get_2d_length

crispy.grid_ridge.get_2d_length(skl3d)

Calculate the sky-projected length of a 3D skeleton.

Computes the length of a skeleton structure when projected onto a 2D plane. The projection is performed by collapsing the third dimension of the input 3D skeleton array.

Parameters:

skl3d (ndarray) – 3D binary array representing the skeletonized structure, where True or 1 indicates skeleton points and False or 0 represents the background.

Returns:

length – The total number of pixels in the projected 2D skeleton.

Return type:

int

Notes

• The function collapses the 3D skeleton along the third axis using a logical OR operation and then applies 2D skeletonization to the resulting binary image.

• This method is useful for evaluating the extent of structures in position-position space regardless of the velocity axis.

Examples

Compute the 2D length of a 3D skeleton:

>>> import numpy as np
>>> from skimage.morphology import skeletonize
>>> from crispy import grid_ridge
>>> skl3d = np.zeros((10, 10, 10), dtype=bool)
>>> skl3d[0, 0, :] = True  # A straight skeleton in 3D
>>> length = grid_ridge.get_2d_length(skl3d)
>>> print(length)
1