Extract lower trunk point cloud — extract_lower_trunk

Returns the trunk points below 1.5 m (above the lowest point of the tree point cloud).

Usage

extract_lower_trunk_pc(
  pc,
  slice_thickness = 0.08,
  concavity = 4,
  dtm = NA,
  r = 5
)

Arguments

pc: The tree point cloud as a data.frame with columns X,Y,Z. Output of read_tree_pc.
slice_thickness: Numeric value (default = 0.08) that determines the thickness of the slice used to determine the lower trunk points.
concavity: Numeric value (default=4) concavity for the computation of the functional diameter using a concave hull based on concaveman.
dtm: The digital terrain model as a data.frame with columns X,Y,Z (default = NA). If the digital terrain model is in the same format as a point cloud it can also be read with read_tree_pc.
r: Numeric value (default=5) r which determines the range taken for the dtm. Should be at least the resolution of the dtm. Only relevant when a dtm is provided.

Value

Data.frame with the lower trunk point cloud (part of the trunk below 1.5 m).

Details

This function iteratively adds trunk points to the trunk point cloud starting from 0.15 m above the lowest point of the tree point cloud (everything below 0.15 m is assumed to be trunk). For each slice as many crown/branch points are removed based on kmeans clustering and the distance of the clusters to the center of the previous slice. When the bottom of the point cloud is incomplete or obstructed you can choose to add a digital terrain model as an input which is used to estimate lowest point of the point cloud in order to obtain slices at the correct height of the tree. Support function used to determine the DBH from a tree point cloud with dbh_pc.

Examples

if (FALSE) {
# Read tree point cloud and calculate the DBH
pc_tree <- read_tree_pc(PC_path = "path/to/point_cloud.txt")
trunk_pc <- extract_lower_trunk_pc(pc = pc_tree)
}