Trik2 {SurfRough} | R Documentation |
It is essentially a roughness radial index. TRIk2 modifies TRI (topographic ruggedness index) using increments of order 2, symmetrical to central pixel, so as to remove the effect of local slope. This version does not correct for diagonal distance. 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).
Trik2(x)
x |
The DEM from which to compute the index |
isotropic roughness (in the same units of input)
Riley, S. J., S. D. DeGloria, and R. Elliott. 1999. A terrain ruggedness index that quantifies topographic heterogeneity. Intermountain Journal of Science 5:23.
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.
Trevisani S., Teza G., Guth P.L., 2023 (Preprint). Hacking the topographic ruggedness index. 10.5281/zenodo.7716785
dem=rast(paste(system.file("extdata", package = "SurfRough"), "/trento1.tif",sep=""))
w <- matrix(1, nrow=5, ncol=5)
roughTrik5x5=focal(dem, w=w, fun=Trik2)
plot(roughTrik5x5)