Spectral analysis and valley spacing

Figures from lsdtt-spectral-analysis: the 2D and radial spectra of a tile, significant frequencies on a polar plot, and valley spacing.

Function	Module	What it draws
plot_valley_spectrum, plot_spacing_vs_ci, plot_landscape_panel	charts.valley_spacing	Valley spacing from lsdtt-spectral-analysis (_valley_spacing.csv, _valley_spacing_spectrum.csv): one landscape's spectrum with both spacing measures, spacing vs channelization index across a sweep, and a side-by-side hillshade panel.
plot_significant_frequencies_polar	charts.spectral	Significant 2D spectrum cells from lsdtt-spectral-analysis (_significant_frequencies_2d.csv, or the legacy _significant_freq.csv) on a North-up polar axis: bearing (wave vector, or crest with orientation="crest") against frequency, rings labelled in wavelength, coloured by normalised PSD. A run with nothing significant draws empty axes with a note.
plot_spectral_tile_summary, plot_normalised_spectrum_2d, plot_radial_spectrum	charts.spectral	One lsdtt-spectral-analysis run on a 2 × 2 figure: the input raster (found from _ingested_params.param), the normalised 2D spectrum north-up with significant cells outlined, the binned radial spectrum with background, normalised PSD and rollover, and the polar plot. The two spectrum panels are also available on their own. Load the run with io.spectral.load_spectral_analysis; panels whose outputs were switched off show a note.