align_to_axis

align_to_axis(coordinates, weights=None, axis=2, flip=False, eigenvector_index=0)

Calculate a rotation matrix that aligns the principal axis of a point cloud with a specified coordinate axis.

Parameters:

coordinatesNDArray

Array of 3D coordinates with shape (n, 3) representing the point cloud.

weightsNDArray

Coordinate weighting factors with shape (n,).

axisint, optional

The target axis to align with, defaults to 2 (z-axis).

flipbool, optional

Whether to align with the negative direction of the axis, default is False.

eigenvector_indexint, optional

Index of eigenvector to select, sorted by descending eigenvalues. 0 = largest eigenvalue (most variance), 1 = second largest, etc. Default is 0 (primary principal component).

Returns:

NDArray

3x3 rotation matrix that aligns the principal component of the coordinates with the specified axis.