spatialEco (version 0.1-5)

tpi: Topographic Position Index (tpi)

Description

Calculates topographic position using mean deviations

Usage

tpi(x, scale = 3, win = "rectangle", normalize = FALSE)

Arguments

x

raster class object

scale

scale (window size)

win

window type. Options are "rectangle" and "circle"

normalize

Apply deviation correction that normalizes to local surface roughness

Value

raster class object of tpi

References

De Reu, J., J. Bourgeois, M. Bats, A. Zwertvaegher, V. Gelorini, et al., (2014) Application of the topographic position index to heterogeneous landscapes. Geomorphology, 186:39-49.

Examples

 library(raster)
 r <- raster(nrows=500, ncols=500, xmn=571823, xmx=616763, 
             ymn=4423540, ymx=4453690)
 proj4string(r) <- crs("+proj=utm +zone=12 +datum=NAD83 +units=m +no_defs")
 r[] <- runif(ncell(r), 1000, 2500)
 r <- focal(r, focalWeight(r, 150, "Gauss") )

# calculate tpi and plot 
  tpi9 <- tpi(r, scale=9)     
    par(mfrow=c(1,2))
      plot(r, main="original raster")
      plot(tpi9, main="tpi 9x9")