The content of the invention
Technical problem solved by the invention is, for the problem that physical model is limited in actual application, also for
Vegetation physical model parameter acquiring and inversion accuracy in application process are solved the problems, such as, a kind of broad-leaved Vegetation canopy reflection is proposed
The computational methods and model of rate, the single blade reflectivity that single blade model is obtained by the use of acquired parameter and transmissivity as hat
The |input paramete of layer model, cooperates with other |input parametes simulation Vegetation canopy reflectivity of canopy model, the vegetation hat after coupling
Layer model can clipped complex parameters acquisition process, while coupling after the integrated model of model, advantageously in plant
By the inverting of parameter.
The technical scheme is that:
A kind of computational methods of broad-leaved Vegetation canopy reflectivity, comprise the following steps:
S1:Parameter is recognized;
Input model parameter;And the parameter of input is tentatively divided into three major types:Blade parameter, soil parameters and canopy ginseng
Number;Wherein blade parameter includes pigment content, dry matter content, equivalent water thickness and blade construction parameter;Soil parameters is soil
The spectral reflectivity of earth;Crown canopy parametre is remaining other specification;
S2:Blade parameter input PROSPECT models in step S1 carry out monolithic leaf spectral simulation, calculate single
The spectral reflectivity and transmissivity of blade;
S3:Soil parameters and Crown canopy parametre in step S1 calculate extinction coefficient and scattering coefficient;
S4:Extinction coefficient and scattering coefficient the input SAIL models that step S3 is calculated, the correlation for calculating canopy are anti-
Penetrate the factor and reflectivity, including sun direct projection direction hemispherical reflectance, observed direction hemispherical reflectance and double direct projection reflectivity;
S5:Calculate canopy reflectance spectrum.
The step S2 specifically includes following steps:
S2.1:Calculate absorption coefficient K;Absorption coefficient is that the linear list of the various content of chemical substances of blade reaches, computing formula
For:
Wherein, c (i) is the concentration of component i in blade, and component i is the chemical substances such as pigment, water, dry;K (i) is group
Divide the specific absorption coefficient of i;N is blade construction parameter, represents blade hierarchy number, and N can be calculated using following empirical equation
Arrive:
N=(0.9*SLA+0.025)/(SLA-0.1)
Wherein, SLA is specific leaf area, refers to the leaf area of per unit dry weight;
S2.2:Calculate the transmissivity of interface:
The transmissivity of interface includes two:One is transmissivity of the light from air into blade, and one is light from blade
The transmissivity of air inlet;
Available light is considered as non-polarized light, and perfact polarization occurs after reflection, refracted light generating unit split pole after transmission
Change.Be may know that according to Snell-Descarts laws, on two media contact surface incidence angle and refraction angle and two refractive indexes it
Between relation, the electromagnetic wave be given further according to Schanda through two media transmissivity by calculate light with solid angle α
It is the average transmittance t of the blade of n by the air incidence refractive index that refractive index is 1av(α, 1, n), make t12=tav(α,1,n);
According to the achievement in research of Stern, light injects the transmissivity of the air that refractive index is 1 from refractive index for the blade of n
t21With t12Between there is relational expression t21=n- 2·t12, the transmissivity of interface is calculated accordingly;The meter of the transmissivity of interface
It is prior art to calculate, and can be used existing software to complete to calculate;
S2.3:Calculate total transmittance τ of the light through plating media1;
For natural light, its total transmittance τ for passing through plating media1It is the integration in the whole spaces of the π of whole hemisphere 2, with suction
Receive COEFFICIENT K and vane thickness D is related, computing formula is:
Wherein, t is intermediate variable;
S2.4:Calculate the reflectivity R of individual layer flat boardαAnd transmissivity T (1)α(1):
Individual layer flat board spectral simulation is carried out, the spectrum of individual layer flat board is the core of whole Spectra of The Leaves simulation, is mainly included
The reflectivity and transmissivity of individual layer flat board are calculated, its computing formula is:
S2.5:Calculate monolithic foliage reflectance RαAnd transmissivity T (N)α(N):
Spectra of The Leaves information simulation is carried out, Stokes is goed deep into the optical phenomena after light penetration finite layer flat board
Research, has drawn light through the mass reflex rate after the flat board of N layers of identical reflectivity and transmissivity and the calculating reason of transmissivity
By can now draw the simulation formula of Spectra of The Leaves information using its theory:
Wherein:
The step S3 specifically includes following steps:
S3.1 shadow compensations:
1. the geometrical factor related to delustring and scattering is calculated:First according to general Leaf angle inclination distribution probability weight and discrete
Change, obtain one group of Leaf inclination of discretization;Afterwards, the corresponding delustring of each Leaf inclination and dispersion factor are calculated;For Leaf inclination
θl, computational methods are as follows:
First, critical angle β is soughtsAnd βo, computing formula is:
Wherein, it is horizontal plane normal direction and blade normal angular separation i.e. Leaf inclination θsIt is solar zenith angle, θoIt is observation
Zenith angle;
Two critical angles are directly calculated when it is determined that denominator is not less than 1 for the result of calculation of 0 and cos β in computing formula
Value;When the result of calculation of cos β is equal to 1, two are faced Jie angle and are equal to π;Wherein cos β refer to βsAnd βoCosine;
Then, it is θ to calculate Leaf inclinationlIndividual blade sun direct projection direction and observed direction extinction coefficient, calculate public
Formula is respectively:
Wherein, L '=lai/h, lai are leaf area index, and h is canopy height;
2. auxiliary azimuthal angle beta is calculated1、β2、β3:The azimuthal calculating of auxiliary depend primarily on two critical angles relatively not
Etc. relation, obtaining value method is as follows:
Wherein, ψ is the relative bearing between solar direction and observed direction, the i.e. difference at both direction azimuth;
The single blade reflectivity multiplier related to transmissivity can be calculated after obtaining three auxiliary azimuths, for calculating pair
To scattering coefficient ω;
3. two-way dispersion coefficient ω (θ are calculatedl):
After auxiliary azimuth is obtained, the single blade reflectivity and transmittance calculation being calculated in cooperation S2 obtain double
To scattering coefficient, computing formula is:
Wherein, ρ, τ, θlThe reflectivity of blade, transmissivity and now corresponding Leaf inclination are represented respectively;Make the ρ=R in S2α
(N);τ=Tα(N)。
S3.2 calculates the scattering coefficient after adding leaf reflectance and transmissivity:
1. the backscattering coefficient computing formula of diffusing radiation E- and E+ is:
2. the forward scattering coefficient formulas of diffusing radiation E- and E+ are:
3. beam radia ESBackscattering coefficient computing formula be:
4. beam radia ESForward scattering coefficient formulas be:
5. the attenuation coefficient computing formula of diffusing radiation E- and E+ is:
6. observed direction radiates E0Backscattering coefficient computing formula be:
7. observed direction radiates E0Forward scattering coefficient formulas be:
S3.3 calculates general Leaf angle inclination distribution probability (blade profile profile element):
Calculate the general Leaf angle inclination distribution under average Leaf angle inclination distribution:Leaf inclination refers to horizontal plane normal direction and blade method
Line angular separation;The different type of Vegetation canopy corresponds to different vegetation blade pitch angles, while corresponding to two leaves point
Cloth parameter LIDFa and LIDFb.
In the case where non-spheroid shape is distributed, general Leaf angle inclination distribution probability can be calculated according to average Leaf inclination, calculated
Journey is completed by following iteration:
X=2 θ
Y=LIDFasin (x)+0.5LIDFbsin (2x)
Dx=0.5 (y-x+2 θ)
X=x+dx
Until | dx | < t;
Then F (θ)=2 (y+ θ)/π.
Wherein, θ is the centrifugal pump of average Leaf inclination, and F (θ) is accumulation Leaf inclination, i.e., general Leaf angle inclination distribution probability.
For elliposoidal distribution, what parameter LIDFa was represented is distribution angle, is 30 degree, and parameter LIDFb is 0, general asking
During Leaf angle inclination distribution probability, the Leaf inclination density function made using Campbell (1986) is tried to achieve;
S3.4 determines the model parameter of whole canopy;
For any canopy, blade tilt will not be fixed, be one from 0 to 90 ever-increasing continuous mistakes
Journey, it is thus determined that during the model parameter of whole canopy, it by Leaf inclination is θ that computational methods arelWhen general Leaf angle inclination distribution probability F
(θl) be added again with after model parameter product, computing formula is:
Z=∑ F (θl)Z(θl)
Wherein, F (θl) it is Leaf inclination θlCorresponding general Leaf angle inclination distribution probability, Z (θl) for single blade parameter, Z be through
Cross Leaf inclination correction model Z=∑ F (θl)Z(θl) it is subject to the parameter of revised whole canopy;, Z (θl) refer to step S3.1 and
K (the θ obtained in S3.2l)、K(θl)、ω(θl)、σ(θl)、σ′(θl)、s(θl)、s′(θl)、a(θl)、v(θl)、u(θl) in appoint
Meaning one;Z correspondingly refer to all coefficient ks in four differential equations of SAIL models for whole canopy, K, w, σ, σ ', s,
Any one in s ', a, v, u.
The step S4 specifically includes following steps:
S4.1:Calculate leaf area parameter;Leaf area parameter is to evaluate the important indicator of Vegetation canopy reflectivity, its parameter meter
Calculating formula is:
τss=e-klai
τoo=e-Klai
ρdd=(emlai-e-mlai)/(h1emlai-h2e-mlai)
τdd=(h1-h2)/(h1emlai-h2e-mlai)
Wherein, K and k represent that observed direction radiates E respectively0Extinction coefficient and beam radia EsExtinction coefficient;
Lai represents leaf area index, is mode input parameter;
S4.2:The parameter after adding hot spot-effect is calculated, computing formula is as follows:
ρsd=CS(1-τssτdd)-DSρdd
τsd=DS(τss-τdd)-CSτssρdd
ρdo=Co(1-τooτdd)-Doρdd
τdo=Do(τoo-τdd)-Coτooρdd
ρso=Ho(1-τssτoo)-Coτsdτoo-Doρsd
Wherein, the computational methods of each intermediate variable are:
h1=(a+m)/σ
h2=(a-m)/σ=1/h1
CS=[s ' (k-a)-s σ]/(k2-m2)
Co=[v (K-a)-u σ]/(K2-m2)
Ds=[- s (k+a)-s ' σ]/(k2-m2)
Do=[- u (K+a)-v σ]/(K2-m2)
Hs=(uCS+vDs+w)/(K+k)
Ho=(sCo+s′Do+w)/(K+k)
Wherein, τssooIt is hot spot-effect corrected parameter;Due to the problem of solar radiation, the particularly soil in sparse vegetation region
The temperature difference of earth and vegetation is quite big, and this is related to its physical surface and Meteorological, it is therefore desirable to a process for temperature adjustmemt,
It is likely to provide extra Vegetation canopy information simultaneously.The makeover process of hot spot-effect is:
Focus correction is carried out according to 2/ (k+K) effect, first according to given focus value calculating parameter:
The initial value of given alf is alf=106,
If 1) focus value q is more than 0, then it is assumed that be there is the hot spot-effect to influence, now Wherein, θsIt is solar zenith angle, θoFor view zenith angle,It is the sun
Azimuth;(its alf value is 200 if α result of calculations are more than 200);If the result of calculation of alf is 0, calculate as follows
The parameter τ gone out under the influence of the pure hot spot-effect of shadow-freessooAnd sumint:
τssoo=τss
If the result of calculation of alf is not 0, then it is assumed that be, without hot spot-effect influence, τ to be calculated by the method in 2)ssooWith
sumint;
If 2) focus value q is 0, then it is assumed that be that, without hot spot-effect influence, the method being added using circulation is calculated without focus
Parameter τ under effectsssooAnd sumint:Concretely comprise the following steps:
The first step, parameter initialization:
Second step, by following iterative calculation τssooAnd sumint:
Step 1, the value for judging i:
If i is less than 20, x2=-log (1-i*fint)/alf is made;
If i=20, x2=1 is made;
If i is more than 20, terminate iteration, make τssoo=f1;;
Step 2, following calculating is carried out successively:
Y2=- (K+k) * lai*x2+fhot* (- exp (- alf*x2))/alf;
F2=exp (y2);
Sumint=sumint+ (f2-f1) * (x2-x1)/(y2-y1);
X1=x2;
Y1=y2;
F1=f2;
Step 3, makes i=i+1, and go to step 1;
Wherein, * represents multiplication.
S4.3:Calculate bidirectional reflectance:
Bidirectional reflectance includes two parts, and scattering,single of the part with hot spot-effect influences, and another part is not with focus
The Multiple Scattering influence of effect, two parts are summed to the result of calculation of the final reflectivity influence at the top of canopy:
ρso2=ρso+w*lai*sumint
S4.4:Introduce soil reflex:
Soil is located at the bottommost of whole canopy reflecting system, and electromagnetic wave can be mapped to soil ground after penetrating canopy, through anti-
Canopy top is reflected back after penetrating again, a part for canopy reflectance spectrum is formed, numerical procedure is:
dn=1-rs*ρdd
S4.5:Calculate double hemispherical reflectance factors:
S4.6:Calculate sun direct projection direction hemispherical reflectance:
ρsd2=ρdd+(τsd+τss)*rs*τdd/dn
S4.7:Calculating observation direction hemispherical reflectance:
ρdo2=ρdo+(τdo+τoo)*rs*τdd/dn
S4.8:Calculate double direct projection reflectivity:
ρsod2=ρso+((τss+τsd)*τdo+(τsd+τss*rs*ρdd)*τoo)*rs/dn
ρso3=ρso2+ρso+τssoo*rs
Wherein, rsIt is spectral reflectance.
The step S5 specifically includes following steps:
First, can be divided in the hope of direct sunlight line and the fundamental radiation amount of atmospheric scattering light according to database data
E is not designated as itsAnd Ed;
Then, calculate scattering in representing air and radiate the coefficient skyl for accounting for global radiation ratio:
Skyl=0.847-1.61*sin (90- θs)+1.04*sin(90-θs)2
Finally, the amount of radiation that calculating observation direction is measured to and the ratio of the amount of radiation of incidence, obtain canopy reflectance spectrum, public
Formula is:
A kind of computation model of broad-leaved Vegetation canopy reflectivity, formula is as follows:
Wherein, R is canopy reflectance spectrum, EsAnd EdThe respectively fundamental radiation amount of direct sunlight line and atmospheric scattering light,
Skyl is that scattering radiates the coefficient for accounting for global radiation ratio in representing air;ρdo2And ρso3Respectively observed direction hemispherical reflectance and
Direct projection reflectivity;Model parameter is solved according to the computational methods of above-mentioned broad-leaved Vegetation canopy reflectivity.
Beneficial effect:
The present invention will simulate broad-leaved based on newest PROSPECT broad-leaveds model and SAIL canopy scale-model investigation achievements
The PROSPECT models of Spectra of The Leaves information are coupled with the SAIL models of simulation canopy spectrum information, and making full use of to obtain
Parameter save Spectra of The Leaves and simulate this process, cancel Vegetation canopy reflectivity simulation process Leaf reflectivity and transmissivity
The process of input, adds canopy SAIL models to complete coupling process leaf model simulation algorithm, directly by vegetation physical and chemical parameter
Simulation canopy spectra.Carry out coupling the essence for being greatly improved physical model simulated spectra using physical model newest research results
Degree, improves model business Motor ability, while the parameter acquiring effectively simplified in Vegetation canopy spectral information simulation process is asked
Inscribe and optimized algorithm, speed-up computation process, improve the inverting ability of vegetation information.
Specific embodiment
The present invention is further described below in conjunction with accompanying drawing.
Based on the present invention is using the SAILH canopy models after hot spot-effect improvement, given parameter is divided first
Class, is divided into blade parameter and Crown canopy parametre two parts, and afterwards using the physical and chemical parameter of blade, the base absorption for calculating blade is made
With in conjunction with reflectivity and transmissivity that individual layer flat board is derived without the transmittance calculation under the absorption of interface, finally utilization point
Shelf theory derives the spectral information of given structural parameters lower blade;Simultaneously for Crown canopy parametre first with given Leaf inclination
Distributed model parameter calculates blade profile profile element, calculates the extinction coefficient of canopy model in conjunction with the geometric element for calculating and dissipates
Penetrate coefficient and combined with blade profile distributed model, the complete Crown canopy parametre under intact leaf is distributed is obtained by cyclic process, finally,
The reflectivity for determining canopy is sought using two radiation parameters and sky scattering coefficient tried to achieve.
The implementation case is by taking the tree that highway side growing state is good and canopy spectra is easily determined as an example to this
The technical scheme of invention is further described.As shown in drawings, improved physical model PROSAILH involved in the present invention
Computational methods it is as follows:
By determining, the parameter such as following table of the tree:
Chlorophyll content |
45.80 |
Leaf angle inclination distribution type |
Apsacline |
Equivalent water thickness |
0.02 |
Leaf area index |
4.30 |
Dry matter content |
0.02 |
Solar zenith angle |
30.00 |
Blade construction parameter |
1.30 |
View zenith angle |
10.00 |
Focus |
8.00 |
Relative bearing |
0.00 |
Choice experiment wavelength is 400nm-2399nm
S1 parametric classifications:It is divided into two parts after the relevant parameter for obtaining vegetation, wherein blade parameter includes the color of blade
Cellulose content, equivalent water thickness, dry matter content and maximum incident angle (generally 59 degree);Crown canopy parametre is joined including Leaf angle inclination distribution
The background reflectivity of number, leaf area index, solar zenith angle, view zenith angle, relative bearing and focus and soil.
S2:Spectra of The Leaves information is resolved:After relevant parameter is obtained, it is necessary first to calculate the spectral reflectivity of individual blade
And transmissivity, numerical procedure is as follows:
(1) absorption coefficient K is calculated:Absorption coefficient is that the linear list of the various content of chemical substances of blade reaches, and computing formula is:
(2) without transmittance calculation under the absorption of interface:Available light is considered as non-polarized light, occurs after reflection complete
Polarization, after transmission there is partial polarization in refracted light.Be may know that on two media contact surface according to Snell-Descarts laws
Relation between incidence angle and refraction angle and two refractive indexes, two media is passed through further according to the electromagnetic wave that Schanda is given
Transmissivity can calculate the average transmittance of blade of the light with α solid angles by air incidence refractive index that refractive index is 1 as n
tav(α, 1, n), now assign its code t12, according to the achievement in research of Stern, light is from refractive index for the blade of n injects refraction
Rate is 1 air transmissivity t21With t12Between there is relational expression t21=n- 2t12, the transmissivity of interface is calculated accordingly.
(3) transmission of the light in isotropic medium:For natural light, its total transmittance τ for passing through plating media is
Integration in the whole π spaces of hemisphere 2, related to absorption coefficient K and vane thickness D, computing formula is:
(4) individual layer flat board spectral simulation:The spectrum of individual layer flat board is the core of whole Spectra of The Leaves simulation, main to include list
The reflectivity and transmissivity of layer flat board, its computing formula is:
(5) monolithic foliage reflectance and transmissivity are simulated:Stokes enters to the optical phenomena after light penetration finite layer flat board
Go further investigation, draw light through the mass reflex rate and transmissivity after the flat board of N layers of identical reflectivity and transmissivity,
The simulation formula of Spectra of The Leaves information can be now drawn using its theory:
Wherein:
S3:Calculate extinction coefficient and scattering coefficient
(6) geometric element is calculated:
(7) blade profile profile element is calculated:
General Leaf angle inclination distribution under average Leaf angle inclination distribution:The different type of Vegetation canopy corresponds to different vegetation leaves
Piece angle of inclination, while corresponding to two leaf distributed constants LIDFa and LIDFb.In the case where non-spheroid shape is distributed, can basis
Average Leaf inclination calculates general inclination angle, and calculating process can be completed with a simple iteration, and false code is:
X=2 θ
Y=LIDFasin (x)+0.5LIDFbsin (2x)
Dx=0.5 (y-x+2 θ)
X=x+dx
Until | dx | < t;
Then F (θ)=2 (y+ θ)/π
Wherein θ is the centrifugal pump of average Leaf inclination, and F (θ) is accumulation Leaf inclination.
For elliposoidal distribution, what parameter LIDFa was represented is distribution angle, is 30 degree, and parameter LIDFb is 0, general asking
During angular distribution, the Leaf inclination density function made using Campbell (1986) is tried to achieve.
(8) delustring and scattering coefficient are calculated:
Shadow compensation:
1. geometrical factor related to delustring and scattering is calculated:First to Leaf angle inclination distribution weighting and discretization, one is obtained
The central angle angle value Leaf angle inclination distribution of group discretization.Afterwards, each Leaf inclination correspondence calculates one group of delustring and dispersion factor, single
Numerical procedure is as follows:
Critical angle β is sought firstsAnd βo, computing formula is:
Two critical angles are directly calculated when it is determined that denominator is not less than 1 for the result of calculation of 0 and cos β in computing formula
Value;When the result of calculation of cos β is more than 1, two are faced Jie angle and are equal to π;Wherein cos β refer to βsAnd βoCosine;
The extinction coefficient that sun direct projection direction and observed direction can be just calculated behind two interim boundaries angle is calculated, calculates public
Formula is respectively:
Wherein, L '=lai/h, lai are leaf area index, and h is canopy height;
2. it is used to calculate the auxiliary azimuthal angle beta of two-way dispersion coefficient W1、β2、β3Calculate:The azimuthal calculating of auxiliary mainly takes
Certainly in the relation such as not relatively of two critical angles, obtaining value method is as follows:
Wherein, ψ is the relative bearing between solar direction and observed direction, the i.e. difference at both direction azimuth;
The single blade reflectivity multiplier related to transmissivity can be calculated after obtaining three auxiliary azimuths, for calculating pair
To scattering coefficient W.
3. two-way dispersion coefficient is calculated:After auxiliary azimuth is obtained, coordinate the single blade reflection being calculated in S2
Rate and transmissivity can be calculated two-way dispersion coefficient, and computing formula is:
Wherein, ρ, τ, θlThe reflectivity of blade, transmissivity and now corresponding Leaf inclination are represented respectively;Make the ρ=R in S2α
(N);τ=Tα(N)。
Model parameter is resolved
(9) calculating (addition of leaf reflectance and transmissivity) of scattering coefficient:
1. the backscattering coefficient computing formula of diffusing radiation E- and E+ is:
2. the forward scattering coefficient formulas of diffusing radiation E- and E+ are:
3. beam radia ESBackscattering coefficient computing formula be:
4. beam radia ESForward scattering coefficient formulas be:
5. the attenuation coefficient computing formula of diffusing radiation E- and E+ is:
6. observed direction E0Backscattering coefficient computing formula be:
7. observed direction E0Forward scattering coefficient formulas be:
For any canopy, blade tilt will not be fixed, be one from 0 to 90 ever-increasing continuous mistakes
Journey, it is thus determined that during the model parameter of whole canopy, computational methods are Leaf angle inclination distribution function as probability function F (θ) and mould
It is added again after shape parameter product, computing formula is:
Z=∑ F (θl)Z(θl)
Wherein, F (θl) it is Leaf inclination θlCorresponding general Leaf angle inclination distribution probability, Z (θl) for single blade parameter, Z be through
Cross Leaf inclination correction model Z=∑ F (θl)Z(θl) it is subject to the parameter of revised whole canopy;, Z (θl) refer to step 1) and step
It is rapid 2) in the k (θ that obtainl)、K(θl)、ω(θl)、σ(θl)、σ′(θl)、s(θl)、s′(θl)、a(θl)、v(θl)、u(θl) in appoint
Meaning one;Z correspondingly refer to all coefficient ks in four differential equations of SAIL models for whole canopy, K, w, σ, σ ', s,
Any one in s ', a, v, u.
S4:Calculate the associated reflections factor and reflectivity of canopy, including sun direct projection direction hemispherical reflectance, observed direction
Hemispherical reflectance and double direct projection reflectivity;
(1) addition of leaf-area coefficient:Leaf area index is to evaluate the important indicator of Vegetation canopy reflectivity, its parameter meter
Calculating formula is:
τss=e-klai
τoo=e-Klai
ρdd=(emlai-e-mlai)/(h1emlai-h2e-mlai)
τdd=(h1-h2)/(h1emlai-h2e-mlai)
(2) parameter of solution is calculated:Parameter after addition hot spot-effect is more complicated, and computing formula is as follows:
ρsd=CS(1-τssτdd)-DSρdd
τsd=DS(τss-τdd)-CSτssρdd
ρdo=Co(1-τooτdd)-Doρdd
τdo=Do(τoo-τdd)-Coτooρdd
ρso=Ho(1-τssτoo)-Coτsdτoo-Doρsd
The computational methods of wherein each variable are:
h1=(a+m)/σ
h2=(a-m)/σ=1/h1
CS=[s ' (k-a)-s σ]/(k2-m2)
Co=[v (K-a)-u σ]/(K2-m2)
Ds=[- s (k+a)-s ' σ]/(k2-m2)
Do=[- u (K+a)-v σ]/(K2-m2)
Hs=(uCS+vDs+w)/(K+k)
Ho=(sCo+s′Do+w)/(K+k)
(3) amendment of hot spot-effect:Due to the problem of solar radiation, the particularly soil in sparse vegetation region and vegetation
The temperature difference is quite big, and this is related to its physical surface and Meteorological, it is therefore desirable to a process for temperature adjustmemt, while being likely to
Extra Vegetation canopy information is provided.The makeover process of hot spot-effect is:
Focus correction is carried out according to 2/ (k+K) effect, first according to given focus value calculating parameter:
The initial value of given alf is alf=106,
If 1) focus value q is more than 0, then it is assumed that be there is the hot spot-effect to influence, now Wherein, θsIt is solar zenith angle, θoFor view zenith angle,It is the sun
Azimuth;(its alf value is 200 if α result of calculations are more than 200);If the result of calculation of alf is for 0, shadow-free is calculated pure
Parameter τ under the influence of hot spot-effectssooAnd sumint, computing formula is:
τssoo=τss
If the result of calculation of alf is not 0, then it is assumed that be, without hot spot-effect influence, τ to be calculated by the method in 2)ssooWith
sumint;
If 2) focus value q is 0, then it is assumed that be that, without hot spot-effect influence, the method being added using circulation is calculated without focus
Parameter τ under effectsssooAnd sumint:Concretely comprise the following steps:
The first step provides the initial parameter in circulation:
Fhot=lai*sqrt (K*k);
X1=0;
Y1=0;
F1=1;
Fint=(- exp (- alf)) * 0.05;
Sumint=0;
Second step calculating parameter:
Finally make τssoo=f1;
* in above-mentioned code represents multiplication;
In program calculating, intermediate parameters x2 is made according to given formula result of calculation in preceding 19 circulations and is substituted into below
Sumint is calculated in formula, intermediate parameters x2 values are made in the 20th circulation to be calculated in 1 and substitution formula below
Sumint, makes τssooEqual to the f1 that the 20th cycle calculations go out.
(4) bidirectional reflectance is calculated:Bidirectional reflectance includes two parts, part band hot spot-effect, the non-band of another part
Hot spot-effect, two parts are summed to final result of calculation:
ρso2=ρso+w*lai*sum
(5) introducing of soil reflex:Soil is located at the bottommost of whole canopy reflecting system, and electromagnetic wave penetrates canopy
After can be mapped to soil ground, be reflected back again after reflection canopy top, formed canopy reflectance spectrum a part, numerical procedure
For:1-rs*ρdd
(6) double hemispherical reflectance factors are calculated:
(7) sun direct projection direction hemispherical reflectance is calculated:
ρsd2=ρdd+(τsd+τss)*rs*τdd/ (1-rs* ρdd)
(8) observed direction hemispherical reflectance is calculated:
ρdo2=ρdo+(τdo+τoo)*rs*τdd/ (1-rs* ρdd)
(9) double direct projection reflectivity are calculated:
ρsod2=ρso+((τss+τsd)*τdo+(τsd+τss*rs*ρdd)*τoo)*rs/ (1-rs* ρdd)
ρso3=ρso2+ρso+τssoo*rs
S5:Calculate canopy reflectance spectrum:
Direct sunlight line can be tried to achieve with the fundamental radiation amount of atmospheric scattering light according to database data, respectively
ESAnd Ed, secondly calculate atmospheric scattering coefficient skyl parameters:
Sskyl=0.847-1.61*sin (90- θs)+1.04*sin(90-θs)2
The ratio of the amount of radiation that the computational methods of canopy reflectance spectrum are measured to for observed direction and the amount of radiation of incidence, formula
For:
The vegetation reflectivity such as Fig. 3 institutes for calculating.
This High-grade highway area vegetation physical and chemical parameter chosen and contrast spectrum used are measured value, modeling knot
Fruit determines availability and precision problem using RMSE.
After testing, the spectral information root-mean-square error (RMSE) of model this example simulation is 0.15706, simulation algorithm simulation
Result is available and precision is higher.
Described example is a part of example of the invention, rather than whole examples, it is impossible to be interpreted as to of the invention
Limitation.Based on the example in the present invention, those of ordinary skill in the art are obtained on the premise of innovative labor is not made
Every other implementation method belong to protection scope of the present invention.