segment_tree_crowns_parallel: Parallel mean shift clustering for individual tree crown...

In Lenostatos/meanshiftr_improved: Tree Delineation from Lidar Using Mean Shift Clustering

Description

The function provides the frame work to apply the adaptive mean shift 3D (AMS3D) algorithm on several sub point clouds of a large investigation area in parallel. It requires a list of sub point clouds as input and returns one large clustered point cloud as output. The input should have buffer zones around the focal areas. The buffer width should correspond to at least the maximal possible tree crown radius.

Usage

segment_tree_crowns_parallel(
  point_clouds,
  used_fraction_of_cores = 0.5,
  version = "classic",
  crown_diameter_2_tree_height,
  crown_height_2_tree_height,
  max_num_centroids_per_mode = 200,
  min_num_neighbors_per_core,
  neighborhood_radius,
  buffer_width = 10,
  min_height = 2
)

Arguments

point_clouds	List of point clouds in data.table format containing columns X, Y and Z (produced by the split_point_cloud_buffered function).
used_fraction_of_cores	Fraction of available cores to use for parallelization.
version	of the AMS3D algorithm. Can be set to "classic" (slow but precise also with small trees) or "voxel" (fast but based on rounded coordinates of 1-m precision) or "classic improved" (like classic but faster).
crown_diameter_2_tree_height	Factor for the ratio of height to crown width. Determines kernel diameter based on its height above ground.
crown_height_2_tree_height	Factor for the ratio of height to crown length. Determines kernel height based on its height above ground.
max_num_centroids_per_mode	Maximum number of iterations, i.e. steps that the kernel can move for each point. If centroid is not found after all iteration, the last position is assigned as centroid and the processing jumps to the next point
min_num_neighbors_per_core	Integer Scalar. The minimum number of neighbors that a point needs to have in order to be considered as a core point by the DBSCAN clustering algorithm.
neighborhood_radius	Numeric Scalar. The radius of the space around a point that is treated as the point's neighborhood.
buffer_width	Width of the buffer around the core area in meters.
min_height	Minimum height above ground for a point to be considered in the analysis. Has to be > 0.

Value

data.table of point cloud with points labelled with tree IDs

Lenostatos/meanshiftr_improved documentation built on May 29, 2020, 7:23 p.m.