lidR: rumple_index – R documentation

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rumple_index

Rumple index of roughness

Description

Computes the roughness of a surface as the ratio between its area and its projected area on the ground. If the input is a gridded object (raster) the function computes the surfaces using Jenness's algorithm (see references). If the input is a point cloud the function uses a Delaunay triangulation of the points and computes the area of each triangle.

Usage

rumple_index(x, y = NULL, z = NULL, ...)

Arguments

`x`	A 'RasterLayer' or a vector of x point coordinates.
`y`	numeric. If `x` is a vector of coordinates: the associated y coordinates.
`z`	numeric. If `x` is a vector of coordinates: the associated z coordinates.
`...`	unused

Value

numeric. The computed Rumple index.

References

Jenness, J. S. (2004). Calculating landscape surface area from digital elevation models. Wildlife Society Bulletin, 32(3), 829–839.

Examples

x <- runif(20, 0, 100)
y <- runif(20, 0, 100)

# Perfectly flat surface, rumple_index = 1
z <- rep(10, 20)
rumple_index(x, y, z)

# Rough surface, rumple_index > 1
z <- runif(20, 0, 10)
rumple_index(x, y, z)

# Rougher surface, rumple_index increases
z <- runif(20, 0, 50)
rumple_index(x, y, z)

# Measure of roughness is scale-dependent
rumple_index(x, y, z)
rumple_index(x/10, y/10, z)

# Use with a canopy height model
LASfile <- system.file("extdata", "Megaplot.laz", package="lidR")
las <- readLAS(LASfile)
chm <- grid_canopy(las, 2, p2r())
rumple_index(chm)

lidR

Airborne LiDAR Data Manipulation and Visualization for Forestry Applications

v3.1.2

GPL-3

Authors

Jean-Romain Roussel [aut, cre, cph], David Auty [aut, ctb] (Reviews the documentation), Florian De Boissieu [ctb] (Fixed bugs and improved catalog features), Andrew Sánchez Meador [ctb] (Implemented wing2015() for segment_snags()), Bourdon Jean-François [ctb] (Contributed to Roussel2020() for track_sensor()), Gatziolis Demetrios [ctb] (Implemented Gatziolis2019() for track_sensor())

Initial release

2021-03-11