Module terrain_processing 

Terrain processing and analysis algorithms.

This module provides a comprehensive suite of Digital Elevation Model (DEM) analysis tools, including:

• Slope and aspect computation (Horn’s method)
• Curvature analysis: profile, planform, and tangential curvature
• Flow direction algorithms: D8 and D-infinity (Tarboton 1997)
• Flow accumulation and watershed delineation
• Stream network extraction
• Terrain Roughness Index (TRI — Riley et al. 1999)
• Terrain Position Index (TPI — Weiss 2001)
• Topographic Wetness Index (TWI — Beven & Kirkby 1979)
• Viewshed analysis (line-of-sight)
• Slope stability index (infinite slope model)
• Solar irradiance on terrain (incidence angle, terrain shading)

Structs

Contour

A single contour polyline at a given elevation.

Dem

A regular-grid Digital Elevation Model.

Observer

Observer specification for viewshed analysis.

SlopeStabilityParams

Parameters for the infinite-slope stability model.

SolarPosition

Solar position in the sky.

Enums

CurvatureKind

Curvature type selector.

LandformClass

Landform classification based on TPI and slope.

RidgeValley

Classify each cell as ridge, valley, or neither.

Constants

D8_OFFSETS

Neighbour offsets and D8 codes for the eight cardinal/diagonal directions.

Functions

classify_landform

Classify landform type using a dual-scale TPI approach (Weiss 2001).

compute_aspect

Terrain aspect in radians at every grid cell.

compute_curvature

Compute terrain curvature (units: 1/m) for every grid cell.

compute_slope

Terrain slope in radians at every grid cell.

compute_viewshed

Compute binary viewshed for a single observer.

cos_incidence

Compute the cosine of incidence angle between the sun and the terrain surface.

cumulative_viewshed

Cumulative viewshed: number of observers that can see each cell.

delineate_watershed

Delineate the watershed (contributing area) upstream of an outlet cell.

extract_contours

Extract contour lines at the specified elevation levels.

extract_streams

Extract stream network by thresholding flow accumulation.

fill_sinks

Fill sinks in a DEM using a simple iterative raising algorithm.

flow_accumulation_d8

Compute D8 flow accumulation (number of upstream cells draining into each cell).

flow_direction_d8

Compute D8 flow direction for every grid cell.

flow_direction_dinf

D-infinity flow direction (Tarboton 1997).

hypsometric_curve

Compute the hypsometric curve for a DEM.

hypsometric_integral

Hypsometric integral — area under the hypsometric curve.

normalise_raster

Normalise a raster to the range [0, 1].

raster_stats

Compute basic statistics of a raster field.

resample_dem

Resample a DEM to a coarser grid using bilinear interpolation.

ridge_valley_lines

Simple ridge and valley detection based on profile curvature sign.

slope_stability_index

Compute the Factor of Safety (FS) for every grid cell.

strahler_order

Strahler stream order for every stream cell.

terrain_position_index

Terrain Position Index (Weiss 2001).

terrain_roughness_index

Terrain Roughness Index (Riley et al. 1999).

terrain_solar_irradiance

Compute global horizontal irradiance (GHI) on every terrain cell.

topographic_wetness_index

Topographic Wetness Index (Beven & Kirkby 1979).

Type Aliases

D8Code

D8 flow direction codes.