Study Of The Tree Measurement Technology By UAV Aerial Photography

Forest resource survey is the necessary premise for forest management, and also is one of hotspots in the field of forest sustainable development research. Obtaining the resource information of the corresponding forest by forest resources investigation, the efficiency of forest management can be improved, and also the exertion of the ecological and economic function of the forest can be promoted for a good environment for people’s production and living. However, with the continuous development of the times, either the traditional forest resource investigation method, or the common aerial survey investigation method which is now rising, there exist the defects of low efficiency, long cycle, high cost and poor stability, resulting in the development bottleneck of forest resource investigation. How to overcome the above defects, on the condition of a more efficient and accurate survey of forest resources, has become one of the urgent problem.First of all, on the basis of studying and summarying of the research results at home and abroad and analysing the actual needs of forest resources survey, a uav photogrammetry system which can extract information of forest vegetation was integrated by combining rotor unmanned aerial with3d digital camera. Secondly, in this paper, based on the research in the post-processing of image data of aerial imagery, uav image processing system was designed. The system can realize the extraction of forest survey factors based on the processing and interpreting of the remote sensing images. Combining the acquired images, such the functions as the compartment zoning and the forest figure drawing and so on can also be achieved. Finally, in the experiments in the JiuFeng experimental forest farm, though the image processing system for aerial images and by using the system to analyse the features of the image spectrum and textures, the main characteristic parameters of the forest can be obtained, such as height, crown breadth of a single tree, forest canopy density and the stand volume, etc. The method of using the uav photogrammetry technology to extract forest factors has been proved to be feasible.The results showed that:through field validation in JiuFeng experimental forest farm, in the experiment of interpreting the tree heights of single trees using the stereo images from the uav photogrammetry system, the maximum relative error was16%and the minimum relative error was0%. The accuracy of the whole experiment was up to93.67%. In the experiments of individual tree crown extraction, relative error of stereo pair method was0.08%, and average relative error of the object segmentation method was0.07%. Both meet the requirements of forestry measurement. The sample accuracy of the two methods was as follows:92.19%and94.31%. The precision of other major parameters of forest features can also meet the accuracy requirements of forest resources survey. From what has been discussed above, compared with the traditional investigation methods of forest resource, the uav aerial photography tree method has the following advantages:①mobile and rapid response capability.②Image acquisition convenient.③hardly affected by climatic conditions.④low cost. It can provide a decision aid for forest resources investigation work. The hardware and software system can provide technical support for forest resource survey.