Estimating tree crown dimensions using digital analysis of vertical photographs

Brown, P. L., Doley, D. and Keenan, R. J. (2000) Estimating tree crown dimensions using digital analysis of vertical photographs. Agricultural and Forest Meteorology, 100 2-3: 199-212. doi:10.1016/S0168-1923(99)00138-0


Author Brown, P. L.
Doley, D.
Keenan, R. J.
Title Estimating tree crown dimensions using digital analysis of vertical photographs
Journal name Agricultural and Forest Meteorology   Check publisher's open access policy
ISSN 0168-1923
Publication date 2000-02-05
Sub-type Article (original research)
DOI 10.1016/S0168-1923(99)00138-0
Volume 100
Issue 2-3
Start page 199
End page 212
Total pages 14
Place of publication Amsterdam, Netherlands
Publisher Elsevier Science B.V.
Collection year 2000
Language eng
Subject C1
300699 Forestry Sciences not elsewhere classified
620300 Forestry
Abstract The aim of this study was to develop a relatively rapid, simple and repeatable method to characterize the crown architecture of Queensland maple (Flindersia brayleyana F. Muell.) by vertical hemispherical photography. Calibration scales were developed to provide horizontal planes of measurement at heights from 15 to 40 m above the camera. Hemispherical images of tree crowns were merged with the specific calibration scale appropriate for the mid-height of the crown in order to adjust for image distortion during measurement. Merged images were analyzed by three procedures to yield measurements of crown diameter and projected area. The most precise measurement of projected crown dimensions was assumed to be provided by a complete analysis of a digital image of the crown, after removal of the trunk image. Crown diameters estimated by tape measurements on the ground were relatively imprecise (R-2 = 0.54), Crowns classified as symmetrical were described much more precisely (R-2 = 0.72) than those classified as asymmetrical (R-2 = 0.37). The precision of estimates of crown dimensions by tape did not alter significantly over the range of crown sizes sampled (2-10 m diameter in trees 15-40 m tall). This novel image analysis method can yield relatively precise and accurate measurements on the relatively shallow crowns of tall trees, often found in rainforests, regardless of the degree of asymmetry in crown shapes. However, the method is slower to apply than conventional tape techniques and additional equipment is required. The principal advantage of the photographic technique is the opportunity for precise measurements of changes in crown size and foliage projected area over time. (C) 2000 Published by Elsevier Science B.V. All rights reserved.
Keyword Agronomy
Forestry
Meteorology & Atmospheric Sciences
Tree Crowns
Crown Asymmetry
Crown Diameter
Crown Projected Area
Hemispherical Photography
Radial Distortion
Forest
Profiles
Dynamics
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collections: Centre for Mined Land Rehabilitation Publications
School of Biological Sciences Publications
 
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Citation counts: TR Web of Science Citation Count  Cited 16 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 18 times in Scopus Article | Citations
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Created: Tue, 10 Jun 2008, 21:06:21 EST