Light irradiance determination method, device, equipment, correction method and remote sensing system

Abstract

The present application relates to the field of optical measurement, and discloses a determination method, device and equipment of downlink light irradiance, a correction method of optical remote sensing data and an optical remote sensing system, the determination method of downlink light irradiance is applied to a flight equipment provided with a downlink light sensor, and comprises the following steps: creating a radiation response equation of the corresponding relationship between the radiation response value of the downlink light sensor and the corresponding horizontal plane total irradiance in advance; the radiation response value in the radiation response equation is equal to the superposition of the response value of the downlink light sensor to direct light and the response value of scattered light; according to the current radiation response value collected by the downlink light sensor and the radiation response equation, the current horizontal plane total irradiance of the downlink light corresponding to the current radiation response value is determined. The radiation response equation in the present application can more accurately determine the horizontal plane total irradiance of the downlink light, which is beneficial to the accuracy of radiation correction of optical remote sensing data.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical measurement technology, in particular to a method and device for determining downwelling light irradiance, a method for correcting optical remote sensing data and an optical remote sensing system. BACKGROUND

[0002] Optical remote sensing technology is a technology for obtaining target and environment information at a distance in the ultraviolet to infrared optical band. Low-altitude optical remote sensing technology applied to aircraft such as unmanned aerial vehicles, especially quantitative remote sensing technology represented by spectral remote sensing, has broad application prospects in the fields of agriculture, forestry, resources, and ecology. One of the prerequisites for quantitative application of low-altitude optical remote sensing data is the accuracy of radiation measurement of remote sensing observation data.

[0003] In the process of collecting remote sensing observation data, in order to ensure that the remote sensing observation data can more accurately reflect the true situation of the observed object, it is necessary to combine the irradiance of the downwelling light generated by the downward radiation of sunlight to perform radiation correction on the remote sensing observation data.

[0004] However, observation data usually needs to be measured for a long time in a complex and variable low-altitude atmospheric environment, which inevitably causes changes in the downward radiation of sunlight during the observation data acquisition process. Therefore, the downwelling light irradiance has spatial and temporal variations.

[0005] In recent years, domestic and foreign scholars have attempted to use downwelling light sensors installed on aircraft to synchronously detect downwelling light irradiance and use the measurement results for radiation correction, which can effectively reduce the influence of spatial and temporal variations of downwelling light radiation. However, the downwelling light irradiance determined in this way still has a large error, which affects the accuracy of the remote sensing observation data and limits the application of low-altitude optical remote sensing technology. SUMMARY

[0006] The purpose of the present application is to provide a method and device for determining downwelling light irradiance, a method for correcting optical remote sensing data, and an optical remote sensing system, which can improve the accuracy of measured downwelling light irradiance to some extent, and thus improve the accuracy of remote sensing observation data correction.

[0007] To solve the above technical problems, the present application provides a method for determining downwelling light irradiance, which is applied to a flight device, and a downwelling light sensor is arranged on the flight device. The determination method comprises:

[0008] A radiation response equation of a corresponding relationship between a radiation response value of the downwelling light sensor and a corresponding horizontal plane total irradiance is created in advance; wherein the radiation response value in the radiation response equation is equal to the superposition of the response value of direct light and the response value of scattered light of the downwelling light sensor respectively;

[0009] According to the current radiation response value collected by the downlight sensor and the radiation response equation, a current horizontal plane total irradiance corresponding to a sampling time point of the current radiation response value is determined.

[0010] Optionally, the radiation response equation is D=a·E·[(1-χ)·F s (β)+χ·F d (γ)]; wherein D is a radiation response value, a is a radiation response coefficient of the downlight sensor when the downlight vertically enters the downlight sensor; E is a horizontal plane total irradiance corresponding to a sampling time point of the radiation response value; χ is a downlight scattering ratio corresponding to the sampling time point of the radiation response value; F s (β) and F d (γ) are respectively a direct light radiation response factor and a scattered light radiation response factor of the downlight sensor when the direct light with an incident angle of β enters the downlight sensor; and γ is an angle between a detection surface of the downlight sensor and a horizontal plane.

[0011] Optionally, the direct light radiation response factor is F s (β)=(cosβ) α ; and the scattered light radiation response factor is wherein β' is an arbitrary incident angle in a hemisphere space on the detection surface of the downlight sensor; and α is a pre-labeled cosine radiation response factor.

[0012] The labeling process of the cosine radiation response factor comprises:

[0013] creating a labeling model of the downlight sensor wherein Res(θ) and Res0 are respectively a first radiation response value and a second radiation response value corresponding to the detection surface of the downlight sensor when the same direct light enters with an incident angle of θ and with a vertical angle.

[0014] a plurality of groups of first radiation response values of the downlight sensor under different direct light incident angles and corresponding second radiation response values of the direct light are respectively collected, and the cosine radiation response factor is fitted and labeled in combination with the labeling model.

[0015] Optionally, according to the current radiation response value collected by the downlight sensor and the radiation response equation, a current horizontal plane total irradiance corresponding to a sampling time point of the current radiation response value is determined, comprising:

[0016] judging whether the current radiation response value is a response value collected under a clear and cloudless weather condition;

[0017] If yes, a first reference radiation response value of the current radiation response value is obtained; wherein the first reference radiation response value is a radiation response value under clear and cloudless weather conditions, a time difference between a sampling time point and a sampling time point of the current radiation response value is not greater than a preset time length; and a difference of corresponding downlight incident angles between the current radiation response value and the first reference radiation response value is not less than a preset angle difference;

[0018] According to the horizontal plane total irradiance and the downlight scattering ratio corresponding to the current radiation response value and the first reference radiation response value being the same, and the current radiation response value and the first reference radiation response value both satisfying the radiation response equation, a current downlight scattering ratio corresponding to the current radiation response value is determined.

[0019] According to the radiation response equation satisfied by the current downlight scattering ratio and the current radiation response value, a current horizontal plane total irradiance corresponding to the current radiation response value is determined.

[0020] Optionally, according to the current radiation response value collected by the downlight sensor and the radiation response equation, a current horizontal plane total irradiance corresponding to a sampling time point of the current radiation response value is determined, including:

[0021] If the current radiation response value is a radiation response value under cloudy conditions, at least two second reference radiation response values are obtained, and according to the second reference radiation response values, reference point horizontal plane total irradiance and reference point downlight scattering ratio corresponding to the second reference radiation response values are determined; wherein the second reference radiation response values are radiation response values collected by the downlight sensor under clear and cloudless conditions; and a difference between downlight incident angles corresponding to each of the second reference radiation response values is not less than a preset angle difference, and a time difference between sampling time points corresponding to each of the second reference radiation response values is not greater than a preset time length.

[0022] According to the reference point horizontal plane total irradiance and the reference point downlight scattering ratio, aerosol optical thickness corresponding to the reference point horizontal plane total irradiance and the reference point downlight scattering ratio is found in a lookup table created in advance;

[0023] According to the second reference radiation response values and corresponding reference point horizontal plane total irradiance and reference point downlight scattering ratio, and the current radiation response value, a radiation response ratio equation is obtained, which is wherein D c , E ref , χ c , and respectively corresponding to the second reference radiation response value, the reference point horizontal plane total irradiance, the reference point downwelling light scattering ratio, the reference point direct light radiation response factor and the reference point scattered light radiation response factor of any one of the reference points;

[0024] In the look-up table, the downwelling light scattering ratio satisfying the radiation response ratio equation under the aerosol optical thickness condition is found, and the downwelling light scattering ratio satisfying the radiation response ratio equation is taken as the current downwelling light scattering ratio corresponding to the current radiation response value;

[0025] According to the current downwelling light scattering ratio and the current radiation response value, the current horizontal plane total irradiance corresponding to the current radiation response value is determined in combination with the radiation response equation.

[0026] The look-up table is a data table of corresponding horizontal plane total irradiance and downwelling light scattering ratio under different atmospheric parameters and different solar zenith angles, which is simulated and determined in advance according to an atmospheric radiation transmission model.

[0027] Optionally, before determining the current horizontal plane total irradiance corresponding to the sampling time point of the current radiation response value according to the current radiation response value collected by the downwelling light sensor and the radiation response equation, the method further includes:

[0028] determining whether the current radiation response value satisfies wherein D0 is a reference radiation response value of the downwelling light sensor collected under a clear and cloudless condition at a time point with a direct light incident angle of β0 and a time point within a preset time length from the sampling time point of the current radiation response value; F s is a reference direct light radiation response factor; T1 and T2 are respectively a first percentage threshold and a second percentage threshold.

[0029] If yes, the current radiation response value is a response value under a clear and cloudless condition.

[0030] If no, the current radiation response value is a response value under a cloudy condition.

[0031] A correction method of optical remote sensing data, applied to a downwelling light sensor and an optical remote sensing data collector arranged on the same flight device, the correction method comprising:

[0032] According to a sampling time point of current optical remote sensing data collected by the optical remote sensing data collector, a current radiation response value of the downwelling light sensor receiving downwelling light irradiation output at the same sampling time point is determined.

[0033] According to the current radiation response value, the current horizontal plane total irradiance corresponding to the sampling time point of the current radiation response value is determined according to the steps of the determination method of the downlink light irradiance as any one of the above.

[0034] According to the current optical remote sensing data and the current horizontal plane total irradiance, the correction data of the current optical remote sensing data is determined.

[0035] A determination device of downlink light irradiance is applied to a flight equipment provided with a downlink light sensor, and the determination device comprises:

[0036] An equation creation module is configured to pre-create a radiation response equation of a corresponding relationship between a radiation response value of the downlink light sensor and a corresponding horizontal plane total irradiance; wherein the radiation response value in the radiation response equation is equal to the superposition of a response value of the downlink light sensor to direct light and a response value of the downlink light sensor to scattered light.

[0037] A data operation module is configured to determine the current horizontal plane total irradiance of the downlink light corresponding to the sampling time point of the current radiation response value according to the current radiation response value collected by the downlink light sensor and the radiation response equation.

[0038] A determination device of downlink light irradiance is applied to a flight equipment, and the flight equipment is provided with a downlink light sensor, and the determination device comprises:

[0039] A memory is configured to store a computer program.

[0040] A processor is configured to execute the computer program to realize the steps of the determination method of the downlink light irradiance as any one of the above.

[0041] An optical remote sensing system comprises a flight equipment, a downlink light sensor and an optical remote sensing data collector arranged on the flight equipment, and further comprises:

[0042] A memory is configured to store a computer program.

[0043] A processor is configured to execute the computer program to realize the steps of the correction method of the optical remote sensing data as above.

[0044] The application provides a downlink light irradiance determination method, device and equipment, and an optical remote sensing data correction method and optical remote sensing system.

[0045] In the application, the radiation response value generated by the downlink light sensor in receiving downlink light radiation simultaneously contains responses to direct light and scattered light, and in variable weather, the radiation response proportion of the downlink light sensor to direct light and scattered light also changes correspondingly. Moreover, in the working process of the downlink light sensor, the attitude of the flight equipment randomly inclines to different degrees, the detection surface cannot be guaranteed to be always horizontal, and this also causes the proportion of the response values of the downlink light sensor to direct light and scattered light under the same downlink light to exist differences. Therefore, in order to more accurately determine the irradiance of the downlink light, in the radiation response equation created in the application, the radiation response value is equal to the superposition of the response value of the downlink light sensor to direct light and the response value of the downlink light sensor to scattered light, so that the radiation response equation in the application can reflect the equation of the different radiation response proportions of direct light and scattered light, the horizontal plane total irradiance of the downlink light determined based on the radiation response equation is more accurate, which is beneficial to the accuracy of the radiation correction of the optical remote sensing data by using the horizontal plane total irradiance, and further promotes the wide application of the optical remote sensing technology. BRIEF DESCRIPTION OF DRAWINGS

[0046] In order to more clearly illustrate the technical solutions of the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0047] Figure 1 A flowchart of the downlink light irradiance determination method provided by the embodiment of the application;

[0048] Figure 2 A flight route and heading schematic diagram of the flight equipment provided by the embodiment of the application;

[0049] Figure 3 A cosine radiation response characteristic calibration device schematic diagram of the downlink light sensor provided by the embodiment of the application;

[0050] Figure 4 FIG. 1 is a schematic diagram of a normalized response value of a downwelling light sensor according to an embodiment of the present application;

[0051] Figure 5 FIG. 2 is a structural block diagram of a downwelling light irradiance determination device according to an embodiment of the present application. DETAILED DESCRIPTION

[0052] When determining the total horizontal irradiance of downwelling light by using a downwelling light sensor in a conventional manner, it is considered that the radiation response value of the downwelling light sensor is equal to a·E; where E is the total horizontal irradiance of downwelling light, and a is the radiation response coefficient. In essence, the difference between the direct light and the scattered light detected by the downwelling light sensor in terms of spatial distribution and radiation response rules is not considered.

[0053] When the downwelling light sensor is tilted, the total horizontal irradiance of downwelling light determined according to the above manner is inaccurate, and the measurement error will change constantly with the proportion change between the direct light and the scattered light of the downwelling light, ultimately leading to inaccurate and unstable radiation correction results based on the synchronous measurement of the downwelling light sensor.

[0054] Therefore, a technical solution for more accurately determining the total horizontal irradiance of downwelling light is proposed in the present application, thereby facilitating the improvement of the accuracy of remote sensing observation data correction in optical remote sensing technology.

[0055] In order for those skilled in the art to better understand the present application, the present application will be further described in detail below in conjunction with the drawings and specific embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0056] As shown in FIG. 1, the normalized response value of the downwelling light sensor is a function of the total horizontal irradiance of downwelling light. Figure 1 As shown in FIG. 1, the normalized response value of the downwelling light sensor is a function of the total horizontal irradiance of downwelling light. Figure 1 FIG. 2 is a structural block diagram of a downwelling light irradiance determination device according to an embodiment of the present application.

[0057] The downwelling light irradiance determination method in the present application is mainly applied to a flight device provided with a downwelling light sensor; the flight device can include a drone, a helicopter, and other types of aircraft, or even a hot air balloon, etc., which are not specifically limited in the present application.

[0058] In a specific embodiment of the present application, the downwelling light irradiance determination method can include:

[0059] S10: Pre-creating a radiation response equation of the corresponding relationship between the radiation response value of the downwelling light sensor and the corresponding total horizontal irradiance.

[0060] wherein the radiation response value in the radiation response equation is equal to the superposition of the response value of the direct light and the response value of the scattered light of the downlight sensor respectively.

[0061] S20: determining the current horizontal plane total irradiance of the downlight corresponding to the sampling time point of the current radiation response value according to the current radiation response value collected by the downlight sensor and the radiation response equation.

[0062] In the radiation response equation of the embodiment, the radiation response value can include two parts, one part is the radiation response generated by the direct light detected by the downlight sensor, and the other part is the radiation response generated by the scattered light detected by the downlight sensor, and the radiation response value finally output by the downlight sensor is the superposition of the two parts of radiation response, and the size of the two parts of different radiation response also reflects the different response proportion of the downlight sensor to the direct light and the scattered light to some extent.

[0063] In an optional embodiment of the present application, the radiation response equation can be: D=a·E·[(1-χ)·F s (β)+χ·F d (γ)];wherein D is the radiation response value, a is the radiation response coefficient of the downlight vertically incident on the downlight sensor, which is a constant coefficient; E is the horizontal plane total irradiance corresponding to the sampling time point of the radiation response value; χ is the downlight scattering ratio corresponding to the sampling time point of the radiation response value; F s (β) and F d (γ) are the direct light radiation response factor and the scattered light radiation response factor of the downlight sensor respectively; γ is the included angle between the detection surface of the downlight sensor and the horizontal plane.

[0064] In the embodiment, the radiation response value of the downlight sensor is divided into two parts, one part is the radiation response generated by the direct light, that is, a·E·(1-χ)·F s , and the other part is a·E·χ·F d , (1-χ)·F s and χ·F dThe proportion of the direct light and the scattered light respectively responded by the down light sensor is characterized to some extent, and it is obvious that the proportion is related to the angle of the direct light incident to the detection surface of the down light sensor, the solar zenith angle, and the atmospheric parameters and various factors. Further, the radiation response equation created in the embodiment fully considers the influence of the changeable weather on the radiation response value of the down light sensor, thereby analyzing the direct light and the scattered light respectively, and setting the down light scattering ratio changing with the weather as the superposition weighting coefficient of the radiation response respectively generated by the direct light and the scattered light, which is beneficial to ensuring the accuracy of the horizontal plane total irradiance determined based on the above radiation response equation.

[0065] Further, in another optional embodiment of the present application, the direct light radiation response factor can be F s (β)=(cosβ) α ; wherein β is the incident angle of the direct light incident to the down light sensor, and a is the pre-calibrated cosine radiation response factor.

[0066] In an optional embodiment of the present application, the calibration process of the cosine radiation response factor can include:

[0067] Creating a calibration model of the down light sensor Wherein Res(θ) and Res0 are respectively the first radiation response value and the second radiation response value corresponding to the direct light incident to the detection surface of the down light sensor at the incident angle θ and at the vertical angle.

[0068] A plurality of groups of the first radiation response values of the down light sensor at different direct light incident angles and the corresponding second radiation response values of the direct light are respectively collected, and the cosine radiation response factor is fitted and calibrated in combination with the calibration model.

[0069] It should be noted that the cosine corrector is mainly used to collect the light in the range of 0-180 degrees in the down light sensor. According to the working characteristics that the response of the cosine corrector conforms to the Lambert cosine law, it is known that, in an ideal case, the direct light radiation response value generated by the down light sensor to the direct light should be equal to a·E·cosβ, that is, F s (β)=cosβ. However, in actual application, the response of the cosine corrector does not absolutely conform to the Lambert cosine law.

[0070] Based on the working characteristics of the down light sensor, the radiation response value of the down light sensor is proportional to (cosθ) α , and thus it can be determined that the radiation response value Res(θ) of the down light sensor at the direct light incident angle θ should satisfy Res(θ)=a·E·F s (θ)∝(cosθ) α .

[0071] According to the Lambert cosine law, the response value of the downlight sensor to the direct light with the incident angle of θ should be a·E·cosθ, where a·E can be the response value of the direct light vertically incident to the detection surface of the downlight sensor, and (cosθ) α is proportional to the radiation response value of the downlight sensor, so that a·E∝(cosθ) α ;

[0072] Based on the above discussion, a calibration model can be created,

[0073] Therefore, F s =(cosθ) α .

[0074] According to repeatedly input light beams with different illumination intensities to the downlight sensor, and change different incident angles (to obtain higher fitting accuracy, the incident angles should be dispersed within the range of 0°-180°) to obtain corresponding multiple sets of first radiation response values and second radiation response values of each light beam with the illumination intensity vertically incident to the downlight sensor, and perform fitting based on the multiple sets of first radiation response values and second radiation response values to finally determine the cosine radiation response factor.

[0075] After determining the direct light radiation response factor F s (β), it is further necessary to determine the scattered light radiation response factor F d . The scattered light radiation response factor can be:

[0076]

[0077] where β' is any incident angle within the hemispherical space on the detection surface of the downlight sensor; and γ is the included angle between the detection surface of the downlight sensor and the horizontal plane.

[0078] Obviously, γ can be determined by the device on the flight equipment for detecting the flight attitude of the flight equipment, and detailed description is not made in this embodiment.

[0079] For the scattered light, since it has light signal distribution in each direction of the hemispherical space, its radiation response can be considered as the superposition of the radiation responses of the direct light in different directions. Assuming that the scattered light is uniformly distributed within the hemispherical space, and the cosine radiation response characteristics of the downlight sensor have circular symmetry, i.e., independent of the azimuth angle. Therefore, in consideration of the inclination of the downlight sensor, the expression of the above scattered light radiation response factor can be derived by integration within the effective solid angle of the hemispherical space.

[0080] Based on the above direct light radiation response factor and the expression corresponding to the scattering light radiation response factor, in practical application, as long as the incident angle of the downlink light incident to the detection surface of the downlink light sensor (i.e. the incident angle of the direct light incident to the detection surface of the downlink light sensor) and the included angle between the detection surface of the downlink light sensor and the horizontal plane are measured, F s (β) and F d (γ) can be determined. The incident angle of the downlink light incident to the detection surface of the downlink light sensor and the included angle between the detection surface of the downlink light sensor and the horizontal plane can be obviously determined by detecting the flight attitude of the flight equipment by using devices such as the integrated navigation system on the flight equipment, and this will not be described in detail in the present application.

[0081] In addition, for the radiation response coefficient a in the radiation response equation D = a · E · [(1 - χ) · F s (β) + χ · F d (γ)], which belongs to a constant parameter related to the performance of the downlink light sensor, in practical application, the coefficient can be determined by calibrating the downlink light sensor in advance.

[0082] Based on the above discussion, after the radiation response equation is determined, the horizontal plane total irradiance corresponding to the sampling time point of the radiation response value can be determined by combining the radiation response value measured by the downlink light sensor each time with the radiation response equation.

[0083] However, in the actual application process, the weather condition corresponding to the time point at which the radiation response value is collected by the downlink light sensor can be sunny and cloudless or cloudy. Relatively speaking, under the condition of sunny and cloudless, the atmospheric parameters are relatively stable, and the influence on the downlink light irradiance is also relatively stable; therefore, in an optional embodiment of the present application, according to the current radiation response value and the radiation response equation, the process of determining the horizontal plane total irradiance corresponding to the sampling time point of the radiation response value can include:

[0084] If yes, a first reference radiation response value of the current radiation response value is obtained; wherein the first reference radiation response value is a radiation response value under the condition of sunny and cloudless weather, the time difference between the sampling time point and the sampling time point of the current radiation response value is not greater than a preset time length; and the difference of the downlink light incident angle corresponding to the current radiation response value and the first reference radiation response value is not less than a preset angle difference;

[0085] According to the horizontal plane total irradiance and the downlink light scattering ratio corresponding to the current radiation response value and the first reference radiation response value, and the fact that the current radiation response value and the first reference radiation response value both satisfy the radiation response equation, the current downlink light scattering ratio corresponding to the current radiation response value is determined;

[0086] According to the radiation response equation satisfied by the current downlink light scattering ratio and the current radiation response value, the current horizontal plane total irradiance corresponding to the current radiation response value is determined.

[0087] It can be understood that the incident angles of the downlink light corresponding to the current radiation response value and the first reference radiation response value are different, which means that the incident angles of the downlink light incident to the downlink light sensor are different when the downlink light sensor collects the current radiation response value and the first reference radiation response value. In general, the radiation response value of the flight direction of the flight equipment and the flight direction when the current radiation response value is collected can be selected as the first reference radiation response value. The size of the preset angle difference can be set based on the actual situation, as long as there is a large enough difference between the sizes of the current radiation response value and the first reference radiation response value.

[0088] In addition, if the flight equipment is in a clear and cloudless weather state during the process of detecting remote sensing data; or it has been in a clear and cloudless weather state for a period of time; or it has been in a clear and cloudless weather state for a period of time, and there is a cloud layer but the cloud layer does not block the light incident to the downlink light sensor. During the process of continuous sampling of the downlink light sensor, the change of the solar zenith angle in a short period of time can be ignored, and correspondingly, the downlink light scattering ratios corresponding to the two radiation response values with close sampling time points can be considered equal, and the downlink light total irradiance can also be considered equal.

[0089] Therefore, in this embodiment, the current downlink light total irradiance corresponding to the current radiation response value is determined. According to the radiation response equations satisfied by the current radiation response value and the first reference radiation response value, and the equal downlink light scattering ratios and downlink light total irradiance corresponding to the two radiation response values, a simultaneous equation group can be obtained.

[0090]

[0091] Obviously, in the above simultaneous equation group, only the horizontal plane total irradiance and the downlink light scattering ratio are unknown quantities. The current radiation response value D and the first reference radiation response value D c0 are substituted into the above simultaneous equation group to determine the two unknown quantities.

[0092] Based on the above discussion, when determining the current horizontal plane total irradiance corresponding to the current radiation response value, one of the radiation response values with a smaller time difference between the sampling time point and the sampling time point corresponding to the current radiation response value can be selected as the first reference radiation response value (not necessarily adjacent in the sampling order) from the multiple radiation response values collected by the downlink light sensor. The current horizontal plane total irradiance can be determined in the same way as described above.

[0093] In addition, when it is necessary to determine the horizontal total irradiance corresponding to a series of radiation response values collected by the downlight sensor under the condition of clear and cloudless weather, the plurality of radiation response values collected continuously within the preset time length can be taken as a group, two radiation response values corresponding to different flight device headings (so that the downlight incidence angles are different) are selected, and the horizontal total irradiance and the downlight scattering ratio are determined according to the above manner, so as to be the corresponding horizontal total irradiance and the downlight scattering ratio corresponding to the plurality of radiation response values.

[0094] As described above, under the weather condition of cloud layer, the change of downlight irradiance is also more complex. In an optional embodiment of the present application, according to the current radiation response value and the radiation response equation, the process of the horizontal total irradiance corresponding to the sampling time point of the radiation response value can include:

[0095] S21: If the current radiation response value is the radiation response value under the condition of cloud layer, at least two second reference radiation response values are obtained, and the reference point horizontal total irradiance and the reference point downlight scattering ratio corresponding to the second reference radiation response value are determined according to the second reference radiation response value.

[0096] The second reference radiation response value is the radiation response value collected by the downlight sensor under the condition of clear and cloudless weather; and the difference between the downlight incidence angles corresponding to each second reference radiation response value is not less than the preset angle difference, and the time difference between the sampling time points corresponding to each second reference radiation response value is not greater than the preset time length.

[0097] As shown in FIG. 1, Figure 2 Figure 2 is a schematic diagram of the flight trajectories of the four routes of the flight device in two headings. It is assumed that the reference point C1 and the reference point C2 are taken on the route 1 and the route 2 respectively, when the flight device passes through the reference point C1, the first second reference radiation response value D c1 is collected and obtained; and when the flight device passes through the reference point C2, the second second reference radiation response value D c2 is collected and obtained; because the headings of the flight device when passing through the reference point C1 and the reference point C2 are different, the incidence angles of the downlight corresponding to D c1 and D c2 are also different in general cases.

[0098] It should be noted that D c1 and D c2 are collected under the condition of clear and cloudless weather, and the sampling time points of the two radiation response values are also very close, that is to say, the time difference of the downlight sensor detecting D c1 and D c2 is very small; therefore, D c1 and D​c2 The corresponding solar zenith angle, atmospheric parameters and other conditions can be considered as the same.

[0099] In addition, D c1 , D c2 The corresponding atmospheric environment and the atmospheric aerosol corresponding to the current radiation response value should also be approximately the same, that is, to ensure D c1 , D c2 The aerosol thickness corresponding to the atmospheric environment and the aerosol thickness corresponding to the current radiation response value under the condition of cloud layer are the same.

[0100] It can be understood that, in the process of continuously collecting the radiation response value by the downlink light sensor, as the weather state changes, the atmospheric environment corresponding to the radiation response value measured without cloud layer blocking in a certain period of time and the radiation response value measured with cloud layer blocking in a certain period of time can be considered as the same, that is, the aerosol thickness is the same.

[0101] Therefore, in actual application, the reference point can be selected based on this. When the flight equipment carries the downlink light sensor to fly, the downlink light sensor collects and outputs a series of radiation response values corresponding to each position point on the flight route (including the current radiation response value under the condition of cloud layer), and the radiation response values corresponding to two reference points selected arbitrarily under the condition of clear and cloudless, with the difference of downlink light incident angle not less than the preset angle difference and the difference of sampling time points not more than the preset time length can be selected as D c1 , D c2 ; or the radiation response values corresponding to two reference points selected according to the above requirements at a specific flight position point when the flight equipment is controlled to fly according to a specific trajectory before and after collecting remote sensing data under the condition of clear and cloudless can also be selected, and the technical solutions in the present application can be realized, and the present application does not make specific limitation in this regard.

[0102] Similar to the above method of determining the horizontal plane total irradiance corresponding to the current radiation response value under the condition of clear and cloudless, D c1 and D c2 corresponding to the horizontal plane total irradiance and the downlink light scattering ratio can also be considered as equal. Thus, the equation can be determined:

[0103] In the equation, the solar zenith angle is known, and the flight attitude of the flight equipment when flying to the reference point C1 and the reference point C2 can also be determined by measurement. Thus, the downlink light incident angle corresponding to D c1 and D c2 respectively collected and obtained by the downlink light sensor can be determined, and thus D c1 and D c2 respectively correspond to the direct light radiation response factor and the scattering light radiation response factor That is, it can be determined. In this equation, only D c1 and D c2 The corresponding reference point down light scattering ratio χ c is an unknown quantity, so that D c1 and D c2 The reference point down light scattering ratio corresponding to the reference point is calculated and determined. Again, any one of D c1 and D c2 χ c is solved and determined, and combined into the radiation response equation, so that D c1 and D c2 The total irradiance E ref of the reference horizontal plane corresponding to the reference horizontal plane is solved.

[0104] S22: According to the reference point horizontal plane total irradiance and the reference point down light scattering ratio, the lookup table is inverted to find the aerosol optical thickness corresponding to the reference point horizontal plane total irradiance and the reference point down light scattering ratio.

[0105] Wherein, the lookup table is a data table corresponding to the horizontal plane total irradiance and the down light scattering ratio under the condition of different atmospheric parameters and different solar zenith angles, which is simulated and determined according to the atmospheric radiation transfer model.

[0106] It should be noted that the atmospheric radiation transfer model referred to in the embodiment can be a model for atmospheric radiation transfer correction, mainly including 5S model, 6S model, LOWTRAN model, MODTRAN model and FASCODE model. Based on the atmospheric radiation transfer model, the lookup table representing the corresponding down light horizontal total irradiance and down light scattering ratio under the condition of different atmospheric parameters and different solar zenith angles can be simulated and determined.

[0107] The lookup table in the application can include two parts, one part is the data table corresponding to the clear and cloudless weather condition, and the other part is the data table corresponding to the weather condition with cloud layer. Correspondingly, for the above different atmospheric parameters, for the clear and cloudless weather, the atmospheric parameters mainly include aerosol type, aerosol optical thickness and the like; and for the weather with cloud layer, the atmospheric parameters mainly include cloud type, cloud optical thickness and the like.

[0108] According to the second reference radiation response value, the reference point horizontal plane total irradiance and the reference point down light scattering ratio, the lookup table is inverted to find, so that the aerosol thickness of the atmosphere corresponding to the second reference radiation response value is determined.

[0109] In addition, in the embodiment, the second reference radiation response value corresponding to only one reference point can be used in combination with the radiation response equation to search and determine the reference point horizontal plane total irradiance and the reference point down light scattering ratio in the lookup table. The aerosol thickness corresponding to the reference point horizontal plane total irradiance and the reference point down light scattering ratio determined by the lookup table is not specifically limited in the present application. However, compared with the two reference points, the reference point horizontal plane total irradiance and the reference point down light scattering ratio determined by the ratio operation of the radiation response equations satisfied by the two reference points can eliminate the simulation error introduced by the lookup table to a certain extent.

[0110] S23: According to the second reference radiation response value and the corresponding reference point horizontal plane total irradiance and the reference point down light scattering, the radiation response ratio equation is obtained, which satisfies the radiation response equation with the current radiation response value. wherein D c , E ref , χ c , and are the second reference radiation response value, the reference point horizontal plane total irradiance, the reference point down light scattering ratio, the reference point direct light radiation response factor and the reference point scattered light radiation response factor corresponding to any one of the two reference points.

[0111] It should be noted that D c in the embodiment can be the second reference radiation response value corresponding to any one of the two reference points, that is, any one of D c1 and D c2 ; accordingly, when D c is D c1 , then is when D c is D c2 , then is

[0112] On this basis, the ratio operation of the radiation response equation satisfied by the current radiation response value and the radiation response equation satisfied by the second reference radiation response value can also be obtained:

[0113] Therefore, the radiation response ratio equation can be further determined as:

[0114] Based on the determined D c , the reference point horizontal plane total irradiance E ref , the reference point down light scattering ratio χ c , the reference point direct light radiation response factor and the reference point scattered light radiation response factor i.e. a deformation equation of the radiation response equation satisfied by the current radiation response value is determined wherein, is a known value that can be determined by the current radiation response value.

[0115] S24: In the lookup table, the downwelling light scattering ratio that satisfies the radiation response ratio equation under the aerosol optical thickness condition is looked up, and the downwelling light scattering ratio that satisfies the radiation response ratio equation is taken as the current downwelling light scattering ratio corresponding to the current radiation response value.

[0116] As described above, the aerosol thickness corresponding to the reference point is the same as the aerosol thickness corresponding to the current radiation response value under the condition of the cloud layer, and thus the aerosol thickness determined by the lookup table inversion based on the second reference radiation response value is also the aerosol thickness corresponding to the current radiation response value under the condition of the cloud layer.

[0117] On this basis, under the premise of taking the aerosol thickness as a fixed input, the current downwelling light scattering ratio corresponding to the current radiation response value is determined in the lookup table according to the aerosol thickness, the current solar zenith angle corresponding to the sampling time point of the current radiation response value, the current radiation response value, and the radiation response equation satisfied by the current radiation response value.

[0118] Thus, based on the deformation equation of the radiation response equation The current downwelling light scattering ratio that makes the current radiation response value satisfy the deformation equation can be determined by the lookup table inversion in the above lookup table. Of course, in actual application, the current horizontal plane total irradiance can also be determined by directly looking up the lookup table based on the current radiation response value and the above radiation response ratio equation without converting the above radiation response ratio equation into the deformation equation of the above radiation response equation, and the technical solution of the present application can also be realized.

[0119] It should be noted that in the present embodiment, the radiation response ratio equation is obtained based on the radiation response equation D=a·E·[(1-χ)·F s (β)+χ·F d (β)]. Or the deformation equation of the radiation response equation Because in the radiation response ratio equation or the deformation equation of the radiation response equation The simulation error introduced by the lookup table determined based on simulation can be eliminated, which is conducive to improving the accuracy of the current horizontal plane total irradiance.

[0120] S25: The current horizontal plane total irradiance corresponding to the current radiation response value is determined according to the current downwelling light scattering ratio and the current radiation response value in combination with the radiation response equation.

[0121] It can be understood that the current horizontal plane total irradiance can also be determined directly by looking up the table.

[0122] In the above embodiment, when the weather condition is clear and cloudless, the current downwelling light scattering ratio and the current horizontal plane total irradiance are determined by combining the first reference radiation response value close to the sampling time point of the current radiation response value and the radiation response equation to calculate the current downwelling light scattering ratio and the current horizontal plane total irradiance. However, it can be understood that in actual application, whether the sampling time point of the current radiation response value is in a cloudy state or a clear and cloudless state, the current downwelling light scattering ratio that can satisfy the above radiation response equation together with the current radiation response value can be determined by looking up the table in the lookup table based on the measured current radiation response value and the solar zenith angle corresponding to the sampling time point, and the current horizontal plane total irradiance is determined accordingly, which is not specifically limited in the present application.

[0123] As described above, different ways are adopted in the present application to determine the current horizontal plane total irradiance corresponding to the current radiation response value according to the weather state (clear and cloudless or cloudy) corresponding to the current radiation response value. Therefore, in another optional embodiment of the present application, it is also necessary to determine the weather state corresponding to the current radiation response value before determining the horizontal plane total irradiance corresponding to the sampling time point of the radiation response value according to the current radiation response value and the radiation response equation, which can specifically include:

[0124] determining whether the current radiation response value satisfies wherein D0 is a reference radiation response value of the direct light incident angle β0 collected by the downwelling light sensor under clear and cloudless conditions at a time point not more than a preset time length from the sampling time point of the current radiation response value; F s (β0) is a reference direct light radiation response factor; T1 and T2 are respectively a first percentage threshold and a second percentage threshold;

[0125] If yes, the current radiation response value is a response value under clear and cloudless conditions;

[0126] If no, the current radiation response value is a response value under cloudy conditions.

[0127] It should be noted that D0 is a reference radiation response value of the direct light incident angle β0 collected by the downwelling light sensor under clear and cloudless conditions at a time point not more than a preset time length from the sampling time point of the current radiation response value; specifically, it can be a radiation response value collected by the downwelling light sensor before and after the flight of the flight equipment, or a certain radiation response value collected during the flight of the flight equipment, which is not specifically limited in the present application.

[0128] Of course, in the actual application process, the entire flight equipment may be cloudy weather during the entire task execution process, so it is impossible to collect and obtain the clear and cloudless condition under the control radiation response value. In this case, it can be directly considered as cloudy weather without the need to judge whether it is clear and cloudless weather.

[0129] Based on the above discussion, the flight equipment in the present application can be mainly used for optical remote sensing data detection. After determining the horizontal plane total irradiance of the downlink light, the horizontal plane total irradiance can be used to correct the optical remote sensing data. However, in actual application, after determining the horizontal plane total irradiance of the downlink light by using the downlink light sensor, it is not necessarily used for the correction of the optical remote sensing data. For all technologies that need to detect the horizontal plane total irradiance of the downlink light, the above-mentioned method for determining the irradiance of the downlink light can be used to achieve it. For this, the present application will not be described one by one.

[0130] In summary, the present application considers that the radiation response value generated by the downlink light sensor in receiving the downlink light radiation contains the response of both direct light and scattered light. In variable weather, the proportion of the radiation response of the downlink light sensor to the direct light and the scattered light also changes accordingly. Therefore, in order to more accurately determine the irradiance of the downlink light, the radiation response equation created in the present application contains the equation created for the radiation response of the direct light and the scattered light respectively. That is to say, the radiation response equation of the sensor in the present application is an equation that can reflect the different radiation response proportions of the direct light and the scattered light. Therefore, the irradiance of the downlink light determined based on the radiation response equation is more accurate, which is conducive to the accuracy of the radiation correction of the optical remote sensing data, and further promotes the wide application of the optical remote sensing technology.

[0131] The process of the method for determining the irradiance of the downlink light will be described below taking the flight equipment as a specific embodiment of the unmanned aerial vehicle. The process of the method for determining the irradiance of the downlink light can include

[0132] Step one: laboratory calibration of the cosine radiation response characteristics of the downlink light sensor. The calibration device is shown in Figure 3 A stable light source and a collimator are used to generate a collimated and stable light beam, which is incident to the detection surface of the downlink light sensor. The incident angle of the light beam is accurately controlled by a high-precision turntable. The response value of the downlink light sensor under different incident angles is recorded, and least square fitting is performed according to to obtain the cosine radiation response factor a of the downlink light sensor. It should be noted that the stable light source and the collimator can also be placed on the high-precision turntable to change the incident angle of the light beam on the downlink light sensor.

[0133] Step two: install the downwelling light sensor on the back of the UAV, the installation method is rigid connection, the detection surface of the downwelling light detector is horizontally upward, and there is no obstruction around, which is used to measure the downwelling light irradiance; at the same time, install the GNSS / INS integrated navigation module, including the inertial measurement unit and the GPS submodule, wherein the inertial measurement unit is rigidly connected with the downwelling light sensor, which ensures that the detection surface of the downwelling light sensor is parallel to the horizontal reference surface of the inertial measurement unit, and is used to record the heading angle, roll angle and pitch angle of the downwelling light sensor; the GPS submodule is used to record the latitude and longitude coordinates, time and altitude. When the UAV low-altitude optical remote sensing system is used for remote sensing observation, each group of images taken by the remote sensor records the corresponding downwelling light irradiance, latitude and longitude coordinates, time, altitude and heading angle, roll angle and pitch angle of the downwelling light sensor. Among them, the GPS submodule can also be replaced by Beidou module or other sensors with real-time measurement function of position, time and altitude.

[0134] Step three: first, calculate the direct light incidence angle β and the angle γ between the detection surface of the downwelling light sensor and the horizontal plane corresponding to each data point. The specific calculation method for each data point is: according to the latitude and longitude coordinates, time and altitude recorded in step two, calculate the solar azimuth angle and zenith angle corresponding to the data collection time; establish a world coordinate system with the north direction as the X axis, the east direction as the Y axis and the vertical downward as the Z axis, calculate the direction vector of the direct sunlight direction in the world coordinate system; establish a local coordinate system of the downwelling light sensor, calculate the direction vector of the detection surface normal direction in the local coordinate system; according to the heading angle, roll angle and pitch angle recorded values of the downwelling light sensor, calculate the coordinate conversion matrix of the local coordinate system of the downwelling light sensor to the world coordinate system, and further obtain the direction vector of the detection surface normal direction of the downwelling light sensor in the world coordinate system; in the world coordinate system, the direction vector of the direct sunlight direction and the direction vector of the detection surface normal direction of the downwelling light sensor are obtained by vector operation between the direction vector of the direct sunlight direction and the direction vector of the detection surface normal direction of the downwelling light sensor, and the direct sunlight incidence angle β is obtained by vector operation between the direction vector of the detection surface normal direction of the downwelling light sensor and the direction vector of the horizontal plane normal.

[0135] Secondly, according to F s (β)=(cosβ) α , the cosine radiation response factor α of the downwelling light sensor and the direct sunlight incidence angle β obtained in step one are used to calculate the direct light radiation response factor corresponding to each data point.

[0136] Finally, according to the direct light radiation response factor, the direct light incidence angle β and the angle γ between the detection surface of the downwelling light sensor and the horizontal plane are used to obtain the scattering light radiation response factor corresponding to each data point by integral operation.

[0137] Step four: 41) Select the data points acquired under clear and cloudless conditions. According to the judgment conditions, the downwelling light sensor response noise, the slow change of downwelling light irradiance due to the change of solar zenith angle during the flight process, and the small amplitude random change of the attitude angle of the UAV are comprehensively considered, and the threshold T1 and T2 are set, for example, the threshold values that can be used are T1 = 90% and T2 = 110%.

[0138] 42) Determine the reference point, establish the radiation response equation group that the reference point satisfies, and solve the downwelling light scattering ratio at the reference point. The heading in this example has two kinds (as shown in Figure 2 ), so two points with high and low responses of the downwelling light sensor are selected as the reference points in the clear and cloudless reference points, and the data acquisition time of the two reference points should be as close as possible during the selection process. The two reference points determined are shown in the reference point diagram (the two points marked D1 and D2 in the figure are the reference points) as shown in Figure 4 ; the radiation response equations of the two reference points are established:

[0139]

[0140]

[0141] The simultaneous equations can be used to obtain the calculation formula of the downwelling light scattering ratio:

[0142]

[0143] 43) Calculate the horizontal total radiation corresponding to the reference point under clear and cloudless conditions. For the reference points selected in 41) under clear and cloudless conditions, the horizontal total radiation E can be calculated according to formula or

[0144] ​​Step five: 51) Based on the atmospheric radiation transfer software MODTRAN, the downwelling light scattering ratio under different atmospheric profile types, different solar zenith angles, different aerosol types, and different aerosol optical thicknesses is calculated, thereby establishing a first type of lookup table about the downwelling light scattering ratio and the solar zenith angle, the aerosol optical thickness. Among them, the atmospheric profile type selects five standard atmospheric profiles of tropical, mid-latitude summer, mid-latitude winter, subarctic summer and subarctic winter, the aerosol type selects two aerosol types of rural and urban, the solar zenith angle is set to 17 levels with an interval of 5° in the range of 0°-80°, and the aerosol optical thickness is set to 31 levels with an interval of 0.05 in the range of 0.01-1.51. According to the time, latitude and longitude coordinates, altitude and scene characteristics when the remote sensing data is acquired, the atmospheric profile type, solar zenith angle and aerosol type corresponding to the data are determined, thereby extracting the first type of local lookup table of the downwelling light scattering ratio and the aerosol optical thickness under the specified conditions. The measured downwelling light scattering ratio obtained by 42) is used to search the lookup table, and when the measured value of the downwelling light scattering ratio is closest to the MODTRAN calculated value in the first type of local lookup table, the corresponding horizontal plane total irradiance can be determined.

[0145] 52) Establish the radiation response equation of the data points under cloud cover. After the reference points under clear and cloudless conditions are screened out according to 41), the remaining data points are the data points under cloud cover, and the deformation equation of the radiation response equation corresponding to each data point in these data points can be established according to the radiation response equation Among them, the downwelling light horizontal plane total irradiance and scattering ratio under cloud cover are quantities to be solved, and the values corresponding to each data point are different and need to be solved respectively.

[0146] 53) Based on the atmospheric radiation transfer software MODTRAN, the M simulated and calculated under different conditions can be obtained, thereby establishing a second type of lookup table of M and the solar zenith angle, the cloud optical thickness. Among them, the solar zenith angle is set to 17 levels with an interval of 5° in the range of 0°-80°, and the cloud optical thickness is set to 39 levels with an interval of 0.2 in the range of 0.4-8. According to the time, latitude and longitude coordinates, and altitude when the remote sensing data is acquired, the solar zenith angle corresponding to each group of data acquired under cloud cover is determined, thereby extracting the second type of local lookup table of M and the cloud optical thickness. The measured value of M corresponding to each data point is calculated by the formula on the left side of the equal sign in formula (9), and for each data, the measured value of M is used to search the second type of lookup table respectively, and when the measured value of M is closest to the MODTRAN calculated value in the second type of local lookup table, the corresponding horizontal plane total irradiance can be determined. It should be noted that due to the rapid change of the state of the cloud, the cloud optical thickness of each data point is not necessarily the same.

[0147] As described above, after the horizontal plane total irradiance of the downwelling light is determined based on the radiation response value measured by the downwelling light sensor in the above embodiment, the correction of the optical remote sensing data can be applied. For this purpose, the present application further discloses an embodiment of a correction method of optical remote sensing data, which is mainly applied to a downwelling light sensor and an optical remote sensing data collector arranged on the same flight device. The correction method can include:

[0148] S31: determining a current radiation response value of the downwelling light sensor receiving the downwelling light irradiation output at the same sampling time point according to the sampling time point of the optical remote sensing data collector collecting the current optical remote sensing data.

[0149] S32: determining the current horizontal plane total irradiance corresponding to the sampling time point of the current radiation response value according to the current radiation response value and according to the steps of the determination method of the downwelling light irradiance as described in any one of the above.

[0150] S33: determining the correction data of the current optical remote sensing data according to the current optical remote sensing data and the current horizontal plane total irradiance.

[0151] For low-altitude optical remote sensing technology, the flight height of the flight device is usually within tens of meters to one kilometer, and the horizontal plane total irradiation of the downwelling light determined by the radiation response value measured by the downwelling light sensor carried on the flight device can be used as the horizontal plane total irradiation incident to the ground. The purpose of the radiation correction of the optical remote sensing data is to calculate the real reflection properties of the ground object target, and there are mainly two methods.

[0152] The calculation formula of the first method is Wherein, r is the reflectivity of the ground object target, L is the ground object reflection radiance measured by the remote sensor, and E is the horizontal plane total irradiation of the downwelling light.

[0153] The second method is combined with the empirical linear method, and a uniform Lambert reference plate with known reflectivity is photographed before and after the flight device takes off, and the calculation formula is: Wherein, r panel is the known reflectivity of the reference plate, L panel is the radiance measured by the remote sensor reflecting the reference plate, and E panel is the horizontal plane total irradiation of the downwelling light measured by the downwelling light sensor when the reflectivity reference plate is photographed in clear and cloudless conditions.

[0154] The downwelling light irradiance determination device provided by the embodiment of the present application is described below. The downwelling light irradiance determination device described below can be correspondingly referred to the downwelling light irradiance determination method described above.

[0155] Figure 5The structural block diagram of the downlink light irradiance determination device provided by the embodiment of the present application is applied to a flight device provided with a downlink light sensor; refer to Figure 5 The downlink light irradiance determination device can comprise:

[0156] An equation creation module 100 is configured to pre-create a radiation response equation of a corresponding relationship between a radiation response value of the downlink light sensor and a corresponding horizontal plane total irradiance; wherein the radiation response value in the radiation response equation is equal to the superposition of a direct light response value and a scattered light response value of the downlink light sensor respectively;

[0157] A data operation module 200 is configured to determine a current horizontal plane total irradiance of downlink light corresponding to a sampling time point of a current radiation response value according to the current radiation response value collected by the downlink light sensor and the radiation response equation.

[0158] In an optional embodiment of the present application, the radiation response equation is D=a·E·[(1-χ)·F s (β)+χ·F d (γ)]; wherein D is a radiation response value, a is a radiation response coefficient of the downlink light when the downlink light is vertically incident on the downlink light sensor; E is a horizontal plane total irradiance corresponding to a sampling time point of the radiation response value; χ is a downlink light scattering ratio corresponding to the sampling time point of the radiation response value; F s (β) and F d (γ) are respectively a direct light radiation response factor and a scattered light radiation response factor of the downlink light sensor when the direct light is incident on the downlink light sensor at an incident angle of β; γ is an included angle between a detection surface of the downlink light sensor and a horizontal plane.

[0159] In an optional embodiment of the present application, the direct light radiation response factor is F s (β)=(cosβ) α ; and the scattered light radiation response factor is wherein β' is an arbitrary incident angle in a hemispherical space on the detection surface of the downlink light sensor; and α is a pre-calibrated cosine radiation response factor.

[0160] Further comprising a calibration module configured to create a calibration model of the downlink light sensor wherein Res(θ) and Res0 are respectively a first radiation response value and a second radiation response value corresponding to the detection surface of the downlink light sensor when the same direct light is incident at an incident angle θ and at a vertical angle; a plurality of groups of the first radiation response values of the downlink light sensor under different direct light incident angles are collected respectively, and the second radiation response values corresponding to each direct light are collected respectively, and the cosine radiation response factor is fitted and calibrated in combination with the calibration model.

[0161] In an alternative embodiment of the present application, the data operation module 200 specifically determines whether the current radiation response value is a response value collected under clear and cloudless weather conditions; if so, a first reference radiation response value of the current radiation response value is obtained; wherein the first reference radiation response value is a radiation response value under clear and cloudless weather conditions, the time difference between the sampling time point and the sampling time point of the current radiation response value is not greater than the preset time length; and the difference of the corresponding downwelling light incident angle between the current radiation response value and the first reference radiation response value is not less than the preset angle difference; according to the same horizontal plane total irradiance and downwelling light scattering ratio corresponding to the current radiation response value and the first reference radiation response value, and the current radiation response value and the first reference radiation response value both satisfy the radiation response equation, the current downwelling light scattering ratio corresponding to the current radiation response value is determined; according to the radiation response equation satisfied by the current downwelling light scattering ratio and the current radiation response value, the current horizontal plane total irradiance corresponding to the current radiation response value is determined.

[0162] In an alternative embodiment of the present application, the data operation module 200 specifically includes:

[0163] The reference data unit is used to obtain at least two second reference radiation response values if the current radiation response value is a radiation response value under cloudy conditions, and determine the reference point horizontal plane total irradiance and the reference point downwelling light scattering ratio corresponding to the second reference radiation response value according to the second reference radiation response value; wherein the second reference radiation response value is a radiation response value collected by the downwelling light sensor under clear and cloudless conditions; and the difference between the downwelling light incident angles corresponding to each second reference radiation response value is not less than the preset angle difference, and the time difference between the sampling time points corresponding to each second reference radiation response value is not greater than the preset time length;

[0164] The aerosol calibration unit is used to look up the aerosol optical thickness corresponding to the reference point horizontal plane total irradiance and the reference point downwelling light scattering ratio in the pre-created lookup table according to the reference point horizontal plane total irradiance and the reference point downwelling light scattering ratio;

[0165] The equation operation unit is used to obtain the radiation response ratio equation according to the second reference radiation response value and the corresponding reference point horizontal plane total irradiance and reference point downwelling light scattering, and the current radiation response value all satisfy the radiation response equation Wherein, D c , E ref , χ c , And The second reference radiation response value, the reference point horizontal plane total irradiance, the reference point down light scattering ratio, the reference point direct light radiation response factor and the reference point scattered light radiation response factor corresponding to any one of the reference points respectively;

[0166] The scattering ratio lookup unit is configured to search for the down light scattering ratio satisfying the radiation response ratio equation under the aerosol optical thickness condition in the lookup table, and take the down light scattering ratio satisfying the radiation response ratio equation as the current down light scattering ratio corresponding to the current radiation response value.

[0167] The irradiance calculation unit is configured to determine the current horizontal plane total irradiance corresponding to the current radiation response value according to the current down light scattering ratio and the current radiation response value in combination with the radiation response equation.

[0168] The lookup table is a data table of the corresponding horizontal plane total irradiance and down light scattering ratio under different atmospheric parameters and different solar zenith angles, which is simulated and determined in advance according to an atmospheric radiation transmission model.

[0169] In an optional embodiment of the present application, the data calculation module 200 is specifically configured to determine whether the current radiation response value satisfies Wherein, D0 is the contrast radiation response value of the direct light incident angle β0 collected by the down light sensor under the clear and cloudless condition at a time point not greater than a preset time length from the sampling time point of the current radiation response value; F s is the contrast direct light radiation response factor; T1 and T2 are respectively the first percentage threshold and the second percentage threshold; if yes, the current radiation response value is the response value under the clear and cloudless condition; if no, the current radiation response value is the response value under the cloudy condition.

[0170] The down light irradiance determination device of the embodiment is used to implement the foregoing down light irradiance determination method, and therefore the specific implementation of the down light irradiance determination device can be seen from the foregoing embodiment part of the down light irradiance determination method, which will not be described here again.

[0171] The present application also provides an embodiment of a down light irradiance determination device, which is applied to a flight device, and the flight device is provided with a down light sensor. The down light irradiance determination device can include:

[0172] The memory is configured to store the computer program.

[0173] The processor is configured to execute the computer program to implement the steps of the down light irradiance determination method according to any one of the foregoing embodiments.

[0174] The application further provides an embodiment of an optical remote sensing system, which can comprise a flight device, a downlink optical sensor and an optical remote sensing data collector arranged on the flight device, and further comprises:

[0175] a memory for storing the computer program;

[0176] a processor for executing the computer program to implement the steps of the optical remote sensing data correction method as described above.

[0177] It should be noted that, in this document, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or sequence between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device inherently includes a series of elements. Without more limitations, the element defined by the statement "includes one" does not exclude the presence of another identical element in the process, method, article or device including the element. In addition, the above technical solutions provided by the embodiments of the present application have not been described in detail, so as not to be too verbose.

[0178] The principles and implementation modes of the present application are described by applying specific examples in this document, and the above embodiment descriptions are only used to help understand the method of the present application and its core idea. It should be pointed out that, for ordinary skilled in the art, without departing from the principles of the present application, the present application can be improved and modified in several ways, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A method for determining downwelling optical irradiance, characterized by, The method is applied to a flight device provided with a downlink light sensor, and comprises the following steps: a radiation response equation of a corresponding relationship between a radiation response value of the downlink light sensor and a corresponding horizontal plane total irradiance is created in advance; wherein the radiation response value in the radiation response equation is equal to a superposition of a direct light response value and a scattered light response value of the downlink light sensor respectively; a current horizontal plane total irradiance corresponding to a sampling time point of a current radiation response value is determined according to the current radiation response value collected by the downlink light sensor and the radiation response equation; The radiation response equation is ; wherein, is a radiation response value, is a radiation response coefficient of the downlight sensor when the downlight is vertically incident on the downlight sensor; is a horizontal plane total irradiance corresponding to a sampling time point of the radiation response value; is a downlight scattering ratio corresponding to the sampling time point of the radiation response value; and are a direct light radiation response factor and a scattered light radiation response factor of the downlight sensor when the incident angle of the direct light incident on the downlight sensor is ; and is an included angle between a detection surface of the downlight sensor and a horizontal plane. The direct light radiation response factor is ; the scattered light radiation response factor is ; wherein, is an arbitrary incident angle in the hemispherical space on the detection surface of the downlight sensor; is a pre-labeled cosine radiation response factor; the calibration process of the cosine radiation response factor comprises: creating a calibration model of the down-looking optical sensor ; wherein and are first and second radiative response values respectively corresponding to the down-looking optical sensor when a same collimated light is incident to a detection surface of the down-looking optical sensor at an incident angle and at a normal angle respectively; a first radiation response value of the downlink light sensor under different direct light incident angles and a second radiation response value corresponding to each direct light are collected respectively, and the cosine radiation response factor is fitted and calibrated in combination with the calibration model.

2. The method of determining downwelling optical irradiance according to claim 1, wherein, the current horizontal plane total irradiance corresponding to the sampling time point of the current radiation response value is determined according to the current radiation response value collected by the downlink light sensor and the radiation response equation, and comprises the following steps: it is judged whether the current radiation response value is a response value collected under a clear and cloudless weather condition; if yes, a first reference radiation response value of the current radiation response value is obtained; wherein the first reference radiation response value is a radiation response value under a clear and cloudless weather condition, a time difference between a sampling time point and the sampling time point of the current radiation response value is not greater than a preset time length, and a difference value of a downlink light incident angle corresponding to the current radiation response value and the first reference radiation response value is not less than a preset angle difference value; a current downlink light scattering ratio corresponding to the current radiation response value is determined according to the fact that the horizontal plane total irradiance and the downlink light scattering ratio corresponding to the current radiation response value and the first reference radiation response value are the same, and the current radiation response value and the first reference radiation response value both satisfy the radiation response equation; the current horizontal plane total irradiance corresponding to the current radiation response value is determined according to the radiation response equation satisfied by the current downlink light scattering ratio and the current radiation response value.

3. The method of determining downwelling optical irradiance according to any one of claims 1 or 2, wherein, the current horizontal plane total irradiance corresponding to the sampling time point of the current radiation response value is determined according to the current radiation response value collected by the downlink light sensor and the radiation response equation, and comprises the following steps: if the current radiation response value is a radiation response value under a cloudy condition, at least two second reference radiation response values are obtained, and reference point horizontal plane total irradiance and reference point downlink light scattering ratios corresponding to the second reference radiation response values are determined according to the second reference radiation response values; wherein the second reference radiation response values are radiation response values collected by the downlink light sensor under a clear and cloudless condition, a difference value between downlink light incident angles corresponding to the second reference radiation response values is not less than a preset angle difference value, and a time difference between sampling time points corresponding to the second reference radiation response values is not greater than a preset time length. According to the reference point horizontal plane total irradiance and the reference point downwelling light scattering ratio, the aerosol optical thickness corresponding to the reference point horizontal plane total irradiance and the reference point downwelling light scattering ratio is found back in a pre-created lookup table; According to the second reference radiation response value and the corresponding reference point horizontal plane total irradiance and the reference point down light scattering, the current radiation response value satisfies the radiation response equation, and a radiation response ratio equation is obtained ; wherein , , , and are the second reference radiation response value, the reference point horizontal plane total irradiance, the reference point down light scattering ratio, the reference point direct light radiation response factor and the reference point scattered light radiation response factor corresponding to any one of the reference points respectively. In the lookup table, the downwelling light scattering ratio satisfying the radiation response ratio equation under the aerosol optical thickness condition is found, and the downwelling light scattering ratio satisfying the radiation response ratio equation is taken as the current downwelling light scattering ratio corresponding to the current radiation response value; According to the current downwelling light scattering ratio and the current radiation response value, the current horizontal plane total irradiance corresponding to the current radiation response value is determined in combination with the radiation response equation; The lookup table is a data table corresponding to the horizontal plane total irradiance and the downwelling light scattering ratio under different atmospheric parameters and different solar zenith angles, which is simulated and determined in advance according to an atmospheric radiation transfer model.

4. The method of determining downwelling optical irradiance according to claim 3, wherein, It is judged whether the current radiation response value is a response value collected under a clear and cloudless weather condition, comprising: determining whether the current radiation response value meets ; wherein, is a control radiation response value of the direct light incident angle collected by the downlight sensor under the clear and cloudless condition at a time point not greater than a preset time length from a sampling time point of the current radiation response value; is a control direct light radiation response factor; , are respectively a first percentage threshold and a second percentage threshold;​ If yes, the current radiation response value is a response value under a clear and cloudless condition; If no, the current radiation response value is a response value under a cloudy condition.

5. A method of correcting optical remote sensing data, characterized in that, The correction method is applied to a downwelling light sensor and an optical remote sensing data collector arranged on the same flight device, and the correction method comprises: According to a sampling time point at which current optical remote sensing data is collected by the optical remote sensing data collector, a current radiation response value of the downwelling light sensor receiving downwelling light irradiation output at the same sampling time point is determined; According to the current radiation response value, the current horizontal plane total irradiance corresponding to the sampling time point of the current radiation response value is determined according to the steps of the downwelling light irradiance determination method in any one of claims 1 to 4; According to the current optical remote sensing data and the current horizontal plane total irradiance, the correction data of the current optical remote sensing data is determined.

6. A device for determining downwelling optical irradiance, characterized in that The determination device is applied to a flight device provided with a downwelling light sensor, and the determination device comprises: An equation creation module is configured to pre-create a radiation response equation of a corresponding relationship between a radiation response value of the downwelling light sensor and a corresponding horizontal plane total irradiance; wherein the radiation response value in the radiation response equation is equal to the superposition of a direct light response value and a scattered light response value of the downwelling light sensor; A data operation module is configured to determine a current horizontal plane total irradiance of downwelling light corresponding to a sampling time point of a current radiation response value according to the current radiation response value collected by the downwelling light sensor and the radiation response equation; wherein the radiation response equation is ; wherein, is a radiation response value, is a radiation response coefficient of the downlight sensor when the downlight is vertically incident on the downlight sensor; is a horizontal plane total irradiance corresponding to a sampling time point of the radiation response value; is a downlight scattering ratio corresponding to a sampling time point of the radiation response value; and are a direct light radiation response factor and a scattered light radiation response factor of the downlight sensor when the incident angle of the direct light incident on the downlight sensor is ; and is an included angle between a detection surface of the downlight sensor and a horizontal plane. The direct light radiation response factor is ; the scattered light radiation response factor is ; wherein, is an arbitrary incident angle in the hemispherical space on the detection surface of the downlight sensor; is a pre-labeled cosine radiation response factor; A calibration module is further included for creating a calibration model of the downlight sensor ; wherein and are respectively a first radiation response value and a second radiation response value corresponding to the downlight sensor when a same straight light is incident to a detection surface of the downlight sensor at an incident angle and a perpendicular angle; a plurality of groups of first radiation response values of the downlight sensor under different incident angles of straight light and corresponding second radiation response values of each straight light are collected, and the cosine radiation response factor is fitted and calibrated in combination with the calibration model.

7. A device for determining downlink optical irradiance, characterized in that, The determination device is applied to a flight device, and the flight device is provided with a downwelling light sensor, and the determination device comprises: A memory is configured to store a computer program; A processor is configured to execute the computer program to realize the steps of the downwelling light irradiance determination method in any one of claims 1 to 4.

8. An optical remote sensing system, characterized in that The flight device, the downwelling light sensor and the optical remote sensing data collector arranged on the flight device, and the determination device are further included, and the determination device comprises: A memory is configured to store a computer program; A processor is configured to execute the computer program to realize the steps of the optical remote sensing data correction method in claim 5.

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