CN109697731A - Plant canopy calculation method of physical volume, system and relevant device based on point cloud data - Google Patents
Plant canopy calculation method of physical volume, system and relevant device based on point cloud data Download PDFInfo
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- G06T7/60—Analysis of geometric attributes
- G06T7/62—Analysis of geometric attributes of area, perimeter, diameter or volume
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Abstract
The present invention relates to volume calculation techniques fields, and in particular to a kind of plant canopy calculation method of physical volume, system and relevant device based on point cloud data, it is therefore intended that it is undesirable to solve the problems, such as that the prior art calculates plant canopy volume.Calculation method of the invention includes: that the coordinate information of plant canopy point cloud data is projected to z-axis, calculates z coordinate probability density function using the three-dimensional coordinate data of plant canopy point cloud data as initial value；According to z coordinate probability density function, the curvature Local Extremum of z coordinate probability density function is calculated；To each Local Extremum, a plane is drawn as a cross section by the point and perpendicular to z-axis；It according to the preset segmentation number of plies, is split between Local Extremum, obtains multiple cross sections perpendicular to z-axis；Plant canopy is divided into a centrum and multiple stage bodies from top to bottom according to cross section, and then calculates the volume of plant canopy.The present invention improves the accuracy of plant canopy volume calculating.
Description
Technical field
The present invention relates to volume calculation techniques fields, and in particular to a kind of plant canopy volume calculating based on point cloud data
Method, system and relevant device.
Background technique
Due to the scrambling and complexity of plant canopy space structure itself, the accurate measurement of plant canopy volume is always
Since all be perplex researcher problem.Traditional method is that plant canopy cutting at equal intervals is abstracted into single solid,
This method has biggish limitation, and error is very big.
Experts and scholars both domestic and external mostly use microtomy at equal intervals, and cross section is abstracted into round, oval, fan-shaped, ladder
The two-dimentional geometric figures such as shape calculate Tree Crown Volume, but above research achievement is to the calculating of cross section and the meter of lateral area
It calculates all it cannot be guaranteed that very high computational accuracy.
Summary of the invention
In order to solve the above problem in the prior art, the invention proposes a kind of plant canopy body based on point cloud data
Product calculation method, system and relevant device, improve the precision of plant canopy volume calculating.
First aspect of the present invention it is proposed a kind of plant canopy calculation method of physical volume based on point cloud data, the method
Include:
Using the three-dimensional coordinate data of plant canopy point cloud data as initial value, by the coordinate of the plant canopy point cloud data
Information projects to z-axis, calculates z coordinate probability density function；
According to the z coordinate probability density function, the curvature local extremum of the z coordinate probability density function is calculated
Point；
To each Local Extremum, a plane is drawn as a cross section by the point and perpendicular to z-axis；Root
It according to the preset segmentation number of plies, is split between the Local Extremum, obtains multiple cross sections perpendicular to z-axis；
According to the cross section, the plant canopy is divided into a centrum and multiple stage bodies, Jin Erji from top to bottom
Calculate the volume of the plant canopy.
Preferably, " according to the z coordinate probability density function, the curvature office of the z coordinate probability density function is calculated
The step of portion's extreme point " includes:
Probability density is modified according to the following formula:
P'=corrp*p
Wherein,
Max (z), min (z) respectively indicate the maximum value and minimum value that the plant canopy point cloud data is projected in z-axis,
The maximum value of max (p) expression probability density p；
The curvature that z-axis projects upper discrete point is calculated according to the following formula:
Wherein,
△fk(t)=f (t+k △ t)-f (t+ (k-1) △ t)
C (t) is calculated curvature value, and f (t) is function, the unit step that k=1,2,3, △ t are the parameter t of function f (t)
It is long, symbol "×" expression cross product, symbol " " expression dot product, symbol " | | | | " indicate that mould is long；
Point of the curvature value greater than curvature threshold is chosen in the discrete point in z-axis projection as extreme point undetermined；
The maximum point of curvature value is selected in the adjacent extreme point undetermined, obtains Local Extremum.
Preferably, it " according to the preset segmentation number of plies, is split, obtains multiple vertical between the Local Extremum
In the cross section of z-axis " the step of include:
The segmentation step-length between each pair of adjacent Local Extremum is calculated according to the following formula:
Between each pair of adjacent Local Extremum, equidistantly divided according to the corresponding segmentation step length,
To obtain multiple cross sections perpendicular to z-axis；
Wherein, LEziAnd LEzi+1The height of respectively i-th and i+1 Local Extremum, and i-th and i+1
Local Extremum is two adjacent Local Extremums, and i=1,2 ..., m, m is the number of the Local Extremum；△ z is point
Cloud level degree, L are the preset segmentation number of plies.
Preferably, " according to the cross section, the plant canopy is divided into a centrum and multiple from top to bottom
The step of body, and then calculate the volume of the plant canopy " includes:
The point in the upper and lower specific distance range in each cross section is projected on corresponding cross section respectively, Jin Erji
Calculate the boundary point of each cross section；
It is sequentially connected with the boundary point of each cross section respectively, obtains the polygonal profile of cross section taken in correspondence, and then calculates every
The area of a cross section；
Using the cross section as interface, the plant canopy is divided into a centrum and multiple stage bodies from top to bottom；
According to the area of the cross section, the volume of the centrum Yu the stage body is calculated separately, and then obtains the plant
The volume of object canopy.
Preferably, " point in the upper and lower specific distance range in each cross section is projected into corresponding cross section respectively
On, so calculate the boundary point of each cross section " the step of include:
Average distance between the point of the plant canopy point cloud data is calculated according to the following formula:
Wherein,
ρ is the density of point cloud in the height direction, and N is the number at the point cloud data midpoint, and S is point cloud in geodetic coordinates
Projected area in horizontal direction；△ z is point cloud level degree；
The point in the upper and lower specific distance range in each cross section is projected in cross section taken in correspondence respectively, wherein the spy
Set a distance is εz/2；
To the point cloud data on each cross section, calculated using the alpha-shape algorithm of two-dimensional surface boundary profile
The boundary point of the cross section.
Preferably, " it is sequentially connected with the boundary point of each cross section respectively, obtains the polygonal profile of cross section taken in correspondence, into
And calculate the area of each cross section " the step of include:
It is sequentially connected with the boundary point of each cross section respectively, obtains the polygonal profile of cross section taken in correspondence；
By first vertex p of the polygonal profile1It is connect respectively with other vertex, obtains multiple triangles；
The area for calculating the polygonal profile according to the following formula, the area as cross section taken in correspondence:
Wherein, SiFor triangle p1pipi+1Area, r be the polygonal profile vertex number；AiFor symbol system
Number, if p1、pi、pi+1For arranged counterclockwise, then Ai=1, if p1、pi、pi+1For arranged clockwise, then Ai=-1.
Preferably, " according to the area of the cross section, the volume of the centrum Yu the stage body is calculated separately, and then is obtained
To the volume of the plant canopy " the step of include:
The volume of i-th of stage body is calculated according to the following formula:
The volume of the centrum is calculated according to the following formula:
The volume of the plant canopy is calculated according to the following formula:
Wherein, SiAnd Si+1The area of cross section corresponding to the bottom surface and upper bottom surface of respectively i-th stage body, i are institute
The serial number for stating stage body arranges, i=1 from the bottom upstream sequence of the plant canopy, and 2 ..., g-2, g are the number of cross section,
ziAnd zi+1The bottom surface of respectively i-th stage body and the z-axis coordinate of upper bottom surface；Sg-1Cross corresponding to bottom surface for the centrum
The area in section, zgAnd zg-1The bottom surface of the respectively described centrum and the z-axis coordinate on vertex.
The second aspect of the present invention proposes a kind of plant canopy volume computing system based on point cloud data, the system
Include:
Probability density function computing module, for inciting somebody to action using the three-dimensional coordinate data of plant canopy point cloud data as initial value
The coordinate information of the plant canopy point cloud data projects to z-axis, calculates z coordinate probability density function；
Extreme point computing module, for calculating the z coordinate probability density according to the z coordinate probability density function
The curvature Local Extremum of function；
Divide module, for drawing a plane conduct by the point and perpendicular to z-axis to each Local Extremum
One cross section；It according to the preset segmentation number of plies, is split, obtains multiple perpendicular to z-axis between the Local Extremum
Cross section；
Volume calculation module, for according to the cross section, the plant canopy to be divided into a centrum from top to bottom
With multiple stage bodies, and then the volume of the plant canopy is calculated.
The third aspect of the present invention proposes a kind of storage equipment, and including memory, the memory is suitable for storage journey
Sequence, described program is suitable for being loaded and being executed by processor, to realize the plant canopy volume recited above based on point cloud data
Calculation method.
The fourth aspect of the present invention proposes a kind of processing equipment, comprising:
Processor is suitable for loading procedure；
Memory is suitable for storing said program；
Described program is suitable for being loaded and being executed by the processor, to realize the plant recited above based on point cloud data
Canopy calculation method of physical volume.
Compared with the immediate prior art, the invention has the following beneficial effects:
Plant canopy calculation method of physical volume proposed by the present invention based on point cloud data, using three-dimensional point cloud in vertical direction
On density information, give unequal spacing segmentation strategy, while the alpha-shape of boundary profile is solved using two-dimensional surface
Algorithm gives more accurate cross-sectional profiles, solves the cross-sectional profiles of equidistant microtomy and side in conventional method
Face shape calculates coarse disadvantage.And the calculating of plant canopy volume is applied the method to, then plant canopy is divided into
The assembly of the multiple stage bodies of one, top centrum and bottom finally calculates plant hat using stage body volume and centrum volume summation
Layer volume, improves the accuracy of plant canopy volume calculating.Utilize plant canopy calculation method of physical volume of the invention, Ke Yiguang
It is applied to agricultural and field of forestry research generally, also can be applied to the environmental assessments such as urban afforestation situation, carbon emission amount.
Detailed description of the invention
Fig. 1 (a) and Fig. 1 (b) is the point cloud data schematic diagram of a rabbit and a tree crown respectively；
Fig. 2 is the key step signal of the plant canopy calculation method of physical volume embodiment of the invention based on point cloud data
Figure；
Fig. 3 is the point cloud data probability density function schematic diagram of tree crown in the embodiment of the present invention；
Fig. 4 is the Contrast on effect schematic diagram of prior art dividing method Yu dividing method of the present invention；
Fig. 5 is the effect that alpha-shape algorithm and other four kinds of tactful cross-sectional profiles are used in the embodiment of the present invention
Fruit contrast schematic diagram；
Fig. 6 is the schematic diagram that polygon is divided into multiple triangles in the embodiment of the present invention；
Fig. 7 is the signal that plant canopy is divided into a centrum and multiple stage bodies from top to bottom in the embodiment of the present invention
Figure；
Fig. 8 is the main composition signal that the plant canopy volume of the invention based on point cloud data calculates system embodiment
Figure.
Specific embodiment
The preferred embodiment of the present invention described with reference to the accompanying drawings.It will be apparent to a skilled person that this
The a little technical principles of embodiment for explaining only the invention, it is not intended that limit the scope of the invention.
Fig. 1 (a) and Fig. 1 (b) is the point cloud data schematic diagram of a rabbit and a tree crown respectively.As shown in Fig. 1 (a)
Point cloud data is the data by the rabbit body surface obtained after laser scanning.And point cloud data shown in Fig. 1 (b), it is logical
Cross the point cloud data of the tree crown obtained after laser scanning.Because with the presence of gap between leaf, when being irradiated by light, one
Light splitter can run through plant canopy, some light can be stopped after being injected into plant canopy inside by branch or leaf and
It returns.Therefore, when scanning plant canopy by instrument, obtained point cloud further includes in canopy other than surface data
Portion's data.Therefore, for the particularity of plant canopy, the present invention uses the unequal interval syncopation based on density, uses
Alpha-shape algorithm detects the contour line of cross section, more accurately to calculate the volume of plant canopy.
Fig. 2 is the key step signal of the plant canopy calculation method of physical volume embodiment of the invention based on point cloud data
Figure.As shown in Fig. 2, the calculation method of the present embodiment includes step S1-S4:
Step S1, using the three-dimensional coordinate data of plant canopy point cloud data as initial value, by plant canopy point cloud data
Coordinate information projects to z-axis, calculates z coordinate probability density function.
Fig. 3 is the point cloud data probability density function schematic diagram of tree crown in the embodiment of the present invention.As shown in figure 3, left one side of something
For the schematic diagram of a tree crown, the right half of corresponding probability density function of point cloud data for the tree crown.Wherein, the longitudinal axis is point cloud
The z coordinate of data, horizontal axis are the probability density that point cloud data projects to z-axis.
Step S2 calculates the curvature Local Extremum of z coordinate probability density function according to z coordinate probability density function.
Step S21-S24 can be specifically included:
Step S21 is modified probability density according to formula (1)-(2):
P'=corrp*p (1)
Wherein, max (z), min (z) respectively indicate the maximum value and minimum value that plant canopy point cloud data is projected in z-axis,
The maximum value of max (p) expression probability density p.
Step S22 calculates the curvature that z-axis projects upper discrete point according to formula (3)-(4):
△fk(t)=f (t+k △ t)-f (t+ (k-1) △ t) (4)
Wherein, c (t) is calculated curvature value, and f (t) is function, and k=1,2,3, △ t are the parameter t's of function f (t)
One step, symbol "×" expression cross product, symbol " " expression dot product, symbol " | | | | " indicate that mould is long.
Here using document [Blankenburg C, Daul C, Ohser J.Parameter free torsion
estimation of curves in 3D images[C]//IEEE International Conference on Image
Processing.IEEE, 2016:1081-1085.] propose the thought that discrete point curvature is calculated using difference.
Step S23 chooses curvature value in the discrete point in z-axis projection and is greater than the point of curvature threshold as extreme value undetermined
Point.
When the curvature threshold of selection is smaller, the quantity of local curvature's extreme point can become more, to increase time cost；
When curvature threshold is larger, the quantity of local curvature's extreme point can tail off, and computational accuracy is inadequate.The present invention is tested by many experiments
Preferable Local Extremum can be obtained when curvature threshold is set as 0.03 for z coordinate probability density function figure after amendment in card
Choose effect.
Step S24 selects the maximum point of curvature value in adjacent extreme point undetermined, obtains Local Extremum.
It is transversal as one to draw a plane by the point and perpendicular to z-axis to each Local Extremum by step S3
Face；It according to the preset segmentation number of plies, is split between Local Extremum, obtains multiple cross sections perpendicular to z-axis.It can be with
Specifically include step S31-S33:
It is transversal as one to draw a plane by the point and perpendicular to z-axis to each Local Extremum by step S31
Face.
Step S32 calculates the segmentation step-length between each pair of adjacent Local Extremum according to formula (5):
Wherein, LEziAnd LEzi+1The height of respectively i-th and i+1 Local Extremum, and i-th and i+1
Local Extremum is two adjacent Local Extremums, is the serial number of the Local Extremum, is sequentially arranged i=1 from the bottom up,
2 ..., m, m are the number of Local Extremum；△ z is point cloud level degree, and L is the preset segmentation number of plies (being 20 in the present embodiment)；Expression rounds up.
Step S33 is equidistantly divided between each pair of adjacent Local Extremum according to corresponding segmentation step length,
To obtain multiple cross sections perpendicular to z-axis.
According to above-mentioned algorithm, because of the reason of rounding up, the segmentation number of plies finally obtained is typically larger than L.
Fig. 4 is the contrast schematic diagram of prior art dividing method Yu dividing method of the present invention.As shown in figure 4, left figure is to adopt
With the equidistant segmentation schematic diagram of the prior art, right figure is the unequal spacing split plot design schematic diagram using this method.Wherein, z1、
z2、z3、z4、z5Respectively represent different cross sections.On longitudinal sectional view, sequentially by the intersection point of cross section and original contour
It connects to obtain segmentation rear profile, it can be seen that using the profile after method segmentation of the invention closer to original contour, accidentally
Difference is smaller.
Plant canopy is divided into a centrum and multiple stage bodies, and then calculate according to cross section by step S4 from top to bottom
The volume of plant canopy.Step S41-S44 can be specifically included:
Point in the upper and lower specific distance range in each cross section is projected to corresponding cross section respectively by step S41
On, and then calculate the boundary point of each cross section.Step S411-S413 can be specifically included:
Step S411 calculates average distance between the point of plant canopy point cloud data according to formula (6)-(7):
Wherein, ρ is the density of point cloud in the height direction, and N is the number at the point cloud data midpoint, and S is point Yun great
Projected area in ground coordinate horizontal direction；△ z is point cloud level degree.
Step S412 respectively projects to the point in the upper and lower specific distance range in each cross section in cross section taken in correspondence,
In, the specific range is εz/2。
Step S413 calculates the point cloud data on each cross section using the alpha-shape of two-dimensional surface boundary profile
Method calculates the boundary point of the cross section, and is stored in the point set of boundary in an orderly manner.
Step S42 is sequentially connected with the boundary point of each cross section respectively, obtains the polygonal profile of cross section taken in correspondence, into
And calculate the area of each cross section.Step S421-S423 can be specifically included:
Step S421 is sequentially connected with the boundary point of each cross section respectively, obtains the polygonal profile of cross section taken in correspondence.
Fig. 5 is the effect pair that alpha-shape algorithm and other four kinds of tactful cross-sectional profiles are used in the present embodiment
Compare schematic diagram.As shown in figure 5, the first is document, " Wang Qi, Hu Hong, Wu Yanlan wait Tree Crown Volume of the based on point cloud data certainly
Dynamic computation [J] Xibei Forest College journal, 2017,32 (2): in 242-246. ", using microtomy, by tree crown point cloud data
Divide according to z-axis, and cross section is abstracted into circle, each layer is abstracted into rotary table or circular cone, finally adds up and solves volume；Second
For document, " Huang Jian, Zhao Zuoxi, Yu Long wait laser measurement fruit tree canopy volume method and experimental study [C] Chinese agriculture engineering
Learn that cross section is abstracted as ellipse in Annual Conference .2011. " in 2011；The third is the document " Beijing Tang Xuehai city six
Cross section in 2011. ", is divided further into end to end three by the estimation of area's three-dimensional green amount and analysis and research [D] Beijing Forestry University
It is angular, intermediate trapezoidal figure；4th kind for document, " Wang Qi, Hu Hong, Wu Yanlan wait Tree Crown Volume of the based on point cloud data certainly
Dynamic computation [J] Xibei Forest College journal, 2017,32 (2): in 242-246. ", is divided into several small fans for cross section
Shape calculates cross-sectional area using sectorial area approximatioss.By comparison, it was found that the alpha-shape algorithm applied herein
Precision highest.
Step S422, by first vertex p of polygonal profile1It is connect respectively with other vertex, obtains multiple triangles.
Fig. 6 is the schematic diagram that polygon is divided into multiple triangles in the present embodiment.As shown in fig. 6, the polygonal wheel
Exterior feature one shares 6 vertex, is p respectively1、p2、...、p6, by first vertex p1It is connect respectively with other vertex, obtains four three
Angular p1p2p3、p1p3p4、p1p4p5、p1p5p6, the area of this four triangles is denoted as S respectively2、S3、S4、S5。
Step S423 calculates the area of polygonal profile according to formula (8), the area as cross section taken in correspondence:
Wherein, SiFor triangle p1pipi+1Area, r is the number on the vertex of polygonal profile, the i.e. polygonal profile
The boundary point number of corresponding cross section；AiFor symbol coefficient, if p1、pi、pi+1Arranged counterclockwise is (as schemed on polygonal profile
Triangle p in 61p2p3、p1p3p4、p1p4p5), then Ai=1, if p1、pi、pi+1Arranged clockwise is (as schemed on polygonal profile
Triangle p in 61p5p6), then Ai=-1.
Plant canopy is divided into a centrum and multiple stage bodies using cross section as interface by step S43 from top to bottom.
Step S44 calculates separately the volume of centrum and stage body according to the area of cross section, and then obtains plant canopy
Volume.Step S441-S443 can be specifically included:
Step S441 calculates the volume of i-th of stage body according to formula (9):
Step S442 calculates the volume of centrum according to formula (10):
Step S443 calculates the volume of plant canopy according to formula (11):
Wherein, SiAnd Si+1The area (i.e. i-th of cross section corresponding to the bottom surface and upper bottom surface of respectively i-th stage body
Bottom area and the upper bottom surface product of a stage body), i is the serial number of stage body, it is arranged from the bottom upstream sequence of plant canopy, i=1,
2 ..., g-2, g be cross section number (including the cross section drawn at uppermost extreme point, but this cross section is to volume
Calculate it is meaningless, therefore actually calculate be g-2 stage body and a centrum the sum of volume), ziAnd zi+1Respectively i-th
The bottom surface of stage body and the z-axis coordinate of upper bottom surface；Sg-1Area (the i.e. bottom of centrum of cross section corresponding to bottom surface for centrum
Area), zgAnd zg-1The respectively z-axis coordinate of the bottom surface and vertex of centrum.
Fig. 7 is the schematic diagram that plant canopy is divided into a centrum and multiple stage bodies from top to bottom in the present embodiment.Such as
Shown in Fig. 7, S1And S2Bottom area and the upper bottom surface product of respectively the 1st stage body, that is, the bottom surface of the 1st stage body and upper
The area of cross section corresponding to bottom surface；z1、z2Coordinate of the bottom surface and upper bottom surface of respectively the 1st stage body in z-axis；Together
Reason, S2And S3The bottom area and upper bottom surface product of respectively the 2nd stage body, Sg-1The face of cross section corresponding to bottom surface for centrum
Product, zgAnd zg-1The respectively z-axis coordinate of the bottom surface and vertex of centrum.
The method of unequal spacing separation calculation Tree Crown Volume proposed by the present invention based on density maximum point compares document
" Wang Qi, Hu Hong, Wu Yanlan wait Tree Crown Volume of the based on point cloud data automatic computation [J] Xibei Forest College journal,
2017,32 (2): 242-246. " and document " estimation of six area's three-dimensional green amount of the Beijing Tang Xuehai city and analysis and research Beijing [D]
Forestry University, the method in 2011. ", computational accuracy are improved.
Although each step is described in the way of above-mentioned precedence in above-described embodiment, this field
Technical staff is appreciated that the effect in order to realize the present embodiment, executes between different steps not necessarily in such order,
It (parallel) execution simultaneously or can be executed with reverse order, these simple variations all protection scope of the present invention it
It is interior.
Based on technical concept identical with above-mentioned calculation method embodiment, the invention also provides computing systems, below into
Row illustrates.
Fig. 8 is the main composition signal that the plant canopy volume of the invention based on point cloud data calculates system embodiment
Figure.As shown in figure 8, the plant canopy volume computing system 1 of the present embodiment includes: probability density function computing module 10, extreme value
Point computing module 20, segmentation module 30 and volume calculation module 40.
Wherein, probability density function computing module 10 is used to the three-dimensional coordinate data of plant canopy point cloud data be initial
The coordinate information of plant canopy point cloud data is projected to z-axis, calculates z coordinate probability density function by value；Extreme point computing module
20 for calculating the curvature Local Extremum of z coordinate probability density function according to z coordinate probability density function；Divide module
30 for drawing a plane as a cross section by the point and perpendicular to z-axis to each Local Extremum；According to default
The segmentation number of plies, be split between Local Extremum, obtain multiple cross sections perpendicular to z-axis；Volume calculation module 40
For plant canopy according to cross section, to be divided into a centrum and multiple stage bodies from top to bottom, and then calculate plant canopy
Volume.
In the present embodiment, extreme point computing module 20 can be specifically included: amending unit, curvature estimation unit, pole undetermined
Value point selection unit and Local Extremum selection unit.
Wherein, amending unit is for being modified probability density according to formula (1)-(2)；Curvature estimation unit is for pressing
The curvature that z-axis projects upper discrete point is calculated according to formula (3)-(4)；Extreme point selection unit undetermined be used for z-axis projection on from
Curvature value is chosen in scatterplot is greater than the point of curvature threshold as extreme point undetermined；Local Extremum selection unit is used for adjacent
The maximum point of curvature value is selected in extreme point undetermined, obtains Local Extremum.
In the present embodiment, segmentation module 30 can be specifically included: extreme point cross section generation unit, segmentation step size computation list
Member and cutting unit.
Wherein, extreme point cross section generation unit is used to draw by the point and perpendicular to z-axis each Local Extremum
One plane is as a cross section；Divide step calculation unit to be used to calculate each pair of adjacent local extremum according to formula (5)
Segmentation step-length between point；Cutting unit is used between each pair of adjacent Local Extremum, according to corresponding segmentation step progress
The equidistant segmentation of row, to obtain multiple cross sections perpendicular to z-axis.
In the present embodiment, volume calculation module 40 can be specifically included: boundary point computing unit, cross-sectional area calculate single
Member, division unit and volume computing unit.
Wherein, boundary point computing unit is for respectively projecting the point in the upper and lower specific distance range in each cross section
Onto corresponding cross section, and then calculate the boundary point of each cross section；Cross-sectional area computing unit for sequentially connecting respectively
The boundary point for connecing each cross section obtains the polygonal profile of cross section taken in correspondence, and then calculates the area of each cross section；It divides
Unit is used to that plant canopy to be divided into a centrum and multiple stage bodies from top to bottom using cross section as interface；Volume calculates
Unit is used for the area according to cross section, calculates separately the volume of centrum and stage body, and then obtain the volume of plant canopy.
Specifically, boundary point computing unit may include: average distance computation subunit, projection between point in the present embodiment
Unit, boundary point computation subunit
Wherein, average distance computation subunit is used to calculate plant canopy point cloud data according to formula (6)-(7) between point
Average distance between point；Projection subelement is for projecting to correspondence for the point in the upper and lower specific distance range in each cross section respectively
On cross section；Boundary point computation subunit is used for the point cloud data on each cross section, using two-dimensional surface boundary profile
Alpha-shape algorithm calculates the boundary point of the cross section.
Specifically, cross-sectional area computing unit may include: that polygonal profile generates subelement, triangle in the present embodiment
Shape generates subelement, cross-sectional area computation subunit.
Wherein, polygonal profile generates the boundary point that subelement is used to be sequentially connected with each cross section respectively, is corresponded to
The polygonal profile of cross section；Triangle generates subelement and is used for first vertex p of polygonal profile1It is pushed up respectively with other
Point connection, obtains multiple triangles；Cross-sectional area computation subunit is used to calculate the face of polygonal profile according to formula (8)
Product, the area as cross section taken in correspondence.
Specifically, volume computing unit may include: stage body volume computation subunit, the calculating of centrum volume in the present embodiment
Subelement, summation subelement.
Wherein, stage body volume computation subunit is used to calculate the volume of stage body according to formula (9)；Centrum stereometer operator list
Member is for calculating the volume of centrum according to formula (10)；Subelement of summing is used to calculate the body of plant canopy according to formula (11)
Product.
Module, dividing elements are carried out to computing system in the application, it is only for more fully understand technology of the invention
Function involved in scheme, in practice, function corresponding to these modules can be by single or multiple hardware loading procedures simultaneously
It executes.
Based on above-mentioned calculation method, the invention also provides a kind of embodiments for storing equipment, including memory, institute
It states memory and is suitable for storage program, described program is suitable for being loaded and being executed by processor, recited above based on point cloud to realize
The plant canopy calculation method of physical volume of data.
Further, the invention also provides a kind of processing equipments, comprising: processor and memory.Wherein, processor is suitable
In loading procedure, memory is suitable for storing said program, and described program is suitable for being loaded and being executed by the processor, on realizing
Plant canopy calculation method of physical volume described in face based on point cloud data.
Those skilled in the art should be able to recognize that, side described in conjunction with the examples disclosed in the embodiments of the present disclosure
Method step, can be realized with electronic hardware, computer software, or a combination of the two, in order to clearly demonstrate electronic hardware and
The interchangeability of software generally describes each exemplary composition and step according to function in the above description.These
Function is executed actually with electronic hardware or software mode, specific application and design constraint depending on technical solution.
Those skilled in the art can use different methods to achieve the described function each specific application, but this reality
Now it should not be considered as beyond the scope of the present invention.
So far, it has been combined preferred embodiment shown in the drawings and describes technical solution of the present invention, still, this field
Technical staff is it is easily understood that protection scope of the present invention is expressly not limited to these specific embodiments.Without departing from this
Under the premise of the principle of invention, those skilled in the art can make equivalent change or replacement to the relevant technologies feature, these
Technical solution after change or replacement will fall within the scope of protection of the present invention.
Claims (10)
1. a kind of plant canopy calculation method of physical volume based on point cloud data, which is characterized in that the described method includes:
Using the three-dimensional coordinate data of plant canopy point cloud data as initial value, by the coordinate information of the plant canopy point cloud data
Z-axis is projected to, z coordinate probability density function is calculated；
According to the z coordinate probability density function, the curvature Local Extremum of the z coordinate probability density function is calculated；
To each Local Extremum, a plane is drawn as a cross section by the point and perpendicular to z-axis；According to pre-
If the segmentation number of plies, be split between the Local Extremum, obtain multiple cross sections perpendicular to z-axis；
According to the cross section, the plant canopy is divided into a centrum and multiple stage bodies from top to bottom, and then calculate institute
State the volume of plant canopy.
2. the plant canopy calculation method of physical volume according to claim 1 based on point cloud data, which is characterized in that " according to
The z coordinate probability density function calculates the curvature Local Extremum of the z coordinate probability density function " the step of include:
Probability density is modified according to the following formula:
P'=corrp*p
Wherein,
Max (z), min (z) respectively indicate the maximum value and minimum value that the plant canopy point cloud data is projected in z-axis, max (p)
Indicate the maximum value of probability density p；
The curvature that z-axis projects upper discrete point is calculated according to the following formula:
Wherein,
△fk(t)=f (t+k △ t)-f (t+ (k-1) △ t)
C (t) is calculated curvature value, and f (t) is function, and k=1,2,3, △ t are the one step of the parameter t of function f (t),
Symbol "×" expression cross product, symbol " " expression dot product, symbol " | | | | " indicate that mould is long；
Point of the curvature value greater than curvature threshold is chosen in the discrete point in z-axis projection as extreme point undetermined；
The maximum point of curvature value is selected in the adjacent extreme point undetermined, obtains Local Extremum.
3. the plant canopy calculation method of physical volume according to claim 1 based on point cloud data, which is characterized in that " according to
The preset segmentation number of plies, is split between the Local Extremum, obtains multiple cross sections perpendicular to z-axis " the step of
Include:
The segmentation step-length between each pair of adjacent Local Extremum is calculated according to the following formula:
Between each pair of adjacent Local Extremum, equidistantly divided according to the corresponding segmentation step length, thus
Obtain multiple cross sections perpendicular to z-axis；
Wherein, LEziAnd LEzi+1The height of respectively i-th and i+1 Local Extremum, and i-th and i+1 part
Extreme point is two adjacent Local Extremums, and i=1,2 ..., m, m is the number of the Local Extremum；△ z is the point cloud level
Degree, L are the preset segmentation number of plies.
4. the plant canopy calculation method of physical volume according to claim 1 based on point cloud data, which is characterized in that " according to
The plant canopy is divided into a centrum and multiple stage bodies by the cross section from top to bottom, and then calculates the plant hat
Layer volume " the step of include:
The point in the upper and lower specific distance range in each cross section is projected on corresponding cross section respectively, and then is calculated every
The boundary point of a cross section；
It is sequentially connected with the boundary point of each cross section respectively, obtains the polygonal profile of cross section taken in correspondence, and then calculate each cross
The area in section；
Using the cross section as interface, the plant canopy is divided into a centrum and multiple stage bodies from top to bottom；
According to the area of the cross section, the volume of the centrum Yu the stage body is calculated separately, and then obtains the plant hat
The volume of layer.
5. the plant canopy calculation method of physical volume according to claim 4 based on point cloud data, which is characterized in that " respectively
Point in the upper and lower specific distance range in each cross section is projected on corresponding cross section, and then calculates each cross section
Boundary point " the step of include:
Average distance between the point of the plant canopy point cloud data is calculated according to the following formula:
Wherein,
ρ is the density of point cloud in the height direction, and N is the number at the point cloud data midpoint, and S is point cloud in geodetic coordinates level
Projected area on direction；△ z is point cloud level degree；
The point in the upper and lower specific distance range in each cross section is projected in cross section taken in correspondence respectively, wherein it is described it is specific away from
From for εz/2；
To the point cloud data on each cross section, which is calculated using the alpha-shape algorithm of two-dimensional surface boundary profile
The boundary point in section.
6. the plant canopy calculation method of physical volume according to claim 4 based on point cloud data, which is characterized in that " respectively
It is sequentially connected with the boundary point of each cross section, obtains the polygonal profile of cross section taken in correspondence, and then calculate the face of each cross section
Product " the step of include:
It is sequentially connected with the boundary point of each cross section respectively, obtains the polygonal profile of cross section taken in correspondence；
By first vertex p of the polygonal profile1It is connect respectively with other vertex, obtains multiple triangles；
The area for calculating the polygonal profile according to the following formula, the area as cross section taken in correspondence:
Wherein, SiFor triangle p1pipi+1Area, r be the polygonal profile vertex number；AiFor symbol coefficient, if
p1、pi、pi+1For arranged counterclockwise, then Ai=1, if p1、pi、pi+1For arranged clockwise, then Ai=-1.
7. the plant canopy calculation method of physical volume according to claim 4 based on point cloud data, which is characterized in that " according to
The area of the cross section, calculates separately the volume of the centrum Yu the stage body, and then obtains the volume of the plant canopy "
The step of include:
The volume of i-th of stage body is calculated according to the following formula:
The volume of the centrum is calculated according to the following formula:
The volume of the plant canopy is calculated according to the following formula:
Wherein, SiAnd Si+1The area of cross section corresponding to the bottom surface and upper bottom surface of respectively i-th stage body, i are described
The serial number of body arranges, i=1 from the bottom upstream sequence of the plant canopy, and 2 ..., g-2, g are the number of cross section, ziWith
zi+1The bottom surface of respectively i-th stage body and the z-axis coordinate of upper bottom surface；Sg-1Cross section corresponding to bottom surface for the centrum
Area, zgAnd zg-1The bottom surface of the respectively described centrum and the z-axis coordinate on vertex.
8. a kind of plant canopy volume computing system based on point cloud data, which is characterized in that the system comprises:
Probability density function computing module will be described for using the three-dimensional coordinate data of plant canopy point cloud data as initial value
The coordinate information of plant canopy point cloud data projects to z-axis, calculates z coordinate probability density function；
Extreme point computing module, for calculating the z coordinate probability density function according to the z coordinate probability density function
Curvature Local Extremum；
Divide module, for drawing a plane as one by the point and perpendicular to z-axis to each Local Extremum
Cross section；It according to the preset segmentation number of plies, is split between the Local Extremum, obtains multiple cross perpendicular to z-axis
Section；
The plant canopy is divided into centrum and more for according to the cross section by volume calculation module from top to bottom
A stage body, and then calculate the volume of the plant canopy.
9. a kind of storage equipment, including memory, the memory is suitable for storage program, which is characterized in that described program
Suitable for being loaded by processor and being executed, to realize the plant canopy of any of claims 1-7 based on point cloud data
Calculation method of physical volume.
10. a kind of processing equipment, comprising:
Processor is suitable for loading procedure；
Memory is suitable for storing said program；
It is characterized in that, described program is suitable for being loaded and being executed by the processor, to realize any one of claim 1-7 institute
The plant canopy calculation method of physical volume based on point cloud data stated.
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