Radiometric calibration method and system based on hyperspectral system

Abstract

The invention belongs to the technical field of remote sensing intelligent processing, and particularly relates to a radiometric calibration method and system based on a hyperspectral system. The method comprises the following steps: on the basis of a ground radiation calibration mode before a diffuse reflection plate takes off, acquiring total solar irradiance by utilizing a solar radiation summary table, and recording the total solar irradiance as TSI; establishing a radiation brightness model as a BRDF model based on the diffuse reflection plate; according to the TSI, utilizing a BRDF model to obtain the radiation brightness of the hyperspectral camera at the wavelength, and recording the radiation brightness as shown in the specification; performing correction processing to obtain a corresponding DN value, and recording the DN value as shown in the specification; through comparison, calibration of the hyperspectral system is realized. According to the invention, the calibration efficiency of the unattended hyperspectral system data can be improved.

Description

Technical Field

[0001] This invention belongs to the field of remote sensing intelligent processing technology, and in particular relates to a radiometric calibration method and system based on a hyperspectral system. Background Technology

[0002] With the advancement and development of hyperspectral remote sensing technology, the calibration technology of hyperspectral cameras has also developed rapidly. However, for calibration in stable scenarios at dedicated calibration test sites, manual on-site measurements are the only option, which is costly and yields limited calibration data. Some calibration devices are expensive and cannot truly simulate test conditions in certain environments, resulting in inconsistent stability and ultimately compromising the quality of the obtained calibration data.

[0003] While existing ground calibration devices are relatively mature, there is no ground radiometric calibration device that can directly calibrate unattended hyperspectral systems.

[0004] Most of the calibration methods for related technologies are based on on-site measurements, and the devices used are simple diffuse reflection whiteboards and imaging spectrometers. The problems encountered in pre-flight field calibration, such as experimental costs, ease of operation, experimental environment limitations, and data quality, have not been solved. Summary of the Invention

[0005] To address the above problems, this invention provides a radiometric calibration method and system based on a hyperspectral system.

[0006] One aspect of the present invention provides a radiometric calibration method for a hyperspectral system, the method comprising: The pre-flight ground radiation calibration method based on diffuse reflectors uses a total solar radiation meter to obtain the total solar irradiance and records it as TSI. A radiance model is established based on the diffuse reflector, and this model is recorded as the BRDF model. Based on the TSI model using the BRDF model, the wavelength of the hyperspectral camera is obtained. The radiance at that location is recorded as [value]. ; right Perform correction processing to obtain the corresponding DN value, and record this DN value. ; By comparison and This enables the calibration of hyperspectral systems.

[0007] Furthermore, The step of establishing a radiance model based on the diffuse reflector, and recording this model as a BRDF model, specifically includes: The BRDF model includes formulas for calculating the radiance of the diffuse reflector and the radiance of the hyperspectral camera; The formula for calculating the radiance of the diffuse reflector is:

[0008] in, For the i-th surface element of the diffuse reflector Radiance at that location For TSI on the i-th surface element of the diffuse reflector The irradiance value at that location For the angle of the diffuse reflector angle of incidence The reflectivity of the reflected light, which is determined in the laboratory, where π is the mathematical constant pi, and i = 1, 2, ..., n; The formula for calculating the radiance of the hyperspectral camera is as follows:

[0009] in, For hyperspectral cameras at source wavelength Radiance at that location To the source wavelength of the diffuse reflector plate Radiance at that location The radiance is Time-based hyperspectral camera at source wavelength The response sensitivity at a given location is determined based on the properties of the hyperspectral camera.

[0010] Furthermore, Calculate the dark current correction value of the hyperspectral camera itself and record the correction value. .

[0011] Furthermore, The method described above uses the BRDF model based on TSI to obtain the wavelength of the hyperspectral camera. The radiance at that location is recorded as [value]. Specifically, it includes: Based on the BRDF model used by TSI, combined with the incident angle of the diffuse reflector... and the angle of the diffuse reflector ,get .

[0012] Furthermore, The pair Perform correction processing to obtain the corresponding DN value, and record this DN value. Specifically, it includes: The correction process includes performing the correction on... Radiation correction and temperature response correction were performed to obtain... ; right After repeated measurements, the average measurement value is calculated and updated. .

[0013] Furthermore, The pair Radiation correction and temperature response correction were performed to obtain... Specifically, it includes: The calculation formula is:

[0014] Where α is the temperature response correction coefficient, determined based on the properties of the hyperspectral camera. Used for radiation correction processing.

[0015] Furthermore, The comparison and To achieve calibration of hyperspectral systems, specifically including: By comparison and Thus, the input-output relationship of the hyperspectral system is obtained.

[0016] In one aspect of the present invention, a hyperspectral system radiometric calibration system is provided, the system comprising: The data acquisition module, based on the ground radiation calibration method before takeoff using the diffuse reflector, obtains the total solar irradiance using the total solar radiation meter and records the total solar irradiance as TSI; The modeling module is used to establish a radiance model based on the diffuse reflector, and this model is recorded as a BRDF model; The brightness acquisition module is used to obtain the wavelength of the hyperspectral camera based on the TSI using the BRDF model. The radiance at that location is recorded as [value]. ; The DN value acquisition module is used to obtain the DN value. Perform correction processing to obtain the corresponding DN value, and record this DN value. ; The calibration module is used to compare... and This enables the calibration of hyperspectral systems.

[0017] The self-calibration module is used to calculate and record the dark current correction value of the hyperspectral camera. .

[0018] Furthermore, The brightness acquisition module specifically includes: The brightness acquisition unit is used to obtain the brightness based on the TSI using the BRDF model and the incident angle of the diffuse reflector. and the angle of the diffuse reflector ,get .

[0019] Furthermore, The DN value acquisition module specifically includes: A correction unit is configured to perform the correction process, including... Radiation correction and temperature response correction were performed to obtain... ; Noise reduction unit, used for After repeated measurements, the average measurement value is calculated and updated. .

[0020] Furthermore, The calibration module specifically includes: Calibration unit, used for comparison and Thus, the input-output relationship of the hyperspectral system is obtained.

[0021] Compared with the prior art, the technical solution provided by the present invention has the following advantages: The hardware foundation of the technical solution provided by this invention includes an unattended intelligent airport, a solar radiation meter, a diffuse reflector, and a hyperspectral camera system. This can improve the calibration efficiency of unattended hyperspectral system data, reduce calibration costs, and enhance the convenience of calibration experiments.

[0022] The technical solution of this invention can be widely applied to the spatial governance of "mountains, rivers, forests, fields, lakes, grasslands, and deserts." Based on the comprehensive advantages of China Tower's "tower, building, power, maintenance, and network," a domestically produced high-performance hyperspectral camera system, combined with a fully automated vertical take-off and landing fixed-wing UAV (including an automated airfield), establishes an automated UAV-borne hyperspectral inspection system. This system can achieve high-precision, high-efficiency, and low-cost acquisition of large-area, high-frequency, long-term hyperspectral data, solving problems such as low automation, high operating costs, small operating area, difficulty in data acquisition and transmission, and high difficulty in processing large-area data applications in UAV hyperspectral remote sensing operations. This will drive the rapid development of UAV technology, hyperspectral technology, and remote sensing application technology.

[0023] The technical solution of this invention can be deployed to hyperspectral system sites in various unmanned intelligent airports, accelerating the development of UAV technology, hyperspectral technology, and remote sensing application technology. It fills gaps in industry applications, elevates the technological standing of China Tower, and establishes a significant advantage for China Tower Vision Link in agriculture, forestry, environmental protection, water conservancy, emergency response, and disaster prevention and mitigation. It provides strong professional technical support for industry applications, ushering in a new era of quantitative remote sensing, and greatly enriches the future service types and profitability of China Tower Smart Link.

[0024] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a flowchart of an embodiment of a hyperspectral system radiometric calibration method provided by the present invention; Figure 2 This is a flowchart of an embodiment of a hyperspectral system radiometric calibration method provided by the present invention; Figure 3 This is a structural diagram of an embodiment of a hyperspectral system radiometric calibration system provided by the present invention; Figure 4 This is a structural diagram of an embodiment of a hyperspectral system radiometric calibration system provided by the present invention; Figure 5 This is a schematic diagram of a computer device structure according to an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The same reference numerals in the accompanying drawings denote the same or similar elements, components, or parts, and therefore, repeated descriptions of the same or similar elements, components, or parts may be omitted below. It should also be understood that although terms such as first, second, third, etc., indicating numbers may be used herein to describe various devices, elements, components, or parts, these devices, elements, components, or parts should not be limited by these terms. That is, these terms are only used to distinguish one from another. For example, a first device may also be referred to as a second device, without departing from the essential technical solution of the invention. Furthermore, the terms "and / or" and "and / or" refer to all combinations including any one or more of the listed items.

[0029] Example 1 Additional aspects and advantages of embodiments of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of embodiments of the invention.

[0030] Combination Figure 1 and Figure 2 This invention provides a method for radiometric calibration of a hyperspectral system, comprising: S1: Ground radiation calibration method based on diffuse reflector before takeoff, using solar radiation total meter to obtain total solar irradiance, and recording this total solar irradiance as TSI.

[0031] S2: Establish a radiance model based on the diffuse reflector and record the model as the BRDF model.

[0032] S3: Based on TSI, using the BRDF model, the wavelength of the hyperspectral camera is obtained. The radiance at that location is recorded as [value]. .

[0033] S4: Yes Perform correction processing to obtain the corresponding DN value, and record this DN value. .

[0034] S5: By comparison and This enables the calibration of hyperspectral systems.

[0035] In this embodiment, the DN value is a digital quantization value. Due to its imaging principle, the hyperspectral camera needs to convert the digital quantization value (DN value) of the image acquired by the hyperspectral camera into physical quantities such as radiance, reflectivity, or surface temperature. Therefore, radiometric calibration of the hyperspectral system is required. Typically, after development, a hyperspectral camera needs to undergo two steps: laboratory calibration and field calibration, to verify and correct its performance. For the field calibration process, in actual use, it is often necessary to lay a standard diffuse reflector plate around the feature of interest and simultaneously perform radiometric calibration using a spectrometer.

[0036] This invention is based on ground-based radiation calibration before takeoff using a diffuse reflector. Solar irradiance is collected, and total solar irradiance is obtained using a solar radiation meter to establish a radiance model. Based on this data and model, the radiance measured by a hyperspectral camera is obtained. The radiance measured by the hyperspectral camera is then calibrated, and by comparing the radiance measured by the hyperspectral camera with the calibrated data, the calibration of the hyperspectral system is completed.

[0037] In related technologies, radiometric calibration of UAV-borne hyperspectral systems can be categorized based on the calibration site: pre-flight laboratory calibration, pre-flight field calibration, and onboard calibration. Pre-flight laboratory radiometric calibration aims to establish a quantitative relationship between the input radiance at the payload's entrance pupil and the digital output, calibrating its wavelength position, radiometric accuracy, spatial positioning, etc., converting the instrument's output values ​​into radiometric values. After the instrument has been in operation, periodic calibration is also required to monitor changes in instrument performance and adjust calibration parameters accordingly.

[0038] Pre-flight site calibration refers to the calibration of the hyperspectral camera under normal operating conditions by selecting a radiometric calibration site and performing synchronous ground measurements. Site calibration can achieve calibration across the entire aperture, field of view, and dynamic range, taking into account the effects of atmospheric transmission and the environment. This calibration method can achieve absolute correction under the exact same conditions as when the remote sensor is operating and acquiring ground images. It can provide calibration throughout the entire lifespan of the remote sensor, verifying its authenticity and the correctness of certain models. However, the ground target should be a typical homogeneous and stable target. Site calibration must also simultaneously measure and calculate atmospheric environmental parameters and ground reflectivity when the hyperspectral camera passes overhead.

[0039] Onboard calibration is an important component of airborne hyperspectral instrument calibration. It is used to perform functions such as onboard radiometric calibration of cameras. Through high-precision onboard radiometric calibration, the performance changes of the instrument's radiometric response during flight can be detected and corrected.

[0040] Pre-flight calibration refers to the absolute radiometric calibration of a hyperspectral camera during its development, using an integrating sphere or solar interferometric signals. Solar reflection band calibration can be divided into laboratory calibration and field calibration. Laboratory calibration in the solar reflection band is primarily achieved by imaging the remote sensor inside a laboratory using an integrating sphere and a halogen tungsten lamp. Based on the measured radiant energy from the integrating sphere and the image captured by the integrating sphere, the radiometric calibration coefficients for each channel of the hyperspectral camera are obtained.

[0041] Solar reflection band field calibration involves selecting a uniform, open site and using the reflected signals of sunlight to radiometrically calibrate the hyperspectral camera. The pre-flight field calibration experiment for UAVs directly uses sunlight as the light source, whose radiance and spectral characteristics are quite consistent with the reflection characteristics of the ground surface and cloud tops. This can serve as a supplement to laboratory calibration, further improving the accuracy of pre-flight hyperspectral camera calibration for UAVs.

[0042] Ground-based calibration devices comprehensively simulate the working environment and conditions of radiometers, solving calibration problems in the laboratory calibration stage. However, field calibration is not mentioned. Remote sensing equipment is also calibrated within the Remote Sensing Instruments Division. Its variable-temperature calibration source is used in the radiometer calibration laboratory to achieve the light source transformation requirements in ground-based radiometric calibration, which is equivalent to indirectly changing the spectral radiance of the solar calibration source. However, the experimental cost is extremely high, and the required calibration equipment has stringent environmental requirements. The blackbody calibration source developed by the Radio Technology Measurement Science Research Institute can achieve an emissivity value of over 0.995, but the accuracy of other calibration devices is relatively general, and they cannot perform field calibration, requiring the construction of specialized environmental simulations of field conditions, which incurs high human and economic costs.

[0043] The diffuse reflection radiance calibration device calibrated the spectrometer's spectral radiance using a diffuse reflector method. By analyzing the effects of the standard light source, the Lambertian diffuse reflector, and the spectrometer's entrance slit on the calibration results using an integral method, the optimal conditions for radiometric calibration were determined. Furthermore, a calculus method was employed to address the issue of uneven spectral irradiance during illumination, resulting in a more accurate spectral radiance. Based on the spectrometer's ground calibration results, the obtained remote sensing measurement data were processed and compared with international measurement results, maintaining a relative error within 10%. This calibration device considered the angle between the standard light source and the diffuse reflector, but it lacked an angle adjustment mechanism for the diffuse reflector.

[0044] To verify the accuracy of the calibration device, the Institute of Optics and Precision Mechanics used a channel-type ATR to measure the radiance of the Earth's surface, including temperature and humidity information. However, this device is a stationary measurement and can only be used for calibration experiments under specific conditions. Although the measuring device is simple, it cannot be moved. The CE318 solar photometer was used to measure the calibration equivalent. This device is also a stationary measurement, with high calibration costs and low ease of operation in calibration experiments.

[0045] Specifically, step S1, based on the ground radiometric calibration before takeoff using the diffuse reflector, obtains the total solar irradiance (TSI) using the total solar radiation table, including: For small-area uniform light sources, by comparing the corresponding measurement values ​​under different emitting surface elements, we can analyze the influence of the light spot size of the uniform light source on the measurement of solar radiation count values ​​and the influence of the size of the incident aperture of the solar radiation total meter on the numerical measurement.

[0046] Based on the area of ​​the light source, the aperture, and the receiving size of the detector, the differences caused by the light path transmission are theoretically corrected according to the Kirchhoff diffraction formula, thereby reducing the error of the laboratory solar radiation meter measurement and thus obtaining TSI. The Kirchhoff diffraction formula is existing technology and will not be elaborated here.

[0047] Since a ground-based radiation calibration method based on diffuse reflectors is used before takeoff, accurate measurement of the total solar irradiance (TSI) in units of W / m² is crucial for subsequent calibration modeling. Therefore, a solar irradiance meter is used to obtain the total solar irradiance.

[0048] The calculation of solar irradiance measurements involves comparing the corresponding measurement values ​​under different luminous surface elements for small-area uniform light sources. This analysis examines the impact of the uniform light source's spot size on the measurement of solar radiation counts. Specifically, step S2 establishes a radiance model based on the diffuse reflector, and records this model as a BRDF model, including: The BRDF model includes formulas for calculating the radiance of the diffuse reflector and the radiance of the hyperspectral camera; The formula for calculating the radiance of a diffuse reflector is:

[0049] in, For the i-th surface element of the diffuse reflector Radiance at that location For TSI on the i-th surface element of the diffuse reflector The irradiance value at that location For the angle of the diffuse reflector angle of incidence The reflectivity of the reflected light is determined in the laboratory. π is the mathematical constant pi, and i = 1, 2, ..., n.

[0050] The formula for calculating the radiance of a hyperspectral camera is:

[0051] in, For hyperspectral cameras at source wavelength Radiance at that location To the source wavelength of the diffuse reflector plate Radiance at that location The radiance is Time-based hyperspectral camera at source wavelength The response sensitivity at a given location is determined based on the properties of the hyperspectral camera.

[0052] In this embodiment, the diffuse reflector, supporting components, and fixing installation materials are different. During each operation, direct sunlight, especially solar ultraviolet radiation, may affect the stability of the diffuse reflector. Therefore, the smart airport shell cover should be closed as much as possible after the drone takes off to reduce the decay of the diffuse reflector.

[0053] In this embodiment, the zenith angle θ and azimuth angle φ of the hyperspectral camera's observation direction are dynamically corrected using UAV attitude data.

[0054] The embodiments of the present invention also include: Calculate the dark current correction value of the hyperspectral camera itself and record the correction value. .

[0055] The operating conditions and environment of UAV-borne hyperspectral systems differ significantly from those in laboratories. It is necessary to consider both the dark current calibration value (correction value) of the hyperspectral camera itself and other factors. Meanwhile, the impact of varying test environments on calibration accuracy during flight missions must also be considered. The camera system on the UAV platform is subject to solar radiation, ambient temperature and humidity, and platform vibration; therefore, the influence of these environmental factors must be quantitatively analyzed. Simulation model calculations mainly include: simulation calculations of the total solar radiation meter, hyperspectral camera, and diffuse reflector.

[0056] Specifically, step S3 uses the BRDF model based on TSI to obtain the wavelength of the hyperspectral camera. The radiance at that location is recorded as [value]. ,include: Based on the BRDF model used by TSI, combined with the incident angle of the diffuse reflector... and the angle of the diffuse reflector ,get .

[0057] Specifically, step S4 is for Perform correction processing to obtain the corresponding DN value, and record this DN value. ,include: S41: Perform the aforementioned correction process, including... Radiation correction and temperature response correction were performed to obtain... .

[0058] S42: Yes After repeated measurements, the average measurement value is calculated and updated. .

[0059] The UAV-borne hyperspectral camera system needs to be calibrated, including radiometric correction. The calibration parameters are as follows: ; and temperature response correction processing, with correction parameters as follows: ; Obtain the DN value actually observed by the UAV-borne hyperspectral camera To minimize the impact of single-observation noise, the calibration source needs to be repeatedly measured and the average value calculated. The DN (Digital Number) value is the original digital quantization value.

[0060] The specific calculation formula is as follows:

[0061] Where α is the temperature response correction coefficient, determined based on the properties of the hyperspectral camera. Used for radiation correction processing.

[0062] Specifically, step S5 involves comparison. and To achieve calibration of hyperspectral systems, including: By comparison and This allows us to obtain the input-output relationship of the hyperspectral system, thereby enabling the calibration of the hyperspectral system and providing a basis for evaluating the calibration accuracy.

[0063] Example 2 Based on the above method, embodiments of the present invention also provide a hyperspectral system radiometric calibration device, comprising: A total solar radiation meter is used to obtain the total solar irradiance.

[0064] A diffuse reflector, installed in an unmanned intelligent airport, is used to collect the incident angle and corresponding reflectivity, receive the irradiance of the total solar irradiance, and reflect sunlight. It is also used for radiometric calibration of a hyperspectral camera.

[0065] A hyperspectral camera is used to receive sunlight reflected by the diffuse reflector and its corresponding wavelength. The dark current correction value of the hyperspectral camera itself is calculated. Combined with the observation angle and the total solar irradiance, the wavelength of the hyperspectral camera is obtained. The radiance at that location.

[0066] A drone is used to carry the hyperspectral camera.

[0067] In this embodiment, preferably, the hyperspectral camera is a domestically produced high-performance hyperspectral camera system, the UAV is a fully automatic vertical take-off and landing fixed-wing UAV (including an automatic airport), and the diffuse reflector is a standard diffuse reflector.

[0068] Example 3 Based on the above methods, combined with Figure 3 and Figure 4 This invention also provides a hyperspectral system radiometric calibration system, comprising: Data acquisition module 01 is used for ground radiation calibration before takeoff based on diffuse reflector. It uses the total solar radiation meter to obtain the total solar radiation irradiance and records the total solar radiation irradiance as TSI.

[0069] Modeling module 02 is used to establish a radiance model based on the diffuse reflector, and the model is recorded as a BRDF model.

[0070] Brightness acquisition module 03 is used to obtain the wavelength of the hyperspectral camera based on the TSI using the BRDF model. The radiance at that location is recorded as [value]. .

[0071] DN value acquisition module 04 is used for... Perform correction processing to obtain the corresponding DN value, and record this DN value. .

[0072] Calibration module 05 is used for comparison and This enables the calibration of hyperspectral systems.

[0073] Self-calibration module 06 is used to calculate and record the dark current correction value of the hyperspectral camera. .

[0074] Specifically, the brightness acquisition module 03 also includes: The brightness acquisition unit is used to obtain the brightness based on the TSI using the BRDF model and the incident angle of the diffuse reflector. and the angle of the diffuse reflector ,get .

[0075] Specifically, the DN value acquisition module 04 also includes: Correction unit 041 is used to perform the correction process, including... Radiation correction and temperature response correction were performed to obtain... .

[0076] Noise reduction unit 042, used for noise reduction After repeated measurements, the average measurement value is calculated and updated. .

[0077] Specifically, calibration module 05 also includes: Calibration unit, used for comparison and Thus, the input-output relationship of the hyperspectral system is obtained.

[0078] Example 3 corresponds to the hyperspectral system radiometric calibration method technical solution in Example 1.

[0079] Example 4 like Figure 5 The present invention also provides a computer device, including a processor 1110, a communication interface 1120, a memory 1130 and a communication bus 1140, wherein the processor 1110, the communication interface 1120 and the memory 1130 communicate with each other through the communication bus 1140. Memory 1130 is used to store computer programs; When the processor 1110 executes the program stored in the memory 1130, it implements any of the above-described determination methods.

[0080] The electronic device provided in this embodiment of the invention includes a processor 1110 that executes a program stored in a memory 1130 to obtain the fluid flow rate of each branch under different switching states and determines the initial volumetric flow rate of each branch; it corrects the initial volumetric flow rate based on the pipe parameters and fluid parameters of each branch when it is in operating condition and standard condition to obtain the standard condition volumetric flow rate of each branch; it obtains multiple total standard condition volumetric flow rates based on the standard condition volumetric flow rates of each branch under different switching states, and determines the optimal switching state of each branch by using the switching state of each branch when the total standard condition volumetric flow rate reaches a preset target.

[0081] The communication bus 1140 mentioned in the above electronic device can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus 1140 can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, it is shown in the figure with only one thick line, but this does not indicate that there is only one bus or one type of bus.

[0082] The communication interface 1120 is used for communication between the above-mentioned electronic device and other devices.

[0083] The memory 1130 may include random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Optionally, the memory 1130 may also be at least one storage device located remotely from the aforementioned processor 1110.

[0084] The processor 1110 mentioned above can be a general-purpose processor 1110, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0085] This invention provides a computer-readable storage medium storing one or more programs that can be executed by one or more processors 1110 to implement the determination method of any of the above embodiments.

[0086] In summary, the technical solution provided by this invention has the following advantages: 1. The technical solution provided by this invention includes an unattended intelligent airport, a solar radiation meter, a diffuse reflector, and a hyperspectral camera system as its hardware foundation. This can improve the calibration efficiency of unattended hyperspectral system data, reduce calibration costs, and enhance the convenience of calibration experiments.

[0087] 2. This invention can be widely applied to spatial governance of "mountains, rivers, forests, fields, lakes, grasslands, and deserts." Based on the comprehensive advantages of China Tower's "tower, building, power, maintenance, and network," a domestically produced high-performance hyperspectral camera system, combined with a fully automated vertical take-off and landing fixed-wing UAV (including automated airfields), establishes an automated UAV-borne hyperspectral inspection system. This system enables the acquisition of large-area, high-frequency, long-term, high-precision, efficient, and low-cost hyperspectral data, solving problems such as low automation, high operating costs, small operating area, difficulty in data acquisition and transmission, and high difficulty in processing large-area data applications in UAV hyperspectral remote sensing operations. This will drive the rapid development of UAV technology, hyperspectral technology, and remote sensing application technology.

[0088] 3. This invention can be deployed at hyperspectral system sites in various unmanned intelligent airports, accelerating the development of UAV technology, hyperspectral technology, and remote sensing application technology. It fills gaps in industry applications, elevates the technological standing of China Tower, and establishes China Tower Vision Link's significant advantages in agriculture, forestry, environmental protection, water conservancy, emergency response, and disaster prevention and mitigation. It provides strong professional technical support for industry applications, ushering in a new era of quantitative remote sensing, and greatly enriches the future service types and profitability of China Tower Smart Link.

[0089] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of the present invention is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)).

[0090] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for radiometric calibration of a hyperspectral system, characterized in that, include: The pre-flight ground radiation calibration method based on diffuse reflectors uses a total solar radiation meter to obtain the total solar irradiance and records it as TSI. A radiance model is established based on the diffuse reflector, and this model is recorded as the BRDF model. Based on the TSI model using the BRDF model, the wavelength of the hyperspectral camera is obtained. The radiance at that location is recorded as [value]. ; right Perform correction processing to obtain the corresponding DN value, and record this DN value. ; By comparison and This enables the calibration of hyperspectral systems.

2. The hyperspectral system radiometric calibration method as described in claim 1, characterized in that, The step of establishing a radiance model based on the diffuse reflector, and recording this model as a BRDF model, specifically includes: The BRDF model includes formulas for calculating the radiance of the diffuse reflector and the radiance of the hyperspectral camera; The formula for calculating the radiance of the diffuse reflector is: in, For the i-th surface element of the diffuse reflector Radiance at that location For TSI on the i-th surface element of the diffuse reflector The irradiance value at that location For the angle of the diffuse reflector angle of incidence The reflectivity of the reflected light, which is determined in the laboratory, where π is the mathematical constant pi, and i = 1, 2, ..., n; The formula for calculating the radiance of the hyperspectral camera is as follows: in, For hyperspectral cameras at source wavelength Radiance at that location To the source wavelength of the diffuse reflector plate Radiance at that location The radiance is Time-based hyperspectral camera at source wavelength The response sensitivity at a given location is determined based on the properties of the hyperspectral camera.

3. The hyperspectral system radiometric calibration method as described in claim 1, characterized in that, Also includes: Calculate the dark current correction value of the hyperspectral camera itself and record the correction value. .

4. The hyperspectral system radiometric calibration method as described in claim 1, characterized in that, The method described above uses the BRDF model based on TSI to obtain the wavelength of the hyperspectral camera. The radiance at that location is recorded as [value]. Specifically, it includes: Based on the BRDF model used by TSI, combined with the incident angle of the diffuse reflector... and the angle of the diffuse reflector ,get .

5. The hyperspectral system radiometric calibration method as described in claim 3, characterized in that, The pair Perform correction processing to obtain the corresponding DN value, and record this DN value. Specifically, it includes: The correction process includes performing the correction on... Radiation correction and temperature response correction were performed to obtain... ; right After repeated measurements, the average measurement value is calculated and updated. .

6. The hyperspectral system radiometric calibration method as described in claim 5, characterized in that, The pair Radiation correction and temperature response correction were performed to obtain... Specifically, it includes: The calculation formula is: Where α is the temperature response correction coefficient, determined based on the properties of the hyperspectral camera. Used for radiation correction processing.

7. The hyperspectral system radiometric calibration method as described in claim 1, characterized in that, The comparison and To achieve calibration of hyperspectral systems, specifically including: By comparison and Thus, the input-output relationship of the hyperspectral system is obtained.

8. A hyperspectral system radiometric calibration system, characterized in that, include: The data acquisition module, based on the ground radiation calibration method before takeoff using the diffuse reflector, obtains the total solar irradiance using the total solar radiation meter and records the total solar irradiance as TSI; The modeling module is used to establish a radiance model based on the diffuse reflector, and this model is recorded as a BRDF model; The brightness acquisition module is used to obtain the wavelength of the hyperspectral camera based on the TSI using the BRDF model. The radiance at that location is recorded as [value]. ; The DN value acquisition module is used to obtain the DN value. Perform correction processing to obtain the corresponding DN value, and record this DN value. ; The calibration module is used to compare... and This enables the calibration of hyperspectral systems.

9. The hyperspectral system radiometric calibration system as described in claim 8, characterized in that, Also includes: The self-calibration module is used to calculate and record the dark current correction value of the hyperspectral camera. .

10. The hyperspectral system radiometric calibration system as described in claim 8, characterized in that, The brightness acquisition module specifically includes: The brightness acquisition unit is used to obtain the brightness based on the TSI using the BRDF model and the incident angle of the diffuse reflector. and the angle of the diffuse reflector ,get .

11. The hyperspectral system radiometric calibration system as described in claim 8, characterized in that, The DN value acquisition module specifically includes: A correction unit is configured to perform the correction process, including... Radiation correction and temperature response correction were performed to obtain... ; Noise reduction unit, used for After repeated measurements, the average measurement value is calculated and updated. .

12. The hyperspectral system radiometric calibration system as described in claim 8, characterized in that, The calibration module specifically includes: Calibration unit, used for comparison and Thus, the input-output relationship of the hyperspectral system is obtained.

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