lmfx: Individual Tree Detection Algorithm

In Jean-Romain/lidRplugins: Extra functions and algorithms for lidR package

Individual Tree Detection Algorithm

Description

This function is made to be used in find_trees. It implements an experimental algorithms for tree detection based on a several ideas from the litterature. First it select the highest points in each cell of a 1 m grid to reduce the amount of data and considerably improve speed, then it performs a local maximum filter to find tree tops. To finish it applies the filtering rule from multichm (step (b))

Usage

lmfx(ws, hmin = 2, dist_2d = 3)

Arguments

ws	numeric or function. Length or diameter of the moving window used to the detect the local maxima in the unit of the input data (usually meters). If it is numeric a fixed windows size is used. If it is a function, the function determines the size of the window at any given location on the canopy. The function should take the height of a given pixel or points as its only argument and return the desired size of the search window when centered on that pixel/point.
hmin	numeric. Minimum height of a tree. Threshold below which a pixel or a point cannot be a local maxima. Default 2.
dist_2d	numeric. 2D distance threshold. A local maximum is considered a detected tree if there is no detected tree within this 2D distance.

Examples

LASfile <- system.file("extdata", "MixedConifer.laz", package="lidR")
las = readLAS(LASfile)

ttops = find_trees(las, lmfx(ws = 3))

x = plot(las)
add_treetops3d(x, ttops)

Jean-Romain/lidRplugins documentation built on Feb. 8, 2023, 5:39 a.m.