Function to change view mode to ZPlane

I am creating a view instance in itkwidgets (i.e. projection_view = itkwidgets.view(geometries=None, background=[0.0, 0.0, 0.0])) and want to be able to, at a later stage, set the view mode to ZPlane.
How do I do this through code? I can do it by clicking on the icon but cannot seem to find the appropriate function.


When trying some things I can see that

TraitError: The 'mode' trait of a Viewer instance expected any of ['x', 'y', 'z', 'v']

but setting projection_view.mode = 'z' has no effect


Is this about ITK or using VTK to render ITK objects?



Apologies @Paulo_Carvalho but I am a bit confused by your question. Maybe a bit more explanation on my part would help.

Basically using this example:

from pyvista import examples
from itkwidgets import view

mesh = examples.download_lidar()
viewer = view(geometries=mesh)

Is there a way to set the view mode to X, Y or Z axis by calling something like viewer.mode = 'z'

Basically I want the axis set when I create the viewer.


I know how to do it in VTK. However, after a bit of googling around, I found that viewer is an object of a class named viewer, but I couldn’t find any on-line docs about it. I’d start by doing some exploratory programming (e.g. do a type(viewer) to look for a method like lookDownXAxis()) or anything along those lines… other than that I can only guess.

take care,


Hi @Kevin_Sweeney! Depending on which version you are currently using there are two ways to do this:

  1. For the main release (v0.x) you can do:
viewer = view(image=...)
viewer.mode = 'z'
  1. For the pre-release (v1.0ax) you can do:
viewer = view(image=...)

For either version you can call view? to get the doc string back with all of the available setters and their expected parameters.

Thanks for the reply @bnmajor

So, I am using the main release.
However it seems this viewer.mode = 'z' only works on image type inputs.

For example, this works:

from urllib.request import urlretrieve
import os
import itk

file_name = '005_32months_T2_RegT1_Reg2Atlas_ManualBrainMask_Stripped.nrrd'
if not os.path.exists(file_name):
    url = ''
    urlretrieve(url, file_name)

image = itk.imread(file_name)
viewer1 = view(image, rotate=True, axes=True, vmin=4000, vmax=17000, gradient_opacity=0.9)

# In a new cell
viewer1.mode = 'z'

But this does not:

import numpy as np

from itkwidgets import view
number_of_points = 3000

gaussian_1_mean = [0.0, 0.0, 0.0]
gaussian_1_cov = [[1.0, 0.0, 0.0], [0.0, 2.0, 0.0], [0.0, 0.0, 0.5]]
point_set_1 = np.random.multivariate_normal(gaussian_1_mean, gaussian_1_cov,

gaussian_2_mean = [4.0, 6.0, 7.0]
gaussian_2_cov = [[2.0, 0.0, 0.0], [0.0, 2.0, 0.0], [0.0, 0.0, 1.5]]
point_set_2 = np.random.multivariate_normal(gaussian_2_mean, gaussian_2_cov,

gaussian_3_mean = [4.0, 0.0, 7.0]
gaussian_3_cov = [[4.0, 0.0, 0.0], [0.0, 1.0, 0.0], [0.0, 0.0, 3.5]]
point_set_3 = np.random.multivariate_normal(gaussian_3_mean, gaussian_3_cov,

viewer2 = view(point_sets=[point_set_1, point_set_2, point_set_3])

# In a new cell
viewer2.mode = 'z'

On investigation it seems that this is the desired result from the code.

in itk-vtk-viewer package → createViewer.jspublicAPI.setViewMode (used by itkwidgets), it specifies to only change the view mode if it is an image. I have overwritten it and it then works for point sets etc. too.
I am unsure as to why it should have been set for images only.