Leveraging a new branch-based taper curve and form factor from terrestrial laser scanning proxies

Modeling branch taper curve and form factor contributes to increasing the efficiency of tree crown reconstruction: the branch taper, defined as the sequential measure of diameters along the course of the branch, is pivotal to accurately estimate key branch variables such as biomass and volume. Branch diameters or volumes have commonly been estimated from terrestrial laser scanning (TLS) based on automatized voxelization or cylinder-fitting approaches, given the whole branch length is sufficiently covered by laser reflections. The results are, however, often affected by ample variations in point cloud characteristics caused by varying point density, occlusions, and noise. As these characteristics of TLS have been difficult to be sufficiently controlled or eliminated in automatized-techniques, we proposed a new branch-based taper curve model and form factor (BFF), which can be employed directly from the laser reflections and under variable point cloud characteristics.
In this paper, the a..., Terrestrial laser scanning (TLS) was used to acquire point cloud datasets of individual trees during the leaf-off season. Scanning was performed for six tree species using Trimble TX5 3D Laser Scanner (Trimble Inc., Sunnyvale, CA, USA). The point clouds are collected based on the scanner setup with 43 million points (mpts) per scan with a quality setting 4x. With this setup, the scan duration was ~11 minutes. We scanned each tree from six scan positions, distributed circularly at a regular interval of 60° from each other.
The processed datasets comprise comma-delimited files (.csv), Excel (.xlsx), Rscript (.R), sample tree point clouds (.asc + .las), quantitative structural model (QSM) pipeline scripts (.xsct2), and the corresponding fitted cylinders (.ply).
Data1.csv file provides the list of tree species with the details of stem and crown variable metrics. All the variables were determined and computed directly from the laser reflections using CloudCompare software version 2.12.0 (Cl...,  

Column Name

Description

Unit

Source

Calculation or Measurement Methods

Software

Data1.csv

Species

The scientific name of the scanned trees

 

 

 

 

Scan_Code

Given code during scanning

 

 

 

 

Branch_ID

Isolated sample branch in each tree. Repetition of similar ID numbers indicates the series point slices taken along the corresponding branch.

 

 

 

 

BP
 

Branch position, indicating where the sample branch was positioned across the crown profile:
LCB – lower crown branch
MCB – middle crown branch
UCB – upper crown branch

 

 

 

 

BO

Branch order, where all the analysis was made for primary branches (BO 01)

 

 

 

 

DBH

Branch diameter at breast height

cm

Field

Diameter tape

 

H

Height of the tree. The vertical distance between the base of the trunk and the tree-top

m

Point Cloud

Zmax – Zmin

R Programming Language

H1

Crown base height. The vertical distance between th..., Abstract
Modeling branch taper curve and form factor contributes to increasing the efficiency of tree crown reconstruction: the branch taper, defined as the sequential measure of diameters along the course of the branch, is pivotal to accurately estimate key branch variables such as biomass and volume. Branch diameters or volumes have commonly been estimated from terrestrial laser scanning (TLS) based on automatized voxelization or cylinder-fitting approaches, given the whole branch length is sufficiently covered by laser reflections. The results are, however, often affected by ample variations in point cloud characteristics caused by varying point density, occlusions, and noise. As these characteristics of TLS have been difficult to be sufficiently controlled or eliminated in automatized-techniques, we proposed a new branch-based taper curve model and form factor (BFF), which can be employed directly from the laser reflections and under variable point cloud characteristics.
In this pap...