VoxelGrid connot create from Octree, vice versa.

[identxxy]

trafficstars

Checklist

• [X] I have searched for similar issues.
• [X] For Python issues, I have tested with the latest development wheel.
• [X] I have checked the release documentation and the latest documentation (for master branch).

Describe the issue

I use Python API.

Octree cannot to_voxel_grid. VoxelGrid cannot create_from_octree Both return a VoxelGrid with only 1 voxels.

Steps to reproduce the bug

import open3d as o3d
import numpy as np

eagle = o3d.data.EaglePointCloud()
pcd = o3d.io.read_point_cloud(eagle.path)
print(pcd)

octree = o3d.geometry.Octree(max_depth=10)
octree.convert_from_point_cloud(pcd)
print(octree)

voxel_from = o3d.geometry.VoxelGrid()
voxel_from.create_from_octree(octree)
voxel_to = octree.to_voxel_grid()
print(voxel_to)
print(voxel_from)

Error message

Outputs: PointCloud with 796825 points. Octree with origin: [-2.93248, -1.54948, -2.94431], size: 8.7113, max_depth: 10 VoxelGrid with 1 voxels. VoxelGrid with 1 voxels.

Expected behavior

VoxelGrid should not be only 1 voxels.

Open3D, Python and System information

- Operating system: Windows 11 64-bit
- Python version: 3.8.8 (default, Apr 13 2021, 15:08:03) [MSC v.1916 64 bit (AMD64)]
- Open3D version: 0.15.2+3e8cfb6
- System architecture: x86 
- Is this a remote workstation?: no
- How did you install Open3D?: pip (latest dev wheel file)

Additional information

No response

[Sentient07]

Hello, I'm also facing the same issue. Does anyone have a solution?

[zichunxx]

Same issue, there is nothing displayed in the window after octree.to_voxel_grid().

This bug still seems to be unresolved？

[KatherineJames]

Same issue - using open3d from a pip installation of open3d-0.17.0-cp38-cp38-manylinux_2_27_x86_64.whl on an Ubuntu 20.04 machine. @identxxy, @Sentient07 and @QUIlToT - did any of you find a solution?

[ziyangyeh]

Same issue.