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Diameter at breast height/above buttresses

Source: R/metrics_Terryn_2020.R
dbh.Rd

Returns the diameter at breast height or diameter above buttresses.

Usage

dbh(
  treedata,
  pc = NA,
  buttress = FALSE,
  thresholdR2 = 0.001,
  slice_thickness = 0.06,
  thresholdbuttress = 0.001,
  maxbuttressheight = 7,
  concavity = 4,
  dtm = NA,
  r = 5
)

Arguments

treedata

Treedata field of a TreeQSM that is returned by read_tree_qsm.

pc

The tree point cloud as a data.frame with columns X,Y,Z. Output of read_tree_pc. Default is NA and indicates no tree point cloud is available.

buttress

Logical (default=FALSE), indicates if the trees have buttresses. Only relevant if pc is available.

thresholdR2

Numeric value (default=0.001). Parameter of the dbh_pc function used to calculate the diameter at breast height. Only relevant if the tree point cloud is available and buttress == FALSE.

slice_thickness

Numeric value (default = 0.06). Parameter of the dbh_pc and dab_pc functions used to calculate the diameter at breast height and above buttresses. Only relevant if the tree point cloud is available.

thresholdbuttress

Numeric value (default=0.001). Parameter of the dab_pc function used to calculate the diameter above buttresses. Only relevant if the tree point cloud is available and buttress == TRUE.

maxbuttressheight

Numeric value (default=7). Parameter of the dab_pc function used to calculate the diameter at breast height. Only relevant if the tree point cloud is available and buttress == TRUE.

concavity

Numeric value (default=4) concavity for the computation of the functional diameter using a concave hull based on concaveman. Only relevant if the tree point cloud is available.

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

The dbh or dab in meters.

Details

If the tree point cloud is available the calculations are based on the point cloud (most accurate). In this case the diameter at breast height (dbh) or diameter above buttresses (dab) is calculated with dbh_pc or dab_pc respectively. If the tree point cloud is not available the dbh is based on the treeQSM with dbh_qsm. 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.

Examples

if (FALSE) {
qsm <- read_tree_qsm(QSM_path = "path/to/qsm.mat")
DBH <- dbh(treedata = qsm$treedata)
pc_tree <- read_tree_pc(PC_path = "path/to/point_cloud.txt")
DBH <- dbh(treedata = qsm$treedata, pc = pc_tree, buttress = TRUE)
}