CubicSymmetry

Targets:

volume

mask3d

keypoints

Image Types:uint8, float32

Applies a random cubic symmetry transformation to a 3D volume.

This transform is a 3D extension of D4. While D4 handles the 8 symmetries of a square (4 rotations x 2 reflections), CubicSymmetry handles all 48 symmetries of a cube. Like D4, this transform does not create any interpolation artifacts as it only remaps voxels from one position to another without any interpolation.

The 48 transformations consist of:

24 rotations (orientation-preserving):
- 4 rotations around each face diagonal (6 face diagonals x 4 rotations = 24)
24 rotoreflections (orientation-reversing):
- Reflection through a plane followed by any of the 24 rotations

For a cube, these transformations preserve:

All face centers (6)
All vertex positions (8)
All edge centers (12)

works with 3D volumes and masks of the shape (D, H, W) or (D, H, W, C)

Arguments

p

float

Probability of applying the transform. Default: 1.0

Examples

>>> import numpy as np
>>> import albumentations as A
>>> volume = np.random.randint(0, 256, (10, 100, 100), dtype=np.uint8)  # (D, H, W)
>>> mask3d = np.random.randint(0, 2, (10, 100, 100), dtype=np.uint8)    # (D, H, W)
>>> transform = A.CubicSymmetry(p=1.0)
>>> transformed = transform(volume=volume, mask3d=mask3d)
>>> transformed_volume = transformed["volume"]
>>> transformed_mask3d = transformed["mask3d"]

Notes

This transform is particularly useful for data augmentation in 3D medical imaging, crystallography, and voxel-based 3D modeling where the object's orientation is arbitrary.
All transformations preserve the object's chirality (handedness) when using pure rotations (indices 0-23) and invert it when using rotoreflections (indices 24-47).