R: Individual Tree Segmentation Algorithm

li2012 {lidR} | R Documentation

## 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.

### See Also

Other individual tree segmentation algorithms: `dalponte2016()`, `silva2016()`, `watershed()`

### 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)

[Package lidR version 3.2.2 Index]