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.
hillShade(slope, aspect, angle=45, direction=0, filename='', normalize=FALSE, ...)
RasterLayer object with slope values (in radians)
RasterLayer object with aspect values (in radians)
The the elevation angle of the light source (sun), in degrees
The direction (azimuth) angle of the light source (sun), in degrees
Character. Optional filename
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
terrain