Urban trace gas hyper-spectral rapid panoramic imaging method

Abstract

The invention discloses an urban trace gas hyper-spectral rapid panoramic imaging method. The method comprises the following steps: acquiring a panoramic spectrum of an urban scene and calculating a dSCD value of each trace component; calculating the height and thickness of each non-uniform layer in the vertical direction of panoramic imaging based on a geometric relationship between a dSCD value of O4 and an acquisition elevation angle; calculating the actually measured VCD value of the trace gas and the volume ratio concentration corresponding to each observation elevation angle based on the dSCD value of each trace component; based on the volume ratio concentration corresponding to each observation elevation angle, obtaining the volume ratio concentration distribution of the trace gas on the non-uniform vertical grid by combining the height and thickness of each non-uniform layer, and carrying out linear interpolation on the volume ratio concentration distribution to obtain the volume ratio concentration distribution on the uniform vertical grid; and the volume ratio concentration distribution on the uniform vertical grid is corrected based on VCD scaling, so that the limitation of the prior art can be overcome, and synchronous and rapid urban scale trace gas vertical distribution panoramic monitoring can be realized.

Description

Technical Field

[0001] This invention belongs to the field of trace gas monitoring technology, specifically relating to a rapid panoramic imaging method for trace gases in urban areas using hyperspectral imaging. Background Technology

[0002] As complex atmospheric chemical reactors, cities exhibit significant heterogeneity in the spatial distribution of trace gases, which is strongly influenced by underlying surface conditions such as buildings, transportation, and green spaces. Currently, in the field of trace gas vertical distribution inversion, the industry mainly relies on algorithms based on one-dimensional hyperspectral instruments combined with radiative transfer models. This type of method has matured technically after long-term research and application, and can, to a certain extent, invert the vertical distribution of trace gases, providing some data support for atmospheric environmental monitoring. Therefore, it has been widely used in existing trace gas monitoring work.

[0003] Traditional one-dimensional hyperspectral instruments typically perform elevation scanning at a fixed azimuth angle during a single measurement. The limitation of this method is that it can only acquire one-dimensional vertical distribution information in a single direction, failing to effectively capture the actual horizontal distribution and transport dynamics of pollutants. In practical urban atmospheric environmental monitoring, the horizontal diffusion and transport of pollutants are crucial for assessing the overall pollution situation; the lack of this information leads to significant biases in the understanding of trace gas distribution. On the other hand, inversion algorithms based on radiative transfer models rely on multiple iterations for forward simulation, resulting in low computational efficiency. Inverting a vertical distribution in a single direction typically takes several minutes. If such algorithms are applied to hyperspectral rapid imaging systems, data generated in a single minute-level push-broom operation may require tens of hours to complete the inversion, creating a significant data processing bottleneck. This bottleneck prevents the "rapid monitoring" advantage of hyperspectral rapid imaging systems from being fully realized, as a large amount of monitoring data cannot be promptly converted into effective monitoring results, severely restricting the efficiency of trace gas monitoring.

[0004] It is worth noting that some studies have attempted to use the O4 differential column concentration produced by the stable oxygen content in the atmosphere as a proxy parameter for the effective optical path, and then to calculate the volume ratio concentration of trace gases. However, since O4 and the target trace gas differ in their vertical distribution, this method is only applicable to the near-ground region and is difficult to accurately assess the effective optical path under high elevation angle conditions. Therefore, it cannot be directly used for the inversion of the vertical distribution of trace gases.

[0005] In summary, existing trace gas vertical distribution inversion techniques still have significant shortcomings in terms of spatial coverage, temporal resolution, and data processing efficiency. These shortcomings make it difficult for current technologies to efficiently, quickly, and accurately acquire three-dimensional distribution information of atmospheric trace gases, thus hindering the in-depth development of air pollution prevention and control and environmental quality improvement efforts. Therefore, developing a trace gas vertical distribution inversion technique that can overcome the above-mentioned technical deficiencies and achieve efficient, rapid, and accurate acquisition of three-dimensional distribution information of atmospheric trace gases has become an urgent technical problem to be solved by those skilled in the art. Summary of the Invention

[0006] In view of the above, the purpose of this invention is to provide a rapid panoramic imaging method for trace gases in cities using hyperspectral imaging, which performs rapid inversion of the vertical distribution of trace gases based on the acquired panoramic spectrum, aiming to overcome the limitations of existing technologies and achieve synchronous and rapid panoramic monitoring of the vertical distribution of trace gases at the urban scale.

[0007] To achieve the above-mentioned objective, a rapid panoramic imaging method for trace gases in urban areas using hyperspectral imaging is provided, characterized by comprising the following steps: The panoramic spectrum of the urban scene was collected, and the dSCD (differential column concentration) values ​​of each trace component were calculated based on the panoramic spectrum. The height and thickness of non-uniform layers in the vertical direction of panoramic imaging are calculated based on the geometric relationship between the dSCD value of O4 and the acquisition elevation angle. The measured VCD (vertical column concentration) values ​​of trace gases and the volume ratio concentration corresponding to each observation elevation angle were calculated based on the dSCD values ​​of each trace component. Based on the volume ratio concentration corresponding to each observation elevation angle, and combined with the height and thickness of each non-uniform layer, the volume ratio concentration distribution of trace gas on the non-uniform vertical grid is obtained. The volume ratio concentration distribution is then linearly interpolated to obtain the volume ratio concentration distribution on the uniform vertical grid. The volume ratio concentration distribution on a non-uniform vertical grid is integrated to obtain the integrated VCD value of trace gas. The scaling factor is calculated based on the integrated VCD value and the measured VCD value. The scaling factor is used to correct the volume ratio concentration distribution on a uniform vertical grid to obtain the panoramic imaging result of trace gas. After removing the building background, the light flux result at the center band of the hyperspectral rapid imaging system is interpolated into a grid of the same resolution as the panoramic imaging result.

[0008] Preferably, the height and thickness of each non-uniform layer in the vertical direction of the panoramic imaging are calculated based on the geometric relationship between the dSCD value of O4 and the acquisition elevation angle, including: In the formula: For the first The height of the floor, To observe the elevation angle dSCD of O4 below The concentration of O4 in the vertical column. The number density of O4, For the first The thickness of the layer.

[0009] Preferably, the number density of O4 Calculated using the following formula: in, It refers to the number density of oxygen in air, which is the density of air under given pressure and temperature conditions. Seek; O4 vertical column concentration It is calculated using the following formula: in, , , These refer to near-surface temperature, relative humidity, and air pressure, respectively. Observation angle of elevation The division depends on the system's elevation angle. The field of view of the lens The number of vertical pixels of the CCD in the atmospheric hyperspectral rapid imager Pixel merging number : .

[0010] Preferably, the measured VCD value of the trace gas is calculated based on the dSCD value of each trace component, including: in, This is the dSCD value calculated for trace gases at a 15° elevation angle. The atmospheric mass factor, calculated at an elevation angle of 15°, is obtained from the following formula: in, It is the dSCD value calculated for O4 at an elevation angle of 15°.

[0011] Preferably, the volumetric concentration ratio corresponding to each observation elevation angle is calculated based on the dSCD value of each trace component: in, and The angle of elevation is respectively The dSCD values ​​of trace gases and O4 were calculated at that time. It is Avogadro's constant. It is the gas constant. It refers to the percentage of oxygen in the air. For temperature, p .

[0012] Preferably, the volume ratio concentration distribution of trace gases on a non-uniform vertical grid is obtained based on the volume ratio concentration corresponding to each observation elevation angle, combined with the height and thickness of each non-uniform layer, including: Each observation elevation angle corresponds to a volume ratio concentration, and each observation elevation angle also corresponds to a height, thus forming a mapping table of volume ratio concentration - observation elevation angle - height. Based on this mapping table, the volume ratio concentration corresponding to each height is obtained, that is, the volume ratio concentration distribution of trace gases on a non-uniform vertical grid is obtained.

[0013] Preferably, interpolating the light flux result at the center band of the hyperspectral rapid imaging system into a grid of the same resolution as the panoramic imaging result includes: In the optical flux grid results at the center band of the hyperspectral fast imaging system, those less than 1×10 5 The value is assigned to a blank value to create a building background mask. This mask is then applied to the panoramic imaging result of trace gas to obtain a panoramic imaging result with the building background removed.

[0014] Preferably, when there are significant emission sources within the city, it further includes: The dSCD of the internal path of the smoke plume is obtained by subtracting the dSCD of the upwind direction at the same height from the observed dSCD of the smoke plume. The concentration inside the plume is calculated using dSCD based on the internal path of the plume, and then interpolated into the panoramic imaging results of trace gases.

[0015] Preferably, the calculation of the internal concentration of the plume based on the dSCD of the internal path of the plume includes: in, M Represents the relative mass of molecules. Indicates the height corresponding to the imaged pixel. i To observe the number of elevation angle sequences, j For frame number, Represents Avogadro's constant. The VCD value corresponding to the image pixel. The dSCD value corresponding to the imaged pixel. This refers to atmospheric quality factors.

[0016] Preferably, interpolating the internal concentration of the plume into the panoramic imaging results of trace gases includes: The element containing the plume in the dSCD value of each trace component is set to null, a plume mask is created, the plume mask is multiplied with the panoramic imaging result to obtain a panoramic imaging result with null values ​​in the plume part, and then the internal concentration of the plume is backfilled into the panoramic imaging result with null values ​​in the plume part.

[0017] Compared with the prior art, the beneficial effects of the present invention include at least the following: 1. Achieved high spatiotemporal resolution synchronous panoramic measurement. Employing a hyperspectral rapid imaging system, spectral data from all directions (360°) and multiple elevation angles can be acquired simultaneously with a single push-scan, completely replacing the traditional one-dimensional instrument's reliance on mechanical rotation scanning. This solves the problem of data spatiotemporal asynchrony caused by long scanning times, achieving true instantaneous panoramic imaging.

[0018] 2. A rapid method for calculating the vertical concentration distribution of trace gases is proposed. By utilizing the dSCD value of O4 and its geometric relationship, vertical height layers are dynamically inverted and divided, establishing a direct mapping relationship from spectral data to a three-dimensional concentration field.

[0019] 3. To address the complex urban environment, two processing schemes are proposed: one for open background environments without strong emission sources, and the other specifically for the quantitative identification and processing of obvious emission sources (such as chimneys). Through background subtraction, separate inversion, and result backfilling, the problem of inconsistent inversion between plume regions and background regions due to different atmospheric parameters is solved, ultimately generating a complete closed-loop panoramic density image that simultaneously includes both area source background and point source plume. Attached Figure Description

[0020] 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 only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart of the rapid panoramic imaging method for trace gases in urban areas provided in the embodiments; Figure 2 This is a flowchart of the rapid panoramic imaging method for trace gases in urban areas provided in the embodiments; Figure 3 This is a panoramic imaging result image of the city provided in the embodiment. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of protection of this invention.

[0023] The inventive concept of this invention is to provide a rapid panoramic imaging method for urban trace gases in the field of environmental monitoring, which further improves the timeliness of monitoring while ensuring the accuracy of basic inversion.

[0024] like Figure 1 and Figure 2 As shown in the embodiment, a rapid urban trace gas panoramic imaging method includes the following steps: S1 collects panoramic spectra of urban scenes and calculates the dSCD values ​​of each trace component based on the panoramic spectra.

[0025] In this embodiment, a ground-based hyperspectral remote sensing system (hereinafter referred to as a hyperspectral rapid imaging system) for rapid high-resolution imaging of multi-component atmospheric trace components, disclosed in CN118858171A, is used to acquire panoramic spectra of urban scenes. Specifically, a suitable observation location and elevation angle are selected to minimize obstruction in the observation image. A 360° pushbroom observation is performed to obtain panoramic spectral information. Then, the elevation angle is switched to 90°, and 20 frames of zenith spectrum are acquired.

[0026] In this embodiment, panoramic differential spectral information is obtained using the zenith spectrum as a reference spectrum. A nonlinear least squares fitting method is used to separate the dSCD (difference column concentration) values ​​of each trace component from the differential spectral information.

[0027] S2, based on the geometric relationship between the dSCD value of O4 and the acquisition elevation angle, calculates the height and thickness of each non-uniform layer in the vertical direction of the panoramic imaging.

[0028] In this embodiment, the following formula is used for calculation: In the formula: For the first The height of the floor, To observe the elevation angle dSCD of O4 below The concentration of O4 in the vertical column. The number density of O4, For the first The thickness of the layer.

[0029] Among them, the number density of O4 Calculated using the following formula: in, It refers to the number density of oxygen in air, which is the density of air under given pressure and temperature conditions. To obtain, generally 1.29kg / m 3 .

[0030] O4 vertical column concentration It is calculated using the following formula: in, , , These refer to near-surface temperature, relative humidity, and air pressure, respectively. It is the unit of O4 column density.

[0031] Observation angle of elevation The division depends on the system's elevation angle. The field of view of the lens The number of vertical pixels of the CCD in the atmospheric hyperspectral rapid imager Pixel merging number : S3, calculate the measured VCD value of trace gases and the volume ratio concentration corresponding to each observation elevation angle based on the dSCD value of each trace component.

[0032] In this embodiment, the measured VCD value of trace gases is calculated based on the dSCD value of each trace component using the following formula: in, This is the dSCD value calculated for trace gases at a 15° elevation angle. The atmospheric mass factor, calculated at an elevation angle of 15°, is obtained from the following formula: in, It is the dSCD value calculated for O4 at an elevation angle of 15°.

[0033] In the embodiment, the volumetric concentration ratio corresponding to each observation elevation angle was also calculated based on the dSCD values ​​of each trace component: in, and The angle of elevation is respectively The dSCD values ​​of trace gases and O4 were calculated at that time. It is Avogadro's constant. It is the gas constant. It refers to the percentage of oxygen in the air. For temperature, p .

[0034] Because the field of view of the hyperspectral rapid imaging system is 16°. When When ≤8°, and It can be obtained directly, when When the angle is greater than 8°, a linear fit is performed using the dSCD values ​​of the five lowest elevation angles, and the fitted formula is extrapolated to obtain the result. and The value, usually Set to 8°.

[0035] S4. Based on the volume ratio concentration corresponding to each observation elevation angle, and combined with the height and thickness of each non-uniform layer, the volume ratio concentration distribution of trace gas on the non-uniform vertical grid is obtained. The volume ratio concentration distribution is linearly interpolated to obtain the volume ratio concentration distribution on the uniform vertical grid.

[0036] In this embodiment, each observation elevation angle corresponds to a volume ratio concentration, and each observation elevation angle also corresponds to a height, thus forming a mapping table of volume ratio concentration-observation elevation angle-height. Based on this mapping table, the volume ratio concentration corresponding to each height is obtained, that is, the volume ratio concentration distribution of trace gas on a non-uniform vertical grid is obtained.

[0037] In this embodiment, linear interpolation is also used to interpolate the non-uniform imaging results to a preset grid, resulting in a uniform panoramic imaging result of trace gases. The preset grid is typically: 0-1000m, with a resolution of 50m; 1000-2500m, with a resolution of 100m; and above 2500m, with a resolution of 200m. Kriging interpolation is used to ensure the smoothness and physical consistency of the vertical concentration profile. To avoid discontinuities between layers due to interpolation or noise, median filtering is added after interpolation to make the concentration distribution in the vertical direction more consistent with actual atmospheric conditions.

[0038] S5. Integrate the volume ratio concentration distribution on the non-uniform vertical grid to obtain the integrated VCD value of the trace gas. Calculate the scaling factor based on the integrated VCD value and the measured VCD value. Use the scaling factor to correct the volume ratio concentration distribution on the uniform vertical grid to obtain the panoramic imaging result of the trace gas.

[0039] In this embodiment, the scaling factor is obtained by dividing the integral VCD value by the measured VCD value, and the resulting scaling factor is used for correction.

[0040] S6, after removing the building background, specifically interpolates the light flux result at the center band of the hyperspectral rapid imaging system into a grid of the same resolution as the panoramic imaging result, so that the spatial resolution of the two remains consistent.

[0041] In the embodiment, the light flux grid results at the center band (e.g., 360 nm) of the hyperspectral fast imaging system are selected, with values ​​less than 1×10⁻⁶. 5 The value is assigned to nan (empty value), a building background mask is created, and the mask is applied to the scene imaging result to obtain a panoramic imaging result with the building background removed.

[0042] Steps S1-S6 above are for panoramic imaging without obvious emission sources (such as chimney exhaust pipes or other obvious plume emission scenarios). When obvious emission sources are included (such as chimney exhaust pipes or other obvious plume emission scenarios), the internal parameters of the plume do not conform to the parameter settings in the above steps (such as oxygen content, temperature, air pressure, etc.), requiring separate processing, specifically including: First, the background concentration is subtracted. The dSCD value of the path within the plume can be obtained by subtracting the upwind dSCD value at the same height from the observed plume dSCD value: in, In dSCD of the internal path of the plume at higher altitudes and These refer to the dSCD values ​​of the observed plume and the upwind dSCD values ​​at the same altitude, respectively.

[0043] Then, the internal concentration of the plume is calculated based on the dSCD of the internal path of the plume: in, M Represents the relative mass of molecules. Indicates the height corresponding to the imaged pixel. i To observe the number of elevation angle sequences, j For frame number, Represents Avogadro's constant. The VCD value corresponding to the image pixel. The dSCD value corresponding to the imaged pixel. This refers to atmospheric quality factors.

[0044] Finally, the concentration inside the plume is interpolated into the panoramic imaging result of the trace gas. Specifically, the element containing the plume in the dSCD value of each trace component is set to null, a plume mask is created, and the plume mask is multiplied with the panoramic imaging result to obtain a panoramic imaging result with null values ​​in the plume part. Then, the concentration inside the plume is backfilled into the panoramic imaging result with null values ​​in the plume part.

[0045] The embodiment also provides panoramic imaging results of SO2 in urban scenes containing obvious emission sources using the above method, as shown in the following figures. Figure 3 As shown. The specific process is as follows: When acquiring the spectrum via S1, the base elevation angle is set to 8°, the integration time to 1200ms, the pushbroom speed to 0.5° / s, and the frame rate to 350. Pushbroom acquisition begins. After pushbroom acquisition is complete, the base elevation angle is set to 90°, the integration time to 1200ms, and the frame rate to 20 to acquire the zenith spectrum. Then, the dSCD result of SO2 is calculated via S2. In the dSCD result matrix, the element containing the plume is set to null, creating a plume mask. Next, the panoramic SO2 imaging result is obtained by calculating via S3-S6. The imaging result is multiplied by the created plume mask to obtain the panoramic SO2 imaging result with null values ​​for the plume portion. Finally, the SO2 concentration result of the separately processed plume portion is backfilled into the panoramic SO2 imaging result to obtain the final result.

[0046] It should be noted that in the final results obtained by this method, the concentration of the plume represents the average concentration inside the plume, while the background concentration represents the average concentration in the upper layer.

[0047] The specific embodiments described above illustrate the technical solution and beneficial effects of the present invention in detail. It should be understood that the above description is only the most preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A rapid panoramic imaging method for trace gases in urban areas using hyperspectral imaging, characterized in that, Includes the following steps: The panoramic spectrum of urban scenes was collected, and the dSCD values ​​of each trace component were calculated based on the panoramic spectrum. The height and thickness of non-uniform layers in the vertical direction of panoramic imaging are calculated based on the geometric relationship between the dSCD value of O4 and the acquisition elevation angle. The measured VCD values ​​of trace gases and the volume ratio concentrations corresponding to each observation elevation angle are calculated based on the dSCD values ​​of each trace component. Based on the volume ratio concentration corresponding to each observation elevation angle, and combined with the height and thickness of each non-uniform layer, the volume ratio concentration distribution of trace gas on the non-uniform vertical grid is obtained. The volume ratio concentration distribution is then linearly interpolated to obtain the volume ratio concentration distribution on the uniform vertical grid. The volume ratio concentration distribution on a non-uniform vertical grid is integrated to obtain the integrated VCD value of trace gas. The scaling factor is calculated based on the integrated VCD value and the measured VCD value. The scaling factor is used to correct the volume ratio concentration distribution on a uniform vertical grid to obtain the panoramic imaging result of trace gas. After removing the building background, the light flux result at the center band of the hyperspectral rapid imaging system is interpolated into a grid of the same resolution in the panoramic imaging result.

2. The rapid panoramic imaging method for trace gases in cities according to claim 1, characterized in that, The height and thickness of non-uniform layers in the vertical direction of the panoramic image are calculated based on the geometric relationship between the dSCD value of O4 and the acquisition elevation angle, including: ， ， In the formula: For the first The height of the floor, To observe the elevation angle dSCD of O4 below The concentration of O4 in the vertical column. The number density of O4, For the first The thickness of the layer.

3. The rapid panoramic imaging method for trace gases in urban areas according to claim 2, characterized in that, Number density of O4 Calculated using the following formula: ， in, It refers to the number density of oxygen in air, which is the density of air under given pressure and temperature conditions. Seek; O4 vertical column concentration It is calculated using the following formula: ， in, , , These refer to near-surface temperature, relative humidity, and air pressure, respectively. Observation angle of elevation The division depends on the system's elevation angle. The field of view of the lens The number of vertical pixels of the CCD in the atmospheric hyperspectral rapid imager Pixel merging number : 。 4. The rapid panoramic imaging method for trace gases in cities according to claim 1, characterized in that, The measured VCD value of trace gases is calculated based on the dSCD values ​​of each trace component, including: ， in, This is the dSCD value calculated for trace gases at a 15° elevation angle. The atmospheric mass factor, calculated at an elevation angle of 15°, is obtained from the following formula: ， in, It is the dSCD value calculated for O4 at an elevation angle of 15°.

5. The rapid panoramic imaging method for trace gases in urban areas according to claim 1, characterized in that, Calculate the volumetric concentration ratio corresponding to each observation elevation angle based on the dSCD values ​​of each trace component: ， in, and These refer to the observed elevation angle as The dSCD values ​​of trace gases and O4 were calculated at that time. It is Avogadro's constant. It is the gas constant. It refers to the percentage of oxygen in the air. For temperature, p This refers to air pressure.

6. The rapid panoramic imaging method for trace gases in cities according to claim 1, characterized in that, Based on the volume ratio concentration corresponding to each observation elevation angle, and combined with the non-uniform layer height and thickness, the volume ratio concentration distribution of trace gases on the non-uniform vertical grid is obtained, including: Each observation elevation angle corresponds to a volume ratio concentration, and each observation elevation angle also corresponds to a height, thus forming a mapping table of volume ratio concentration - observation elevation angle - height. Based on this mapping table, the volume ratio concentration corresponding to each height is obtained, that is, the volume ratio concentration distribution of trace gases on a non-uniform vertical grid is obtained.

7. The rapid panoramic imaging method for trace gases in cities according to claim 1, characterized in that, The light flux results at the center band of the hyperspectral fast imaging system are interpolated into a grid of the same resolution as the panoramic imaging results, including: In the optical flux grid results at the center band of the hyperspectral fast imaging system, those less than 1×10 5 The value is assigned to a blank value to create a building background mask. This mask is then applied to the panoramic imaging result of trace gas to obtain a panoramic imaging result with the building background removed.

8. The rapid panoramic imaging method for trace gases in cities according to claim 1, characterized in that, When the city contains significant emission sources, it also includes: The dSCD of the internal path of the smoke plume is obtained by subtracting the dSCD of the upwind direction at the same height from the observed dSCD of the smoke plume. The concentration inside the plume is calculated using dSCD based on the internal path of the plume, and then interpolated into the panoramic imaging results of trace gases.

9. The rapid panoramic imaging method for trace gases in cities according to claim 8, characterized in that, dSCD calculation of plume interior concentration based on plume interior paths includes: ， ， in, M Represents the relative mass of molecules. Indicates the height corresponding to the imaged pixel. i To observe the number of elevation angle sequences, j For frame number, Represents Avogadro's constant. The VCD value corresponding to the image pixel. The dSCD value corresponding to the imaged pixel. This refers to atmospheric quality factors.

10. The rapid panoramic imaging method for trace gases in urban areas according to claim 8, characterized in that, Interpolating the internal concentration of the plume into the panoramic imaging results of trace gases includes: The element containing the plume in the dSCD value of each trace component is set to null, a plume mask is created, the plume mask is multiplied with the panoramic imaging result to obtain a panoramic imaging result with null values ​​in the plume part, and then the internal concentration of the plume is backfilled into the panoramic imaging result with null values ​​in the plume part.

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