Trik2.SpatRaster: Improved TRI (with differences of order 2), reducing/removing...

In SurfRough: Calculate Surface/Image Texture Indexes

Improved TRI (with differences of order 2), reducing/removing slope dependence.

Description

It is essentially a radial roughness index. TRIk2 modifies TRI (topographic ruggedness index) using increments of order 2, symmetrical to central pixel, so as to reduce/remove the effect of local slope. This version does not correct for diagonal distance and therefore is mainly for testing/simulation purposes, so in practice the Radial Roughness Index calculated by the RRI function should be used instead. It uses a 5x5 kernel, consequently 12 directional differences of order k (2) are used in the estimation. One could also use a 3x3 kernel using only the 4 differences centered on the central pixel but the metric would be very noisy. The input is the DEM (no need to detrend).

Usage

## S3 method for class 'SpatRaster'
Trik2(x)

Arguments

x	A DEM as a SpatRaster or a vector of numeric values from a focal window in a DEM from which to compute the index

Value

isotropic roughness (in the same units of input)

References

1. Riley, S. J., S. D. DeGloria, and R. Elliott. 1999. A terrain ruggedness index that quantifies topographic heterogeneity. Intermountain Journal of Science 5:23.

2. Wilson, M.F.J., O'Connell, B., Brown, C., Guinan, J.C. & Grehan, A.J. 2007. Multiscale terrain analysis of multibeam bathymetry data for habitat mapping on the continental slope". Marine Geodesy, vol. 30, no. 1-2, pp. 3-35.

3. Trevisani S., Teza G., Guth P.L., 2023. Hacking the topographic ruggedness index. Geomorphology https://doi.org/10.1016/j.geomorph.2023.108838

Examples

library(terra)
dem=rast(paste(system.file("extdata", package = "SurfRough"), "/trento1.tif",sep=""))
roughTrik5x5=Trik2(dem)
plot(roughTrik5x5)

SurfRough documentation built on April 4, 2025, 2:19 a.m.