>
> IMAGEPATH = ‚/models3d/'
> VIDEOPATH = "20180816-133303.mp4“
>
> def main():
>    cap = cv2.VideoCapture(VIDEOPATH)
>    success, frame = cap.read()
>
>    frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
>    vtk_array = numpy_support.numpy_to_vtk(frame.reshape((-1, 3),
> order='F'), deep=False)
>
>    # Create a vtkImage Object. This is filled with the vtkArray data later
>    vtk_image = vtk.vtkImageData()
>    vtk_image.SetDimensions(720, 1280, 1)
>    vtk_image.SetSpacing(720, 1280, 1)
>    vtk_image.SetOrigin(720, 1280, 0)
>    vtk_image.GetPointData().SetScalars(vtk_array)
>    # create the Texture for a plane
>
>    # The Screen where the movie is mapped onto
>    plane = vtk.vtkPlaneSource()
>
>    plane_mapper = vtk.vtkPolyDataMapper()
>    plane_mapper.SetInputConnection(plane.GetOutputPort())
>
>    plane_actor = vtk.vtkImageActor()
>    plane_actor.SetInputData(vtk_image)
>    plane_actor.SetScale(1, 0.5625, 1)
>    plane_actor.SetOrientation(180, 180, 90)
>
>    # add the spine object
>    obj_importer = vtk.vtkOBJReader()
>    obj_importer.SetFileName(IMAGEPATH + 'Spine.obj')
>    obj_importer.Update()
>
>    spine_mapper = vtk.vtkPolyDataMapper()
>    spine_mapper.SetInputConnection(obj_importer.GetOutputPort())
>
>    spine_actor = vtk.vtkActor()
>    spine_actor.SetMapper(spine_mapper)
>    spine_actor.SetOrientation(90, 10, 90)
>    spine_actor.SetScale(0.3, 0.3, 0.3)
>
>    # set up the renderer and the window
>    ren = vtk.vtkRenderer()
>    ren_win = vtk.vtkRenderWindow()
>    ren_win.AddRenderer(ren)
>    ren_win.SetSize(1500, 1500)
>
>    ren.AddActor(spine_actor)
>    ren.AddActor(plane_actor)
>
>    ren.SetBackground(0, 0, 0.1)
>
>    iren = vtk.vtkRenderWindowInteractor()
>    iren.SetRenderWindow(ren_win)
>
>    # Initialize must be called prior to creating timer events.
>    iren.Initialize()
>
>    # start the interaction and timer
>    iren.Start()
>
> if __name__ == '__main__':
>    main()
>
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