Research On Root Identification And Location Technology Of Tree Radar Based On Hough Transform

Underground roots are an important part of trees and play an important role in the ecosystem.However,the root is criss-crossing in the ground and has many branches,so the opacity of soil impedes the detection of roots,which becomes the main technical hinder of in-situ nondestructive detection of tree roots.Traditional detection method of tree root is time-consuming and destructive.In order to solve this problem,this paper use tree radar to detect tree roots,that is,when electromagnetic waves pass through different root-soil interface with different dielectric constants,it will form a clear hyperbolic reflection on the radar map,so as to realize true nondestructive detection of tree roots.Based on this principle,the research contents and methods used in this paper are as follows:Firstly,the basic principle of tree radar is expounded from the theory of radar wave propagation and reflection,including the working mode of tree radar,the data interpretation form of tree radar and the main technical parameter.Secondly,the forming principle of tree radar echo hyperbola is briefly explained.Based the research of root detection and root nondestructive testing,the influence of different root growth distribution on tree radar root detection was studied by combining the forward simulation experiment and field control experiment,and the feasibility and effectiveness of Gpr Max simulation tree radar root detection was confirmed.On the basis of the forward simulation experiment and the control experiment,the randomized Hough transform algorithm is implemented to identify the curve of the root system.The algorithm combining the symmetry curve and Hough transform is used to locate the forward results of different root directions,and the influence of different root directions on the radarsignal transmission is analyzed and studied.In addition,the research results of forward simulation experiment and control experiment were applied to the field experiment in the Summer Palace,and the radar images of underground root system of pine and cypress trees were analyzed and the distribution of underground root system was predicted.The results show that:(1)the preprocessing method has a good effect on the suppression of radar image noise and clutter;(2)in the process of detection,the bigger and the shallower root was easier to be detected;(3)horizontal spacing,vertical spacing and root orientation of roots also affect the accuracy of tree radar recognition;(4)the recognition accuracy of hyperbola abscissa vertex is higher than hyperbola ordinate.The results can provide a theoretical basis for tree root detection,underground biomass estimation and three-dimensional mapping of root distribution.