`skimage.morphology.footprints:ball`

source: /dev/scikit-image/src/skimage/morphology/footprints.py :820

Signature

   def     ball (    radius    ,    dtype    =  <class 'numpy.uint8'>   ,  * ,     strict_radius    =  True   ,    decomposition    =  None     )

Summary

Generates a ball-shaped footprint.

Extended Summary

This is the 3D equivalent of a disk. A pixel is within the neighborhood if the Euclidean distance between it and the origin is no greater than radius.

Parameters

radius : float: The radius of the ball-shaped footprint.

Returns

footprint : ndarray or tuple: The footprint where elements of the neighborhood are 1 and 0 otherwise.

Other Parameters

dtype : dtype-like, optional: The data type of the footprint.
strict_radius : bool, optional: If False, extend the radius by 0.5. This allows the circle to expand further within a cube that remains of size 2 * radius + 1 along each axis. This parameter is ignored if decomposition is not None.
decomposition : {None, 'sequence'}, optional: If None, a single array is returned. For 'sequence', a tuple of smaller footprints is returned. Applying this series of smaller footprints will given a result equivalent to a single, larger footprint, but with better computational performance. For ball footprints, the sequence decomposition is not exactly equivalent to decomposition=None. See Notes for more details.

Notes

The disk produced by the decomposition='sequence' mode is not identical to that with decomposition=None. Here we extend the approach taken in ^[1] for disks to the 3D case, using 3-dimensional extensions of the "square", "diamond" and "t-shaped" elements from that publication. All of these elementary elements have size (3,) * ndim. We numerically computed the number of repetitions of each element that gives the closest match to the ball computed with kwargs strict_radius=False, decomposition=None.

Empirically, the equivalent composite footprint to the sequence decomposition approaches a rhombicuboctahedron (26-faces ^[2]).

Aliases

skimage.morphology.ball