Study On 2D Image Reconstruction For Wood Defects Based On Ray Tracing Of Shortest Path

Wood interior defects will seriously affect its physical and mechanical properties,severely reducing the quality of the wood.Through the detection of stumpage,we can decide whether to take measures such as treating and cutting trees,which will achieve the purpose of protecting the trees and the social stability and at the same time has important practical significance in improving the utilization rate of wood and maintaining the sustainable development of forest ecological environment.Image reconstruction including ray tracing and inversion algorithm,which takes advantage of the wave field travel-time information to inverse image on the detected wood’s speed (or slowness), is an effective means to study internal defects of wood.The ray tracing algorithm is designed to find the relationship between the model and data,and compared with the other tracing algorithm,the shortest path ray tracing method is more adaptable,quicker and easier to implement.This paper applies the method of stress wave nondestructive testing,tomography traveltime theory and other related theory and the analysis method,and is mainly around the research of the shortest path ray tracing algorithm,the establishing of model, the acquiring of experimental data, the simulation analysis of shortest path ray tracing algorithm and the index analysis of imaging results.the main research results are as follows:(1) The principle, realization process and the use of Dijkstra algorithm of the shortest path ray tracing method is studied in this paper, and according to the characteristic and principle of the forward algorithm, the article choose the most suitable image reconstruction algorithm.(2) The numerical model is established, and the velocity model and network model based on the shortest path ray tracing is constructed.(3) Prime factors decomposition method is used to establish the nodes of the shortest path ray tracing automatic search function, the use of Matlab programming achieve the shortest path ray tracing forward tracking simulation and the tomographic inversion algorithm of ART.The innovation of this paper lies in:(1) Proving the rationality of the reference speed by studying the relationship between content and the wood speed in the radial direction.(2) Using the shortest path ray tracing algorithm, so that the wave propagation path are more accurate.