Canopy Segmentation of Overlapping Fruit Trees Based on Unmanned Aerial Vehicle LiDAR

Utilizing LiDAR sensors mounted on unmanned aerial vehicles (UAVs) to acquire three-dimensional data of fruit orchards and extract precise information about individual trees can greatly facilitate unmanned management. To address the issue of low accuracy in traditional watershed segmentation methods...

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Main Authors: Shiji Wang, Jie Ji, Lijun Zhao, Jiacheng Li, Mian Zhang, Shengling Li
Format: Article
Language:English
Published: MDPI AG 2025-01-01
Series:Agriculture
Subjects:
Online Access:https://www.mdpi.com/2077-0472/15/3/295
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author Shiji Wang
Jie Ji
Lijun Zhao
Jiacheng Li
Mian Zhang
Shengling Li
author_facet Shiji Wang
Jie Ji
Lijun Zhao
Jiacheng Li
Mian Zhang
Shengling Li
author_sort Shiji Wang
collection DOAJ
description Utilizing LiDAR sensors mounted on unmanned aerial vehicles (UAVs) to acquire three-dimensional data of fruit orchards and extract precise information about individual trees can greatly facilitate unmanned management. To address the issue of low accuracy in traditional watershed segmentation methods based on canopy height models, this paper proposes an enhanced method to extract individual tree crowns in fruit orchards, enabling the improved detection of overlapping crown features. Firstly, a distribution curve of single-row or single-column treetops is fitted based on the detected treetops using variable window size. Subsequently, a cubic spatial region extending infinitely along the Z-axis is generated with equal width around this curve, and all crown points falling within this region are extracted and then projected onto the central plane. The projecting contour of the crowns on the plane is then fitted using Gaussian functions. Treetops are detected by identifying peak points on the curve fitted by Gaussian functions. Finally, the watershed algorithm is applied to segment fruit tree crowns. The results demonstrate that in citrus orchards with pronounced crown overlap, this novel method significantly reduces the number of undetected trees with a recall of 97.04%, and the F1 score representing the detection accuracy for fruit trees reaches 98.01%. Comparisons between the traditional method and the Gaussian fitting–watershed fusion algorithm across orchards exhibiting varying degrees of crown overlap reveal that the fusion algorithm achieves high segmentation accuracy when dealing with overlapping crowns characterized by significant height variations.
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issn 2077-0472
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publishDate 2025-01-01
publisher MDPI AG
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spelling doaj-art-ed57395302ad49de800fed29052f5c492025-08-20T02:12:23ZengMDPI AGAgriculture2077-04722025-01-0115329510.3390/agriculture15030295Canopy Segmentation of Overlapping Fruit Trees Based on Unmanned Aerial Vehicle LiDARShiji Wang0Jie Ji1Lijun Zhao2Jiacheng Li3Mian Zhang4Shengling Li5College of Engineering and Technology, Southwest University, Chongqing 400715, ChinaCollege of Engineering and Technology, Southwest University, Chongqing 400715, ChinaSchool of Intelligent and Manufacturing Engineering, Chongqing University of Arts and Sciences, Chongqing 402160, ChinaCollege of Engineering and Technology, Southwest University, Chongqing 400715, ChinaCollege of Engineering and Technology, Southwest University, Chongqing 400715, ChinaCollege of Engineering and Technology, Southwest University, Chongqing 400715, ChinaUtilizing LiDAR sensors mounted on unmanned aerial vehicles (UAVs) to acquire three-dimensional data of fruit orchards and extract precise information about individual trees can greatly facilitate unmanned management. To address the issue of low accuracy in traditional watershed segmentation methods based on canopy height models, this paper proposes an enhanced method to extract individual tree crowns in fruit orchards, enabling the improved detection of overlapping crown features. Firstly, a distribution curve of single-row or single-column treetops is fitted based on the detected treetops using variable window size. Subsequently, a cubic spatial region extending infinitely along the Z-axis is generated with equal width around this curve, and all crown points falling within this region are extracted and then projected onto the central plane. The projecting contour of the crowns on the plane is then fitted using Gaussian functions. Treetops are detected by identifying peak points on the curve fitted by Gaussian functions. Finally, the watershed algorithm is applied to segment fruit tree crowns. The results demonstrate that in citrus orchards with pronounced crown overlap, this novel method significantly reduces the number of undetected trees with a recall of 97.04%, and the F1 score representing the detection accuracy for fruit trees reaches 98.01%. Comparisons between the traditional method and the Gaussian fitting–watershed fusion algorithm across orchards exhibiting varying degrees of crown overlap reveal that the fusion algorithm achieves high segmentation accuracy when dealing with overlapping crowns characterized by significant height variations.https://www.mdpi.com/2077-0472/15/3/295overlapping fruit crown segmentationGaussian fittingtreetop detectionwatershed algorithm
spellingShingle Shiji Wang
Jie Ji
Lijun Zhao
Jiacheng Li
Mian Zhang
Shengling Li
Canopy Segmentation of Overlapping Fruit Trees Based on Unmanned Aerial Vehicle LiDAR
Agriculture
overlapping fruit crown segmentation
Gaussian fitting
treetop detection
watershed algorithm
title Canopy Segmentation of Overlapping Fruit Trees Based on Unmanned Aerial Vehicle LiDAR
title_full Canopy Segmentation of Overlapping Fruit Trees Based on Unmanned Aerial Vehicle LiDAR
title_fullStr Canopy Segmentation of Overlapping Fruit Trees Based on Unmanned Aerial Vehicle LiDAR
title_full_unstemmed Canopy Segmentation of Overlapping Fruit Trees Based on Unmanned Aerial Vehicle LiDAR
title_short Canopy Segmentation of Overlapping Fruit Trees Based on Unmanned Aerial Vehicle LiDAR
title_sort canopy segmentation of overlapping fruit trees based on unmanned aerial vehicle lidar
topic overlapping fruit crown segmentation
Gaussian fitting
treetop detection
watershed algorithm
url https://www.mdpi.com/2077-0472/15/3/295
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AT jiachengli canopysegmentationofoverlappingfruittreesbasedonunmannedaerialvehiclelidar
AT mianzhang canopysegmentationofoverlappingfruittreesbasedonunmannedaerialvehiclelidar
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