Auxiliary measuring system and method for diameter at breast height of tree

Abstract

The invention discloses a tree diameter at breast height auxiliary measurement system and method, and relates to the technical field of diameter at breast height measurement. A navigation auxiliary module is used for loading a navigation file of a corresponding measurement area before the operation of measurement personnel, and all trees in a to-be-measured state at present are selected as target trees in sequence for auxiliary navigation; the problem of target loss caused by dense trees in a measurement area by measurement personnel is thoroughly avoided, whether detour exists or not is judged by obtaining the real-time latitude and longitude of any tree reaching the target tree when the tree is determined as the target tree, and a virtual auxiliary tree is selected to be added in front of the tree according to the judgment result. When the next measurement task is executed again, a visual guide arrow is generated to navigate to the auxiliary tree firstly and then navigate to the auxiliary tree, so that the problem of navigation interference caused by misleading of the visual arrow due to the fact that the detouring requirement of the forest area cannot be recognized in traditional navigation is effectively solved, and the safety of auxiliary navigation is further improved.

Description

Technical Field

[0001] This invention relates to the field of diameter at breast height (DBH) measurement technology, specifically to an auxiliary system and method for measuring the DBH of trees. Background Technology

[0002] In forestry resource surveys, ecological monitoring, and timber reserve assessment, tree diameter at breast height (DBH) is one of the core measurement indicators. Its measurement accuracy and efficiency directly affect the overall quality and progress of forestry work. With technological advancements, the traditional method of manually carrying measuring tools to locate and measure each tree in the forest farm is no longer sufficient to meet the demands of modern forestry management for high efficiency and precision. This is due to the vast area of ​​the forest farm, the scattered distribution of trees, and the complex terrain, which results in high labor intensity, long measurement cycles, and high personnel safety risks.

[0003] To address the pain points of manual measurement, drone technology is increasingly being introduced to assist in the tree diameter at breast height (DBH) measurement process. The core application logic is as follows: a drone equipped with a positioning module and image acquisition equipment scans the entire or partial area of ​​the target forest. Based on image recognition algorithms, it identifies individual trees and extracts their location information, thereby determining the latitude and longitude coordinates of each target tree. Subsequently, the system generates navigation information based on these coordinates and assists in generating guide arrows to guide the surveyors to the target trees with their measuring tools to complete the DBH measurement. This solution uses drones to achieve rapid tree location and navigation guidance, which to some extent shortens the time spent searching for trees in the forest and improves measurement efficiency, becoming one of the mainstream auxiliary technologies in the current forestry DBH measurement field. However, when drones scan forests to determine the latitude and longitude of trees, their image acquisition and recognition logic primarily focuses on the trees themselves, lacking effective identification capabilities for terrain obstacles (such as deep ditches and dense shrubbery) prevalent within the forest. In this case, the generated guide arrows will only point to the location of the target trees, posing a risk to surveyors following this navigation path. Furthermore, if obstacles are encountered, the guide arrows will interfere with the surveyors' movement. Moreover, because the inability to effectively identify terrain obstacles means that the method of delineating the survey area does not take into account the difficulty of movement for surveyors within that area, leading to an imbalance between the actual operational difficulty and workload in different survey areas. To address the above problems, this invention proposes a solution. Summary of the Invention

[0004] The purpose of this invention is to provide an auxiliary system and method for measuring tree diameter at breast height (DBH) in order to solve the problems mentioned in the background art.

[0005] This invention provides an auxiliary system for measuring tree diameter at breast height (DBH), comprising: The overall measurement control platform is used to manage the data generated when measuring the diameter at breast height (DBH) of all trees in the target forest area. The overall measurement control platform includes a data management unit and a data analysis unit. The data management unit stores navigation files for all measurement areas in the target forest area and the identity information of the measurement personnel. The navigation files include the tree number, latitude and longitude, and measurement status of all trees in the measurement area. The navigation assistance module is used to load the navigation file received by the surveyor, determine the target tree that the surveyor needs to measure and obtain its latitude and longitude, and provide auxiliary navigation for the surveyor in conjunction with the navigation device carried by the surveyor to guide the surveyor to the target tree for diameter at breast height measurement. The navigation assistance module is also used to transmit the real-time latitude and longitude of the surveyor, which is obtained from the moment the target tree is identified until the moment the surveyor arrives at the target tree, as the measurement travel data of the target tree, together with the diameter at breast height measurement data and the tree number of the target tree, to the measurement control platform. When the data analysis unit receives measurement travel data, diameter at breast height (DBH) measurement data, and tree number for a target tree, it analyzes the measurement travel data to determine whether the surveyor detours around the tree. If detours are found, the latitude and longitude of the virtual node of the tree are determined. After receiving the latitude and longitude of a virtual node of a tree, the data management unit creates a virtual auxiliary tree for the tree in the stored navigation file containing the tree based on the latitude and longitude, uses the latitude and longitude of the virtual node as the latitude and longitude of the auxiliary tree, and generates a tree number for it. After completing the measurement tasks for all measurement areas within the target forest farm, the data management unit conducts a rationality assessment of the division of all measurement areas within the target forest farm. Based on the assessment results, several unreasonable areas are identified. The management personnel of the target forest farm then re-divide these measurement areas based on the navigation files of all the unreasonable areas. The re-divided measurement areas and their navigation files are then updated and stored in the data management unit.

[0006] Furthermore, before any surveyor performs a measurement task, the navigation assistance module obtains the identity information entered by the surveyor and transmits the identity information to the data management unit; The data management unit stores navigation files for all measurement areas within the target forest farm and the identity information of the measurement personnel. After receiving the identity information of the measurement personnel, the data management unit extracts the navigation files of the measurement personnel and transmits them to the navigation assistance module.

[0007] Furthermore, the target trees that the surveyors need to measure are determined as follows: The navigation file filters out all trees whose measurement status is pending, and the tree with the smallest tree number is selected as the target tree.

[0008] Furthermore, the following are the auxiliary navigation methods provided for surveyors: Based on the real-time latitude and longitude of the surveyor and the target tree, a visual guide arrow is generated on the navigation device's display screen. The arrow direction always dynamically points to the target tree, and the direction is adjusted in real time as the surveyor moves. The straight-line distance between the surveyor and the target tree is displayed above the arrow in the format of "XX meters".

[0009] Furthermore, the measurement data is analyzed to determine whether the surveyor detoured around the tree. If detouring is determined, the steps for determining the latitude and longitude of the virtual node of the tree are as follows: S11: Obtain the latitude and longitude of the tree from the data management unit according to the number of the received data and perform coordinate transformation to obtain the planar coordinates A1 of the tree, and create the result variable Z1 of the tree. The initial value of the result variable Z1 is 0. The latitude and longitude coordinates contained in the measurement data are sequentially transformed according to the order from the earliest to the latest time, to obtain the corresponding plane coordinates B1, B2, ..., Bb, where b is the total number of latitude and longitude coordinates contained in the measurement data. S12: Establish a Cartesian coordinate system with (0, 0) as the origin. Select the horizontal rightward direction as the x-axis and extend it from the origin. Select the vertical upward direction as the y-axis and extend it from the origin. Based on the planar coordinates A1, B1, ..., Bb, find the corresponding coordinate points in the Cartesian coordinate system, and label them as C1, C2, ..., Cb+1; S13: Determine the deflection angle D1 of plane coordinate B1 relative to plane coordinate A1 and the straight-line distance E1 based on coordinate points C1 and C2. The formula for calculating the deflection angle is D1 = arctan(|y1-y2| / |x1-x2|), and the formula for calculating the straight-line distance E1 is... ; where x1 and y1 are the x and y coordinates of the corresponding points of plane coordinate A1 in the plane rectangular coordinate system, respectively, and x2 and y2 are the x and y coordinates of the corresponding points of plane coordinate B1 in the plane rectangular coordinate system, respectively; S14: According to S13, determine the deflection angle D2 and straight-line distance E2 of plane coordinate B2 relative to plane coordinate A1 based on coordinate points C1 and C3; S15: Based on coordinate points C1 and C2, determine whether the result variable Z1 should be incremented by 1, as follows: Calculate the difference F1 between the deviation angles D1 and D2, and the difference F2 between the straight distances E1 and E2. Compare F1 with P1 and F2 with the interval [P2, P3]. If F1 > P1 and F2 ∉ [P2, P3], increment the value of the result variable Z1. At the same time, obtain the latitude and longitude of the plane coordinates corresponding to the coordinate point C2 in the Cartesian coordinate system. Use the latitude and longitude as the latitude and longitude of the result variable Z1 for this change. Otherwise, do not perform any processing. P1 is the preset standard travel angle threshold, and its value is based on the deflection angle D1, the preset standard travel speed, and the stride setting. In the interval [P2, P3], the left endpoint P2 and the right endpoint P3 are the preset minimum and maximum single movement distances, respectively. S16: Following S13 to S15, based on coordinate points C2 and C3, C3 and C4, ..., Cb and Cb+1, determine whether the result variable Z1 should be incremented by 1, and obtain the final value D1 of the result variable Z1. Compare D1 and P4. If D1 > P4, it is determined that there is a detour between the surveyor and the tree. At this time, the latitude and longitude with the largest difference between the converted coordinate point and the deflection angle D1 is selected from the latitude and longitude of the result variable Z1 that has changed continuously multiple times as the virtual node of the tree. Otherwise, it is determined that there is no detour between the surveyor and the tree. P4 is the preset detour determination threshold.

[0010] Furthermore, during the navigation file loading process, if a tree has an auxiliary tree, a visual guide arrow is generated to guide the surveyor to the tree. The arrow direction initially points dynamically to the auxiliary tree, and when the surveyor reaches the auxiliary tree, the visual guide arrow direction dynamically points to the tree.

[0011] Furthermore, the rationality assessment for any given measurement area includes the following: Obtain the number of virtual nodes of trees in the measurement area, G1, and compare G1 with P5. If G1 ≥ P5, it is determined that detours in the measurement area have a significant impact on the measurement task of the measurement area, and the measurement area is marked as an unreasonable area. Otherwise, it is determined that detours in the measurement area have no impact on the measurement task of the measurement area or can be ignored.

[0012] A method for auxiliary measurement of tree diameter at breast height (DBH) includes the following steps: Step 1: Before performing a measurement task, any surveyor must first enter their identity information, which will be acquired by the navigation assistance module and transmitted to the data management unit. Step 2: After receiving the transmitted identity information, the data management unit extracts the navigation file of the surveyor and transmits it to the navigation assistance module; Step 3: The navigation assistance module loads the received navigation file, determines the target tree that the surveyor needs to measure, and obtains its latitude and longitude. Combined with the navigation device carried by the surveyor, the module provides navigation assistance to guide the surveyor to the target tree for diameter at breast height measurement. Step 4: After the surveyor completes the diameter at breast height (DBH) measurement of the target tree, the navigation assistance module obtains the DBH measurement data of the target tree. It uses the real-time latitude and longitude of the surveyor, which is obtained from the moment the target tree is identified until the moment the surveyor arrives at the target tree, as the measurement movement data of the target tree. This data, along with the DBH measurement data and the tree number of the target tree, is transmitted to the measurement control platform. Step 5: When the data analysis unit receives measurement travel data, diameter at breast height (DBH) measurement data, and tree number for a target tree, it analyzes the measurement travel data to determine whether the surveyor detours around the tree. If detours are found, the latitude and longitude of the virtual node of the tree are determined and transmitted to the data management unit. Step Six: After receiving the latitude and longitude of a virtual node of a tree, the data management unit creates a virtual auxiliary tree for the tree in the stored navigation file containing the tree based on the latitude and longitude, uses the latitude and longitude of the virtual node as the latitude and longitude of the auxiliary tree, and generates a tree number for it. Step 7: After all the measurement tasks in all measurement areas within the target forest farm have been completed, the data management unit will conduct a rationality assessment of the division of all measurement areas in the target forest farm. Based on the assessment results, several unreasonable areas will be identified. The management personnel of the target forest farm will then re-divide the several measurement areas of the target forest farm based on the navigation files of all the unreasonable areas. The re-divided measurement areas and their navigation files will be updated and stored in the data management unit.

[0013] Compared with existing technologies, it has the following advantages: This invention utilizes a navigation assistance module to acquire and load a navigation file representing the measurement area within a target forest before the surveyor begins their measurement task. During loading, all trees currently awaiting measurement are sequentially selected as target trees based on their tree numbers. The system provides navigation assistance as the surveyor reaches each target tree in sequence. After measuring the diameter at breast height (DBH) of a target tree, the measurement status of that tree is updated. This approach completely avoids the problem of surveyors getting lost due to dense tree cover within the measurement area, eliminating missed measurements at the source. Furthermore, through explicit tree-by-tree navigation, it significantly reduces ineffective walking time and substantially improves the overall efficiency of the measurement task. This invention uses a navigation device carried by the surveyor to obtain the latitude and longitude from when any tree is identified as a target tree until the surveyor reaches the tree. It then determines whether the surveyor needs to detour between reaching the tree and the target tree. Based on the determination result, a virtual auxiliary tree is added in the navigation file before the target tree. When the next survey task is executed and navigation to the target tree is required, a visual guide arrow is generated to first navigate to the auxiliary tree to remind the surveyor that a detour is needed. Once the surveyor reaches the auxiliary tree, the navigation then proceeds to the auxiliary tree. This method effectively avoids the navigation interference problem caused by the visual arrow being misleading due to the inability of traditional navigation to recognize detour requirements in forest areas, and further improves the safety of assisted navigation. This invention assesses the rationality of all measurement areas within the target forest farm after all surveyors have completed their measurement tasks, based on the number of measurement areas that need to be detoured. Unreasonable areas are then identified and redefined by the forest farm management personnel to ensure that the actual operational difficulty and workload of each measurement area remain balanced. Attached Figure Description

[0014] Figure 1 This is a system block diagram of the present invention; Figure 2 This is a flowchart of the method of the present invention. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Please see Figure 1 , Figure 2 This application provides a tree diameter at breast height (DBH) auxiliary measurement system and method, including a navigation auxiliary module and a measurement control platform; The navigation assistance module is used to assist surveyors in navigating to the target tree to complete the diameter at breast height (DBH) measurement in real time. Before performing a measurement task, any surveyor first enters their identity information, which is then acquired by the navigation assistance module and transmitted to the overall measurement control platform. The identity information includes, but is not limited to, name, ID number, and personnel-tree number. The personnel-tree number is a unique identifier assigned to each surveyor, consisting of a letter prefix and a combination of numbers, such as RY-001, which is used to associate the surveyor with the corresponding measurement area and navigation file. It should be noted that for any given measurement area, the entrance that the surveyor enters when performing a measurement task in the measurement area is fixed, that is, the location where the surveyor obtains the navigation file for the measurement area is the same. After receiving the transmitted identity information, the measurement control platform transmits it to the data management unit. The data management unit extracts the navigation file of the surveyor based on the received identity information and transmits it to the navigation assistance module. The navigation file includes the tree number, latitude and longitude, measurement status, and items to be measured for all trees in the measurement area. The measurement status is divided into two types: to be measured and measured. The format of the navigation file can be either JSON or CSV. It should be noted that, by default, all trees in the navigation files transmitted from the measurement control platform are in the measurement status as pending measurement. In this application, the item to be measured is diameter at breast height (DBH). In this application, the tree number consists of two parts: area identifier and tree identifier. For example, the tree numbers in measurement area 1 are T1-001, T1-002, ..., where T1 is the area identifier of measurement area 1 and 001 is the tree identifier of the first tree in measurement area 1 that needs to be measured for diameter at breast height. In this application, the smaller the value of the tree identifier in the tree number, the higher the priority of the tree's diameter at breast height measurement. After receiving the transmitted navigation file, the navigation assistance module first parses its format and loads its data. After loading, it determines the target trees that the surveyor needs to measure based on the navigation file. The determined content is as follows: Filter out all trees in the navigation file whose measurement status is to be measured, and select the tree with the smallest tree number as the target tree, and obtain the latitude and longitude of the target tree; The surveyor's latitude and longitude are obtained in real time using a navigation device carried by the surveyor. This latitude and longitude are then combined with those of the target tree to provide auxiliary navigation, guiding the surveyor to the target tree. The auxiliary navigation content is as follows: Based on the real-time latitude and longitude of the surveyor and the target tree, a visual guide arrow is generated on the display screen of the navigation device. The arrow direction always dynamically points to the target tree and adjusts its direction in real time as the surveyor moves. The straight-line distance between the surveyor and the target tree is displayed above the arrow in the format of "XX meters". Once the surveyor reaches the target tree, the diameter at breast height (DBH) of the target tree is measured using a measuring device to obtain the DBH measurement data. The real-time latitude and longitude of the surveyor, obtained from the moment the target tree is identified until the moment the surveyor reaches the target tree, is used as the measurement movement data of the target tree. This data, along with the DBH measurement data and the tree number of the target tree, is transmitted to the measurement control platform. The measurement data also includes the acquisition time corresponding to the latitude and longitude. In this application, the measuring device is a DBH measuring tape. Synchronously, the navigation assistance module updates the navigation file within it, changing the "to be measured" status of the target trees in the navigation file to "measured". After the modification is completed, the navigation assistance module continues to determine the next target tree according to the updated navigation file, until all target trees in the measurement area are determined as target trees and the diameter at breast height measurement is completed. The overall measurement control platform is used to manage the data generated when measuring the diameter at breast height (DBH) of all trees in the target forest area. The overall measurement control platform includes a data management unit and a data analysis unit. The data management unit stores navigation files for all measurement areas within the target forest area, along with the identity information of the surveyors. The process for generating the initial navigation file for any measurement area is as follows: The drone flies within the measurement area according to the pre-input flight trajectory to complete the scanning of the measurement area. During the scanning process, the drone will carry out data collection work simultaneously with multiple sensor devices, including but not limited to acquiring forest-related data through LiDAR and high-resolution optical cameras, and recording the coordinates of sampling points in combination with GNSS positioning module to ensure that core data such as tree number, latitude and longitude can be accurately generated in subsequent navigation files. After the scanning task is completed, the collected multi-source data is processed by the backend to form a navigation file of the measurement area containing all tree numbers, latitude and longitude, measurement status and items to be measured. The file is then packaged in a standard format and stored in the data management unit. It should be noted that the initial division of the target forest area was done by the management personnel, who divided the target forest area into several measurement areas according to the size of the target forest area, the number of trees to be measured, and the topographical boundaries within the target forest area, and assigned measurement personnel to each measurement area. When the measurement control platform receives measurement movement data, diameter at breast height (DBH) measurement data, and tree number for a target tree, it transmits them to the data analysis unit. Upon receiving the same data, the data analysis unit first stores the DBH measurement data and then analyzes the movement data to determine if the surveyor has detoured between the trees. If detouring is found, the latitude and longitude of the virtual node of the tree are determined. The analysis steps are as follows: S11: Obtain the latitude and longitude of the tree from the data management unit according to the tree number received in the data and perform coordinate transformation to obtain the planar coordinates A1 of the tree, and create the result variable Z1 of the tree. The initial value of the result variable Z1 is 0. The latitude and longitude coordinates contained in the measurement data are sequentially transformed according to the order from the earliest to the latest time, to obtain the corresponding plane coordinates B1, B2, ..., Bb, where b is the total number of latitude and longitude coordinates contained in the measurement data. S12: Establish a Cartesian coordinate system with (0, 0) as the origin. Select the horizontal rightward direction as the x-axis and extend it from the origin. Select the vertical upward direction as the y-axis and extend it from the origin. Based on the planar coordinates A1, B1, ..., Bb, find the corresponding coordinate points in the Cartesian coordinate system, and label them as C1, C2, ..., Cb+1; S13: Determine the deflection angle D1 of plane coordinate B1 relative to plane coordinate A1 and the straight-line distance E1 based on coordinate points C1 and C2. The formula for calculating the deflection angle is D1 = arctan(|y1-y2| / |x1-x2|), and the formula for calculating the straight-line distance E1 is... ; where x1 and y1 are the x and y coordinates of the corresponding points of plane coordinate A1 in the plane rectangular coordinate system, respectively, and x2 and y2 are the x and y coordinates of the corresponding points of plane coordinate B1 in the plane rectangular coordinate system, respectively; S14: According to S13, determine the deflection angle D2 and straight-line distance E2 of plane coordinate B2 relative to plane coordinate A1 based on coordinate points C1 and C3; S15: Based on coordinate points C1 and C2, determine whether the result variable Z1 should be incremented by 1, as follows: Calculate the difference F1 between the deviation angles D1 and D2, and the difference F2 between the straight distances E1 and E2. Compare F1 with P1 and F2 with P2. If F1 > P1 and F2 ∉ [P2, P3], increment the value of the result variable Z1. At the same time, obtain the latitude and longitude of the plane coordinates corresponding to the coordinate point C2 in the Cartesian coordinate system. Use the latitude and longitude as the latitude and longitude of the result variable Z1 for this change. Otherwise, do not perform any processing. P1 is the preset standard travel angle threshold. Its value is based on the deflection angle D1, the preset standard travel speed, and the stride setting. In the interval [P2, P3], the left and right endpoints are the preset minimum and maximum single movement distances, respectively. The speed and stride settings are based on the preset standards. S16: Following S13 to S15, based on coordinate points C2 and C3, C3 and C4, ..., Cb and Cb+1, determine whether the result variable Z1 should be incremented by 1, and obtain the final value D1 of the result variable Z1. Compare D1 and P4. If D1 > P4, it is determined that there is a detour between the surveyor and the tree. In this case, select the latitude and longitude with the largest difference between the converted coordinate point and the deflection angle D1 from the latitude and longitude of the continuously changing result variable Z1 as the virtual node of the tree. It should be noted that if there are several continuously changing result variables Z1, the latitude and longitude with the largest difference is selected as the latitude and longitude of the virtual node of the tree. Otherwise, it is determined that there is no detour between the surveyor and the tree. P4 is a preset detour determination threshold. The data analysis unit determines the latitude and longitude of a virtual node for each tree and transmits it to the data management unit. The data management unit creates a virtual auxiliary tree for the tree in the navigation file containing the tree based on the latitude and longitude. The latitude and longitude of the virtual node are used as the latitude and longitude of the auxiliary tree. Based on the tree number, the tree number is decremented by 1 and used as the tree number of the auxiliary tree. The tree number of the remaining trees is incremented by 1 in sequence. It should be noted that the auxiliary trees in the navigation file only have tree numbers and latitude and longitude, and do not have measurement status or items to be measured; the system can use this to distinguish between trees and auxiliary trees. It should be noted that during the navigation file loading process, if there are auxiliary trees for a tree, the generated visual guidance arrow will first dynamically point to the auxiliary tree while guiding the surveyor to the tree. When the surveyor reaches the auxiliary tree, the visual guidance arrow will then dynamically point to the tree to help the surveyor automatically avoid obstacles, improve the practicality of the assisted navigation, and avoid navigation interference caused by the assisted navigation failing to recognize obstacles. After all measurement tasks within the target forest area have been completed, the data management unit will conduct a rationality assessment of the division of all measurement areas within the target forest area. The rationality assessment for any given measurement area includes the following: Obtain the number of virtual nodes of trees in the measurement area, G1, and compare G1 with P5. If G1 ≥ P5, it is determined that detours in the measurement area have a significant impact on the measurement task of the measurement area, and the measurement area is marked as an unreasonable area. Otherwise, it is determined that detours in the measurement area have no impact on the measurement task of the measurement area or can be ignored. P5 is a preset standard impact quantification value. All areas marked as unreasonable and their navigation files are displayed to the management personnel of the target forest farm. The management personnel then re-divide the measurement area of ​​the target forest farm based on all the virtual auxiliary trees in these unreasonable areas. All the re-divided measurement areas and their navigation files are updated and stored in the data management unit. It should be noted that the management personnel only divide the measurement area according to the number and type of trees in the measurement area. Therefore, the auxiliary trees still exist when measuring individual trees, and can still help the surveyors automatically avoid obstacles when the next measurement task is started.

[0017] Some of the data in the above formulas are numerical calculations with dimensions removed, and the contents not described in detail in this specification are all prior art known to those skilled in the art.

[0018] The above embodiments are only used to illustrate the technical methods of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical methods of the present invention without departing from the spirit and scope of the technical methods of the present invention.

Claims

1. A tree girth auxiliary measuring system, characterized by, The application relates to a measurement control platform for managing data generated when the diameters of all trees in a target forest are measured, the measurement control platform comprising a data management unit and a data analysis unit, the data management unit storing navigation files of all measurement areas in the target forest and identity information of measurement personnel, the navigation files comprising tree numbers, longitude and latitude of all trees in the measurement areas and measurement states. The navigation auxiliary module is used for loading the navigation files of the measurement personnel after receiving the navigation files, determining target trees to be measured by the measurement personnel, and obtaining longitude and latitude of the target trees, and the navigation auxiliary module is used for assisting navigation of the measurement personnel and guiding the measurement personnel to the target trees for diameter measurement in combination with navigation equipment carried by the measurement personnel. The navigation auxiliary module is also used for transmitting real-time longitude and latitude of the measurement personnel during a period from a time point of determining the target trees to a time point of the measurement personnel reaching the target trees as measurement travel data of the target trees to the data analysis unit together with diameter measurement data of the target trees and tree numbers. The data analysis unit is used for analyzing the measurement travel data of the target trees when the data analysis unit receives the measurement travel data, the diameter measurement data and the tree numbers of the target trees, and determining whether the measurement personnel travels around the target trees, and the data analysis unit is used for determining longitude and latitude of a virtual node of the target trees when it is determined that the measurement personnel travels around the target trees. The data management unit is used for creating a virtual auxiliary tree for the target trees in the navigation files of the target trees according to the longitude and latitude of the virtual node of the target trees when the data management unit receives the longitude and latitude of the virtual node of the target trees, and the data management unit is used for generating tree numbers of the virtual auxiliary trees and taking the longitude and latitude of the virtual node as the longitude and latitude of the virtual auxiliary trees. The data management unit is used for reasonably evaluating division of all measurement areas in the target forest after all measurement tasks of the measurement areas are completed, obtaining a plurality of unreasonable areas based on the evaluation results, and re-dividing a plurality of measurement areas of the target forest based on navigation files of the all unreasonable areas by management personnel of the target forest, and the data management unit is used for updating and storing the plurality of measurement areas and the navigation files after the plurality of measurement areas are divided. The navigation auxiliary module is used for obtaining identity information input by the measurement personnel before any measurement personnel performs a measurement task, and the navigation auxiliary module is used for transmitting the identity information to the data management unit.

2. The tree diameter auxiliary measuring system according to claim 1, wherein, The data management unit stores navigation files of all measurement areas in the target forest and identity information of measurement personnel, and the data management unit extracts the navigation files of the measurement personnel and transmits the navigation files to the navigation auxiliary module after receiving the identity information of the measurement personnel. The target trees to be measured by the measurement personnel are determined as follows:

3. The tree diameter auxiliary measuring system according to claim 1, wherein, All trees with a measurement state of to-be-measured are selected from the navigation files, and a tree with a minimum tree number value is selected as the target tree from the selected trees. The navigation auxiliary module is used for assisting navigation of the measurement personnel as follows:

4. The tree diameter auxiliary measuring system according to claim 1, wherein, ​ According to the real-time measurement personnel's latitude and longitude and the target tree's latitude and longitude, a visual guide arrow is generated in the navigation device's display screen, the arrow direction is always dynamically pointing to the target tree, and the direction is adjusted in real time with the measurement personnel's movement, and the measurement personnel's straight-line interval distance from the target tree is displayed above the arrow in the format of "X.X meters".

5. The tree diameter auxiliary measuring system according to claim 1, wherein, The measurement travel data is analyzed to determine whether the measurement personnel travels around the trees, and if it is determined that there is a roundabout, the latitude and longitude of the virtual node of the tree is determined as follows: S11: According to the received data number, the latitude and longitude of the tree is obtained from the data management unit and is coordinate-converted to obtain the plane coordinates A1 of the tree, and a result variable Z1 of the tree is created, and the initial value of the result variable Z1 is 0; According to the order from far to near of the distance between the collection time and the current time, all the latitudes and longitudes contained in the measurement travel data are sequentially coordinate-converted to obtain the corresponding plane coordinates B1, B2,..., Bb, b is the total number of latitudes and longitudes contained in the measurement travel data; S12: A plane rectangular coordinate system is established with (0, 0) as the coordinate origin, the horizontal right direction is selected as the x-axis direction, and the vertical upward direction is selected as the y-axis direction; According to the plane coordinates A1, B1,..., Bb, the corresponding coordinate points in the plane rectangular coordinate system are found in sequence, and are marked as C1, C2,..., Cb+1; S13: determining the deflection angle D1 and the straight line distance E1 of the plane coordinate B1 relative to the plane coordinate A1 according to the coordinate points C1 and C2, the calculation formula of the deflection angle is D1=arctan(|y1-y2| / |x1-x2|), and the calculation formula of the straight line distance E1 is ; wherein x1 and y1 are respectively the horizontal and vertical coordinate values of the coordinate point corresponding to the plane coordinate A1 in the plane rectangular coordinate system, and x2 and y2 are respectively the horizontal and vertical coordinate values of the coordinate point corresponding to the plane coordinate B1 in the plane rectangular coordinate system. S14: According to S13, the deflection angle D2 and the straight-line distance E2 of the plane coordinate B2 relative to the plane coordinate A1 are determined based on the coordinate points C1 and C3; S15: Based on the coordinate points C1 and C2, it is determined whether the result variable Z1 is increased by 1, and the content is as follows: The difference F1 between the deviation angles D1 and D2 and the difference F2 between the straight-line distances E1 and E2 are calculated, and F1 and P1, F2 and the interval [P2, P3] are compared, if F1>P1 and F2∉[P2, P3], the value of the result variable Z1 is increased, and the latitude and longitude of the plane coordinate corresponding to the coordinate point C2 is converted as the latitude and longitude of the value of the result variable Z1 changed this time, otherwise, no processing is performed, P1 is a preset standard travel angle threshold, the value of which is set based on the deflection angle D1, a preset standard travel speed, and a step, and the left end point P2 and the right end point P3 in the interval [P2, P3] are the preset minimum and maximum single movement distances respectively; S16: According to S13 to S15, it is determined whether the result variable Z1 is increased by 1 based on the coordinate points C2 and C3, C3 and C4,..., Cb and Cb+1 in sequence, and the final value D1 of the result variable Z1 is obtained, and D1 and P4 are compared, if D1>P4, it is determined that the measurement personnel travels around the trees, at this time, the latitude and longitude of the coordinate point converted from the continuously changed latitude and longitude of the result variable Z1 and the difference between the deflection angles D1 is selected as the virtual node of the tree, otherwise, it is determined that the measurement personnel does not travel around the trees, P4 is a preset roundabout determination threshold.

6. The tree diameter auxiliary measuring system according to claim 1, wherein, In the navigation file loading process, if a tree has an auxiliary tree, in the process of guiding the measurer to the tree, the generated visual guide arrow is first dynamically pointed to the auxiliary tree, and when the measurer reaches the auxiliary tree, the arrow direction of the visual guide arrow is dynamically pointed to the tree.

7. The tree diameter auxiliary measuring system according to claim 1, wherein, The content of the rationality evaluation of any one measurement area is as follows: Obtain the number G1 of the latitude and longitude of the virtual node of the tree in the measurement area stored, compare G1 and P5 in size, if G1≥P5, determine that the roundabout in the measurement area has a greater impact on the measurement task of the measurement area, and mark the measurement area as an unreasonable area, otherwise, determine that the roundabout in the measurement area has no effect or negligible effect on the measurement task of the measurement area.

8. A method for measuring the diameter of a tree trunk, using a system for measuring the diameter of a tree trunk according to any one of claims 1 to 7, characterized in that, It comprises the following steps: Step one: before any measurer executes a measurement task, first enter his / her identity information, which is acquired by the navigation assistance module and transmitted to the data management unit; Step two: after the data management unit receives the transmitted identity information, extract the navigation file of the measurer and transmit it to the navigation assistance module; Step three: the navigation assistance module loads the received navigation file and determines the target tree that the measurer needs to measure and obtains its latitude and longitude, and assists the navigation of the measurer in combination with the navigation equipment carried by the measurer to guide the measurer to reach the target tree for diameter at breast height measurement; Step four: after the navigation assistance module obtains the diameter at breast height measurement data of the target tree after the measurer completes the diameter at breast height measurement of the target tree, the real-time latitude and longitude of the measurer during the period from the time when the target tree is determined to the time when the measurer reaches the target tree is transmitted to the data analysis unit as the measurement travel data of the target tree, the diameter at breast height measurement data and the tree number; Step five: the data analysis unit analyzes the measurement travel data of each tree received as the target tree, determines whether the measurer travels around the tree, and if it is determined that there is a roundabout, determines the latitude and longitude of the virtual node of the tree, and transmits the latitude and longitude to the data management unit; Step six: the data management unit creates a virtual auxiliary tree for the tree in the navigation file containing the tree according to the latitude and longitude of the virtual node of the tree received each time, and generates a tree number for the virtual node as the latitude and longitude of the auxiliary tree; Step seven: after the measurement tasks of all measurement areas in the target forest are completed, the data management unit evaluates the rationality of the division of all measurement areas of the target forest, and obtains a number of unreasonable areas based on the evaluation result. The management personnel of the target forest redivide a number of measurement areas based on the navigation files of all unreasonable areas, and update the divided a number of measurement areas and their navigation files in the data management unit.

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