CN105136746B - A kind of multispectral plant growth sensor spectrum reflectivity correction method - Google Patents
A kind of multispectral plant growth sensor spectrum reflectivity correction method Download PDFInfo
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- CN105136746B CN105136746B CN201510422641.0A CN201510422641A CN105136746B CN 105136746 B CN105136746 B CN 105136746B CN 201510422641 A CN201510422641 A CN 201510422641A CN 105136746 B CN105136746 B CN 105136746B
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Abstract
The invention discloses a kind of bearing calibrations of multispectral crop sensor spectral reflectivity, belong to Digital Agriculture field.Uplink optical sensor and downlink optical sensor incident intensity are converted into voltage value by multispectral plant growth sensor, uplink linght sensor voltage value is converted into the corresponding voltage value of sensor incidence interface light intensity by this method, reflectivity is obtained by the ratio of downlink optical sensor and incident interface light intensity voltage, the reflectivity and standard reflectivity are established into one-variable linear regression correction equation again, the spectral reflectivity after can be obtained by the correction equation.Influence this method eliminates solar elevation to spectral reflectivity has preferable universality.
Description
Technical field
The present invention relates to a kind of bearing calibrations of multispectral plant growth sensor spectral reflectivity.Belong to Digital Agriculture neck
Domain.
Background technique
The crops such as leaf area index, Leaf nitrogen concentration, chlorophyll content can be obtained using the spectral reflectivity of crop canopies
Growth information, this has important directive significance to the accurate management regulation of crop production.For this purpose, being developed anti-based on spectrum
The inexpensive crop growth monitoring instrument for penetrating rate calculates the growth information of crop according to reflectivity using relevant model, it is seen then that
Reflectivity fundamentally determines the accuracy of instrument monitoring plant growth information.The spectral reflectivity of sensor monitoring needs to carry out
Linearity correction, linear calibration equation are using the reflectivity of instrument monitoring and the corresponding relationship of standard reflectivity by establishing unitary
What linear regression obtained.
The method that reflectivity linear calibration equation is established in the above-mentioned reflection using standard reflectivity and instrument monitoring, following
It is described in document：The development of the portable NDVI measuring instrument of the winter wheat growth such as Wang Xiu, Zhao Chunjiang, Zhou Hanchang and test [J]
Journal of Agricultural Engineering, 2004 (4):95-98,2004 (4):95-98；The intelligent portable such as Hao Xiaojian, Hao Lina, Liu Liangyun
NDVI measuring instrument [J] Chinese journal of scientific instrument, 2005 (3):246-248,2005 (3):246-248.
The above-mentioned method for carrying out linearity correction to the reflectivity that sensor acquires merely with standard reflectivity, has ignored the sun
The influence of elevation angle, so that the reflectivity that same visual field under identical light intensity, is measured by the change sensor of solar elevation
Large change, the serious accuracy and practicability for affecting sensor monitoring can be presented.
Summary of the invention
The purpose of the present invention is the deficiencies for the correction of background technique spectral reflectivity, provide a kind of multispectral plant growth
It is anti-to improve spectrum by the modified spectral reflectivity bearing calibration of solar elevation for the bearing calibration of sensor spectral reflectivity
Penetrate the monitoring accuracy of rate.
The present invention is in order to solve the above technical problems, using following technical scheme：
A kind of bearing calibration of multispectral plant growth sensor spectral reflectivity, using following steps：
1. multispectral plant growth sensor acquisition uplink optical sensor and downlink optical sensor incident intensity respectively correspond
Voltage VupAnd Vdown, and record the solar elevation θ at acquisition moment.
2. calculating the corresponding voltage value V ' of light intensity before sunlight incidence uplink linght sensor interfaceup,TsFor light intensity
Transmitance.
3. reflectivity R is calculated,
4. establishing the unitary linearity correction side of spectral reflectivity R according to the corresponding relationship of reflectivity R and standard reflectivity
Journey：Y=1.191x-8.3589.
In above-mentioned technical proposal, TsCalculation method be：
The refractive index for the frosted glass relative atmospheric that n is covered by uplink optical sensor.
α is incidence angle,
Further, the bearing calibration of a kind of multispectral plant growth sensor spectral reflectivity of the invention, standard reflection
Rate can be used gray scale plate and other spectrometers also can be used using the nominal value of gray scale plate as standard reflectivity for measurand
The reflectivity of device measurement is standard reflectivity.
The invention adopts the above technical scheme, compared with prior art, has the following technical effects：
The present invention solves the reflectivity of multispectral plant growth sensor monitoring in background technique by solar elevation shadow
Loud defect provides a kind of process modified spectral reflectivity bearing calibration of solar elevation, improves spectral reflectivity
Monitoring accuracy has preferable application value.
Detailed description of the invention
The relational graph of uplink linght sensor voltage value and light intensity before Fig. 1 is corrected.
The relational graph of uplink linght sensor voltage value and light intensity after Fig. 2 correction.
Reflectivity comparison diagram of the Fig. 3 using 40% standard reflectivity gray scale plate as monitoring object, before and after voltage correction.
The spectral reflectivity correction graph of Fig. 4 the present embodiment.
Fig. 5 is multispectral plant growth sensor structure figure.
Fig. 6 is the sectional structure chart of uplink linght, downlink light plant growth sensor.
Fig. 7 is the structure chart of uplink linght plant growth sensor.
Fig. 8 is the structure chart of downlink light plant growth sensor.
Figure label：1-uplink linght plant growth sensor, 2-downlink light plant growth sensors, 3-fixed brackets,
4-movable support rods, 5-porous sensor firmwares, 6-photodetector arrays, 7-spectral filters, 8-cleaning glass,
9-filtering circles, 10-cosine correctors, 11-protection glass.
Specific embodiment
Present invention is further described in detail With reference to embodiment.
1) in fair weather 10:00:00-14:00:Between 00, with standard reflectivity be 5%, 10%, 20%, 40%,
60%, 75% and 99% gray scale plate is monitoring object, records uplink optical sensor and downlink optical sensor incident intensity is corresponding
VoltageWithAnd record the solar elevation θ at acquisition momenti, i ∈ [1, n], n are the total degree for acquiring data,For data pair.The relationship of uplink linght sensor voltage value and light intensity is shown in Fig. 1 before correcting, the morning and afternoon in Fig. 1
At the time of identical light intensity, because of the difference of solar elevation, uplink linght voltage value is not changed linearly with light intensity, is showed in figure
The morning and afternoon to be respectively a curve.
2) refractive index n=1.53 calculates light intensity transmitance according to formula (1), (2) and (3)WithData are to correspondence.According toIt calculatesSolar elevation is eliminated to sensing by calculating
Device receives the influence of light intensity signal, makes voltage valueGood linear relationship is presented with light intensity, uplink optical sensor electricity after correction
The relationship of pressure value and light intensity is shown in Fig. 2.By taking visual field is 40% standard reflectivity gray scale plate as an example, the correction of uplink linght sensor voltage value
Front-reflection rateWith correction back reflection rateFig. 3 is seen with the relationship of light intensity, reflectivity R in Fig. 31With too
The increase of positive elevation angle and become smaller, and reflectivity R2It is not influenced by solar elevation.
3) reflectivity R is calculated, establishes the unitary line of spectral reflectivity R with the standard reflectivity of corresponding gray scale plate according to R
Property correction equation, obtains y=1.191x-8.3589, r2=0.9906, wherein x=R, y are the spectral reflectivity after correction, linearly
Correction equation is shown in Fig. 4.
Referring to Fig. 5, the structure of multispectral plant growth sensor includes uplink linght plant growth sensor 1, downlink light work
Object growth sensors 2, fixed bracket 3, movable support rod 4.Uplink linght plant growth sensor 1 and horizontal position connection in 90 °
In fixed 3 upper surface of bracket；Downlink light plant growth sensor 2 with horizontal position is in 90 ° is fixedly connected on fixed 3 following table of bracket
Face；Fixed bracket 3 is fixed on the top of movable support rod 4 by fastening screw.Movable support rod 4 is adjusted, setting downlink light is made
Object growth sensors and horizontal position are in 90 °, and apart from crop canopies height 1m~1.3m, to obtain resolution visual field appropriate.
Referring to Fig. 6, Fig. 7 and Fig. 8, uplink linght plant growth sensor 1 includes porous sensor firmware 5, photodetector
Array 6, spectral filter 7, cleaning glass 8, filtering circle 9 and cosine corrector 10；Photodetector array 6 is by four photoelectricity
Diode is alternatively arranged；Spectral filter 7 selects center wave band 560nm, tetra- kinds of 710nm, 720nm 810nm；Photoelectricity is visited
Device array 6, spectral filter 7, cleaning glass 8 is surveyed to be sequentially arranged at intervals in porous sensor firmware 5 and sealed；Filtering circle
9 are connected to porous 5 surface of sensor firmware by fastening screw；Cosine corrector 10 is applied to filtering circle surface；
Downlink light optical sensor 2 includes porous sensor firmware 5, photodetector array 6, spectral filter 7, cleaning glass
Glass 8, filtering circle 9 and protection glass 11；Photodetector array 6 is alternatively arranged by four photodiodes；Spectrum filter
Mating plate 7 select center wave band 560nm, 710nm, 720nm, tetra- kinds of 810nm；Photodetector array 6, spectral filter 7, cleaning
Glass 8 is sequentially arranged at intervals in three hole sensor firmwares 5 and is sealed；Filtering circle 9 is connected to porous biography by fastening screw
5 surface of sensor firmware；Protection glass 11 is applied to filtering circle surface；One end that five cores shield transfer wire connects photodetection
Device, the other end connect the current-voltage conversion circuit.
What onechipmicroprocessor was selected is STC89C516 single-chip microcontroller, acquires multispectral information and test by data port
Ambient temperature information.Control keyboard is made of Reset, " measurement ", " monitoring ", " diagnosis " four keys, wherein " measurement " key is used
It acquires crop canopies spectral information in real time and collected information is handled, and by display when fructufy in display liquid crystal
On screen；" monitoring " key is used to interrupt current real-time measurement, captures current value；" diagnosis " key is used to couple plant growth mould
Type, the growth informations such as inverting crop nitrogen content, nitrogen accumulation, leaf area index and leaf dry weight, and the results are shown in display liquid
On crystalline substance screen, for evaluating crop growth conditions；Reset key is used to restore to init state, and at the beginning of liquid crystal screen display
Beginningization information and preset test environment temperature.
During monitoring field crop growth information, multispectral plant growth sensor 1 is installed on movable support rod 4
On the fixation bracket 3 at top, adjusting movable support rod 4 keeps downlink light spectrum sensor and horizontal position in 90 °, and apart from crop
Canopy height 0.7m~1.1m, to obtain certain spectral information differentiated in visual field, through current-voltage conversion circuit, sensitivity
Circuit, filter circuit processing are adjusted, crop canopies reflectance signature spectral information is extracted.Onechipmicroprocessor provides three kinds
Operating mode：Reset, " measurement ", " monitoring " and " diagnosis " are selected to switch by control keyboard.Under " measurement " mode, monolithic
Microprocessor acquires crop canopies spectral information in real time and handles collected information, and display when fructufy is existed
It shows on liquid crystal display；Under " monitoring " mode, onechipmicroprocessor interrupts current real-time measurement, captures current value；It " is examining
It is disconnected " under mode, system couples crop growth model, and inverting crop nitrogen content, nitrogen accumulation, leaf area index and leaf dry weight etc. are raw
Long message, and the results are shown in showing on liquid crystal display, for evaluating crop growth conditions；Under Reset mode, system is extensive
It answers to init state, and in liquid crystal screen display initialization information and preset test environment temperature.
Claims (2)
1. a kind of bearing calibration of multispectral plant growth sensor spectral reflectivity, which is characterized in that use following steps：
(1) multispectral plant growth sensor acquisition uplink optical sensor and the corresponding electricity of downlink optical sensor incident intensity
Press VupAnd Vdown, and record the solar elevation θ at acquisition moment；
(2) the corresponding voltage value V ' of light intensity before calculating sunlight incidence uplink linght sensor interfaceup,TsFor light intensity transmission
Rate；
(3) reflectivity R is calculated,
(4) according to the corresponding relationship of reflectivity R and standard reflectivity, the unitary linear calibration equation of spectral reflectivity R is established：y
=1.191x-8.3589；
Step (2) TsCalculation method be：
The refractive index for the frosted glass relative atmospheric that n is covered by uplink optical sensor, wherein
α is incidence angle,
2. a kind of bearing calibration of multispectral plant growth sensor spectral reflectivity according to claim 1, feature
Being that gray scale plate can be used in the step (4) standard reflectivity is measurand, using the nominal value of gray scale plate as standard reflection
Rate, the reflectivity that other spectral instrument measurements also can be used is standard reflectivity.
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| CN110672553B (en) * | 2019-10-21 | 2021-11-30 | 四川长虹电器股份有限公司 | Spectrum output compensation method for spectrometer |
| CN114965306B (en) * | 2022-05-27 | 2024-02-20 | 淮阴师范学院 | Calibration method of optical sensor for measuring reflectivity |
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| CN101672777A (en) * | 2009-10-16 | 2010-03-17 | 中国科学院南海海洋研究所 | Device for measuring bi-directional reflectance of ice layer on any position |
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