Cropping a cropped PCD returns empty

[MartinPedersenpp]

Checklist

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

Describe the issue

I am trying to extract a cropped part of my point cloud, which is already cropped from a much larger point cloud.
When I perform the second crop using:
crop = point_cloud.crop(bbox)
it returns an empty point cloud, even though the object is clearly inside the bbox.
This might be an error on my end, but I assume it is a bug in some way?

Original cropped point cloud:

Point cloud with the bbox to be cropped, clearly some points are inside:

Result of cropping the cropped point cloud, nothing:

Any help is much appreciated.

Steps to reproduce the bug

Running this on a point cloud returned from another crop:

crop_bounding_box = o3d.geometry.AxisAlignedBoundingBox(min_bound=min_bound_bbox, max_bound=max_bound_bbox)
crop_bounding_box.color = [255,255,0]
o3d.visualization.draw_geometries([point_cloud, crop_bounding_box])
cropped_pcd = point_cloud.crop(crop_bounding_box)
o3d.visualization.draw_geometries([cropped_pcd])

Error message

No response

Expected behavior

The object within the bbox appears in the cropped point cloud

Open3D, Python and System information

- Operating system: Windows 10 64-bit
- Python version: 3.8.1 (tags/v3.8.1:1b293b6, Dec 18 2019, 23:11:46) [MSC v.1916 64 bit (AMD64)]
- Open3D version: 0.15.1
- System architecture: x86
- Is this a remote workstation?: no
- How did you install Open3D?: pip

Additional information

No response

[MartinPedersenpp]

I fixed it, but it might still be a bug.
I switched the min/max bounds of the bbox and this resulted in the cropped point cloud containing the object.
So I guess that if the bounding box is created in inverse it will not give the correct output?
Feel free to close this when you see this.

Best regards
Martin

[marco-paladini]

should o3d.geometry.AxisAlignedBoundingBox raise exception if min point > max point?

[MartinPedersenpp]

Either the bounding box or pointcloud.crop should probably return something if min point > max point which could result in the crop not returning anything.
An alternative could be to let crop accept a list of two points and then let it take the min and max for the two points.

[yuecideng]

We will consider these suggestions in tensor based bounding box. Many thanks.