The Influence of Cross-Section Thickness on Diameter at Breast Height Estimation from Point Cloud

Milan Koreň,Juliana Chudá,Peter Surový,Martin Mokroš,Milan Hunčaga

doi:10.3390/ijgi9090495

Abstract

Circle-fitting methods are commonly used to estimate diameter at breast height (DBH) of trees from horizontal cross-section of point clouds. In this paper, we addressed the problem of cross-section thickness optimization regarding DBH estimation bias and accuracy. DBH of 121 European beeches (Fagus sylvatica L.) and 43 Sessile oaks (Quercus petraea (Matt.) Liebl.) was estimated from cross-sections with thicknesses ranging from 1 to 100 cm. The impact of cross-section thickness on the bias, standard error, and accuracy of DBH estimation was statistically significant. However, the biases, standard errors, and accuracies of DBH estimation were not significantly different among 1–10-cm cross-sections, except for oak DBH estimation accuracy from an 8-cm cross-section. DBH estimations from 10–100-cm cross-sections were considerably different. These results provide insight to the influence of cross-section thickness on DBH estimation by circle-fitting methods, which is beneficial for point cloud data acquisition planning and processing. The optimal setting of cross-section thickness facilitates point cloud processing and DBH estimation by circle-fitting algorithms.

Highlights

Circle-fitting methods are efficient algorithms of tree diameter at breast height (DBH) estimation from point clouds obtained by terrestrial laser scanning (TLS), close-range photogrammetry, and depth-images
The minimum number of points used in DBH estimation was 79 in a 1-cm cross-section of beech
Number of points used in DBH estimation was 79 in a 1-cm cross-section of beech, 9.05 cm), and the maximum number of points in a cross-section was 309,329 for beech (DBH = 40.1 and the maximum number of points in a cross-section was 309,329 for beech (DBH = 40.1 cm) (Table A1)

Summary

Introduction

Circle-fitting methods are efficient algorithms of tree diameter at breast height (DBH) estimation from point clouds obtained by terrestrial laser scanning (TLS), close-range photogrammetry, and depth-images. These algorithms search for the parameters of the circle that optimally fit to the set of points in a horizontal cross-section of the point cloud representing a horizontal slice of the measured trunk [1]. A cross-section thickness in the range of 2−10 cm is common in studies focused on accuracy of derived tree characteristics [2,3,4,5,6,7,8], while cross-sections of several 10s of centimeters are used for low-density point clouds, tree identification purposes, cylinder fitting, and 3D trunk modelling [4,9,10,11,12,13]. Few studies have addressed cross-section thickness optimization for DBH estimation from TLS point clouds, i.e., cross-section

Results

Discussion

Conclusion