CN103256895A - Method for carrying out forestry investigation with three-dimensional laser scanner utilized - Google Patents

Abstract

The invention discloses a method for carrying out forestry investigation with a three-dimensional laser scanner utilized, and relates to the field of the forestry investigation, in particular to the method for carrying out the forestry investigation with the three-dimensional laser scanner utilized. According to a range of an investigation forest region, reference targets are arranged, and the positions of sites are confirmed. The sites are erected, and data are scanned. Point cloud data of each site are spliced. The diameter at breast height, the tree height and the crown diameter of woods are measured. Amount of growing stock of standing trees is calculated. A three-dimensional forest region map is drawn up. The method for carrying out the forestry investigation with the three-dimensional laser scanner utilized has the advantages of being capable of greatly reducing workload and working time of forestry investigation personnel, and improving investigation efficiency. Meanwhile, the high-precision three-dimensional laser scanner ensures precision of measured data, the trees do not need to be cut down when in investigation, and natural environment is protected. The point cloud data are utilized to build the three-dimensional topographic map of the forest region, a three-dimensional digit file of the forest region is built conveniently, the method can be combined with a 3S technology, and protection, management and subsequent investigation of the forest region are convenient.

Description

A kind of three-dimensional laser scanner that utilizes carries out the forestry investigation methods

Technical field

The present invention relates to forestry investigation field, particularly a kind of three-dimensional laser scanner that utilizes carries out the forestry investigation methods.

Background technology

The forestry investigation has very long developing history.The tree volume table that just there was more accurate forest map in Germany and works out with the figurate number method in 19 beginning of the century.20 middle of century, sample survey and photogrammetric measurement technology are used to improve investigation efficient.Along with the rise of computer technology, 3S technology, remote sensing technology etc. all progressively are used to the establishment of enquiry data processing and drawing material.Over nearly 20 years, particularly enter the new century after, the technological means of forestry investigation is more attained perfect, has set up comparatively perfect forest inventory control infosystem.But because the economic development worldwide energy, the environmental crisis that cause make forest day by day reduce and be on the rise, the forest survey of enterprise of original forestry basic unit has been not enough to grasp the overall situation.It is imperative to set up the forest resource database automatization system.

According to " forest inventory investigation major technique regulation " that Ministry of Forestry of the People's Republic of China (PRC) issued in 2003, the main contents of investigation comprise: check the boundary line of forest management unit, and carry out in the operation control scope or adjust (check) and manage zoning; The area in all kinds of forest lands; Investigate all kinds of forests, standing crop; The physical geographic environment relevant with the forest reserves and ecologic environment factor; Orest management condition, main operation measure in early stage and management performance etc.

The form of investigation generally comprises: be foundation with map (topomap, planimetric map or, empty photo etc.), design survey plan and the route that carries out carry out resource exploration with range estimation and actual measurement.As sketching indoor according to recent aerial image, determine in conjunction with on-the-spot again; Also can enter on the inherent map of woods and sketch; During height intensive farming, can divide by actual measurement.Survey item is decided with actual conditions as required, and the look-see emphasis is accumulation.Investigation method commonly used has sample ground measurement method, ocular estimate, recurrence estimation method and the overall method of sampling control.In addition, increment, mortality, natural and artificial regeneration effect, soil, disease and pest, fire hazard rating, land occupation condition, rare animal and plant resource etc. all are the contents of investigation.Adopt forestry investigation range estimation commonly used, tradition mapping (tape measure, stadimeter etc.), remote sensing, aeroplane photography etc. at present.At survey items such as topmost forest stock, increments, range estimation is higher with the precision of tradition mapping, but inefficiency is difficult to satisfy large-area fast investigation demand; Though remote sensing, aerophotographic method have solved efficiency, can not penetrate the vegetation surface, are difficult to obtain comprehensively and accurately the information in forest zone, how to solve the contradiction between the efficiency and precision, it is a problem that presses for solution.

Summary of the invention

The objective of the invention is to: at the problems referred to above, the invention provides a kind of method of utilizing three-dimensional laser scanner to obtain the forest zone spatial information, under the condition that does not cut down forest, utilize three-dimensional laser scanner to obtain the forest cloud data, set up the three-dimensional model of forest, and then calculate each data that need.

A kind of three-dimensional laser scanner that utilizes carries out the forestry investigation methods, realizes according to following steps:

Step 1: lay reference target, determine to establish station location;

Step 2: set up website, scan-data;

Step 3: splice each website cloud data;

Step 4: measure the forest diameter of a cross-section of a tree trunk 1.3 meters above the ground, the height of tree, crown diameter;

Step 5: calculate growing stock;

Step 6: work out three-dimensional forest zone map.

Wherein step 1 is laid reference target, and the condition of determining to establish station location is as follows: all establish the station location addition can cover whole zone to be scanned; Establish the public target that should guarantee between the station to have in the visual field more than 3, and have 3 targets at least not at grade for per two; Assurance wait to investigate arbitrary trees in the forest zone apart from the air line distance of its nearest website for more than or equal to 1m, smaller or equal to 30m; All lay website visual field addition, can cover whole all trees of waiting to investigate in the forest zone.

Wherein the method for each website cloud data of the described splicing of step 3 is based on the registration Algorithm of least square and error.Its computing method are: at first, consider two corresponding point set { x _i, { y _i, i=1,2 ..., n, (x _iAnd y _iBe the column vector of 3*1), 1. x of digital-to-analogue is then arranged _i=Ry _i+ T; Secondly, according to digital-to-analogue 2.

Find suitable R, these two point sets of T registration, make Euclidean distance and the minimum of match point; Then, suppose that the center of gravity of the corresponding point set of two amplitude deepness images is respectively p, q, have digital-to-analogue 3.

Set 4. p of digital-to-analogue _i=x _i-p, q _i=y _i-q, then 5. 2. digital-to-analogue become digital-to-analogue

Again to the matrix digital-to-analogue 6.

Be SVD and decompose, draw rotation matrix, draw the translation vector digital-to-analogue more 7. At last, through behind the thick registration, utilize digital-to-analogue

$\mathrm{\Φ}=\underset{\mathrm{\μ}=1}{\overset{P}{\mathrm{\Σ}}}\underset{i=1}{\overset{N^{\mathrm{\μ}}}{\mathrm{\Σ}}}{\mathrm{\ω}}_i^{\mathrm{\μ}}{(T^{\mathrm{\α}\left(\mathrm{\μ}\right)}-T^{\mathrm{\β}\left(\mathrm{\μ}\right)})}^T\[2(R^{\mathrm{\α}\left(\mathrm{\μ}\right)}{x}_i^{\mathrm{\μ}}-R^{\mathrm{\β}\left(\mathrm{\μ}\right)}{y}_i^{\mathrm{\μ}})+(T^{\mathrm{\α}\left(\mathrm{\μ}\right)}-T^{\mathrm{\β}\left(\mathrm{\μ}\right)})\]$

⑧ $+\underset{\mathrm{\μ}}{\overset{P}{\mathrm{\Σ}}}\underset{i=1}{\overset{N^{\mathrm{\μ}}}{\mathrm{\Σ}}}{\mathrm{\ω}}_i^{\mathrm{\μ}}{\left|\right|R^{\mathrm{\α}\left(\mathrm{\μ}\right)}{x}_i^{\mathrm{\μ}}-R^{\mathrm{\β}\left(\mathrm{\μ}\right)}{y}_i^{\mathrm{\μ}}\left|\right|}^2$

Calculate the transformation parameter of each viewpoint cloud correspondence, obtain final registration results.

The method of wherein measuring the forest diameter of a cross-section of a tree trunk 1.3 meters above the ground in the step 4 is to delete forest apart from the some cloud part of ground more than 1.3 meters, rebuilds the three-dimensional model of remainder branch cloud, measures the diameter of a cross-section of a tree trunk 1.3 meters above the ground of every trees.

Wherein according to digital-to-analogue 9. the calculating growing stock metering method described in the step 5 is

Calculate volume of timber amount.

Beneficial effect of the present invention: the present invention can greatly reduce forestry investigator's workload and the working time, improves investigation efficient.Simultaneously, the high accuracy three-dimensional laser scanner has guaranteed the precision of measurement data, and investigation the time need not fall trees, and has protected physical environment.By utilizing cloud data to set up the forest zone three-dimensional land map, can set up forest zone 3-dimensional digital archives easily, and can combine with the 3S technology, make things convenient for protection, management and the follow-up investigation in forest zone.

Embodiment

Determine to wait to investigate the forest zone scope, the different trees trunk surface in this scope are laid the scanning target of somes, determine that three-dimensional laser scanner establishes station quantity and establish station location.The laying of scanning target and three-dimensional laser scanner are established station location and need be met the following conditions:

1. all are established the station location addition and can cover whole zone to be scanned.

2. establish the public target that should guarantee between the station location to have in the visual field more than 3 for per two, and have 3 targets at least not at grade, as not satisfying condition, need set up target.

3. guarantee to wait to investigate arbitrary trees in the forest zone apart from the air line distance of its nearest website more than or equal to 1m smaller or equal to 30m.

4. all lay website visual field addition, can cover whole all trees of waiting to investigate in the forest zone.

Set up three-dimensional laser scanner at the site location of determining, scanning forest zone cloud data is stored, splice each website cloud data then.When splicing each website cloud data, adopt the registration Algorithm based on least square and error: now consider two corresponding point set { x _i, { y _i, i=1,2 ..., n, (x _iAnd y _iBe the column vector of 3*1), then have:

x _i=Ry _i+T (1)

Wherein, R is rotation matrix, and T is translation vector.

Want these two point sets of registration, target will find suitable R exactly, and T makes the Euclidean distance of match point and (as shown in Equation (2)) minimum.

${\mathrm{\Σ}}^2=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\left|\right|x_i-(R{y}_i+T)\left|\right|}^2---\left(2\right)$

Suppose that the corresponding point set of two amplitude deepness images is { x _i), { y _i, i=1,2 ..., n, its center of gravity is respectively pq, then has:

$p=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{x}_i$ $q=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{y}_i---\left(3\right)$

Definition: p _i=x _i-p, q _i=y _i-q, then the total error formula of formula (2) becomes:

${\mathrm{\Σ}}^2=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\left|\right|p_i-R{q}_i\left|\right|}^2---\left(4\right)$

Compute matrix:

$H=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{q}_i{p}_i^T---\left(5\right)$

Matrix H is made SVD decomposes:

H=UDV ^T (6)

Calculate: X=VU ^T, X is the rotation matrix R that asks.

Suppose that formula is arranged least square solution R, the T of (1), then { x _iAnd { y _i'=Ry _i+ T) have:

$\stackrel{\‾}{x}=\frac{1}{N}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{x}_i,$ $\stackrel{\‾}{y}=\frac{1}{N}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{y}_i,$ $\stackrel{\‾}{y^{\′}}=\frac{1}{N}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{y_i}^{\′}=R\stackrel{\‾}{y}+T,$ When R is known, obviously have $T=\stackrel{\‾}{x}-R\stackrel{\‾}{y}---\left(7\right).$

Public target point in each station for acquiring cloud data as corresponding point set, is calculated rotation matrix as stated above, and will act on corresponding cloud data, obtain the thick registration results of each viewpoint cloud.

Through behind the thick registration, can minimize formula (8), calculate the transformation parameter of each viewpoint cloud correspondence then, thereby obtain final registration results.

$\mathrm{\φ}=\underset{\mathrm{\μ}=1}{\overset{P}{\mathrm{\Σ}}}\underset{i=1}{\overset{N^{\mathrm{\μ}}}{\mathrm{\Σ}}}{\mathrm{\ω}}_i^{\mathrm{\μ}}(T^{\mathrm{\α}\left(\mathrm{\μ}\right)}-T^{\mathrm{\β}\left(\mathrm{\μ}\right)}{)}^T\[2(R^{\mathrm{\α}\left(\mathrm{\μ}\right)}{x}_i^{\mathrm{\μ}}-R^{\mathrm{\β}\left(\mathrm{\μ}\right)}{y}_i^{\mathrm{\μ}})+(T^{\mathrm{\α}\left(\mathrm{\μ}\right)}-T^{\mathrm{\β}\left(\mathrm{\μ}\right)})\]$

$+\underset{\mathrm{\μ}=1}{\overset{P}{\mathrm{\Σ}}}\underset{i=1}{\overset{N^{\mathrm{\μ}}}{\mathrm{\Σ}}}{\mathrm{\ω}}_i^{\mathrm{\μ}}{\left|\right|R^{\mathrm{\α}\left(\mathrm{\μ}\right)}{x}_i^{\mathrm{\μ}}-R^{\mathrm{\β}\left(\mathrm{\μ}\right)}{y}_i^{\mathrm{\μ}}\left|\right|}^2$

（8）

In formula (8), wherein μ is each website scan image of three-dimensional laser scanner numeral number of overlapping region in twos, and α (μ), β (μ) are the numeral numbers of two scan images under the corresponding overlapping region of μ value, N ^μBe counting in the corresponding overlapping region of μ value, P is the number of overlapping region, and R is rotation matrix, and T is translation vector.

According to the splicing cloud data that obtains, be separated out territory, the some cloud sector scope of each trees by hand, measure the crown diameter of every trees.According to a cloud measurement of coordinates height of crop.The deletion forest is rebuild the three-dimensional model of remainder branch cloud apart from the some cloud part of ground more than 1.3 meters, measures the diameter of a cross-section of a tree trunk 1.3 meters above the ground of every trees.Inquire about the Volume table of the relevant seeds of local forest department, calculate the volume of timber according to formula (9), and then obtain the timber reserves in whole forest zone.

$\stackrel{\‾}{V}=a{\left(D^{2}H\right)}^b---\left(9\right)$

In the formula

Be the standing volume (m of unit ²), D is the diameter of a cross-section of a tree trunk 1.3 meters above the ground (cm of unit), and H is the height of tree (m of unit), and a, b are dimensionless group.Three-dimensional point cloud atlas with zones of different carries out registration, integration at last, thereby obtains the three-dimensional land map in large tracts of land forest zone, is beneficial to the protection management in forest zone, and provides the data foundation for follow-up forest inventory investigation in the future.

The above only is preferred embodiment of the present invention, not in order to limiting the present invention, all any modifications of doing within the spirit and principles in the present invention, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.

Claims (6)

1. one kind is utilized three-dimensional laser scanner to carry out the forestry investigation methods, it is characterized in that:

Step 1: lay reference target, determine to establish station location;

Step 2: set up website, scan-data;

Step 3: splice each website cloud data;

Step 4: measure the forest diameter of a cross-section of a tree trunk 1.3 meters above the ground, the height of tree, crown diameter;

Step 5: calculate growing stock;

Step 6: work out three-dimensional forest zone map.

2. the three-dimensional laser scanner that utilizes according to claim 1 carries out the forestry investigation methods, it is characterized in that: wherein to establish the condition of station location as follows for the described laying reference target of step 1 and determining: all establish the station location addition can cover whole zone to be scanned; Establish the public target that should guarantee between the station to have in the visual field more than 3, and have 3 targets at least not at grade for per two; Assurance wait to investigate arbitrary trees in the forest zone apart from the air line distance of its nearest website more than or equal to 1m, smaller or equal to 30m; All lay website visual field addition, can cover whole all trees of waiting to investigate in the forest zone.

3. the three-dimensional laser scanner that utilizes according to claim 1 carries out the forestry investigation methods, it is characterized in that: wherein the method for each website cloud data of the described splicing of step 3 is based on the registration Algorithm of least square and error.

4. the three-dimensional laser scanner that utilizes according to claim 3 carries out the forestry investigation methods, it is characterized in that: the computing method of described registration Algorithm based on least square and error are: at first, consider two corresponding point set { x _i, { y _i, i=1,2 ..., n, (x _iAnd y _iBe the column vector of 3*1), 1. x of digital-to-analogue is then arranged _i=Ry _i+ T; Secondly, according to digital-to-analogue 2.

Find suitable R, these two point sets of T registration, make Euclidean distance and the minimum of match point; Then, suppose that the center of gravity of the corresponding point set of two amplitude deepness images is respectively p, q, have digital-to-analogue 3.

Set 4. p of digital-to-analogue _i=x _i-p, q _i=y _i-q, then 5. 2. digital-to-analogue become digital-to-analogue

Again to the matrix digital-to-analogue 6. Be SVD and decompose, draw rotation matrix, draw the translation vector digital-to-analogue more 7.

At last, through behind the thick registration, utilize digital-to-analogue

$\mathrm{\Φ}=\underset{\mathrm{\μ}=1}{\overset{P}{\mathrm{\Σ}}}\underset{i=1}{\overset{N^{\mathrm{\μ}}}{\mathrm{\Σ}}}{\mathrm{\ω}}_i^{\mathrm{\μ}}{(T^{\mathrm{\α}\left(\mathrm{\μ}\right)}-T^{\mathrm{\β}\left(\mathrm{\μ}\right)})}^T\[2(R^{\mathrm{\α}\left(\mathrm{\μ}\right)}{x}_i^{\mathrm{\μ}}-R^{\mathrm{\β}\left(\mathrm{\μ}\right)}{y}_i^{\mathrm{\μ}})+(T^{\mathrm{\α}\left(\mathrm{\μ}\right)}-T^{\mathrm{\β}\left(\mathrm{\μ}\right)})\]$

⑧ $+\underset{\mathrm{\μ}=1}{\overset{P}{\mathrm{\Σ}}}\underset{i=1}{\overset{N^{\mathrm{\μ}}}{\mathrm{\Σ}}}{\mathrm{\ω}}_i^{\mathrm{\μ}}{\left|\right|R^{\mathrm{\α}\left(\mathrm{\μ}\right)}{x}_i^{\mathrm{\μ}}-R^{\mathrm{\β}\left(\mathrm{\μ}\right)}{y}_i^{\mathrm{\μ}}\left|\right|}^2$ Calculate the transformation parameter of each viewpoint cloud correspondence, obtain final registration results.

5. the three-dimensional laser scanner that utilizes according to claim 1 carries out the forestry investigation methods, it is characterized in that: the method for wherein measuring the forest diameter of a cross-section of a tree trunk 1.3 meters above the ground described in the step 4 is that the deletion forest is apart from the some cloud part of ground more than 1.3 meters, rebuild the three-dimensional model of remainder branch cloud, measure the diameter of a cross-section of a tree trunk 1.3 meters above the ground of every trees.

6. the three-dimensional laser scanner that utilizes according to claim 1 carries out the forestry investigation methods, it is characterized in that: wherein the calculating growing stock described in the step 5 according to digital-to-analogue 9.

Calculate.