R: Hill shading

hillShade {raster} | R Documentation

## Hill shading

### Description

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, ...)

### Arguments

`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

### Author(s)

Andrew Bevan, Robert J. Hijmans

### References

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

### See Also

`terrain`

### Examples

    ## Not run:
    alt <- getData('alt', country='CHE')
    slope <- terrain(alt, opt='slope')
    aspect <- terrain(alt, opt='aspect')
    hill <- hillShade(slope, aspect, 40, 270)
    plot(hill, col=grey(0:100/100), legend=FALSE, main='Switzerland')
    plot(alt, col=rainbow(25, alpha=0.35), add=TRUE)

    ## End(Not run)

[Package raster version 3.3-7 Index]