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[ENH]: Provide axis('equal') for Axes3D. #22570
Description
Bug summary
In the example below, I wish to observe a unitary 3D cube in its diagonal axis (1, 1, 1).
azimut and elevation angle should be both 45°, normally.
Why do I need to set elevation = 28° ????
Thanks,
Patrick
Code for reproduction
import numpy as np
import matplotlib.pyplot as plt
fig, ax = plt.subplots(1, 3, figsize=(15, 5),
subplot_kw=dict(projection="3d",
proj_type='ortho'))
ax[0].voxels(np.ones((1, 1, 1)), facecolors=[0, 0, 0, 0], edgecolors='k')
ax[0].quiver(0, 0, 0, 1, 1, 1, color='r', linewidth=5)
ax[1].set_title("azim=45°, elev=45°")
ax[1].voxels(np.ones((1, 1, 1)), facecolors=[0, 0, 0, 0], edgecolors='k')
ax[1].view_init(azim=45, elev=45)
ax[1].quiver(0, 0, 0, 1, 1, 1, color='r', linewidth=5)
ax[2].set_title("azim=45°, elev=28°")
ax[2].voxels(np.ones((1, 1, 1)), facecolors=[0, 0, 0, 0], edgecolors='k')
ax[2].view_init(azim=45, elev=28)
ax[2].quiver(0, 0, 0, 1, 1, 1, color='r', linewidth=5)
plt.show()Actual outcome
Expected outcome
view_init(azim=45, elev=45) and not view_init(azim=45, elev=28) to have the expected 3D representation
Additional information
No response
Operating system
Windows
Matplotlib Version
3.4.2
Matplotlib Backend
No response
Python version
Python 3.7.7
Jupyter version
No response
Installation
pip
Activity
oscargus commented on Feb 28, 2022
Ideally, it should be possible to do ax[1].axis('equal') to obtain what you are looking for (see https://matplotlib.org/stable/gallery/subplots_axes_and_figures/axis_equal_demo.html). However, Axes3D does not (yet) support that:
Traceback (most recent call last): Input In [18] in <module> ax[1].axis('equal') File /local/data1/miniconda3/lib/python3.8/site-packages/matplotlib/axes/_base.py:2047 in axis self.set_aspect('equal', adjustable='datalim') File /local/data1/miniconda3/lib/python3.8/site-packages/mpl_toolkits/mplot3d/axes3d.py:311 in set_aspect raise NotImplementedError( NotImplementedError: Axes3D currently only supports the aspect argument 'auto'. You passed in 'equal'.So, basically, there is a different scaling for the z-axis compared to the x- and y-axes. You can see that from the grid blocks being rectangles (rather than squares, as for the bottom surface).
oscargus commented on Feb 28, 2022
You can get a bit closer by using: ax[1].set_box_aspect((4, 4, 4)), but it is still not exact. (Of course, you can probably find a better value for the last number, but that is about as bad as 28 degrees...) Now it at least looks like a cube.
patquem commented on Feb 28, 2022
Hi @oscargus,
Thanks for your reply.
using ax[1].set_box_aspect((1, 1, 1)), the elevation angle is now 35°.
That is the correct elevation angle (atan(1/sqrt(2) ~35°) and not 45° as I have previously written.
Thanks.
jondo commented on Aug 2, 2022
B.t.w., this is a successor of #1077.