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Topographic hillshading

Source: R/hillshading.R
hill_shade.Rd

Computes the hypothetical illumination of a surface by setting the position of the sun and calculating the illumination values for each grid cell of a DEM. The hill_shade function is based upon the vectorial algebra algorithms developed by Corripio (2003) . This function has been optimized and updated to take advantage of the infrastructure provided by the terra package.

Usage

hill_shade(dem, SZA, SAA)

Arguments

dem

SpatRaster. Digital elevation model representing terrain elevation on a regular grid.

SZA

SpatRaster or numeric. Solar zenith angle in degrees.

SAA

SpatRaster or numeric. Solar azimuth angle in degrees.

Value

Returns a hillshade map in SpatRaster format.

References

Corripio JG (2003). “Vectorial algebra algorithms for calculating terrain parameters from DEMs and solar radiation modelling in mountainous terrain.” International Journal of Geographical Information Science, 17(1), 1–23. doi:10.1080/713811744 .

See also

normal_vector(), sun_vector()

Examples

library(terra)
dem <- system.file("extdata/athabasca_dem.tif", package = "SatRbedo")
dem <- terra::rast(dem)
SZA <- 49
SAA <- 165
hs <- hill_shade(dem, SZA, SAA)
plot(hs, col = grey(1:100 / 100))