lidR: li2012 – R documentation

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li2012

Individual Tree Segmentation Algorithm

Description

This functions is made to be used in segment_trees. It implements an algorithm for tree segmentation based on the Li et al. (2012) article (see reference). This method is a growing region method working at the point cloud level. It is an implementation, as strict as possible, made by the lidR author but with the addition of a parameter hmin to prevent over-segmentation for objects that are too low.

Usage

li2012(dt1 = 1.5, dt2 = 2, R = 2, Zu = 15, hmin = 2, speed_up = 10)

Arguments

`dt1`	numeric. Threshold number 1. See reference page 79 in Li et al. (2012). Default is 1.5.
`dt2`	numeric. Threshold number 2. See reference page 79 in Li et al. (2012). Default is 2.
`R`	numeric. Search radius. See page 79 in Li et al. (2012). Default is 2. If `R = 0` all the points are automatically considered as local maxima and the search step is skipped (much faster).
`Zu`	numeric. If point elevation is greater than Zu, `dt2` is used, otherwise `dt1` is used. See page 79 in Li et al. (2012). Default is 15.
`hmin`	numeric. Minimum height of a detected tree. Default is 2.
`speed_up`	numeric. Maximum radius of a crown. Any value greater than a crown is good because this parameter does not affect the result. However, it greatly affects the computation speed. The lower the value, the faster the method. Default is 10.

References

Li, W., Guo, Q., Jakubowski, M. K., & Kelly, M. (2012). A new method for segmenting individual trees from the lidar point cloud. Photogrammetric Engineering & Remote Sensing, 78(1), 75-84.

Examples

LASfile <- system.file("extdata", "MixedConifer.laz", package="lidR")
las <- readLAS(LASfile, select = "xyz", filter = "-drop_z_below 0")
col <- pastel.colors(200)

las <- segment_trees(las, li2012(dt1 = 1.4))
#plot(las, color = "treeID", colorPalette = col)

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