xcorduroy

Slope, aspect and hillshade from digital elevation models, as an Xarray accessor.

xcorduroy is deliberately small: numpy, xarray, dask and xproj, nothing else. Gradients use the Horn (1981) 3x3 kernel; aspect and hillshade follow the ESRI/GDAL conventions (not numerically cross-checked against gdaldem). Chunked arrays are handled with a dask halo, so the result is identical whether the DEM is lazy or in memory.

Experimental

APIs may change without notice.

Installation

uv add xcorduroy
# or
pip install xcorduroy

Quick look

import xarray as xr
import xproj    # registers the .proj accessor
import xcorduroy  # registers the .dem accessor

ds = xr.open_dataset("DEM.zarr", engine="zarr", chunks="auto")
ds = ds.proj.assign_crs(spatial_ref="EPSG:4326")

hillshade = ds["dem"].dem.hillshade()
slope = ds["dem"].dem.slope()
aspect = ds["dem"].dem.aspect()

See Usage for the full worked example, and the API Reference for conventions and signatures.

Scope

The methods are inspired by xdem and xarray-spatial. If you need well-validated functions for scientific analysis, use one of those. This is a limited-scope, lightweight take on a few of the methods, not a replacement.

What's in the name

Corduroy is the textured snow surface left by groomers, regular peaks and valleys.