R: Local Maximum Filter

find_localmaxima {lidR} | R Documentation

## Local Maximum Filter

### Description

Generic local maximum filter. For individual tree detection use find_trees with the lmf algorithm that is more adequate for ITD. This function is a more generic method for multiple purposes other than tree segmentation. This function is natively parallelized with OpenMP.

### Usage

    find_localmaxima(las, w, filter = NULL)

### Arguments

`las` | An object of class LAS
`w` | numeric. Window shape. 1 number for the diameter of a disc, 2 numbers for a rectangle (width, height), 3 numbers for an oriented rectangle (width, height, angle). The angle must be in radians.
`filter` | formula. Memory efficient way to work only with a subset of the data without creating a copy of the data.

### Value

`SpatialPointsDataFrame` with attributes from the corresponding point in the LAS object,

### Examples

    LASfile <- system.file("extdata", "MixedConifer.laz", package="lidR")
    las <- readLAS(LASfile, select = "xyzi", filter = "-drop_z_below 0 -keep_random_fraction 0.5")

    # Using a 20x5 rectangle with a 45 degrees angle.
    # This won't find the tree properly in the general case
    # but may find some oriented structure.
    lm = find_localmaxima(las, c(20, 5, pi/4))
    plot(lm)

[Package lidR version 3.2.2 Index]