| Trees are an important part of the ecological environment,which play an important role in maintaining the balance of carbon and oxygen,protecting biodiversity and water conservation.In the study of ecology and urban landscape design,they are very important to study the basic parameters and 3D visualization of trees.There are many disadvantages which are low efficiency,high labor intensity,influenced by the environmental in traditional methods of forest resources survey.With the development of the virtual reality technology and Forestry Surveying and mapping technology,especially the development of 3D laser scanning technology,these problems in the traditional method have been solved.Terrestrial laser scanning technology is a new technology of Surveying and mapping,and it can acquire the three-dimensional point cloud data of trees accurately and rapidly without damage,which provides a convenient means for biodiversity research,forestry resources survey and forest ecological landscape reconstruction.In view of the problems which the traditional survey method of forest resources is in low efficiency,high labor intensity,poor visualization,this article takes the ground 3D laser scanner as the carrier,using the method of algorithm theory,the program combined with examples,achieving to extract two basic parameters of the diameter at breast height(DBH)and tree crown volume,in addition visualization.Main research contents and results are as follows:(1)The diameter at breast height(DBH)is one of the basic parameters of trees,which plays an important role in the estimation of biomass and the growth of trees.In view of the low degree of automation of contact-type artificial field measurement,and the low accuracy of existing algorithms based on point cloud,a new method using 3D laser scanning technology to automatically obtain the diameter of trees at breast height is proposed.Based on tree point cloud data obtained by 3D laser scanning technology,using ant colony algorithm and B-spline curve fitting technique,combined with the mathematical formula,it finally gets the wood diameter at breast height by programming automatically.Sample trees in the experimentation area were measured and calculated,the results show that the root-mean-square error of the algorithm for the extraction of tree diameter is ± 0.19cm which is improved by 50%compared with the traditional algorithm based on point cloud,and the average-absolute error is 0.15cm,which is improved by 60.7%compared with the traditional algorithm based on point cloud.Based on high precision point cloud data,this method can achieve the automatic extraction of tree diameter at breast height,which provides accurate data for the calculation of biomass and other ecological research,and has popularization value.(2)Tree crown volume is an important parameter in the study of biomass and 3D green biomass.In view of the problems which contain complex crown topology structure,the poor accuracy and low degree of automation in the existing method,this paper presents an automatic extraction measurement of the tree crown volume method with laser point cloud data.Based on the tree point cloud data,the automatic calculation is achieved by using the sector area approximation and the irregular slice segmentation algorithm.Sample trees in the experimentation area were measured and calculated,the results show that the accuracy obtained from the automatic calculation is greatly higher than that from the conventional method.Also,the precision is increased by 6.17%compared with the manual measurement method based on point cloud data.In addition,it can save the manpower.Based on high precision point cloud data,this method can achieve the automatic calculation of single tree crown volume,which can provide reference for the calculation of 3D green quantity,carbon cycle and the study of crown structure.(3)In view of the problems which contain complex topology structure of trees,tree point cloud based terrestrial 3D laser scanning technology to obtain the data source,using the cyclone software registration of all sites of the point cloud,removing the noise,segmenting the tree branches point cloud into different parts manually.Constructing triangle network model of the single branch uses Geomagic Studio software "package" command.Merging all of the branches makes the triangulation model as a whole tree.Putting the tree model into 3ds MAX to map processing,real 3D tree model is obtained,so as to realize the visualization.Taking leafless trees as an example,the construction of trees model uses the above method.The accuracy of the model was verified by two parameters of tree height and DBH.In this paper,tree point cloud data with high precision as the data source,using Geomagic studio and 3dsMAX as platform,realize the visualization of tree model expression,can provide the basic data for the detailed research on ecology and forestry science,to provide a friendly platform for information science education.The application of 3D laser scanning technology to the extraction and visualization of tree parameters is an innovation and development of ecology and forestry research.The results of this study indicate that the point cloud data acquisition by terrestrial laser scanning technology as the foundation,the design of the related algorithm,in the premise of no damage to trees and save human resources,realize the DBH and crown volume parameters of the accurate automatic extraction and tree visualization expression,which provides basic data for making accurate estimates of biomass and related decisions and also provides a good platform for the exchange of ecology. |
PDF Full Text Request