Study On Handheld Tree Measurement Smart Station Manufacture And Function Test

Forest measuration is one of the important basic information gathering work in forest management and dendrometer, whose mensuration accuracy, automatic efficiency and costs play a decisive role in forestry inventory accuracy data quality, is the basic tool for forest mensuration. The existing dendrometers seriously restrict the development of forest inventory work with its outdated data gathering method, functional singleness, low-efficiency, low-precision, high prices and vast indoor work methods. Therefore, an automatic, digitized, accurate, multifunctional and portable dendrometer is urgently needed to promote the development of forest resource information acquisition technology. This research is based on forest survey sampling and statistical theory, combining with forest mensuration-. mathematics、physics、mechanical engineering、microelectronics science and computer etc. This research studied forest precision mensuration theory, modeling, implementation methods and the design of digitized-microminiaturized and integrated dendrometer. Meanwhile this paper developed the handheld mensuration smart station prototype and its application system. And an experiment was carried out to measure its functionalities and precision. This paper aimed at realizing the digitization, informatization, automation and intelligence, and it provides services for forest management and forest modernization. Main research conclusions can be summarized as following:I. Digitized, microminiaturized and integrated multifunction system designs of handheld smart station dendrometersDigitized and portable multifunction dendrometer developing idea is put forward to realize the digitized, multifunction, microminiaturized and precision mensuration of forest. And a handheld mensuration smart station dendrometer was developed, whose foundation is MEMS (micro-electro-mechanical systems) angle measurement sensor、laser ranging sensor and electronic compass etc. Operating system is developed through measurement distances、inclination and magnetic azimuth, combined with forest mensuration theory. It realized individual tree mensuration, plot gauging, and number of density mensuration of plants, electronic stereo angle gauge mensuration and Neighborhood Comparison, mingling, uniform angle index mensuration in stand spatial structure. The first and the second generation products have been developed with its indoor processing software, which realizes the direct input of field data into interior work software as to calculate, being free from the problems brought by paper records of field data and second inputs. II. Models, theories and accuracy testing for individual tree mensuration based on handheld smart station dendrometersModels of tree height mensuration, diameter mensuration, non-contact diameter at breast height and individual tree volume are put forward based on laser ranging, inclination mensuration and azimuth mensuration. Realizing the mensuration model on the handheld smart station dendrometer and the experiments aimed at each functionality were conducted. Experiments showed that the measurement errors of smart station dendrometers to total stations for the first product are between0.28%-1.59%. The mensuration accuracy of the second product is between20-27cm, its degree of precision is between18-27cm and its precision is between97.37%%-98.33%. CCD diameter measurement is divided into right angle photogrammetry and lean measurement and its measurement values were compared with those of diameter tape. The DBH measurement accuracy is within1cm for this method, degree of precision is between3.8mm-6.8mm.Its measurement accuracy is between96.11%～98.44%, relative error of lean measurement (between-40°and+40°)is between-5.28%～6.26%.Two methods for non-contact diameter mensuration at breast height were studied-fixed point scale mensuration and mobile angle gauge mensuration, though they aren’t ideal in precision, their feasibility of modeling, theory and implementation methods are verified. Individual tree volume measurement theory and method is put forward and experimented, however, its mensuration error is bigger for the mensuration of diameter at breast height, causing the bigger error in volume mensuration. Compared with the error of total station, its error is smaller.III. Study of the plot mensuration model, theories and functional precision testingThe plot mensuration model studied in this paper includes closed traverse calibration, coordinate measuring in the plot, polar coordinate mensuration, number density mensuration of plants, average height mensuration of forest, circle plot gauging and polygon plot measurement gauging. What is more, each function is tested. Verifying the feasibility and precision as follows:total length closing errors of closed traverse and calibration line are between1.41%～14.20%and relative error for area measurement is between-2.52%and2.32%; realization of tree coordinate mensuration in the plot and the automatic drawing of sample tree distribution map; area mensuration error of polar coordinate mensuration function is between0.85%and5.51%.The relative error between number density mensuration of plant and manual measuring is3.89%; the relative error for forest average height is5.03%.It can be draw from the data of tally in the circular plot that the relative error for stand density, stand average height, average DBH and volume is4.32%,-0.71%,-4.07%and-1.25%;as for the polygon plot mensuration, the relative error for number density mensuration of plant is between-0.76%and4.34%,and error of plot area mensuration between1.19%and2.22%, relative error for the DBH between-4.90%and-20.82%, relative error for volume evaluation between-8.96%and-18.45%.IV. Mensuration functionalities and functional precision verifying of electronic stereo angle gauges Automatic counting of angle gauge counting was realized by electronic stereo angle gauge, whose relative error is between-0.33%and-0.07%compared with traditional angle gauge counting. Tree height, DBH is measured on the angle gauge points, the evaluation of number density of plants, average height and volume in forest is realized. Results compared with the data of field individual measurement shows that the relative error for volume evaluating is-5.84%,9.10%, and0.12%for average height mensuration error. Meanwhile, problems of automatic judgment for f trees in the borderline is resolved, exempt from the trouble of tape ranging in the traditional way of judging borderline trees.V. Study on measurement models and principles of stand spatial structure parametersA way of calculating the angle between reference trees and their closest tree is put forward by measuring the coordinates between reference trees and their closest tree. Meanwhile, DBH mensuration is add according to the method of intersection angle measuring uniform angle indice. And coordinates in the tree center of the reference tree are obtained, eliminating the angle measurement error caused by the reference tree DBH in traditional angle measuring. Mingling mensuration and uniform angle mensuration are realized, and uniform angle mensuration, mingling mensuration and neighborhood comparison measurement are run in stand spatial structure, verifying it feasibility.This research provides a new portable practical multifunction technical equipment for forest mensuration, playing a role in promoting forest inventory level, promoting the integration of field work and indoor work, informatization and intelligentization. The ideal of electronization and digitization is adopted in the development, which can make sure the electronic storage of data. Field data can be directly inputted into the computer and calculated by Serial Communication Interface and multifunction is integrated, offering guidance and lessons for the development of our country’s multifunction dendrometers.