Hill shading

Compute hill shade from slope and aspect layers (both in radians). Slope and aspect can be computed with function terrain.

A hill shade layer is often used as a backdrop on top of which another, semi-transparent, layer is drawn.

Usage

hillShade(slope, aspect, angle=45, direction=0, filename='', normalize=FALSE, ...)

slope: RasterLayer object with slope values (in radians)
aspect: RasterLayer object with aspect values (in radians)
angle: The the elevation angle of the light source (sun), in degrees
direction: The direction (azimuth) angle of the light source (sun), in degrees
filename: Character. Optional filename
normalize: Logical. If TRUE, values below zero are set to zero and the results are multiplied with 255
...: Standard additional arguments for writing RasterLayer files

Andrew Bevan, Robert J. Hijmans

Horn, B.K.P., 1981. Hill shading and the reflectance map. Proceedings of the IEEE 69(1):14-47