Hurst exponents calculation

Raster operations

all_rasters_to_polygons()

This function transforms all rasters found into a directory into SpatVector and save them to shapefiles.

compute_Hurst_rasters()

Wrapper function around the computation of Hurst coefficients from box-counting and log-log regression

compute_Hurst_rasters_internal()

Compute Hurst rasters from a log-log regression between scales and mean standard deviation

get_mean_res()

Compute the mean resolution of lat long raster in meters

get_mean_sd_rasters()

Compute box-counting mean standard deviation rasters

merge_Hurst_rasters()

merge all Hurst raster

Factoring

get_all_R_L()

Get a list of upper spatial scale at which the roughness coefficient is calculated

get_factors()

Get factor of an integer

2D Fourier analysis of topography

Basic functions

Hann2D()

A two-dimensional Hann window

detrend_dem()

Detrends a DEM with pracma::odregress()

fft2D()

Perfoms a two-dimensional Fourier transform

get_beta()

Derive the slope of the binned power spectrum

pad_mat()

Pads a matrix with zeros so it has a given dimension

Rotating DEMs

bin()

Bins a power spectrum

filter_spectral_power_matrix()

Returns a quantile-filtered raster of the logarithm of the real-part of the normalized spectral power matrix

get_fourier_angle()

Get the angle of the 2D Fourier spectrum

get_normalized_spectral_power_matrix()

Normalizes the spectral power matrix with the background spectrum

rotate_raster()

Rotates the detrended DEM according to the main direction of the Fourier spectrum

Visualizations

matrix_for_rayshader()

Transforms matrix for be used by rayshader.

spectrum_plot()

Plot a radial Fourier spectrum

view_matrix()

Visualizes values of a matrix

Roughness and anisotropy exponents

HHCF()

Internal; derives a one-dimensional height-height correlation function

alpha_plot()

Internal companion function to get_alpha.

filter_alpha()

Filters the alpha values of alpha returned by get_all_alpha() between zero and the 99.9% quantile of the initial alphas

get_all_alpha()

Wrapper to extract all roughness exponents from the HHCFs

get_alpha()

Estimates the roughness exponent from the HHCF from spline fit.

get_hhcf()

This wrapper function derives the one-dimensional HHCF() for all columns or rows of a matrix

get_zeta()

Wrapper function to derive the anisotropy exponent from a non-rotated raster

get_zeta_()

Internal function to derive the anisotropy exponent from two roughness exponents

summarise_alpha()

Wrapper to summarize alpha values