Detection And Recognition Of Tree Trunk Internal Defects Based On Radar

Ancient trees are the focus of the protection of the country.Trees are prone to recession due to various adverse environmental factors or their own physiological causes in the natural environment.Trees are infested in the early stages of the recession,usually from the inside to start the air rot and irreversible and it can’t be obtained the accurate monitoring and determination from outside of trees.To ensure the healthy growth of trees and avoid unnecessary loss,conservation measures should be adopted.The application of tree nondestructive testing technology on trees is very important.This paper focuses on a field of non-destructive detection of trees,that is,radar wave non-destructive detection.Compared to other non-destructive detecting technologies,such as stress wave,ultrasound,computed tomography,radar-detection are have many advantages for wood detection,such as completely non-invasive,environment-friendly,high speed.It is suitable for detecting wooden structure of ancient building,ancient trees.The moisture content of wood,the individual differences and others(heartwood,sapwood and bark and scarring,cracking,decay,and hollow exception)increase the difficulty of non-destructive testing.Currently,there is no high precision,low degree of visual for detecting the abnormality in wooden body with radar.So as to solve above problems,a new measurement method based on Ground Penetrating Radar(GPR)is proposed to accomplish the abnormal localization.According to radar wave amplitude,velocity changes as well as reflection,transmission and other transmission characteristics,the characteristics of the reflected signal in the inner of trees could be analyzed by threshold,match filter,Hilbert.Meanwhile,taking the laser scanning to collect the contour data and accomplish the location and presentation of the abnormal of the internal tree.Finally,verify the Hilbert algorithm is better through the forward model and do a comparison with the ancient willow of Summer Palace.The result shows the error rate for locating abnormal in the depth and area can be controlled within 10%and 5%.Consequently,the method based on GPR of locating the abnormal of the tree was effective and feasible and laser scanning combined with contour data can present the size of the abnormal regions within the trees.