spatialEco (version 1.3-2)

tpi: Topographic Position Index (tpi)

Description

Calculates topographic position using mean deviations

Usage

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

Arguments

x

A raster class object

scale

focal window size (n-cell x n-cell for rectangle or distance for circle)

win

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

normalize

Apply deviation correction that normalizes to local surface roughness

zero.correct

Apply correction for zero values in matrix weights

Value

raster class object of tpi metric

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

# NOT RUN {
 library(raster)
 data(elev)

# calculate tpi and plot 
  tpi7 <- tpi(elev, scale=7) 
  tpi025 <- tpi(elev, win = "circle", scale=0.025)
  tpi025.zc <- tpi(elev, win = "circle", scale=0.025, 
                   zero.correct = TRUE)

opar <- par(no.readonly=TRUE)
    par(mfrow=c(2,2))
      plot(elev, main="original raster")
      plot(tpi7, main="tpi 7x7")
      plot(tpi025, main="tpi Circular window d=0.025")
   plot(tpi025, main="tpi Circular window d=0.025, zero correct")
par(opar)
# }
# NOT RUN {
# }