Research On Tree-mensuration Technology Based On Oblique-photograph Measuring System

The investigation of forest resources is an important prerequisite for the content of forest management,and it is also one of the hot topics in the field of sustainable development of forest management in the new era.Through the investigation of forest resources,the accurate acquisition of basic forest and forest resources information can improve the forest management efficiency,promote the economic function of forest resources and ecological functions,and provide a good production and living environment for people in the new era.With the continuous development of high and new technology,whether it is the traditional forestry manager survey method or the modern aerospace photogrammetry survey and estimation method,there are many defects such as long time,low data acquisition efficiency,high cost,and poor stability.Overcoming these deficiencies and finding a more efficient and accurate investigation method for forest resources has become one of the issues that needs to be solved in the new era.This study aims to summarize the research results of various aspects of tilted photogrammetric systems at home and abroad.Based on this,combined with the actual needs of forest resources investigation,drones are used as platforms,equipped with tilt photography cameras,and integrated to suit the forest.Resource survey,standing tree information,and forestry information extraction drone tilt photogrammetry system.In this study,2110 tilted photographs of the study area were acquired by drones,a total of 10 navigation bands were designed,image preprocessing,joint adjustment,and intensive matching were performed,and a three-dimensional real model of the study area was generated,and based on which,orthophotos were performed.Corrective processing generates digital orthophotomaps(DOM),resulting in higher accuracy of the data,which meets the accuracyrequirements of Guizhou mountain areas.At the same time,using the professional Smart 3D Capture module for inclined photogrammetry,the east-west,north-south crown and tree-height factors of 42 single trees in the Tiantai Forest Park were measured,and the volume of the single wood was measured;the tilt photogrammetry system was used.Combined with GIS software and ERDAS software,the forest area factors such as stand area,average stand height,canopy closure,and average stand width of the stand were measured,and the volume of forest stand was calculated.This provides methods and means for using forest aerial images to quickly and efficiently extract forest trees.The following main conclusions are obtained through research:(1)Smart 3D Capture software was used to create a real three-dimensional model of the study area,Using Smart 3D Capture Software for Realistic 3D Model Creation and the specific processes include: the acquisition of raw images,POS data and image control point data,data preprocessing and quality inspection,multi-view empty three-image settlement,multi-view image joint adjustment,intensive matching,model editing output,finally,a real three-dimensional model of the study area is generated.Experiments show that it is feasible to establish a realistic three-dimensional model of single trees and stands using an inclined photogrammetry system,and the current situation is strong and true.(2)By the inclined photogrammetry system may extract a single high wood trees and tree crown of parameters,and extracts the study area and the menu tree crown high wood,calculated from the individual tree volume.Using an inclined photogrammetric system to measure the tree height and crown width of 42 single trees in the Tiantai Mountain Forest Park in Puyang County,and compare it with measured data,the average precision of the height of the single tree was calculated to be 92.21%,and the average accuracy of the extracted independent wood crown was 86.43%;the accuracy of the binary volume measurement of the photogrammetric stand-alone wood can be up to 69.78% by comparing the binary volume of photogrammetry with the log volume of the binary material table.(3)The forest tree parameters such as stand area,average tree height,canopydensity,stand density,and average stand width of forest stand can be extracted using the tilted photogrammetry system combined with 3S technology,and the average tree height,canopy density,and average crown width of selected forests in the study area were extracted and the volume of stand accumulation was calculated.Using real three-dimensional model generated photogrammetric system is inclined,the hook contour plot of the three stands,calculate the area using surface mapping module,and compared with the measured area,it is concluded that the precision of the forested area delineated on the model can reach 87.91%;DSM and DEM are generated using the oblique photogrammetry system,combined with the spatial analysis function of GIS,the average height of the three forest stands in the study area was calculated.The average tree height of the sampling sites using DVHM was 87.47%,and the average tree height of the sample sites for photogrammetry and measurement was lower than the measured tree height,the canopy values obtained by supervised classification using the generated orthophotos are close to the measured canopy values,with an accuracy of 93.7%.