CN114415204A - Tree breast-height diameter obtaining method based on mobile phone laser radar - Google Patents
Tree breast-height diameter obtaining method based on mobile phone laser radar Download PDFInfo
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- CN114415204A CN114415204A CN202210225033.0A CN202210225033A CN114415204A CN 114415204 A CN114415204 A CN 114415204A CN 202210225033 A CN202210225033 A CN 202210225033A CN 114415204 A CN114415204 A CN 114415204A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/88—Lidar systems specially adapted for specific applications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/08—Measuring arrangements characterised by the use of optical techniques for measuring diameters
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/4802—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
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Abstract
The application discloses a tree breast height diameter obtaining method based on a mobile phone laser radar, which comprises the following steps: selecting ground characteristic points on a forest to be detected as three-dimensional coordinate reference points to establish a three-dimensional coordinate system; a terminal carrying a built-in laser radar measures the breast-height diameter of the tree to obtain data breast-height diameter data; and determining final measurement data by combining the acquired breast diameter data with the information of the measuring staff, the time information, the tree species ID and the three-dimensional coordinate system. Through the simple and fast operation of similar shooting, the breast-height diameter and the stem base three-dimensional coordinate parameters of the forest trees are directly and efficiently acquired, stored and processed, a geographic space data set is constructed, the integration level, the structuralization, the popularization and the fusion applicability of the data are improved, and the forest manager and the forest ecological environment research are facilitated. Meanwhile, centimeter-level positioning can be realized by matching with an RTK technology, so that the aims of improving the working efficiency of field investigation of a forest manager and assisting in forest carbon sink accounting and evaluation are fulfilled.
Description
Technical Field
The application relates to the technical field of tree monitoring, in particular to a tree breast height diameter obtaining method based on a mobile phone laser radar.
Background
In recent years, with the development of 3s technology and the development and innovation of new technology, new idea and new state of the internet + intelligent forestry, forest natural resource survey has advanced with great development and innovation in many technical aspects, but many methods and tools in forest resource monitoring and evaluation are still more traditional, and have high cost in time, capital, manpower and material resources, and the like, but the efficiency is low, which seriously hinders the promotion of the work of natural resource protection, ecological and resource evaluation, evaluation and the like, especially under the large background of global climate change of global warming and increasing of greenhouse benefit, forest carbon sink has been generally accepted by all the communities as one of the most effective, most economical and most sustainable approaches for improving the deterioration trend.
Taking the measurement of the breast height diameter of a tree in forest investigation as an example, the existing ground measurement technology can be divided into two categories according to whether the tree to be measured is contacted or not: contact measurement and non-contact measurement, the ground contact measurement (circumference ruler, wheel ruler) is the most primitive, and is the most widely applied method at present; most non-contact equipment devices are complex in system, multiple in auxiliary conditions, poor in handedness, high in learning and using cost, high in price and single in applicable scene, most of the non-contact equipment devices are only suitable for application scenes such as artificial forests or nurseries and the like which are regularly planted and simple in terrain environment, and the popularization and application performance is poor.
The traditional method has obvious technical lag and defects mainly in the following aspects. The traditional method is characterized in that in the aspect of data acquisition: the tools are simple and crude or heavy, and the function is single, so that the tool is not beneficial to carrying and using in the field. The manual plant-by-plant measurement has large workload and low efficiency. When tools such as a surrounding ruler, a wheel ruler and the like are used for measurement, procedures such as operation, reading, recording and the like are inconvenient, the subjectivity is strong, the error is large, and the error is easy to make mistakes. The data recording form by handwriting with a paper pen is not visual, and the data recording form is missed and inconvenient to modify and check. Paper records and field investigation are easy to damage, pollute or lose, and the data security is poor. In terms of data processing: the data recording, reading and recording work is repeated, the workload is large, and errors are easy to occur. Different time sequence data are difficult to compare and analyze. In terms of data quality: the biggest disadvantage is large artificial operation error and strong subjectivity.
Disclosure of Invention
In order to solve the technical problems, the following technical scheme is provided:
in a first aspect, an embodiment of the present application provides a tree breast height diameter obtaining method based on a mobile laser radar, where the method includes: selecting ground characteristic points on a forest to be detected as three-dimensional coordinate reference points to establish a three-dimensional coordinate system; a terminal carrying a built-in laser radar measures the breast-height diameter of the tree to obtain data breast-height diameter data; and determining final measurement data by combining the acquired breast diameter data with the information of the measuring staff, the time information, the tree species ID and the three-dimensional coordinate system.
By adopting the implementation mode, the breast-height diameter and stem base three-dimensional coordinate parameters of the forest trees can be directly and efficiently acquired, stored and processed through simple and quick operation similar to photographing, a geographic space data set is constructed, the integration level, the structuralization, the popularization and the fusion applicability of data are improved, and the forest manager and the forest ecological environment research are facilitated. Meanwhile, centimeter-level positioning can be realized by matching with an RTK technology, so that the aims of improving the working efficiency of field investigation of a forest manager and assisting in forest carbon sink accounting and evaluation are fulfilled.
With reference to the first aspect, in a first possible implementation manner of the first aspect, the measuring the breast height diameter of the tree by the terminal with the built-in laser radar to obtain data breast height diameter data includes: constructing a trunk model and a measuring environment; calculating and identifying the chest diameter measuring position on the trunk; determining a plurality of intermediate parameters in the measurement of the breast-height diameter of the tree; and determining the final tree breast diameter according to the acquired intermediate measurement.
With reference to the first possible implementation manner of the first aspect, in a second possible implementation manner of the first aspect, the constructing a measurement environment includes: setting the cross section position of the chest diameter measurement value position at 1.3m on the longitudinal (growth direction) geometric central axis above the trunk stem base; approximately generalizing the trunk cross-sectional shape to a circle; defining the circular radius of the cross section to be measured of the trunk diameter at breast height; determining the radius of a trunk cross section circle where an intersection point of a laser beam vertically emitted by a mobile phone laser radar in shooting and a projection of a trunk central longitudinal geometric central axis of a trunk diameter to-be-measured cross section central point on the surface of one trunk shooting side is located; a circular radius of a cross section of a trunk stem base (a cross section position where a trunk intersects with the ground) is defined.
With reference to the first or second possible implementation manner of the first aspect, in a third possible implementation manner of the first aspect, the constructing a trunk model includes: determining the projection of a central longitudinal geometric central axis of a trunk, where a cell phone laser radar emission point and a central point of a cross section to be detected are located, on the surface of one side of the trunk shooting; determining a first axis formed by a set of points of tangency of the trunk surface on the right side in the shooting direction and the laser radar emission beam (the laser radar scans from the shooting point to the trunk direction, and the axis formed by a row of points on the outermost side of the trunk surface can be identified); determining a second axis formed by a set of points of tangency of the trunk surface on the left side of the shooting direction and the laser radar emission beam (the laser radar scans from the shooting point to the trunk direction, and the axis formed by a row of points on the outermost side of the trunk surface can be identified); respectively determining a first intersection point, a second intersection point and a third intersection point of the cross section circle at the junction of the trunk and the ground, the plane where the mobile phone laser horizontal beam is located, the cross section circle at 1.3m of the trunk to be measured and the projection; and respectively determining the first intersection point, the second intersection point, the third intersection point and the intersection points of the first axis and the second axis.
With reference to the third possible implementation manner of the first aspect, in a fourth possible implementation manner of the first aspect, the calculating and identifying a chest diameter measurement position on a trunk includes: automatically modeling and identifying the position of a tree stem base (the position of a cross section where the tree stem is connected with the ground) through laser radar scanning and a visual algorithm; meanwhile, calculating and identifying a projection axis of a longitudinal (growing direction) geometric central axis of a part of the trunk shot in the viewfinder on the surface of the trunk on the shooting side; and calculating the position of the cross section of the trunk with the height of 1.3 meters by using a trigonometric function sine theorem.
With reference to the first aspect or any one of the first to fourth possible implementation manners of the first aspect, in a fifth possible implementation manner of the first aspect, the selecting, from the forest to be tested, the ground feature point as a three-dimensional coordinate reference point to establish a three-dimensional coordinate system includes: randomly selecting ground characteristic points which are convenient to measure and easy to identify and search in or around the forest land block to be measured and have obvious positions; the ground characteristic point is used as the origin of a relative coordinate system for next data acquisition of all users and is also used as one of coordinate points required by the RTK equipment for converting the correction of the relative coordinate into an absolute coordinate; meanwhile, subsequent points are uniformly distributed in the whole area of the forest land to be detected as much as possible, and all the selected reference points need to be acquired by the mobile phone according to the relative three-dimensional coordinate data.
With reference to the fifth possible implementation manner of the first aspect, in a sixth possible implementation manner of the first aspect, a measurer stands in any direction of a tree to be measured, is within 5 meters from the position of the trunk, keeps the mobile phone vertical to the ground relatively, and aims at the position between 1 and 1.5 meters of the height of the trunk, so as to ensure that all parts of the tree from the stem base to the 1.3 meter diameter-chest measurement part fall into a camera lens viewing frame, and the shooting approximate direction is along the vertical direction.
With reference to the sixth possible implementation manner of the first aspect, in a seventh possible implementation manner of the first aspect, the determining final measurement data by combining the acquired chest diameter data with the staff information, the time information, the tree seed ID, and the three-dimensional coordinate system includes: in the measuring process, each user mobile phone end APP can record measuring personnel ID, tree species ID, measuring time and measuring sequence (code) besides acquiring the chest diameter value and the trunk base three-dimensional coordinate value of each tree, wherein the user ID and the tree species ID need to be manually input, and other parameters can be automatically identified, generated and acquired; and fusing the acquired data to obtain tree breast-height diameter measurement data.
With reference to the seventh possible implementation manner of the first aspect, in an eighth possible implementation manner of the first aspect, the mobile phone end performs lightweight processing on the obtained breast diameter measurement, and can also perform cloud computing through the cloud server under the condition of having a mobile network, so as to generate a digital elevation model of a measured land block, a measurement sequence plane path diagram (a numbered tree trunk base plane coordinate position connection diagram), a tree composite terrain 3D model, forest stand area computing, forest stand density computing, forest stand carbon storage capacity, carbon density computing, data visualization chart analysis, and provide a specific display interface corresponding to each function and result in real time.
With reference to the eighth possible implementation manner of the first aspect, in a ninth possible implementation manner of the first aspect, a user may synchronously download field acquired data from a cloud, check and supervise measurement work in real time, and perform deep data analysis and data visualization processing with reference to related data analysis and a geographic information management tool; through planned data acquisition and storage, different time sequence data comparison analysis is carried out, and important key information such as forest growth parameter time sequence change monitoring analysis, forest productivity, carbon reserves, carbon density dynamic change monitoring, carbon sink potential prediction and the like can be provided.
Drawings
Fig. 1 is a schematic flow chart of a tree breast height diameter obtaining method based on a mobile phone laser radar according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a model building and measurement environment setup provided in an embodiment of the present application;
FIG. 3 is a schematic diagram of a measurement provided by an embodiment of the present application;
FIG. 4 is a schematic diagram of measurements provided by an embodiment of the present application;
fig. 5 is a schematic diagram of identifying a chest diameter position according to an embodiment of the present application;
FIG. 6 is a schematic view of a breast diameter measurement provided by an embodiment of the present application;
FIG. 7 is a schematic diagram of an intermediate parameter measurement provided in an embodiment of the present application;
FIG. 8 is a schematic diagram of solving intermediate parameters according to an embodiment of the present application;
FIG. 9 is a schematic diagram of solving intermediate parameters according to an embodiment of the present application;
FIG. 10 is a schematic diagram of solving intermediate parameters and target parameters according to an embodiment of the present application;
FIG. 11 is a schematic diagram of solving intermediate parameters according to an embodiment of the present application;
fig. 12 is a schematic diagram of solving objective parameters provided in the embodiment of the present application.
Detailed Description
The present invention will be described with reference to the accompanying drawings and embodiments.
Fig. 1 is a schematic flow chart of a tree breast height diameter obtaining method based on a mobile laser radar according to an embodiment of the present application, and referring to fig. 1, the tree breast height diameter obtaining method based on a mobile laser radar according to the present embodiment includes:
s101, selecting ground characteristic points on the forest to be measured as three-dimensional coordinate reference points to establish a three-dimensional coordinate system.
In practical application, whether absolute three-dimensional coordinate transformation of relative position and elevation information needs to be carried out by adopting an RTK technology and whether multi-person cooperation distributed synchronous sharing operation is needed can be determined according to the required data type, data precision and task time.
The method for simultaneously acquiring the breast diameter and the three-dimensional absolute coordinates of the tree in the field forest scene and performing multi-person distributed synchronous shared measurement (the most complex application scene) is taken as an example for introduction.
Two or more mobile phones which are provided with mobile terminals APP developed by the system and are provided with laser radar sensors are adopted; and one set of RTK equipment (a reference station/CORS station, a mobile station and a radio station) (determining whether to equip the mobile phone and an RTK standby battery or charging equipment according to the measurement task plan time length).
The method has the advantages that the field plot where the forest to be detected is located is achieved, a mobile phone APP is started, and a multi-user local area network networking is achieved (a Bluetooth or WiFi hotspot is required to be within 10 meters during data transmission, breakpoint reconnection is supported, data sharing synchronization among multiple users and a network server synchronization function are supported, so that the main purpose is to ensure that the local data collects multi-user backup in real time under the condition that no mobile network exists, and the data security is improved);
setting a three-dimensional coordinate reference point (optionally selecting a ground characteristic point which is convenient to measure and identify and search in or around the forest land block to be measured and has a remarkable position) on site, using the point as the origin of a relative coordinate system for next data acquisition of all users, meanwhile, the method is also taken as one of coordinate points required by the RTK for converting the relative coordinate correction into the absolute coordinate (the relative coordinate is converted into the absolute coordinate by the RTK, generally 3-5 calibration points can ensure higher data quality, and the specific selected point quantity is correspondingly determined according to the terrain complexity and project scale of the forest land to be measured), the other conversion calibration points can be selected according to the point selection principle, and the subsequent point selection points are uniformly distributed in the whole area of the forest land to be detected as much as possible, all the selected datum points need the mobile phone to acquire relative three-dimensional coordinate data and the RTK acquires absolute three-dimensional coordinate data respectively.
S102, measuring the breast height diameter of the tree by a terminal with a built-in laser radar to obtain data breast height diameter data.
The measuring staff stands in any direction of the tree to be measured, the distance between the measuring staff and the trunk position is within 5 meters, the mobile phone is kept to be vertical to the ground relatively, the camera lens of the mobile phone is aligned to the position between 1 and 1.5 meters of the height of the trunk (the tree is guaranteed to fall into a camera lens viewing frame from the stem base to the 1.3 meter breast-height measuring part, the general shooting direction can be along the vertical direction, if the tree with a large inclination angle (bending) is encountered, the mobile phone viewing angle can be properly adjusted on a vertical plane vertical to the shooting direction), and the camera automatically focuses and captures the trunk (virtual background) in the picture.
Laser measurement, calculating breast diameter and measured tree trunk base ground three-dimensional coordinates, and the specific process is as follows:
the first step is as follows: model construction and measurement environment setting.
Referring to fig. 2, the environment settings are measured.
The cross-sectional shape of the trunk is approximately summarized as a circle by setting the position of the cross-section of the trunk at 1.3m (defined by forestry disciplines) on the longitudinal (growth direction) geometric axis above the base of the trunk.
r: is defined as the radius of the cross section circle of the trunk (height 1.3 m) to be measured, and the radius of the cross section circle of the trunk where the point C is located in the figure.
r1: defined as the laser beam (OD direction) and O emitted vertically from the laser radar of the mobile phone to the shooting direction2O3And (3) the radius of a cross-sectional circle of the trunk, in which the intersection point D of the projection of iota' of the central longitudinal geometric central axis of the trunk on the surface on the photographing side of the trunk is located.
r2: is defined as the radius of the cross section circle of the base of the trunk (the cross section position of the trunk and the ground), namely the radius of the cross section circle of the trunk at the point E in the figure.
r<r1 <r2(physiological characteristics common to tree growth).
Referring to fig. 3 and 4, a trunk model is constructed.
And point O: cell-phone lidar transmission point.
ιι´：O2O3The projection of the central longitudinal geometric central axis of the trunk, in which O' is located, on the surface on the side where the trunk is photographed.
Mu' is an axis formed by a set of points of tangency of the right trunk surface in the shooting direction with the laser radar emission beam (an axis formed by a row of points on the outermost side of the trunk surface which can be identified by scanning the laser radar from the shooting point in the trunk direction).
λ λ ″: and the axis formed by the set of points where the trunk surface on the left side of the shooting direction is tangent to the laser radar emission beam (the axis formed by the row of points on the outermost side of the trunk surface which can be identified by scanning the laser radar from the shooting point to the trunk direction).
E, point: and the cross section of the junction of the trunk and the ground is circular, and the intersection point of the trunk and the ground is iota'.
And D, point: and the intersection point of the plane of the mobile phone laser horizontal beam and the iota' is formed.
D' point: is the point where point E crosses the OD vertically and directly above.
And C, point: and the intersection point of the circular cross section and the iota' at the position of 1.3m of the trunk to be tested.
O1Point: as an auxiliary point, set the vertical distance right above O as O2O3Point (2) of (c).
O2Point: the center of the circle of the cross section circle (target breast diameter extraction plane) of the trunk where the point C is located.
O3Point: and D is the circle center of the cross section of the trunk where the point D is located.
O' point: and E, the center of a circular cross section of the trunk where the point E is located (a target three-dimensional coordinate extraction point).
And (B) point A: the cross section of the trunk where point C is located is circular and intersects mu'.
And B, point: and the cross section of the trunk where the point C is located is circular and is intersected with lambda'.
And F point: and D, the cross section of the trunk where the point D is located is circular and is intersected with lambda'.
And point G: and D, the cross section of the trunk where the point D is located is circular and is intersected with mu'.
J point: and the cross section of the trunk where the point E is located is circular and is intersected with lambda'.
And point K: the cross section of the trunk where point E is located is circular and intersects μ ″.
H, point: o is2The point is at the midpoint of the chord length AB of the trunk cross-section circle.
Angle θ: the angle between OD and OE.
And (2) supporting the angle epsilon: the angle between OD and OC.
∠α：O1B or O1The included angle between A and OC.
And (2) h: the OD is angled from the X-axis (east direction) of the measurement coordinate system.
Coordinate points (x, y, z): and the three-dimensional coordinates of the O point are three-dimensional coordinates of the position of the mobile phone identified by the mobile phone positioning equipment during measurement.
Coordinate points (x ', y', z): intermediate parameter, O3Three-dimensional coordinates of the points.
Coordinate points (x ', y ', z '): and the three-dimensional coordinates of the O' point, the three-dimensional coordinates of the trunk base of the tree to be detected and a target measurement value.
The second step is that: and calculating and identifying the chest diameter measuring position on the trunk.
Referring to fig. 5, the APP automatically models and identifies the position (fig. 2, point E) of the trunk base (where the trunk is connected with the ground cross section) of the tree through laser radar scanning and a vision algorithm, and calculates and identifies the longitudinal (growing direction) geometric central axis (O) of the part of the trunk shot in the viewfinder2O3Axis on which O ') is located) at the projection axis iota' of the trunk surface on the photographing side (fig. 2, fig. 4), by the trigonometric function sine theorem: OE = sin (θ) = D' E = O3O' and 1.3-O3O´= O2O3The position where the cross section of the tall trunk of 1.3m is located is calculated (point C is the intersection of this plane and iota').
In the above formula, point E is an intersection point of the ground and the tree trunk base, and can be identified by a visual algorithm, point D is an intersection point of the mobile phone laser horizontal beam plane and iota 'and can be identified by a geometric algorithm, so OE and OD can be directly read by a laser radar, point D is a point where point E is vertically and directly above and crossed with OD and can be solved by geometric solution, and a model Δ OD' E is constructed based on the above information, that is, θ can be read, which is detailed in fig. 6.
Based on the above calculation, O can be obtained2O3Length, along O ″3Directionally elongated O3Length equal to O2O3And determining the circular position of the cross section of the trunk where the target chest diameter is located, and then calculating and identifying the intersection point of the circular section and the iota' as a C point.
For a detailed illustration see below:
measuring a plane: an OEC plane;
measurable parameters: OE and theta;
intermediate parameters: d 'E = O' O3；
Target solving parameters: o is2O3；
The principle is as follows: the theorem of Zhengxuan;
the formula: OE ═ sin (· θ) = D 'E = O' O3,
1.3- O´O3= O2O3。
The third step: solving for intermediate parameters (O)1C)。
Referring to fig. 7, after the position of the point C at iota' is found in the second step, OC length and ∈ can be read simultaneously by calculating and recognizing an OC beam emitted by a laser radar, because O is1O= O2O3O is therefore O1O2∥OO3So that is less than O1CO=∠ε,△OCO1For a right-angled triangle, after OC and ∈ are known, O can be solved by the cosine theorem1C。
For a detailed illustration see below:
measuring a plane: OO1A C plane;
measurable/known parameters: angle epsilon, OC;
target solving parameters: o is1C；
The principle is as follows: the cosine theorem;
the formula: OC COS (epsilon) = O1C；
The fourth step: the intermediate parameter (CH) is solved.
Referring to FIG. 8, based on the round shape O of the cross section of the trunk where the diameter of the target breast height of the tree to be measured has been determined in the second step2Calculating and identifying the cross section circle O of the plane2The intersection A, B with the axes λ λ' and μ ″, calculates and identifies the midpoint H in AB, connects CH, and then directly calculates and identifies the CH length.
The fifth step: solving for intermediate parameters (O)1B) (FIG. 11).
Referring to FIG. 9, the middle O is obtained based on the "third step1C, obtaining CH by the 'fourth step', and obtaining O1H=O1C + CH. In a "fourth step", AB and its midpoint have been modeled by known parameters, BH can be directly identified by calculation. So that at right triangle O1In HB, the Pythagorean theorem can be used to find O1The length of B.
For a detailed illustration see below:
measuring a plane: o is1HB plane;
measuring deviceKnown parameters: BH. O is1C、CH；
Target solving parameters: o is1B；
The principle is as follows: pythagorean theorem;
the formula: BH + (O)1C+CH) ²= O1B ²；
And a sixth step: solving the intermediate parameter (r).
Referring to FIG. 10, the middle O is obtained based on the "third step1C, solving O in the fifth step1B, so that the right triangle O can be formed1O2In B, establishing an equation by using Pythagorean theorem: r + O1B ²=(O1C + r), obtaining r.
For a detailed illustration see below:
measuring a plane: o is1O2A plane B;
measurable/known parameters: o is1B、O1C、；
Target solving parameters: r;
the principle is as follows: pythagorean theorem;
the formula: r + O1B ²=(O1C+r)²。
The seventh step: solving the target parameter 1: the diameter at breast height d of the tree.
Referring to fig. 10, the measurement plane: point O2The cross section of the tree trunk is circular;
the formula: d (trunk diameter) =2 × r;
eighth step: solving for intermediate parameters (r)1）。
Referring to fig. 11, point D is an intersection point OF a plane where a horizontal beam OF laser light OF the mobile phone is located and iota' and can be directly identified through scanning by a laser radar, point F is an intersection point OF a cross section circle OF a trunk where point D is located and λ λ ″, and can also be directly identified through scanning by a laser radar, and point O is a known point (a laser radar transmission point), so that OF and OD can be directly identified through calculation by a laser radar. Based on the above conditions, by constructing the right triangle OFO3Model, using the pythagorean theorem: (OD + r)1) ²=OF ² + r1Ready to obtain r1。
For a detailed illustration see below:
measuring a plane: OFO3A plane;
measurable/known parameters: OF, OD;
target solving parameters: r is1；
The principle is as follows: pythagorean theorem;
the formula: (OD + r)1) ²=OF ² + r1²。
The ninth step: solving the target parameter 2: and (3) three-dimensional coordinates (x ', y ', z ') of the tree trunk base to be detected.
Referring to FIG. 12, OD can be read directly based on "second step", r based on "eighth step1The coordinates (x, y, z) can be obtained: is O point three-dimensional coordinate, namely the three-dimensional coordinate of the position of the mobile phone identified by the mobile phone positioning equipment during measurement, and the angle beta is the included angle between the OD and the X axis (east direction) of the measurement coordinate system and can be identified by the relevant sensors (a magnetic field sensor and a gyroscope) of the mobile phone, O3O' has been determined in the "second step", so that O to O can be achieved by the above conditions3And then converting to the coordinates of O'.
For a detailed illustration see below:
measurable/known parameters: x, y, z,. sub.beta.and O3O´、OD、r1；
Intermediate solution parameters: x ', y';
target solving parameters: x ', y ', z ';
the formula: OO3=OD+ r1，
x´=x+OO3*cos(β)，
y´=y+OO3* sin(β)，
z´=z- O3O´。
Absolute conversion and calibration of three-dimensional coordinates: the method ensures that the measurement codes of all selected calibration points at the APP end of the mobile phone and the RTK data end are consistent, and the software automatically resolves, converts and calibrates all relative three-dimensional coordinates into absolute three-dimensional coordinates through the calibration point data by importing all calibration point absolute three-dimensional coordinates acquired by RTK into the APP end of the mobile phone.
S103, the acquired breast diameter data is combined with the information of the measuring staff, the time information, the tree species ID and the three-dimensional coordinate system to determine final measuring data.
The measurement calculation result is displayed in real time on an APP operation interface, and meanwhile, prompt is broadcasted through voice (synchronous check and confirmation of measurement personnel are facilitated), and storage (local multi-user distributed storage and cloud storage) is carried out;
in the measuring process, each user mobile phone end APP can record measuring personnel ID, tree species ID, measuring time (start-stop time and duration), and measuring sequence (code) besides obtaining the chest diameter value and the stem base three-dimensional coordinate value of each tree, wherein the user ID and the tree species ID need to be manually input, and other parameters can be automatically identified, generated and obtained;
the mobile phone end performs light weight processing on the obtained original data, and can also realize cloud computing through a cloud server under the condition of a mobile network, so that a Digital Elevation Model (DEM) of a measured land block, a measurement sequence plane path diagram (a tree trunk base plane coordinate position connection diagram with numbers), a tree composite terrain 3D model, forest stand area calculation, forest stand density calculation, forest stand carbon storage capacity and carbon density calculation and data visualization chart analysis are generated in real time, and specific display interfaces corresponding to all functions and results are provided in real time, so that measuring personnel can know the conditions of measurement results, quality, effect and progress at any time.
The field acquisition data can be synchronously downloaded by the field staff from the cloud, the checking and monitoring of the measurement work (progress and quality) can be carried out in real time, and meanwhile, the deep data analysis and the data visualization processing can be carried out by combining related data analysis and geographic information management tools (SAS, R, ARCGIS, CAD and the like).
In addition, the system carries out different time sequence (historical) data comparison analysis through planned data acquisition and storage, can provide forest growth parameter time sequence change monitoring analysis, important key information such as forest productivity, carbon reserves, carbon density dynamic change monitoring and carbon sink potential prediction for a forest manager, and the comprehensive function of the system can comprehensively innovate and promote the deep development of intelligent forestry and Internet + forestry.
It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Claims (10)
1. A tree breast height diameter obtaining method based on a mobile phone laser radar is characterized by comprising the following steps:
selecting ground characteristic points on a forest to be detected as three-dimensional coordinate reference points to establish a three-dimensional coordinate system;
a terminal carrying a built-in laser radar measures the breast-height diameter of the tree to obtain data breast-height diameter data;
and determining final measurement data by combining the acquired breast diameter data with the information of the measuring staff, the time information, the tree species ID and the three-dimensional coordinate system.
2. The method for obtaining the breast-height diameter of the tree based on the mobile phone lidar as claimed in claim 1, wherein the step of measuring the breast-height diameter of the tree by the terminal with the built-in lidar to obtain the data breast-height diameter data comprises:
constructing a trunk model and a measuring environment;
calculating and identifying the chest diameter measuring position on the trunk;
determining a plurality of intermediate parameters in the measurement of the breast-height diameter of the tree;
and determining the final tree breast diameter according to the acquired intermediate measurement.
3. The tree breast-height diameter obtaining method based on the mobile phone lidar according to claim 2, wherein the constructing of the measuring environment comprises:
setting the cross section position of the chest diameter measurement value position at 1.3m on the longitudinal (growth direction) geometric central axis above the trunk stem base;
approximately generalizing the trunk cross-sectional shape to a circle;
defining the circular radius of the cross section to be measured of the trunk diameter at breast height;
determining the radius of a trunk cross section circle where an intersection point of a laser beam vertically emitted by a mobile phone laser radar in shooting and a projection of a trunk central longitudinal geometric central axis of a trunk diameter to-be-measured cross section central point on the surface of one trunk shooting side is located;
a circular radius of a cross section of a trunk stem base (a cross section position where a trunk intersects with the ground) is defined.
4. The mobile-lidar-based tree breast-height diameter acquisition method according to claim 2 or 3, wherein the constructing of the tree trunk model comprises:
determining the projection of a central longitudinal geometric central axis of a trunk, where a cell phone laser radar emission point and a central point of a cross section to be detected are located, on the surface of one side of the trunk shooting;
determining a first axis formed by a set of points of tangency of the trunk surface on the right side in the shooting direction and the laser radar emission beam (the laser radar scans from the shooting point to the trunk direction, and the axis formed by a row of points on the outermost side of the trunk surface can be identified);
determining a second axis formed by a set of points of tangency of the trunk surface on the left side of the shooting direction and the laser radar emission beam (the laser radar scans from the shooting point to the trunk direction, and the axis formed by a row of points on the outermost side of the trunk surface can be identified);
respectively determining a first intersection point, a second intersection point and a third intersection point of the cross section circle at the junction of the trunk and the ground, the plane where the mobile phone laser horizontal beam is located, the cross section circle at 1.3m of the trunk to be measured and the projection;
and respectively determining the first intersection point, the second intersection point, the third intersection point and the intersection points of the first axis and the second axis.
5. The method for obtaining the breast diameter of the tree based on the mobile phone lidar as claimed in claim 4, wherein the calculating and identifying the measuring position of the breast diameter on the trunk comprises:
automatically modeling and identifying the position of a tree stem base (the position of a cross section where the tree stem is connected with the ground) through laser radar scanning and a visual algorithm;
meanwhile, calculating and identifying a projection axis of a longitudinal (growing direction) geometric central axis of a part of the trunk shot in the viewfinder on the surface of the trunk on the shooting side;
and calculating the position of the cross section of the trunk with the height of 1.3 meters by using a trigonometric function sine theorem.
6. The method for obtaining the breast-height diameter of the tree based on the mobile phone laser radar as claimed in any one of claims 1 to 5, wherein the step of selecting the ground feature points as the three-dimensional coordinate reference points on the forest to be tested to establish the three-dimensional coordinate system comprises the following steps:
randomly selecting ground characteristic points which are convenient to measure and easy to identify and search in or around the forest land block to be measured and have obvious positions;
the ground characteristic point is used as the origin of a relative coordinate system for next data acquisition of all users and is also used as one of coordinate points required by the RTK equipment for converting the correction of the relative coordinate into an absolute coordinate;
meanwhile, subsequent points are uniformly distributed in the whole area of the forest land to be detected as much as possible, and all the selected reference points need to be acquired by the mobile phone according to the relative three-dimensional coordinate data.
7. The method for obtaining the breast diameter of the tree based on the mobile phone lidar as claimed in claim 6, wherein a measurer stands in any direction of the tree to be measured within 5 meters from the trunk position, the mobile phone is kept relatively perpendicular to the ground, the camera lens of the mobile phone is aligned to the position between 1 and 1.5 meters of the trunk height, the trees are guaranteed to fall into the camera lens view-finding frame from the stem base to the 1.3 meter breast diameter measuring part, and the shooting approximate direction is along the vertical direction.
8. The method for obtaining tree breast-height diameter based on mobile phone lidar according to claim 7, wherein the step of determining the final measurement data by combining the obtained breast-height diameter data with the staff information, the time information, the tree species ID and the three-dimensional coordinate system comprises:
in the measuring process, each user mobile phone end APP can record measuring personnel ID, tree species ID, measuring time and measuring sequence (code) besides acquiring the chest diameter value and the trunk base three-dimensional coordinate value of each tree, wherein the user ID and the tree species ID need to be manually input, and other parameters can be automatically identified, generated and acquired;
and fusing the acquired data to obtain tree breast-height diameter measurement data.
9. The method for obtaining the breast diameter of the tree based on the mobile phone lidar as claimed in claim 8, wherein the mobile phone end performs lightweight processing on the obtained breast diameter measurement, and can generate a digital elevation model of a measured land block, a measurement sequence plane path diagram (a numbered tree trunk base plane coordinate position connection diagram), a tree composite terrain 3D model, forest stand area calculation, forest stand density calculation, forest stand carbon storage capacity calculation, carbon density calculation, data visualization chart analysis in real time in a cloud computing manner through a cloud server under the condition of a mobile network, and provide a specific display interface corresponding to each function and result in real time.
10. The tree breast-height diameter acquiring method based on the mobile phone laser radar as claimed in claim 9, wherein a user can synchronously download field acquisition data from a cloud end, check and supervise measurement work in real time, and perform depth data analysis and data visualization processing by combining related data analysis and geographic information management tools;
through planned data acquisition and storage, different time sequence data comparison analysis is carried out, and important key information such as forest growth parameter time sequence change monitoring analysis, forest productivity, carbon reserves, carbon density dynamic change monitoring, carbon sink potential prediction and the like can be provided.
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