xdem.coreg.TerrainBias#

class xdem.coreg.TerrainBias(terrain_attribute='maximum_curvature', fit_or_bin='bin', fit_func='norder_polynomial', fit_optimizer=<function curve_fit>, bin_sizes=100, bin_statistic=<function nanmedian>, bin_apply_method='linear')[source]#

Correct a bias according to terrain, such as elevation or curvature.

With elevation: often useful for nadir image DEM correction, where the focal length is slightly miscalculated. With curvature: often useful for a difference of DEMs with different effective resolution.

DISCLAIMER: An elevation correction may introduce error when correcting non-photogrammetric biases, as generally elevation biases are interlinked with curvature biases. See Gardelle et al. (2012) (Figure 2), http://dx.doi.org/10.3189/2012jog11j175, for curvature-related biases.

__init__(terrain_attribute='maximum_curvature', fit_or_bin='bin', fit_func='norder_polynomial', fit_optimizer=<function curve_fit>, bin_sizes=100, bin_statistic=<function nanmedian>, bin_apply_method='linear')[source]#

Instantiate a terrain bias correction.

Parameters

  • terrain_attribute (str) – Terrain attribute to use for correction.

  • fit_or_bin (Union[Literal['bin_and_fit'], Literal['fit'], Literal['bin']]) – Whether to fit or bin. Use “fit” to correct by optimizing a function or “bin” to correct with a statistic of central tendency in defined bins.

  • fit_func (Union[Callable[..., ndarray[Any, dtype[floating[Any]]]], Literal['norder_polynomial'], Literal['nfreq_sumsin']]) – Function to fit to the bias with variables later passed in .fit().

  • fit_optimizer (Callable[..., tuple[ndarray[Any, dtype[floating[Any]]], Any]]) – Optimizer to minimize the function.

  • bin_sizes (int | dict[str, Union[int, Iterable[float]]]) – Size (if integer) or edges (if iterable) for binning variables later passed in .fit().

  • bin_statistic (Callable[[ndarray[Any, dtype[floating[Any]]]], floating[Any]]) – Statistic of central tendency (e.g., mean) to apply during the binning.

  • bin_apply_method (Union[Literal['linear'], Literal['per_bin']]) – Method to correct with the binned statistics, either “linear” to interpolate linearly between bins, or “per_bin” to apply the statistic for each bin.

Methods

__init__([terrain_attribute, fit_or_bin, ...])

Instantiate a terrain bias correction.

apply(dem[, bias_vars, transform, crs, resample])

Apply the estimated transform to a DEM.

apply_pts(coords)

Apply the estimated transform to a set of 3D points.

copy()

Return an identical copy of the class.

error(reference_dem, dem_to_be_aligned[, ...])

Calculate the error of a coregistration approach.

fit(reference_dem, dem_to_be_aligned[, ...])

Estimate the coregistration transform on the given DEMs.

fit_pts(reference_dem, dem_to_be_aligned[, ...])

Estimate the coregistration transform between a DEM and a reference point elevation data.

residuals(reference_dem, dem_to_be_aligned)

Calculate the residual offsets (the difference) between two DEMs after applying the transformation.