Information Extraction and Security Risk Assessment of Street Trees Based on Vehicle-Borne LiDAR Data

doi:10.13466/j.cnki.lyzygl.2022.05.012

Abstract

Abstract:

Rapid and accurate acquisition of the structural characteristics and safety risk status of urban street trees based on LiDAR point cloud data is of great significance to assist smart city management.In order to solve the problem that LiDAR point cloud data is difficult to segment regions with unclear morphological characteristics in street tree parameter acquisition,a individual tree extraction method based on circular index of trunk center point was proposed.Firstly,it obtained the sliced point cloud of the trunk layer according to the elevation information,then,segmented the sliced data based on the improved DBSCAN clustering algorithm.Secondly,it identified the trunk through the morphological characteristics of the ground features and obtained the central point,so as to complete the extraction through the circular index method based on the central point.Finally,it combined with the risk matrix method to evaluate the safety risk of the stability and traffic impact of the street trees in the study area.The results showed that the proposed individual tree extraction method could effectively improve the segmentation accuracy of individual trees of street trees in areas with unclear morphological characteristics,and accurately obtain the structural parameter information such as the number,shape and position of street trees;The safety risk assessment found that the stability of most street trees and the risk of traffic impact in the study area werein a level I negligible risk state,but there were some street trees whose stability and risk of traffic impact were level II and level III.These trees were mainly distributed in the area with dense and interlaced roadside trees in the study area.The results can provid corresponding decision support for relevant departments to monitor street trees in a timely and effective manner.

Key words: vehicle-borne LiDAR, extraction of information, street trees, security risk assessment

CLC Number:

P225.1
TN249

MU Tianbao, WU Linna, ZHANG Haitao, ZHANG Han. Information Extraction and Security Risk Assessment of Street Trees Based on Vehicle-Borne LiDAR Data[J]. FOREST RESOURCES WANAGEMENT, 2022, 0(5): 91-98.

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评价类型	评价种类	评价指标	指标定义	评分标准
稳定性风险	可能性评价 (P)	树冠偏冠状况 (P₁)	树冠生长不均匀导致的树冠偏向一边的情况	1(可忽略)	2(轻)	3(中)	4(重)
稳定性风险	可能性评价 (P)	树干倾斜度>10° (P₂)	树干与垂直方向的夹角,夹角越大倾斜程度越大	1(可忽略)	2(轻)	3(中)	4(重)
	严重性评价 (S)	胸径粗细 (S₁)	树干地表胸高处的直径	1(低危)	2(中危)	3(高危)	4(极危)
对交通影响风险	可能性评价 (P)	分支点高度 (P₃)	从地面至树木第一层活分支点的高度	1(可忽略)	2(轻)	3(中)	4(重)
对交通影响风险	可能性评价 (P)	分支点开张角度 (P₄)	分支点以上区域的枝条与垂直方向所构成的夹角	1(可忽略)	2(轻)	3(中)	4(重)
	严重性评价 (S)	行道树位置 (S₂)	行道树所处道路的位置(包括道路等级、是否处于路口、与道路的距离等)	1(低危)	2(中危)	3(高危)	4(极危)

风险等级(R)	分值	解释说明
Ⅳ	12~16	重大风险(该风险因素非常不安全,并会引起较为严重的后果)
Ⅲ	7~9	中等风险(该风险因素不安全,应立即采取措施控制,并非常有可能发生树木倒塌或者其他风险事件)
Ⅱ	4~6	可接受的风险(该风险因素比较安全,担忧潜在风险,应引起注意)
Ⅰ	1~3	可忽略的风险(该风险因素基本安全,但不排除其存在一定的安全隐患,应当继续观察)

项目	行道树/株
人工判读	261
算法识别	263
精细化处理结果	243
误差识别差值	20
行道树提取差值	18
识别率/%	93.10

风险等级	稳定性风险	对交通影响风险
Ⅰ(可忽略的风险)	236	224
Ⅱ(可接受的风险)	6	15
Ⅲ(中等风险)	1	4
Ⅳ(重大风险)	0	0