tpi {spatialEco}

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 terra SpatRaster 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

A terra SpatRaster object of tpi A terra SpatRaster object

Author(s)

Jeffrey S. Evans <[e-mail]>

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(terra)
elev <- rast(system.file("extdata/elev.tif", package="spatialEco"))

# calculate tpi and plot 
  tpi7 <- tpi(elev, scale=7) 
  tpi025 <- tpi(elev, win = "circle", scale=2500)
  tpi025.zc <- tpi(elev, win = "circle", scale=2500, 
                   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=2500m")
   plot(tpi025, main="tpi Circular window d=2500m, zero correct")
par(opar)