hiking.speed: Hiking Speed Function(s)

In f-silva-archaeo/fastmaRching: Fast Marching method for modelling evolving boundaries, competing dispersal processes and cost surfaces

Description

This function outputs the hiking speed in km/hr dependant on slope for a variety of functions (see below).

Usage

hiking.speed(slope, units = "degree", fun = "Tobler", v0 = NA,
  off.path = F, horseback = F, cutoff)

Arguments

slope	Slope values in either degrees, radians or unitless. Can be array, matrix or raster object.
units	(Optional) Either 'degree', 'radian' or 'nounit'. Default is 'degree'.
fun	(Optional) Hiking function. Either 'Tobler', 'Naismith', 'Langmuir1' or 'Langmuir2'. Default is 'Tobler'.
v0	(Optional) Speed at flat surface. If given it will normalise hiking function outputs to the value given.
off.path	(Optional) Boolean for Tobler hiking function. Default is FALSE.
horseback	(Optional) Boolean for Tobler hiking function.Default is FALSE.
cutoff	(Optional) If a value is given any slopes above the cutoff will output speed zero.

References

Sethian, J.A. (1996), A fast marching level set method for monotonically advancing fronts, Proc. Natl. Acad. Sci. 93 (4), 1591-1595.

Tobler, Waldo (1993), Three presentations on geographical analysis and modeling: Non-isotropic geographic modeling speculations on the geometry of geography global spatial analysis, Technical report. National center for geographic information and analysis 93 (1).

Naismith, W. W. (1892), Excursions: Cruach Ardran, Stobinian, and Ben More, Scottish Mountaineering Club Journal 2 (3): 136.

Langmuir, Eric (1984), Mountaincraft and Leadership: Official Handbook of the Mountain Leader Training Boards of Great Britain and Northern Ireland. Edinburgh Scotland: Britain & Scottish Sports Council. (Langmuir1)

Langmuir, Eric (2013). Mountaincraft and Leadership: A Handbook for Mountaineers and Hillwalking Leaders in the British Isles (Fourth ed.). Mountain Training England; Mountain Training Scotland.

Examples

hiking.speed(20, fun='Tobler')
hiking.speed(20, fun='Tobler', horseback=TRUE)
hiking.speed(-10, fun='Langmuir1')
plot(seq(-20,20,1), hiking.speed(seq(-20,20,1), fun='Langmuir1'))

dem <- raster::raster(system.file("external/test.grd", package="raster"))
slope <- raster::terrain(dem)
speed1 <- hiking.speed(slope)
speed2 <- hiking.speed(slope, fun='Naismith')

f-silva-archaeo/fastmaRching documentation built on Sept. 6, 2019, 9:13 p.m.