Topographic Position Index (tpi)
Calculates topographic position using mean deviations
tpi(x, scale = 3, win = "rectangle", normalize = FALSE, zero.correct = FALSE)
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 |
raster class object of tpi metric
Jeffrey S. Evans <jeffrey_evans@tnc.org>
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.
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)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.