JPWO2016181743A1 - Plant growth index measuring apparatus and method, and plant growth index measuring system - Google Patents

Abstract

In the plant growth index measuring device, the plant growth index measuring method, and the plant growth index measuring system according to the present invention, each light of the reflected light of the measuring object having a plurality of leaves obtained by measuring at the first and second wavelengths. Growth in the measurement object based on the intensity, the solar angle that is the incident angle of the sunlight to the measurement object at the time of measurement, and the solar direction that is the direction of the sun with respect to the measurement direction of the reflected light A growth index that represents the degree of the above is obtained.

Description

  The present invention relates to a plant growth index measuring apparatus, a plant growth index measuring method, and a plant growth index measuring system for obtaining a growth index representing the degree of growth in a plant.

  In agriculture, it is necessary to appropriately carry out fertilization management such as the time of topdressing and the amount of topdressing, for example, in order to grow plants of high quality and stable crops. Therefore, the current plant state is determined. For this determination, a leaf color plate (leaf color scale) provided with a plurality of color samples whose colors gradually changed from yellowish green to dark green, for example, since the darkness of the leaf color represents the state of the plant. It is used. Since the determination of the state of a plant using such a leaf-colored plate is a subjective determination or is not suitable for agricultural industrialization, various devices have been researched and developed in recent years. For example, there is a technique disclosed in Patent Document 1.

  The plant growth degree measuring apparatus disclosed in Patent Document 1 is an apparatus for optically measuring the growth degree of a plant, in which sunlight reflected by a plant is incident and spectroscopically, and two or more kinds of identifications are made. A first light receiving unit that measures the reflection intensity of light having a wavelength; and a second light that directly enters sunlight and splits it into light having the same wavelength as that of the first light receiving unit, and measures the received light intensity as reference light. The reflected light intensity of the specific wavelength detected by the light receiving unit and the first light receiving unit is corrected based on the received light intensity of the reference light detected by the second light receiving unit, and the measurement plant is calculated based on the corrected reflection intensity. A calculation unit for obtaining at least one of leaf color (SPAD value), plant height, dry weight, (plant height x number of stems), {plant height x leaf color (SPAD value)} and {plant height x number of stems x leaf color (SPAD value)} .

  By the way, the plant growth degree measuring apparatus disclosed in Patent Document 1 corrects the reflection intensity of the specific wavelength based on the received light intensity of the reference light in order to obtain the growth degree. However, in an actual field, the leaves of the plant are not only a single leaf but a plurality of foliage. For this reason, the sunlight reflected by the plant will be received after repeating transmission and reflection in the foliage, and as a result, the received light intensity is, for example, when received by a camera (imaging unit) It depends on the positional relationship with the sun. Therefore, the plant growth degree measuring apparatus disclosed in Patent Document 1 has room for improvement in terms of accuracy.

JP 2002-168771 A (Patent No. 4243014)

  The present invention has been made in view of the above circumstances, and its object is to provide a plant growth index measuring device, a plant growth index measuring method, and a plant growth index measuring system capable of measuring a growth index with higher accuracy. It is.

  In the plant growth index measuring device, the plant growth index measuring method, and the plant growth index measuring system according to the present invention, each light of the reflected light of the measuring object having a plurality of leaves obtained by measuring at the first and second wavelengths. Growth in the measurement object based on the intensity, the solar angle that is the incident angle of the sunlight to the measurement object at the time of measurement, and the solar direction that is the direction of the sun with respect to the measurement direction of the reflected light A growth index that represents the degree of the above is obtained. Therefore, the plant growth index measuring apparatus and the plant growth index measuring method according to the present invention can measure the plant growth index with higher accuracy.

  The above and other objects, features and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.

It is a figure for demonstrating a measurement system. It is a figure which shows the relationship between the sun direction (phi) according to camera angle (measurement angle) (beta), and NDVI value when the diffusivity W is relatively low. It is a figure which shows the relationship between the sun direction (phi) according to camera angle (measurement angle) (beta), and NDVI value in case a diffusivity W is medium. It is a figure which shows the relationship between the sun direction (phi) according to camera angle (measurement angle) (beta), and NDVI value in the case where the diffusivity W is relatively high. It is a block diagram which shows the structure of the plant growth parameter | index measurement system in embodiment. It is a flowchart which shows operation | movement of the plant growth parameter | index measurement system in embodiment. It is a figure which shows an example of the measurement result in the plant growth parameter | index measurement system of embodiment.

  Hereinafter, an embodiment according to the present invention will be described with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted suitably. In this specification, when referring generically, it shows with the reference symbol which abbreviate | omitted the suffix, and when referring to an individual structure, it shows with the reference symbol which attached the suffix.

  When measuring the NDVI (Normalized Difference Vegetation Index) value of a foliage consisting of a plurality of leaves in an actual field, a camera that captures the measurement object of the foliage to obtain the reflection intensity and the sun First, the effect of the positional relationship with the above on the NDVI value will be described.

  FIG. 1 is a diagram for explaining a measurement system. FIG. 2 is a diagram illustrating the relationship between the sun direction φ for each camera angle (measurement angle) β and the NDVI value when the diffusivity W is relatively low. FIG. 3 is a diagram showing the relationship between the sun direction φ and the NDVI value for each camera angle (measurement angle) β when the diffusivity W is medium. FIG. 4 is a diagram illustrating the relationship between the sun direction φ and the NDVI value for each camera angle (measurement angle) β when the diffusivity W is relatively high. 2 to 4, FIG. A shows the NDVI value when the sun angle α is 0, FIG. B shows the NDVI value when the sun angle α is 30, and FIG. C shows the sun angle. The NDVI value when α is 60 is shown. A solid line indicates a measurement result when the camera angle β is 0 degrees, a broken line indicates a measurement result when the camera angle β is 30 degrees, and a two-dot chain line indicates a case where the camera angle β is 60 degrees The alternate long and short dash line indicates the measurement result when the camera angle β is 90 degrees. In each of these figures, the horizontal axis is the solar direction φ expressed in degrees, and the vertical axis is the NDVI value.

  In this experiment, the measurement object is a foliage consisting of a plurality of leaves. As shown in FIG. 1, when the measurement object is irradiated with sunlight from the sun at the sun angle α, the measurement object is , Measured by an NDVI camera that measures NDVI values at a camera angle (measurement angle) β. In the measurement, when the sun direction is φ and the sun diffusivity is W, the NDVI value was measured using the sun angle α, camera angle β, sun direction φ, and diffusivity W as parameters. The results are shown in FIGS. 2 to 4 respectively.

  Here, the sun angle α represents the height of the sun, and is represented by the angle of sunlight incident on the measurement object with reference to the vertical direction that is the normal direction of the horizontal plane (with the vertical direction set to 0 degree). That is, the sun angle α is an incident angle of sunlight incident on the horizontal plane. The camera angle (measurement angle) β is an angle formed by the measurement direction (the direction along the optical axis of the NDVI camera) and the vertical direction with respect to the vertical direction (the vertical direction is 0 degree). The sun direction φ is the direction of the sun with respect to the measurement direction of the NDVI camera, and the angle formed by the measurement direction of the NDVI camera with respect to the measurement target and the irradiation direction (incidence direction) of sunlight irradiated (incident) on the measurement target It is. The diffusivity W is the degree to which the sunlight is diffused by the atmospheric state (meteorological conditions) such as clouds and fog before the measurement object is irradiated.

  As can be seen from FIGS. 2 to 4, the NDVI value depends on the sun angle α, the camera angle β, the sun direction φ, and the diffusivity W. For example, the NDVI value tends to decrease as the camera angle β changes from 0 degrees to 90 degrees. For example, when the diffusivity W is low and the diffusivity W is medium, the NDVI value tends to depend on the solar direction φ as the sun angle α changes from 0 degrees to 90 degrees. .

  The reason why the NDVI value depends on the sun angle α, the camera angle (measurement angle) β, the sun direction φ, and the diffusivity W is presumed as follows. That is, in the case of foliage, sunlight repeats transmission and reflection, but the number of transmission and reflection changes depending on the sun angle α, the camera angle β, the sun direction φ, and the diffusivity W. For this reason, the reflected light intensity of sunlight reflected by the foliage changes depending on the sun angle α, the camera angle β, the sun direction φ, and the diffusivity W. As a result, the NDVI value is determined by the sun angle α, the camera. It depends on the angle β, the sun direction φ and the diffusivity W. Here, the foliage density (occupation ratio of foliage in a unit area) L also affects the number of transmissions and reflections, and therefore the NDVI value depends on the foliage density L of the foliage.

  Therefore, the NDVI value is corrected based on such a cause, so that the accuracy becomes higher. From this viewpoint, in one aspect, the NDVI value is preferably corrected based on the sun angle α and the sun direction φ. In another aspect, the NDVI value is more preferably corrected based on the sun angle α, the sun direction φ, and the diffusivity W. In another aspect, it is more preferable that the NDVI value is corrected based on the sun angle α, the sun direction φ, the diffusivity W, the camera angle (measurement angle), and the leaf density L.

  Next, this embodiment will be described. FIG. 5 is a block diagram illustrating a configuration of a plant growth index measurement system in the embodiment.

  The plant growth index measuring device according to the embodiment measures the light intensity data of the reflected light of the measurement target having a plurality of leaves, measured at the first and second wavelengths, and the solar angle that is the incident angle of sunlight to the measurement target. A growth index calculation unit that obtains a growth index that represents the degree of growth in the measurement target is provided based on the data and solar direction data that is the direction of the sun relative to the measurement direction of each light intensity data. Preferably, in the above-described plant growth index measuring apparatus, the growth index calculation unit further includes light intensity data of the solar sunlight and diffusivity of the solar sunlight measured at the third and fourth wavelengths. The growth index of the measurement object is obtained based on the data. More preferably, in the above-described plant growth index measuring apparatus, the growth index calculation unit further includes measurement angle data that is an angle in a measurement direction of each light intensity data with respect to the measurement target, and leaf density data of the measurement target. And determining the growth index of the measurement target.

  In order to input these data, such a plant growth index measuring apparatus is functionally provided with an input circuit for inputting data or an interface circuit for inputting / outputting data to / from an external device, and the growth index calculating unit. However, in this case, a plant growth index measuring system including each section for obtaining the data and the growth index calculation section. The embodiment will be described. That is, the plant growth index measurement system in the present embodiment is a device for obtaining a growth index representing the degree of growth in a measurement target having a plurality of leaves, and the light intensity of the reflected light of the measurement target having a plurality of leaves, A reflected light measurement unit that measures at different first and second wavelengths, a solar angle acquisition unit that acquires the solar altitude as a solar angle, and the sun direction relative to the measurement direction of the reflected light measurement unit is acquired as the solar direction. The solar direction acquisition unit, each light intensity of the reflected light at each of the first and second wavelengths measured by the reflected light measurement unit, the solar angle acquired by the solar angle acquisition unit, and the solar direction A growth index calculation unit for obtaining a growth index of the measurement target based on the solar direction acquired by the acquisition unit. Preferably, the plant growth index measurement system includes a solar light measurement unit that measures the light intensity of the solar sunlight at third and fourth wavelengths different from each other, and a diffusion that acquires the solar sunlight diffusion degree. A degree acquisition unit, and the growth index calculation unit, when obtaining the growth index, each light intensity of the sunlight at each of the third and fourth wavelengths measured by the sunlight measurement unit, and The diffusion degree acquired by the diffusion degree acquisition unit is further taken into consideration. More preferably, the plant growth index measurement system includes a measurement angle acquisition unit that acquires an angle of a measurement direction of the reflected light measurement unit with respect to the measurement target as a measurement angle, and a leaf density acquisition that acquires the leaf density of the measurement target. And the growth index calculation unit further considers the measurement angle acquired by the measurement angle acquisition unit and the leaf density acquired by the leaf density measurement unit when obtaining the growth index. Is.

  The plant growth index measurement system M in such an embodiment includes, for example, a reflected light measurement unit 1, a GPS (Global Positioning System) unit 2, an azimuth meter 3, as shown in FIG. An inclinometer 4, a sunlight measurement unit 5, a control processing unit 6, a clock unit 7, a storage unit 8, an interface unit 9, and a power supply unit 10 are provided.

  The reflected light measurement unit 1 is an apparatus that is connected to the control processing unit 6 and measures the light intensity of the reflected light to be measured at different first and second wavelengths according to the control of the control processing unit 6. The result is output to the control processing unit 6. The first and second wavelengths may be appropriate wavelengths according to the growth index to be obtained. For example, when the NDVI value is obtained as the growth index, the wavelength of visible light near 650 nm and infrared light of 750 nm or more are used. Is the wavelength.

  More specifically, the reflected light measurement unit 1 includes a first visible imaging unit 1-1 that generates a visible light image (visible image) and a first red that generates an infrared light image (infrared image). And an external imaging unit 1-2. The first visible imaging unit 1-1 includes, for example, a first bandpass filter that transmits light in a relatively narrow band having a wavelength of 650 nm as a center wavelength, and optical light of a measurement target that has passed through the first bandpass filter. A first image-forming optical system for forming an image on a predetermined image-forming surface; a light-receiving surface that is aligned with the first image-forming surface; and an optical image of the visible light to be measured as an electrical signal A first image sensor for conversion, a first digital signal processor (DSP) for performing known image processing on the output of the first image sensor to generate first image data Rv with visible light, and the like are configured. A so-called camera or the like. The second infrared imaging unit 1-2 includes, for example, a second bandpass filter that transmits light in a relatively narrow band having a wavelength of 800 nm as a center wavelength, and infrared light of a measurement target that has passed through the second bandpass filter. A second image-forming optical system that forms an optical image on a predetermined image-forming surface, and a light-receiving surface that coincides with the second image-forming surface. A so-called second image sensor for converting to a simple signal, a second DSP for generating a second image data Ri with infrared light by performing known image processing on the output of the second image sensor, and so on. An infrared camera or the like. The first visible image capturing unit 1-1 outputs the first image data Rv in visible light to the control processing unit 6, and the first infrared image capturing unit 1-2 in the second image data in infrared light. Ri is output to the control processing unit 6. The first measurement direction (first direction along the first optical axis) of the first visible imaging unit 1-1 and the second measurement direction (second along the second optical axis) of the first infrared imaging unit 1-2. The first visible imaging unit 1-1 and the first infrared imaging unit 1-2 are arranged so that the direction is parallel to each other. The first measurement direction of the first visible imaging unit 1-1 and the second measurement direction of the first infrared imaging unit 1-2 that are parallel to each other are the measurement directions of the plant growth index measuring apparatus M.

  In the above description, the reflected light measurement unit 1 includes the first visible imaging unit 1-1 and the first infrared imaging unit 1-2. However, the reflected light measurement unit 1 receives R in red. Image sensor (RGBIr image sensor) having a unit arrangement in which pixels, G pixels that receive green, B pixels that receive blue, and Ir pixels that receive infrared are arranged in 2 rows and 2 columns, and W pixels that receive white By using an image sensor (WYRIr image sensor) having a unit arrangement in which Y pixels for receiving yellow light, R pixels for receiving red light, and Ir pixels for receiving infrared light are arranged in 2 rows and 2 columns, one image pickup is performed. A portion may be provided. In this case, for example, the output of the R pixel and the output of the Ir pixel are used. For example, the output of G pixel and the output of Ir pixel are used. Further, for example, the output of the B pixel and the output of the Ir pixel are used. For example, the output of W pixel and the output of Ir pixel are used. For example, the output of Y pixel and the output of Ir pixel are used. The reflected light measurement unit 1 may be configured with a spectroscope.

  The GPS unit 2 is an apparatus that is connected to the control processing unit 6 and measures the position of the plant growth index measuring device M by a satellite positioning system for measuring the current position on the earth according to the control of the control processing unit 6. Yes, the positioning result (latitude X, longitude Y, altitude Z) is output to the control processing unit 6. The GPS unit 2 may be a GPS having a correction function for correcting an error such as DGSP (Differential GSP).

  The azimuth meter (compass) 3 is connected to the control processing unit 6 and measures the azimuth in the measurement direction of the plant growth index measuring device M by measuring the azimuth based on geomagnetism or the like according to the control of the control processing unit 6. The measurement direction φc is output to the control processing unit 6. The azimuth φc is expressed as 0 degrees north, 90 degrees east, 180 degrees south, and 270 degrees west.

  The inclinometer 4 is an apparatus that is connected to the control processing unit 6 and measures the angle in the measurement direction of the plant growth index measuring device M by measuring the inclination according to the control of the control processing unit 6. β is output to the control processing unit 6.

  The solar light measuring unit 5 is an apparatus that is connected to the control processing unit 6 and measures the light intensity of the solar sunlight at different third and fourth wavelengths according to the control of the control processing unit 6, and the measurement thereof. The result is output to the control processing unit 6. Although the said 3rd and 4th wavelength may be a suitable wavelength according to the growth parameter | index calculated | required, in this embodiment, the sunlight measurement part 5 is the structure similar to the reflected light measurement part 1, Therefore, The third wavelength is the first wavelength, and the fourth wavelength is the second wavelength. The sunlight measuring unit 5 includes a second visible imaging unit 5-1 having the same configuration as the first visible imaging unit 1-1 and a second infrared imaging unit having the same configuration as the second infrared imaging unit 1-2. 5-2, the second visible imaging unit 5-1 generates the third image data Sv with visible light and outputs it to the control processing unit 6, and the second infrared imaging unit 5-2 The fourth image data Si with external light is generated and output to the control processing unit 6. The third measurement direction (third direction along the third optical axis) of the second visible imaging unit 5-1 and the fourth measurement direction (fourth along the fourth optical axis) of the second infrared imaging unit 5-2. The second visible imaging unit 5-1 and the second infrared imaging unit 5-2 so that the third and fourth measurement directions face the sky (upward). Is arranged. Since the sunlight measuring unit 5 aims to acquire the light intensity of sunlight irradiated to the measurement object, a wide-angle lens such as a fish-eye lens may be used for the imaging optical system, A diffusion plate may be disposed on the front surface (for example, the incident surface). As a result, sunlight from a wide range can be obtained.

  The clock unit 7 is connected to the control processing unit 6 and is a circuit that measures the year / month / day / hour / day according to the control of the control processing unit 6, and outputs the current year / month / date / time to the control processing unit 6.

  The IF unit 9 is a circuit that is connected to the control processing unit 6 and inputs / outputs data to / from an external device according to the control of the control processing unit 6. For example, an RS232C interface circuit that is a serial communication method, Bluetooth An interface circuit using the (registered trademark) standard, an interface circuit for performing infrared communication such as an IrDA (Infrared Data Association) standard, and an interface circuit using the USB (Universal Serial Bus) standard. The IF unit 9 is a communication card or the like that communicates by wire or wireless, and may communicate with an external device such as a server device via a communication network such as an Ethernet environment (Ethernet is a registered trademark). ).

  The power supply unit 10 is a circuit that supplies power to each unit of the plant growth index measuring apparatus M that requires power at a voltage corresponding to each unit.

  The storage unit 8 is a circuit that is connected to the control processing unit 6 and stores various predetermined programs and various predetermined data under the control of the control processing unit 6. Examples of the various predetermined programs include control processing programs such as a control program for controlling each part of the plant growth index measurement system M according to the function of each part, and a growth index calculation program for obtaining a growth index to be measured. Is included. The various kinds of predetermined data include data necessary for calculating the growth index, such as correction information for correcting the growth index and growth information for obtaining the leaf density. The storage unit 8 includes, for example, a ROM (Read Only Memory) that is a nonvolatile storage element, an EEPROM (Electrically Erasable Programmable Read Only Memory) that is a rewritable nonvolatile storage element, and the like. The storage unit 8 includes a random access memory (RAM) serving as a working memory of a so-called control processing unit 6 that stores data generated during execution of the predetermined program. The storage unit 8 may include a relatively large capacity hard disk.

  The storage unit 8 functionally includes a correction information storage unit 81 that stores the correction information in advance and a growth information storage unit 82 that stores the growth information in advance in order to store the correction information and the growth information. Prepare. The correction information is, for example, information (first correction information) indicating a correspondence relationship between the sun angle α and the sun direction φ and a correction value (first correction value). The correction value is a value for correcting the growth index obtained based on each light intensity of the reflected light at each of the first and second wavelengths measured by the reflected light measuring unit 1. Further, for example, the correction information is information (second correction information) indicating a correspondence relationship between the sun angle α, the sun direction φ, the diffusivity W, and the correction value (second correction value). Further, for example, the correction information is information (third correction information) indicating a correspondence relationship between the sun angle α, the sun direction φ, the diffusivity W, the measurement angle β, the leaf density L, and the correction value (third correction value). is there. The correction information (first to third correction information) is created in advance by an experiment using a plurality of samples. The correction information (first to third correction information) may be stored in the correction information storage unit 81 in the form of a predetermined function formula, but in the present embodiment, the correction information is stored in a table format (lookup table). Stored in the unit 81 in advance. The growth information is information indicating the correspondence between the number of days since planting (for example, rice planting) and the leaf density L, for example. Instead of the number of days since planting, any of date, leaf age (number of leaves of main stem (parent stem)), average plant height and average number of stems may be used. The growth information is created in advance based on a normal value obtained from a plurality of samples. The growth information may be stored in the growth information storage unit 82 in the form of a predetermined functional expression, but in the present embodiment, it is stored in advance in the growth information storage unit 82 in a table format (lookup table).

  The control processing unit 6 is a circuit for controlling each part of the plant growth index measurement system M in accordance with the function of each part to obtain a growth index. The control processing unit 6 includes, for example, a CPU (Central Processing Unit) and its peripheral circuits. In the control processing unit 6, a control processing program is executed, whereby a control unit 61, a sun angle calculation unit 62, a sun direction calculation unit 63, a diffusivity calculation unit 64, a leaf density calculation unit 65, and a growth index calculation unit 66. Is functionally configured.

  The control unit 61 controls each part of the plant growth index measurement system M according to the function of each part.

The sun angle calculation unit 62 obtains the sun angle α by a known method based on the latitude X and longitude Y acquired by the GPS unit 2 and the year, month, day and time measured by the clock unit 7. As a method for obtaining the sun angle α, for example, ““ Solar orientation, altitude, calculation of solar radiation amount outside the atmosphere ”, [online], search on March 23, 2015, Internet <http://www.es.ris.ac .Jp / ˜nakagawa / met_cal / solar.html> ”can be used to obtain the solar altitude A and the solar orientation ψ. The solar altitude A is an elevation angle, and the solar angle α = 90 degrees−the solar altitude A. More specifically, first, θ0 is obtained from θn = 2π (dn−1) / 365 from the number of consecutive days dn from January 1st. Next, the solar declination δ is obtained by the following equation 1, and the equation of time Eq is obtained by the following equation 2. Next, the solar hour angle h is obtained from the Japanese standard time JST by the following equation 3. Then, the solar altitude A is obtained by the following expression 4. The sun azimuth ψ is obtained by the following equation 5.
δ = 0.006918−0.399912 cos (θ0) +0.070257 sin (θ0) −0.006758 cos (2θ0) −0.000907 sin (2θ0) −0.002697 cos (3θ0) −0.001480 sin (3θ0) Formula 1)
Eq = 0.000075 + 0.001868 cos (θ0) + 0.032077sin (θ0) −0.014615cos (2θ0) −0.040849sin (2θ0) (Equation 2)
h = (JST-12) π / 12 + longitude difference from standard meridian + equal time difference Eq (Expression 3)
A = arcsin [sin (Y) sin (δ) + cos (Y) cos (δ) cos (h)] (Formula 4)
ψ = arctan [cos (Y) cos (δ) sin (h) / [sin (Y) sin (α) −sin (δ)]] (Formula 5)

  Based on the latitude X and longitude Y acquired by the GPS unit 2 and the year, month, day and time measured by the clock unit 7, the solar direction calculation unit 63 obtains the solar direction ψ by a known method, and the obtained sun Based on the azimuth ψ and the azimuth φc in the measurement direction of the reflected light measurement unit 1 obtained by the azimuth meter 3, the solar direction φ is obtained. More specifically, the sun direction calculation unit 63 obtains the sun direction φ as a difference between the direction φc measured by the direction meter 3 and the sun direction φ obtained from the equation 5 (φ = ψ−φc). .

  The diffusivity calculating unit 64 obtains the diffusivity W. More specifically, for example, the diffusivity calculating unit 64 obtains the diffusivity W based on the measurement result of the sunlight measuring unit 5. For example, the diffusivity calculating unit 64 obtains the standard deviation σsv of the third image data Sv with visible light generated by the second visible imaging unit 5-1, and divides the predetermined coefficient K by the obtained standard deviation σsv. Thus, the diffusivity W is obtained (W = K / σsv). Alternatively, for example, the diffusivity calculating unit 64 obtains the standard deviation σsi of the fourth image data Si with the infrared light generated by the second infrared imaging unit 5-2, and uses the obtained standard deviation σsi to determine a predetermined coefficient. The diffusivity W is obtained by dividing K (W = K / σsi). The predetermined coefficient K is normal so that the diffusivity W is 0 when the cloud is clear (cloud amount 0, no cloud) and the diffusivity W is 1 when cloudy (cloud amount 8, all clouds). It is a coefficient for making it. Since the standard deviation σsv (σsi) increases as it becomes cloudy and clear, the diffusivity decreases. Therefore, the standard deviation σsv (σsi) can be used for the diffusivity W. Further, for example, the diffusivity calculating unit 64 acquires the shutter speed SS of the reflected light measuring unit 1 (for example, the shutter speed of the first visible imaging unit 1-1) SS from the reflected light measuring unit 1, and uses the acquired shutter speed SS. The diffusion degree W is set as it is (W = SS). Since the shutter speed SS becomes higher and the diffusivity W decreases as it becomes cloudy and clear, the shutter speed SS can be set to the diffusivity W as it is.

  The leaf density calculation unit 65 calculates the leaf density based on the growth information stored in the growth information storage unit 82. For example, in the case where the growth information is information indicating the correspondence between the number of days since planting (for example, rice planting) and the leaf density L, the leaf density calculation unit 65 uses the number of days since planting acquired via the IF unit 9. Is determined from the growth information stored in the growth information storage unit 82. The plant growth index measuring device M further includes an input unit (for example, a numeric keypad or a keyboard) for inputting data from the outside, and the number of days since planting is input to the plant growth index measuring device M via this input unit. May be.

  The growth index calculation unit 66 is configured to measure each light intensity of the reflected light at each of the first and second wavelengths measured by the reflected light measurement unit 1, the sun angle α obtained by the sun angle calculation unit 62, and the sun direction calculation unit 63. The growth index representing the degree of growth in the measurement target is obtained based on the sun direction φ obtained in step (1). According to this, since the sun angle and the sun direction are taken into consideration when obtaining the growth index, the growth index can be measured with higher accuracy. Preferably, the growth index calculation unit 66 has the light intensity of the reflected light at each of the first and second wavelengths measured by the reflected light measurement unit 1, the sun angle α obtained by the sun angle calculation unit 62, and the sun direction calculation unit. Measured based on the sun direction φ obtained in 63, the light intensity of sunlight at each of the third and fourth wavelengths measured by the sunlight measuring unit 5, and the diffusivity W obtained by the diffusivity calculating unit 64 A growth index representing the degree of growth in the subject is obtained. According to this, since the light intensity and the diffusivity W of sunlight at each of the third and fourth wavelengths are further taken into consideration when obtaining the growth index, the growth index can be measured with higher accuracy. More preferably, the growth index calculation unit 66 calculates each light intensity of the reflected light at each of the first and second wavelengths measured by the reflected light measurement unit 1, the sun angle α obtained by the sun angle calculation unit 62, and the sun direction calculation. The solar direction φ obtained by the unit 63, the light intensity of sunlight at each of the third and fourth wavelengths measured by the sunlight measuring unit 5, the diffusivity W obtained by the diffusivity calculating unit 64, and obtained by the inclinometer 4 Based on the measured angle β and the leaf density L obtained by the leaf density calculator 65, a growth index representing the degree of growth in the measurement target is obtained. According to this, when the growth index is obtained, the measurement angle β and the leaf density L are further taken into consideration, so that the growth index can be measured with higher accuracy.

  More specifically, when the first correction information is stored in the correction information storage unit 81, the growth information storage unit 82 can be omitted, and the growth index calculation unit 66 is the reflected light measurement unit 1. Based on the measured light intensity of each reflected light at the first and second wavelengths, a growth index before correction is obtained, and the sun angle α obtained by the sun angle computing unit 62 and the sun direction computing unit 63 are obtained. A first correction value corresponding to the sun direction φ is obtained from the first correction information, and the growth index before correction is corrected with the calculated first correction value to obtain a final growth index (a growth index after correction). )

  Moreover, when the 2nd correction information is memorize | stored in the correction information storage part 81, the growth information storage part 82 is omissible, and the growth index calculating part 66 is the 3rd measured by the sunlight measurement part 5. Based on the respective light intensities of sunlight at each of the fourth wavelengths, the ratio of the respective light intensities of the reflected light at the first and second wavelengths measured by the reflected light measuring unit 1 is normalized so as to be a predetermined value. While calculating, based on each light intensity of the reflected light at each of the first and second wavelengths measured by the reflected light measuring unit 1, a growth index before correction is obtained, and the sun angle α obtained by the sun angle calculating unit 62, A second correction value corresponding to the sun direction φ obtained by the sun direction calculation unit 63 and the diffusivity W obtained by the diffusivity calculation unit 64 is obtained from the second correction information, and the obtained second correction value is used. The growth index before the correction is corrected to obtain the final growth index (the corrected growth index). (Education index).

  Further, when the third correction information is stored in the correction information storage unit 81, the growth index calculation unit 66 uses each light of sunlight at the third and fourth wavelengths measured by the solar light measurement unit 5. Based on the intensity, the first measured by the reflected light measuring unit 1 while normalizing the ratio of the respective light intensities of the reflected light at the first and second wavelengths measured by the reflected light measuring unit 1 to be a predetermined value. Based on each light intensity of the reflected light at each of the first and second wavelengths, a growth index before correction is obtained, the solar angle α obtained by the sun angle computing unit 62, the solar direction φ obtained by the solar direction computing unit 63, The third correction value corresponding to the diffusivity W obtained by the diffusivity calculating unit 64, the measurement angle β obtained by the inclinometer 4, and the leaf density L obtained by the leaf density calculating unit 65 is the third correction value. It is calculated from the information, and the growth index before the correction is compensated with the calculated third correction value. To obtain a final growth index (growth index after correction).

  In such a plant growth index measuring device M, the GPS unit 2, the clock unit 7, and the sun angle calculation unit 62 constitute an example of a solar angle acquisition unit that acquires the incident angle of sunlight on the measurement target as the solar angle. The The GPS unit 2, the clock unit 7, the azimuth meter 3, and the sun direction calculation unit 63 constitute an example of a solar direction acquisition unit that acquires the sun direction with respect to the measurement direction of the reflected light measurement unit 1 as the solar direction.

  As described above, the plant growth index measurement system M may further include an input unit that is connected to the control processing unit 6 and inputs, for example, various commands and various data, as necessary. You may provide the output part etc. which output the various commands input by the part, various data, a measurement result, etc.

  Next, the operation of this embodiment will be described. Here, a case will be described in which the third correction information is stored in the correction information storage unit 81 and the growth index calculation unit 66 obtains a final growth index (corrected growth index) using the third correction value. However, the first correction information is stored in the correction information storage unit 81, and the growth index calculation unit 66 obtains the final growth index using the first correction value, or the correction information storage unit 81 performs the second correction. The information is stored, and the growth index calculation unit 66 can similarly explain the process described below by appropriately omitting the process described below when obtaining the final growth index using the second correction value.

  FIG. 6 is a flowchart showing the operation of the plant growth index measurement system in the embodiment. Drawing 7 is a figure showing an example of a measurement result in a plant growth index measuring system of an embodiment. The horizontal axis in FIG. 7 is a SPAD (Soil & Plant Analyzer Development) value, and the vertical axis is an NDVI value.

  In such a plant growth index measuring system M, first, the plant growth index measuring system M is arranged so that the reflected light measuring unit 1 faces the foliage to be measured by a user (operator). When a power switch (not shown) is turned on by the user, the control processing unit 6 executes initialization of each necessary unit, and by executing the control processing program, the control processing unit 6 includes the control unit 61, the sun angle calculation. The unit 62, the sun direction calculation unit 63, the diffusivity calculation unit 64, the leaf density calculation unit 65, and the growth index calculation unit 66 are functionally configured. The plant growth index measurement system M operates as follows.

  In FIG. 6, the control processing unit 6 controls the reflected light measurement unit 1 by the control unit 61, so that the reflected light measurement unit 1 has the first image data Rv for visible light and the second image data Ri for infrared light. And the solar measurement unit 5 is controlled by the control unit 61 so that the solar measurement unit 5 generates the third image data Sv in the visible light and the fourth image data Si in the infrared light, and the reflected light The first image data Rv in visible light and the second image data Ri in infrared light are acquired from the measurement unit 1, and the third image data Sv in visible light and the first image data in infrared light are obtained from the sunlight measurement unit 5. Four image data Si is acquired (S1).

  Next, the control processing unit 6 controls the GPS unit 2 by the control unit 61 to cause the GPS unit 2 to measure the latitude X and longitude Y, and the control unit 61 controls the direction meter 3 to cause the direction meter 3 to The azimuth φc is measured, and the inclinometer 4 is controlled by the control unit 61 to cause the inclinometer 4 to measure the measurement angle β, the latitude X and the longitude Y are obtained from the GPS unit 2, and the azimuth φc is obtained from the direction meter 3. Then, the measurement angle β is obtained from the inclinometer 4 (S2).

  Next, the control processing unit 6 obtains the year / month / date / time from the clock unit 7 (S3).

  Next, the control processing unit 6 calculates the spectral characteristic correction coefficient I of sunlight based on the third image data Sv and the fourth image data Si measured by the sunlight measuring unit 5 by the growth index calculating unit 66 ( S4). More specifically, the growth index calculation unit 66 calculates the pixel value sv (x, y) of the third image data Sv and the pixel value of the fourth image data Si for each pixel at the same pixel position (x, y). The ratio with si (x, y) is obtained as the spectral characteristic correction coefficient I (x, y) of sunlight (I (x, y) = sv (x, y) / si (x, y)). The spectrum of sunlight changes depending on time, weather, humidity, and the like, so that the ratio of the first image data Rv with visible light and the second image data Ri with infrared light becomes a predetermined value. Can be processed.

Next, the control processing unit 6 uses the growth index calculation unit 66 to calculate the reflected light measurement unit 1 based on the light intensities Sv and Si of sunlight at the third and fourth wavelengths measured by the sunlight measurement unit 5. Each of the first and second wavelengths measured by the reflected light measuring unit 1 while normalizing the ratios Rv and Ri of the respective light intensities of the reflected light at the first and second wavelengths measured in Step 1 to be predetermined values. Based on the respective light intensities Rv and Ri of the reflected light, a growth index before correction, for example, an NDVI value is obtained (S5). More specifically, the growth index calculation unit 66 calculates the sun obtained in the process S4 to the pixel value ri (x, y) of the second image data Ri for each pixel at the same pixel position (x, y). By multiplying the spectral characteristic correction coefficient I (x, y) of light, the pixel value ri ′ (x, y) (= ri (x, y) × I (x, y) of the normalized second image data Ri is obtained. )) For each pixel at the same pixel position (x, y). Note that rv (x, y) is a pixel value of the first image data Rv at the pixel position (x, y).
NDVI (x, y) = [ri′−rv] / [ri ′ + rv] (Expression 6)

  Next, the control processing unit 6 obtains the diffusivity W by the diffusivity calculating unit 64 (S6). More specifically, in one example, the diffusivity calculating unit 64 obtains the standard deviation σsv of the third image data Sv with visible light generated by the second visible imaging unit 5-1, and the obtained standard deviation σsv. Then, the diffusivity W is obtained by dividing the predetermined coefficient K by (W = K / σsv).

  Next, the control processing unit 6 obtains the sun angle α based on the latitude X and longitude Y acquired by the GPS unit 2 and the year, month, date and time measured by the clock unit 7 by the sun angle calculation unit 62 ( S7).

  Next, the control processing unit 6 obtains the solar azimuth direction ψ based on the latitude X and longitude Y acquired by the GPS unit 2 and the year, month, day and time measured by the clock unit 7 by the sun direction calculation unit 63. The solar direction φ is obtained as a difference between the direction φc measured by the direction meter 3 and the obtained solar direction φ (φ = φ−φc) (S8).

  Next, the control processing unit 6 uses the leaf density calculation unit 65 to calculate the leaf density L corresponding to the number of days from planting acquired through the IF unit 9 and the like from the growth information stored in the growth information storage unit 82. Obtain (S9).

  Next, the control processing unit 6 uses the growth index calculation unit 66 to measure the measurement angle β obtained in the process S2, the diffusivity W obtained in the process S6, the sun angle α obtained in the process S7, and the sun direction obtained in the process S8. A third correction value corresponding to φ and the leaf density L obtained in step S9 is obtained from the third correction information stored in the correction information storage unit 81, and the pre-correction obtained in step S5 with the obtained third correction value. In this example, the NDVI value is corrected to obtain a final growth index (corrected growth index). For example, the growth index calculating unit 66 obtains a corrected NDVI value by multiplying the calculated third correction value by the uncorrected NDVI value obtained in step S5 ((corrected NDVI value) = (first 3 correction value) × (NDVI value before correction)). Note that addition may be used instead of multiplication.

  Next, the control processing unit 6 stores the obtained final growth index (corrected growth index) in the storage unit 8 in association with the year, month, day, hour, and day obtained in the process S3, and the above-described calculation. The final growth index (corrected growth index) is output to the outside via the IF unit 9 in association with the year / month / day / date obtained in step S3 (S11).

  And the control process part 6 returns a process to process S1, and repeats said each process.

  FIG. 7 shows an example of measurement results obtained by the plant growth index measurement system M of the present embodiment. As can be seen from FIG. 7, there is almost one calibration curve, which is corrected well and a more accurate NDVI value is required.

  As described above, the plant growth index measuring device, the method, and the plant growth index measuring system in the present embodiment can measure the growth index with higher accuracy.

In the above-described embodiment, the NDVI value is obtained as the growth index, but the present invention is not limited to this. For example, RVI (Ratio Vegetation Index, specific vegetation index) may be obtained (RVI = Ri ′ / Rv, RVI (x, y) = ri ′ (x, y) / rv (x, y)). Further, for example, DVI (Difference Vegetation Index, differential vegetation index) may be obtained (DVI = Ri′−Rv, DVI (x, y) = ri ′ (x, y) −rv (x, y)). Further, for example, TVI (Transformed Vegetation Index) may be obtained (TVI = NDVI + 0.5) ^0.5 ). Further, for example, an IPVI (Infrared Percentage Index) may be obtained (IPVI = Ri ′ / (Ri ′ + Rv) = (NDVI + 1) / 2).

  The above-described plant growth index measuring device system M calculates the leaf density L based on the growth information stored in the growth information storage unit 82, but the first image data with visible light generated by the reflected light measurement unit 1. Based on the second image data Ri with Rv and infrared light, an area ratio between the area of the soil portion and the area of the plant portion may be obtained to obtain the leaf density.

  In the above-described plant growth index measurement system M, any one of the first to third correction information is used, but the sun angle α, the sun direction φ, the diffusivity W, the measurement angle β, the leaf density L, and the sunlight. The correspondence relationship between the spectral characteristic correction coefficient I and the correction value (fourth correction value) may be used.

  In the above-described plant growth index measurement system M, the solar light measurement unit 5 is used to obtain the third image data Sv with visible light and the fourth image data Si with infrared light. A member for measuring sunlight having a known spectral reflectance may be used. In this case, the member for measuring sunlight is measured by the reflected light measuring unit 1, and an average value of pixel values in an image region in which the member for measuring sunlight is imaged in the first image data Rv with visible light is visible. The third image data Sv with light, and the average value of the pixel values in the image region in which the solar measurement member is imaged in the second image data Ri with infrared light is the fourth image with infrared light. Data Si.

  The present specification discloses various aspects of the technology as described above, and the main technologies are summarized below.

  The plant growth index measuring apparatus according to one aspect includes the light intensity data of the reflected light of the measurement target having a plurality of leaves and the incident angle of sunlight to the measurement target, measured at the first and second wavelengths. Based on the angle data and solar direction data that is the direction of the sun with respect to the measurement direction of each light intensity data, a growth index calculation unit that obtains a growth index that represents the degree of growth in the measurement target is provided.

  Such a plant growth index measuring apparatus takes into account not only the light intensity of the reflected light at each of the first and second wavelengths, but also the sun angle and the sun direction when determining the growth index. Indicators can be measured.

  In another aspect, in the above-described plant growth index measuring apparatus, the growth index calculation unit further includes light intensity data of the solar sunlight measured at the third and fourth wavelengths, and the solar sunlight. The growth index of the measurement object is obtained based on the diffusivity data.

  Such a plant growth index measuring apparatus can further measure the growth index with higher accuracy since it also considers the light intensity and diffusivity of sunlight at the third and fourth wavelengths when determining the growth index. .

  In another aspect, in the above-described plant growth index measurement apparatus, the growth index calculation unit further includes measurement angle data that is an angle in a measurement direction of each light intensity data with respect to the measurement object, and leaves of the measurement object Based on the density data, the growth index of the measurement object is obtained.

  Such a plant growth index measuring apparatus can take into account the measurement angle and the leaf density when determining the growth index, so that the growth index can be measured with higher accuracy.

  The plant growth index measurement method according to another aspect includes a reflected light measurement step of measuring the light intensity of reflected light of a measurement object having a plurality of leaves at different first and second wavelengths, and a measurement object of sunlight. A solar angle acquisition step of acquiring the incident angle as a solar angle, a solar direction acquisition step of acquiring the sun direction as a solar direction with respect to the measurement direction of the reflected light, and the first measured in the reflected light measurement step And the light intensity of the reflected light at each of the second wavelengths, the sun angle acquired in the solar angle acquisition step, and the solar direction acquired in the solar direction acquisition step, A growth index calculating step for obtaining a growth index representing the degree.

  Such a plant growth index measurement method takes into account not only the light intensity of the reflected light at each of the first and second wavelengths, but also the sun angle and the sun direction when determining the growth index. Indicators can be measured.

  A plant growth index measurement system according to another aspect includes a reflected light measurement unit that measures the light intensity of reflected light of a measurement object having a plurality of leaves at different first and second wavelengths, and a measurement object of sunlight. The solar angle acquisition unit that acquires the incident angle to the sun as the solar angle, the solar direction acquisition unit that acquires the solar direction as the solar direction with respect to the measurement direction of the reflected light measurement unit, and the reflected light measurement unit Based on each light intensity of the reflected light at each of the first and second wavelengths, the sun angle acquired by the sun angle acquisition unit, and the solar direction acquired by the solar direction acquisition unit, in the measurement object A growth index calculating unit for obtaining a growth index representing the degree of growth. Preferably, in the above-described plant growth index measurement system, the sun angle acquisition unit includes a GPS unit that acquires latitude and longitude, a clock unit that measures the date and time, the latitude and longitude acquired by the GPS unit, and A sun angle calculation unit that obtains the sun angle based on the date and time measured by the clock unit. Preferably, in the above-described plant growth index measurement system, the solar direction acquisition unit includes a GPS unit that acquires latitude and longitude, a clock unit that measures the date and time, and an orientation in the measurement direction of the reflected light measurement unit. Obtain the direction of the sun, determine the solar direction based on the latitude and longitude acquired by the GPS unit and the date and time measured by the clock unit, and the reflected light measurement obtained by the calculated direction of the sun and the direction meter A solar direction calculation unit that obtains the solar direction based on the direction of the measurement direction of the unit. Preferably, in the above-described plant growth index measurement system, the system further includes a first correction information storage unit that stores a correspondence relationship between the sun angle and the sun direction and the first correction value of the growth index as first correction information, The growth index calculation unit obtains a growth index before correction based on each light intensity of the reflected light at each of the first and second wavelengths measured by the reflected light measurement unit, and the sun angle acquisition unit A first correction value corresponding to the acquired sun angle and the sun direction acquired by the sun direction acquisition unit is obtained from the first correction information, and the growth index before the correction is calculated using the obtained first correction value. Is corrected to obtain the growth index.

  Such a plant growth index measurement system takes into account not only the light intensity of the reflected light at each of the first and second wavelengths but also the sun angle and the sun direction when determining the growth index, so that it grows more accurately. Indicators can be measured.

  In another aspect, in the above-described plant growth index measurement system, a solar light measuring unit that measures the light intensity of the solar sunlight at different third and fourth wavelengths, and the solar sunlight diffusivity A diffusivity acquisition unit that acquires the light intensity of the reflected light at each of the first and second wavelengths measured by the reflected light measurement unit, and the solar angle acquisition unit. The solar angle acquired in Step 1, the solar direction acquired by the solar direction acquisition unit, the light intensity of the sunlight at each of the third and fourth wavelengths measured by the solar light measurement unit, and the diffusivity Based on the diffusivity acquired by the acquisition unit, a growth index representing the degree of growth in the measurement target is obtained. Preferably, in the above-described plant growth index measurement system, the diffusivity acquisition unit obtains the diffusivity based on a measurement result of the sunlight measurement unit. Preferably, in the above-described plant growth index measurement system, the reflected light measurement unit includes a camera that images the measurement target, and the diffusion degree acquisition unit sets the shutter speed of the camera as the diffusion degree. . Preferably, in the above-described plant growth index measurement system, a second correction information storage unit that stores a correspondence relationship between the sun angle, the sun direction, the diffusivity, and the second correction value of the growth index as second correction information. The growth index calculation unit is further configured to measure the reflected light measurement unit based on the light intensity of the sunlight at the third and fourth wavelengths measured by the sunlight measurement unit. While normalizing the ratio of each light intensity of the reflected light at each of the first and second wavelengths to be a predetermined value, the reflected light at each of the first and second wavelengths measured by the reflected light measurement unit Based on each light intensity, a growth index before correction is obtained, the sun angle acquired by the sun angle acquisition unit, the solar direction acquired by the solar direction acquisition unit, and the diffusivity acquisition unit acquired Expansion Obtains a second correction value corresponding to the degree of the second correction information to correct the growth index before the correction by the second correction value calculated said determining the growth index.

  Such a plant growth index measurement system can measure the growth index with higher accuracy because it further considers each light intensity and diffusivity of sunlight at the third and fourth wavelengths when determining the growth index. .

  In another aspect, in the above-described plant growth index measurement system, a measurement angle acquisition unit that acquires an angle of a measurement direction of the reflected light measurement unit with respect to the measurement target as a measurement angle, and acquires a leaf density of the measurement target A leaf density acquisition unit, and the growth index calculation unit acquires the light intensity of the reflected light at each of the first and second wavelengths measured by the reflected light measurement unit, acquired by the sun angle acquisition unit. The solar angle, the solar direction acquired by the solar direction acquisition unit, the light intensity of the sunlight at each of the third and fourth wavelengths measured by the solar light measurement unit, and acquired by the diffusivity acquisition unit Based on the diffusivity, the measurement angle acquired by the measurement angle acquisition unit, and the leaf density acquired by the leaf density measurement unit, a growth index representing the degree of growth in the measurement target is obtained. That. Preferably, in the above-described plant growth index measurement system, the correspondence between the sun angle, the sun direction, the diffusivity, the measurement angle, the leaf density, and the third correction value of the growth index is used as third correction information. And further comprising a third correction information storage unit for storing the growth index calculation unit based on the light intensity of the sunlight at each of the third and fourth wavelengths measured by the sunlight measurement unit. The first and second measured by the reflected light measurement unit while normalizing the ratio of each light intensity of the reflected light at each of the first and second wavelengths measured by the light measurement unit to be a predetermined value. Based on each light intensity of the reflected light at each wavelength, a growth index before correction is obtained, the sun angle acquired by the sun angle acquisition unit, the solar direction acquired by the solar direction acquisition unit, and the diffusivity Get A third correction value corresponding to the diffusivity acquired in Step 1, the measurement angle acquired in the measurement angle acquisition unit, and the leaf density acquired in the leaf density measurement unit is obtained from the third correction information, The growth index before correction is corrected with the calculated third correction value to determine the growth index.

  Such a plant growth index measurement system can further measure the growth index with higher accuracy because the measurement angle and the leaf density are further taken into account when determining the growth index.

  This application is based on Japanese Patent Application No. 2015-97586 filed on May 12, 2015, the contents of which are included in the present application.

  In order to express the present invention, the present invention has been properly and fully described through the embodiments with reference to the drawings. However, those skilled in the art can easily change and / or improve the above-described embodiments. It should be recognized that this is possible. Therefore, unless the modifications or improvements implemented by those skilled in the art are at a level that departs from the scope of the claims recited in the claims, the modifications or improvements are not covered by the claims. To be construed as inclusive.

According to the present invention, a plant growth index measuring device, a plant growth index measuring method, and a plant growth index measuring system can be provided.

Claims (5)

Measurement of each light intensity data of reflected light of a measurement object having a plurality of leaves, solar angle data which is an incident angle of sunlight to the measurement object, and measurement of each light intensity data measured at the first and second wavelengths Based on solar direction data that is the direction of the sun with respect to a direction, a growth index calculation unit that obtains a growth index that represents the degree of growth in the measurement target,
Plant growth index measuring device. The growth index calculation unit further measures the measurement target based on the light intensity data of the solar sunlight and the diffusivity data of the solar sunlight measured at the third and fourth wavelengths. Find the growth index,
The plant growth index measuring device according to claim 1. The growth index calculation unit is further configured to measure the growth index of the measurement target based on measurement angle data that is an angle in a measurement direction of the light intensity data with respect to the measurement target and leaf density data of the measurement target. Seeking
The plant growth index measuring device according to claim 2. A reflected light measurement step of measuring the light intensity of the reflected light of the measurement object having a plurality of leaves at different first and second wavelengths;
A solar angle acquisition step of acquiring the incident angle of the sunlight on the measurement object as a solar angle;
A solar direction acquisition step of acquiring the solar direction as the solar direction with respect to the measurement direction of the reflected light;
Each light intensity of the reflected light at each of the first and second wavelengths measured in the reflected light measurement step, the sun angle obtained in the sun angle obtaining step, and the sun obtained in the solar direction obtaining step A growth index calculating step for obtaining a growth index representing the degree of growth in the measurement object based on the direction,
Plant growth index measurement method. A reflected light measuring unit that measures the light intensity of the reflected light of the measurement object having a plurality of leaves at the first and second wavelengths;
A solar angle acquisition unit that acquires the incident angle of the sunlight on the measurement target as a solar angle;
A solar direction acquisition unit that acquires, as a solar direction, the direction of the sun with respect to the measurement direction of the reflected light measurement unit;
Each light intensity of the reflected light at each of the first and second wavelengths measured by the reflected light measurement unit, the sun angle acquired by the sun angle acquisition unit, and the sun acquired by the solar direction acquisition unit A growth index calculation unit for obtaining a growth index representing the degree of growth in the measurement object based on the direction,
Plant growth index measurement system.

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