TRI: Compute a terrain ruggedness index following sappington et al...
In cyrilmi/myfunctions: Rpackage cyril

Description Usage Arguments Details Author(s) Examples

it returns a raster layer with the sum of the absolute values of the elevation differences between a central grid cell and its 8 neighboring cells

1	Terrain <- TRI(r1= veg_mask,gri=3,na.rm=TRUE)

`r1`	is the raster layer to compute TRI from
`gri`	is the resolution of the grid in which TRI should be calculated. grid=3 (default) will look like this :
`na.rm`	whether NA cells should be computed or not.

1,1,1, 1,0,1, 1.1,1 where 0 is the focal cell where the index is calculated and 1 the cells used to calculated the relative index

Cyril Milleret

 
 library(raster)
 r1 <- raster(nrows=5, ncols=5, xmn=0, xmx=10)
 r1
 values(r1) <- c(1:25)
 hey <- TRI(r1, gri=3, na.rm=TRUE)
 image(hey)
 matrix(values(r1), ncol=4, byrow=T)
 values(hey)