tree_metrics: Estimates a set of morphological parameters from a tls point...

In VoxR: Trees Geometry and Morphology from Unstructured TLS Data

Description

Estimates a set of morphological parameters from a tls point cloud of a tree.

Usage

tree_metrics(
  data,
  dbh,
  height,
  crown_diameter,
  crown_proj_area,
  volume,
  message
)

Arguments

data	a data.frame or data.table containing the x, y, z, ... coordinates of a point cloud.
dbh	numeric and optional. Estimate tree DBH ?
height	numeric and optional. Estimate tree height ?
crown_diameter	numeric and optional. Estimate tree average crown diameter ?
crown_proj_area	numeric and optional. Estimate tree crown projected area ?
volume	numeric and optional. Estimate tree volume ?
message	logical. If FALSE, messages are disabled. Default = TRUE.

Details

Selecting parameters to compute

If none of dbh,height,crown_diameter, crown_proj_area and volume are passed, all parameters are computed. However, the user can select a set of parameters by declaring wich parameters should be computed (all other are not).

Parameters estimates

The tree DBH is estimated as the diameter of a circle fitted to the point cloud between 1.2m and 1.4m above the ground. The tree height is computed as the elevation difference between the lowest and the highest points of the point cloud. Two values are provided for crown parameter. First a 2D convex hull is used to identify the external points of the crown. Then, a first estimate of the crown diameter ("distant_points") is computed as the average distance of each point to the further point. A second estimate ("circle_fitting") correspond to the diameter of a circle fitted to the crown external points. The crown projected area is computed as the area of a 2D convex hull that wraps the projected crown. The volume is computed as the volume of a 3D convex hull that wraps the point cloud.

Value

a list containing the estimated value for each parameter.

Examples

#- import tls data
tls=data.table::fread(system.file("extdata", "Tree_t0.asc", package="VoxR"))

#- compute all metrics
VoxR::tree_metrics(tls)

#- compute DBH only
VoxR::tree_metrics(tls,dbh = TRUE)

#- compute DBH and height
VoxR::tree_metrics(tls,dbh = TRUE,height = TRUE)

VoxR documentation built on Nov. 16, 2020, 9:14 a.m.