xdem.DEM.texture_shading

xdem.DEM.texture_shading#

DEM.texture_shading(alpha=0.8, mp_config=None)[source]#

Generate a texture shaded relief map using fractional Laplacian operator.

This technique, developed by Leland Brown, applies a fractional Laplacian operator in the frequency domain to enhance terrain texture and fine-scale topographic features. It’s particularly effective for visualizing subtle terrain variations that may not be apparent in traditional hillshading.

The fractional Laplacian operator is controlled by the alpha parameter: - alpha = 0: Preserves all frequencies with mean removed (~zero-centered DEM) - alpha = 1: Standard Laplacian operator (edge detection) - alpha = 2: Enhanced high-frequency features

Based on: Brown, L. (2010). Texture Shading: A New Technique for Depicting Terrain Relief. Workshop on Mountain Cartography, Banff, Canada.

Also described in: Allmendinger and Karabinos (2023), https://doi.org/10.1130/GES02531.1

Adapted from the Python implementation at fasiha/texshade-py

Parameters:

  • alpha (float) – Fractional exponent for Laplacian operator (0-2, default 0.8). Higher values enhance fine details, lower values provide smoother results.

  • mp_config (MultiprocConfig | None) – Multiprocessing configuration, run the function in multiprocessing if not None

Raises:

ValueError – If alpha is not between 0 and 2

Return type:

TypeVar(RasterType, bound= Raster)