xdem.coreg.CPD

class xdem.coreg.CPD(weight=0, only_translation=False, max_iterations=100, tolerance=0.01, standardize=True, subsample=5000.0)

Coherent Point Drift coregistration, based on Myronenko and Song (2010), https://doi.org/10.1109/TPAMI.2010.46.

Estimate translations and rotations.

The estimated transform is stored in the self.meta[“outputs”][“affine”] key “matrix”, with rotation centered on the coordinates in the key “centroid”. The translation parameters are also stored individually in the keys “shift_x”, “shift_y” and “shift_z” (in georeferenced units for horizontal shifts, and unit of the elevation dataset inputs for the vertical shift).

__init__(weight=0, only_translation=False, max_iterations=100, tolerance=0.01, standardize=True, subsample=5000.0)

Instantiate a CPD coregistration object.

Parameters:

• weight (float) – Weight contribution of the uniform distribution to account for outliers, from 0 (inclusive) to 1 (exclusive).

• only_translation (bool) – Whether to solve only for a translation, otherwise solves for both translation and rotation as default.

• max_iterations (int) – Maximum allowed iterations before stopping.

• tolerance (float) – Residual change threshold after which to stop the iterations.

• standardize (bool) – Whether to standardize input point clouds to the unit sphere for numerical convergence (tolerance is also standardized by the same factor).

• subsample (int | float) – Subsample the input for speed-up. <1 is parsed as a fraction. >1 is a pixel count.

Methods

__init__([weight, only_translation, ...])	Instantiate a CPD coregistration object.
apply(elev[, bias_vars, resample, ...])
centroid()	Get the centroid of the coregistration, if defined.
copy()	Return an identical copy of the class.
fit(reference_elev, to_be_aligned_elev[, ...])	Estimate the coregistration transform on the given DEMs.
fit_and_apply(reference_elev, to_be_aligned_elev)
from_matrix(matrix)	Instantiate a generic Coreg class from a transformation matrix.
from_rotations([x_rot, y_rot, z_rot, ...])	Instantiate a generic Coreg class from a X/Y/Z rotation.
from_translations([x_off, y_off, z_off])	Instantiate a generic Coreg class from a X/Y/Z translation.
info([as_str])
to_matrix()	Convert the transform to a 4x4 transformation matrix.
to_rotations([return_degrees])	Extract X/Y/Z euler rotations (extrinsic convention) from the affine transformation matrix.
to_translations()	Extract X/Y/Z translations from the affine transformation matrix.

Attributes

is_affine	Check if the transform be explained by a 3D affine transform.
is_translation
meta	Metadata dictionary of the coregistration.