A system and method for dynamic multi-point calibration at different angles for a scanning camera

Abstract

The present invention provides a system and method for dynamic multi-point calibration of a scanning camera at different angles. The scanning camera is placed at the center of a two-dimensional turntable platform, and a surface source blackbody is placed at a specific angle position within the scanning field of view of the scanning camera. During dynamic rotation scanning, the scanning mirror of the scanning camera sequentially scans the surfaces of the high-temperature blackbody, the surface source blackbody, and the low-temperature blackbody on the satellite, thereby obtaining calibration radiation information of the blackbody on the satellite and the surface source blackbody. A calibration image is acquired by a calibration acquisition system, and the image data is processed to obtain the calibration coefficient at the angle position. The two-dimensional turntable drives the scanning camera to rotate as a whole, causing the relative position of the surface source blackbody and the scanning camera to change. During dynamic rotation, the scanning mirror scans the surface source blackbody at a new angle position, and the above calibration image acquisition and processing process is repeated to obtain the calibration coefficient at the new angle position. Polynomial fitting is performed on the calibration coefficients at multiple different angle positions to obtain the calibration coefficient fitting result at any angle position.

Description

Technical Field

[0001] The invention belongs to the technical field of aerospace optical remote sensing quantitative detection, and relates to a system and method for dynamic calibration of multiple points at different angles for a scanning camera. Background Art

[0002] High-precision absolute calibration technology is key to the quantitative acquisition of camera information and directly determines the level of quantitative camera application. For scanning cameras, due to differences in system transmittance at different scanning angles, traditional static calibration methods at fixed positions cannot meet the calibration accuracy requirements for different scanning fields of view. Dynamic calibration of scanning cameras at different angles can improve radiometric calibration accuracy, reduce quantitative inversion errors, and enhance the level of quantitative application.

[0003] Currently, the aerospace industry typically uses absolute radiometric calibration at a static, fixed angle for infrared camera systems. This method, typically based on national standards, rarely considers calibration errors introduced by varying angles. However, for scanning, wide-width, and highly quantitative ocean remote sensing and Earth observation cameras, this method cannot meet the absolute radiometric calibration accuracy requirements of better than 0.5K across different scanning fields of view in the mid- and long-wave infrared bands. Summary of the Invention

[0004] The technical problem solved by the present invention is to overcome the shortcomings of the existing technology and provide a system and method for dynamic multi-point calibration of a scanning camera at different angles. This method traverses multiple calibration positions and can obtain more effective calibration data. At the same time, it improves the calibration accuracy at different angles and positions, and the calibration accuracy is better than 0.5K.

[0005] The technical solution of the present invention is: a multi-point dynamic calibration system for scanning cameras at different angles, comprising: a scanning camera system, a two-dimensional turntable system, a calibration source system and a calibration acquisition and processing system;

[0006] The scanning camera system is installed at the center of the two-dimensional turntable system, and the two rotate on the same axis. When the scanning camera system scans the high-temperature blackbody on the satellite, the low-temperature blackbody on the satellite, and the calibration source system, the scanning camera system collects the corresponding radiation energy, converts the radiation energy into photoelectricity, and outputs the electrical signal of the image to the calibration acquisition system.

[0007] The 2D turntable system is installed on the vacuum tank truss inside the vacuum tank. The 2D turntable system is controlled to rotate horizontally through commands, thereby driving the scanning camera system installed on the 2D turntable system to rotate horizontally to the corresponding angle position;

[0008] The calibration source system includes a surface source blackbody and a vacuum tank. The surface source blackbody is mounted on a blackbody mounting base in the vacuum tank to ensure that the scanning camera system can scan the surface of the surface source blackbody during rotation. By setting the temperature of the surface source blackbody, the blackbody surface emits blackbody radiation energy at the set temperature.

[0009] The calibration acquisition and processing system receives the electrical signal of the image sent by the scanning camera system, converts it into dynamic calibration image data of different scanning angle positions and different blackbody temperature values, calculates the calibration coefficients at different angle positions based on the data, and then performs polynomial fitting on the calibration coefficients at different angle positions according to the angle to complete the multi-point dynamic calibration at different angles.

[0010] The scanning camera system includes a camera body and a video electronic device. The camera body rotates 360 degrees around the scanning mirror to scan. When scanning the high-temperature black body on the satellite, the low-temperature black body on the satellite, and the calibration source system, the camera body collects the corresponding radiation energy and converts the radiation energy into analog electrical signals through photoelectric conversion. The video electronic device amplifies, processes, and arranges the analog electrical signals and outputs the electrical signals of digital images.

[0011] The two-dimensional turntable system includes a two-dimensional turntable platform and a two-dimensional turntable controller; the two-dimensional turntable platform is installed on the vacuum tank truss inside the vacuum tank, and the two-dimensional turntable controller is placed outside the vacuum tank; the two-dimensional turntable platform is kept horizontal by adjusting the pitch direction of the two-dimensional turntable platform; the scanning camera system is installed on the two-dimensional turntable platform, and the installation position is adjusted so that the rotation axis of the scanning camera system is located on the rotation center axis of the two-dimensional turntable; the two-dimensional turntable controller sends instructions to control the two-dimensional turntable platform to rotate to any angle position in the horizontal direction, thereby driving the scanning camera body installed on the two-dimensional turntable platform to rotate to the corresponding angle position.

[0012] The calibration source system includes a surface source blackbody, a blackbody controller for setting the temperature of the surface source blackbody, a blackbody mounting base for mounting the surface source blackbody, and a vacuum tank for maintaining a vacuum environment; the surface source blackbody is mounted on the blackbody mounting base and placed in the vacuum tank; after the vacuum tank door is closed, vacuuming is started, and after reaching the required vacuum degree, the blackbody controller is turned on and set to the required temperature point to control the temperature of the surface source blackbody, thereby emitting blackbody radiation energy at a specific temperature in a vacuum environment.

[0013] The height of the surface source blackbody mounting base is consistent with the center height of the scanning mirror, ensuring that the scanning mirror can scan the surface of the surface source blackbody when rotating.

[0014] The orientation of the blackbody mounting seat is adjusted to ensure that when the scanning mirror scans the surface of the surface source blackbody, the optical axis direction of the scanning mirror is consistent with the normal direction of the surface source blackbody.

[0015] The distance between the surface source blackbody and the scanning mirror is adjusted to ensure that the effective aperture of the surface source blackbody completely covers the optical field of view of the scanning mirror.

[0016] A method for dynamic multi-point calibration of a scanning camera at different angles, comprising:

[0017] The two-dimensional turntable platform is adjusted to a preset angle, the surface source blackbody is set to a preset temperature, and the scanning mirror dynamically scans the surface of the surface source blackbody to obtain the radiation energy of the surface source blackbody at different temperatures, thereby obtaining dynamic calibration image data of different scanning angle positions and different blackbody temperature values; calibration coefficients of different scanning angle positions and different blackbody temperature values ​​are calculated based on the data, and polynomial fitting is performed according to the angle to obtain multi-point dynamic calibration coefficients of different angles.

[0018] The calibration coefficients for different scanning angles and blackbody temperatures are calculated based on the dynamic calibration image data at different scanning angles and blackbody temperatures. Polynomial fitting is performed according to the angles to obtain dynamic calibration coefficients for multiple points at different angles, including:

[0019] Calculate the radiance L corresponding to different blackbody temperatures T;

[0020] Calculate the DN value of the calibration image corresponding to the surface source blackbody at different blackbody temperatures T;

[0021] The least squares fitting of multiple sets of data DN=K is performed on the calibration image DN value and radiance L of the area source blackbody at different blackbody temperatures T. w *L+C w , the external calibration coefficient K at a certain scanning angle A is obtained by linear fitting w 、C w ;

[0022] The least squares fitting of multiple sets of data DN'=K is performed on the calibration images DN' and radiance L' corresponding to the high-temperature blackbody and low-temperature blackbody on the satellite. n *L`+C n , the internal calibration coefficient K at a certain scanning angle A is obtained by linear fitting n 、C n ;

[0023] Establish a correlation between the high-temperature blackbody on the star, the low-temperature blackbody on the star and the surface source blackbody, and obtain the correlation relationship of the external calibration coefficient The correlation relationship between the internal calibration coefficient and R2=(C n -C w ) / K w ;

[0024] A cubic polynomial fitting is performed on the relationship between R1, R2 and the scanning angle θ, and the calibration coefficients R1(θ) and E2(θ) at any angle position θ are calculated.

[0025] The Planck blackbody formula is used to calculate the radiance L corresponding to different blackbody temperatures T, as follows:

[0026]

[0027] Where:

[0028] μ——blackbody emissivity;

[0029] L——spectral radiance;

[0030] T——absolute temperature;

[0031] λ——wavelength;

[0032] Constant c1=3.7415×10 8 ;

[0033] Constant c2=1.43879×10 4 .

[0034] The calculation results in the calibration coefficients R1(θ) and R2(θ) at any angle position θ as follows:

[0035] R1(θ)=a3θ 3 +a2θ 2 +a1θ+a0

[0036] R2(θ)=b3θ 3 +b2θ 2 +b1θ+b0

[0037] Where:

[0038] θ is the scanning angle; a2, a1, a0, b3, b2, b1, and b0 are fitting coefficients respectively.

[0039] The advantages of the present invention compared with the prior art are:

[0040] The present invention's method for dynamic multi-point calibration at different angles employs internal calibration using high-temperature and low-temperature blackbodies onboard a satellite, dynamic multi-point calibration at different angles using high-precision surface-source blackbodies on the ground, and image data processing for multi-point dynamic calibration. Compared to conventional single-point static calibration methods at specific locations, this method adds dynamic calibration of the scanning dimension, significantly increasing the amount of calibration data. Through real-time processing of calibration image data, external calibration coefficients at different angles are calculated and correlated with internal calibration coefficients of high- and low-temperature blackbodies onboard the satellite to obtain calibration coefficients at different angles. Finally, through multi-term fitting, calibration coefficients are obtained for all angles. This method significantly improves the calibration accuracy of scanning cameras, achieving a calibration accuracy of 0.5K for all positions within the scanning range. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a diagram of the composition of the multi-point dynamic calibration system at different angles.

[0042] Figure 2 Calibrate the blackbody position on the main star of the scanning camera.

[0043] Figure 3 This is a calibration diagram of the multi-point dynamic calibration system at different angles. DETAILED DESCRIPTION

[0044] The embodiments of the present invention are described in detail below with reference to the accompanying drawings:

[0045] The present invention relates to a calibration system, comprising: a scanning camera system, a two-dimensional turntable system, a calibration source system and a calibration acquisition and processing system.

[0046] The composition of the multi-point dynamic calibration system at different angles is detailed in the attached Figure 1 and attached Figure 2 As shown:

[0047] The scanning camera system includes a camera body 25 and video electronics 26. The camera body 25 primarily performs the functions of light splitting and focusing the light onto the focal plane, while the video electronics 26 controls the camera's imaging timing and logic, amplifying, processing, and arranging analog electrical signals to output the electrical signals for the image. The camera body 25 is mounted at the center of a two-dimensional turntable platform 31, with the two sharing a common rotation axis. The scanning mirror 22 can rotate and scan at a constant speed throughout a full 360°. As the scanning mirror 22 scans over the onboard high-temperature blackbody 10, onboard low-temperature blackbody 11, and surface-source blackbody 21, the scanning camera system collects the corresponding blackbody's radiation energy, converts it into photoelectric energy, and outputs a digital image signal. The scanning camera system's scanning mirror has an entrance pupil diameter of 96mm and an optical field of view of 3°. It rotates uniformly throughout a full 360°, calibrating the spectral ranges B16 (3.645μm to 3.835μm), B17 (10.3μm to 11.3μm), and B18 (11.5μm to 12.5μm). The onboard high-temperature blackbody is positioned at -90° and 90°, resulting in a scanning field of view of -57.5° to 57.5°. The scanning mirror rotates once every 5.2 seconds.

[0048] The two-dimensional turntable system includes a two-dimensional turntable platform 31 and a two-dimensional turntable controller 32. The two-dimensional turntable platform 31 is installed on the vacuum tank truss 27 in the vacuum tank, and its position can be adjusted through the vacuum tank guide rail 30. The two-dimensional turntable platform 31 is mainly used for the installation of the main body of the scanning camera, and the two rotate together with the central axis. The two-dimensional turntable controller 32 is placed outside the vacuum tank, and by sending an angle position instruction, it controls the two-dimensional turntable platform 31 to rotate to a specific angle position in the horizontal direction, thereby driving the camera body 25 installed on the two-dimensional turntable platform to rotate to the corresponding angle position. The settable angle range of the two-dimensional turntable platform 31 is -60° to 60°, which can cover a scanning field angle of -57.5° to 57.5°.

[0049] The calibration source system includes a surface source blackbody 21, a blackbody mounting base 24, a blackbody controller 33 and a vacuum tank 29. The surface source blackbody 21 is mounted on the blackbody mounting base 24, which is mounted on the vacuum tank truss 27. The height of the blackbody mounting base 24 is adjusted so that the height of the surface source blackbody 21 is consistent with the center height of the scanning mirror 22, thereby ensuring that the scanning mirror 22 can scan the surface of the surface source blackbody 21 during rotation. When the light inlet of the scanning mirror points to the center of the blackbody radiation surface, the angle between the normal of the blackbody radiation surface and the optical axis of the scanning mirror is ≤1°, and the distance between the blackbody radiation surface and the scanning mirror is ≤500mm, thereby ensuring that the effective size of the surface source blackbody 21 can completely cover the optical field of view 23 of the scanning mirror. The surface source blackbody can emit radiation energy corresponding to a specific temperature, and its effective size is The normal emissivity μ is 0.99, the temperature is adjustable from 110K to 400K, and the temperature instability is better than ±0.1K / h. The blackbody controller 33 is used to set the temperature of the surface source blackbody 21. The blackbody controller 33 is placed outside the vacuum tank and connected to the surface source blackbody 21 via a through-tank cable to set the blackbody temperature. The vacuum tank truss 27 and vacuum tank guide rails 30 are installed at the bottom of the vacuum tank 29, providing an interface for installing and operating equipment within the vacuum tank.

[0050] The calibration acquisition system primarily consists of an image acquisition workstation and image acquisition software. The image acquisition workstation 28 receives electronic image signals from the video electronics 26 via a card and converts them into dynamic calibration image data for different scanning angles and blackbody temperatures. Based on this data, calibration coefficients are calculated for each angular position. These coefficients are then fitted with angle-based polynomials to achieve dynamic multi-point calibration at different angles. The image acquisition output bit count is 14 bits, and the data transmission clock is 50 MHz ± 400 Hz with a duty cycle of 45% to 55%, with a continuous clock. A total of 3527 lines of image data are transmitted during a single scan cycle, at a data rate of 4.05316 Mbps.

[0051] The present invention also relates to a method for dynamic calibration of multiple points at different angles, as shown in the attached figure. Figure 3 As shown: The multi-point dynamic calibration process is carried out by rotating the scanning mirror of the scanning camera system. The scanning mirror dynamically scans the positions of the high-temperature black body on the satellite, the surface source black body, and the low-temperature black body on the satellite in turn, and obtains the radiation energy of the black body on the satellite and the surface source black body at different temperatures. Among them, the positions of the high-temperature black body on the satellite and the low-temperature black body on the satellite are fixed, and the position of the surface source black body within the scanning field angle range of the scanning mirror can be adjusted arbitrarily. This is achieved by rotating the two-dimensional turntable platform in the horizontal direction, driving the scanning camera body installed on the two-dimensional turntable platform to rotate horizontally to the corresponding angle position, realizing the change of the surface source black body within the scanning field angle range of the scanning mirror, thereby obtaining dynamic scanning calibration image data of the scanning mirror at different scanning angle positions and different black body temperature values. The specific steps are as follows:

[0052] 1) The two-dimensional turntable rotates to the set angle position;

[0053] 2) The blackbody controller sets the temperature of the surface source blackbody;

[0054] 3) The scanning camera system sets the scanning mirror to dynamically rotate and scan;

[0055] 4) The calibration acquisition system acquires calibration image data of a set angle position and a set blackbody temperature;

[0056] 5) The blackbody controller sets a new blackbody temperature and repeats steps 2) to 4);

[0057] 6) The two-dimensional turntable rotates to the newly set angle position and repeats steps 1) to 5).

[0058] First, according to step 1), set the two-dimensional turntable to rotate to the initial angle of -50°, according to step 2), set the temperature of the surface source blackbody to the initial temperature of 220K, and according to steps 2) to 4), perform the -50° position to complete the calibration image data acquisition of the surface source blackbody 220K. According to step 5), repeat steps 2) to 4), and set the temperature points of the surface source blackbody to 220K, 230K, 243K, 256K, 268K, 279K, 285K, 293K, 300K, 308K, 317K, 323K, 330K, 340K, 350K, and 360K in sequence to complete the calibration image data acquisition of all temperature points. According to step 6), start the calibration data acquisition at the next angle position -40°. All the two-dimensional turntable angles implemented are shown in Table 1:

[0059] Table 1 Angular position of the two-dimensional turntable

[0060] Serial number 2D turntable angle 1 -50° 2 -40° 3 -20° 4 0° 5 20° 6 40°

[0061] Since the two-dimensional turntable selects the above-mentioned six angular positions during the multi-point dynamic calibration process, compared with the traditional single-point static calibration method at a specific angular position, the number of calibration positions in the scanning dimension is increased, more positions are traversed, and more effective calibration data can be obtained, which naturally has the advantage of improving the calibration accuracy at different angular positions.

[0062] The calculation of the multi-point dynamic calibration coefficients is to process the dynamic calibration image data at different angles, calculate the calibration coefficients at different angles, and then perform polynomial fitting on the calibration coefficients at different angles to complete the multi-point dynamic calibration at different angles. The following takes the B18 (11.5um to 12.5um) band as an example to calculate the calibration coefficients. The specific calculation process is as follows:

[0063] 1) Calculate the radiance L corresponding to different blackbody temperatures T using the Planck blackbody formula as follows:

[0064]

[0065] Where:

[0066] μ——blackbody emissivity;

[0067] L——spectral radiance (W / m 2 .Sr.μm);

[0068] T——absolute temperature (K);

[0069] λ——wavelength (μm);

[0070] c1=3.7415×10 8 Wm －2 .μm 4 ;

[0071] c²=1.43879×10 4 μm.K.

[0072] In the above formula, the blackbody emissivity μ is taken as 0.99, the wavelength range is taken as the B18 band 11.5um~12.5um, and the temperature point is taken as 220K~360K. The spectral radiance L of the surface source blackbody at different temperatures can be calculated. The calculation results are shown in Table 2:

[0073] Table 2 Spectral radiance of surface source blackbody at different temperatures

[0074]

[0075] 2) Calculate the DN value of the calibration image corresponding to different blackbody temperatures T. From the calibration image, the average DN value of all pixels within the image region corresponding to the center of the blackbody at a certain temperature is selected as the image DN value at that temperature. In this embodiment, the scanning mirror scans the surfaces of the high-temperature blackbody, the low-temperature blackbody, and the surface source blackbody, and the average DN value of all pixels in the image region corresponding to the center of the blackbody is used for the calculation. Since the detector has 80 pixels, the image DN value of 80 pixels is used as the calculated DN value.

[0076] 3) Perform the least squares fitting of multiple sets of data on the calibration image DN value and radiance L corresponding to the surface source blackbody, and calculate the external calibration coefficient at the angle position. Where DN = K w *L+C w , the external calibration coefficient K at this angle is obtained by linear fitting w 、C w .

[0077] 4) Perform the least squares fitting of multiple sets of data on the calibration image DN' value and radiance L' corresponding to the high-temperature blackbody and low-temperature blackbody on the satellite, and calculate the internal calibration coefficient at the angle position. Where DN' = K n *L`+C n , the internal calibration coefficient K at this angle is obtained by linear fitting n 、C n .

[0078] 5) Due to the differences between the camera's on-board high-temperature blackbody, on-board low-temperature blackbody, and external surface-source blackbody, the radiance at the on-board high-temperature blackbody and on-board low-temperature blackbody cannot be directly equated with the radiance of the entrance pupil spectrum at the camera's scanning mirror position. Therefore, it is necessary to establish an internal and external correlation relationship between the on-board high-temperature blackbody, on-board low-temperature blackbody, and the external surface-source blackbody. The internal and external correlation relationship can be used to calculate the camera entrance pupil spectrum radiance corresponding to the internal calibration blackbody temperature. The internal and external correlation relationship reflects the calibration coefficient of the infrared band. When the DN value of the internal calibration image is the same as the DN value of the external calibration image, the following conversion relationship can be established according to the formula:

[0079] K w L w +C w =K n L n +C n

[0080] make R2=(C n -C w ) / K w , we can get:

[0081] L w =R1L n +R2

[0082] In the above formula: R1 and R2 are the internal and external correlation calibration coefficients of infrared calibration.

[0083] According to the K at different turntable angle positions calculated in step 3) and step 4) n 、C n and K w 、C w , substitute into the above R1 and R2 formulas to calculate the calibration coefficients, as shown in Table 3:

[0084] Table 3B18 band calibration coefficient changes with turntable angle

[0085] Angle (°) <![CDATA[K w ]]> <![CDATA[C w ]]> <![CDATA[K n ]]> <![CDATA[C n ]]> <![CDATA[R1]]> <![CDATA[R2]]> -50 184.249 10416.289 129.451 10806.690 0.7026 2.1189 -40 204.994 10236.157 129.458 10787.053 0.6315 2.6874 -20 233.0671 10026.2 129.5435 10773.87 0.5558 3.2079 0 265.417 9775.988 129.635 10759.047 0.4884 3.7038 20 267.706 9759.491 129.560 10757.482 0.4840 3.7279 40 235.674 9990.169 129.569 10756.073 0.5498 3.2498

[0086] 6) Perform a cubic polynomial fit on the relationship between the calibration coefficients R1, R2 and the scanning angle θ to calculate the calibration coefficients R1(θ) and R2(θ) at any angle position θ. The fitting formula is as follows:

[0087] R1(θ)=a3θ 3 +a2θ 2 +a1θ+a0

[0088] R2(θ)=b3θ 3 +b2θ 2 +b1θ+b0

[0089] Where:

[0090] θ is the scanning angle;

[0091] a3, a2, a1, a0, b3, b2, b1, and b0 are the fitting coefficients respectively.

[0092] A cubic polynomial fitting is performed based on the values ​​of the calibration correlation coefficients R1 and R2 of the B18 band at different angular positions, as shown in Table 4:

[0093] Table 4. Fitting results of cubic polynomials for calibration coefficients at different angles in the B18 band

[0094] coefficient Fitted values Fitting coefficients Fitted values <![CDATA[a3]]> 0.00000033 <![CDATA[b3]]> -0.00000200 <![CDATA[a2]]> 0.00006563 <![CDATA[b2]]> -0.00047739 <![CDATA[a1]]> -0.00169037 <![CDATA[b1]]> 0.01154635 <![CDATA[a0]]> 0.49041030 <![CDATA[b0]]> 3.68765208

[0095] The calibration coefficient is obtained according to the fitting, and the calibration coefficient fitting formula is obtained by substituting it into the fitting formula:

[0096] R1(θ)=0.00000033θ 3 +0.00006563θ 2 -0.00169037θ+0.49041030

[0097] R2(θ)=-0.00000200θ 3 -0.00047739θ 2 +0.01154635θ+3.68765208

[0098] During this implementation, external calibration coefficients at different angular positions were calculated and correlated with internal calibration coefficients for the onboard high-temperature and low-temperature blackbodies. Calibration coefficients for different angular positions were then derived. Finally, a multinomial fitting method was used to obtain calibration coefficients for all angular ranges. This method significantly improved the calibration accuracy of the scanning camera, achieving a calibration accuracy of 0.5K at all positions within the scanning range.

[0099] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solutions of the present invention using the technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the scope of protection of the technical solutions of the present invention.

Claims

1. A multi-point dynamic calibration system for scanning cameras at different angles, characterized in that: include: Scanning camera system, 2D turntable system, calibration source system and calibration acquisition and processing system; The scanning camera system is installed at the center of the two-dimensional turntable system, and the two rotate on the same axis. When the scanning camera system scans the high-temperature blackbody on the satellite, the low-temperature blackbody on the satellite, and the calibration source system, the scanning camera system collects the corresponding radiation energy, converts the radiation energy into photoelectricity, and outputs the electrical signal of the image to the calibration acquisition system. The 2D turntable system is installed on the vacuum tank truss inside the vacuum tank. The 2D turntable system is controlled to rotate horizontally through commands, thereby driving the scanning camera system installed on the 2D turntable system to rotate horizontally to the corresponding angle position; The calibration source system includes a surface source blackbody and a vacuum tank. The surface source blackbody is installed on a blackbody mounting base in the vacuum tank to ensure that the scanning camera system can scan the surface of the surface source blackbody during rotation. By setting the temperature of the surface source blackbody, the blackbody surface emits blackbody radiation energy at the set temperature; The calibration acquisition and processing system receives the electrical signal of the image sent by the scanning camera system, converts it into dynamic calibration image data of different scanning angle positions and different blackbody temperature values, calculates the calibration coefficients at different angle positions based on the data, and then performs polynomial fitting on the calibration coefficients at different angle positions according to the angle to complete the multi-point dynamic calibration at different angles.

2. The multi-point dynamic calibration system for scanning cameras at different angles according to claim 1, characterized in that: The scanning camera system includes a camera body and a video electronic device. The camera body rotates 360 degrees around the scanning mirror to scan. When scanning the high-temperature black body on the satellite, the low-temperature black body on the satellite, and the calibration source system, the camera body collects the corresponding radiation energy and converts the radiation energy into analog electrical signals through photoelectric conversion. The video electronic device amplifies, processes, and arranges the analog electrical signals and outputs the electrical signals of digital images.

3. The multi-point dynamic calibration system for scanning cameras at different angles according to claim 2, characterized in that: The two-dimensional turntable system includes a two-dimensional turntable platform and a two-dimensional turntable controller; the two-dimensional turntable platform is installed on the vacuum tank truss inside the vacuum tank, and the two-dimensional turntable controller is placed outside the vacuum tank; the two-dimensional turntable platform is kept horizontal by adjusting the pitch direction of the two-dimensional turntable platform; the scanning camera system is installed on the two-dimensional turntable platform, and the installation position is adjusted so that the rotation axis of the scanning camera system is located on the rotation center axis of the two-dimensional turntable; the two-dimensional turntable controller sends instructions to control the two-dimensional turntable platform to rotate to any angle position in the horizontal direction, thereby driving the scanning camera body installed on the two-dimensional turntable platform to rotate to the corresponding angle position.

4. The multi-point dynamic calibration system for scanning cameras at different angles according to claim 3, characterized in that: The calibration source system includes a surface source blackbody, a blackbody controller for setting the temperature of the surface source blackbody, a blackbody mounting base for mounting the surface source blackbody, and a vacuum tank for maintaining a vacuum environment; the surface source blackbody is mounted on the blackbody mounting base and placed in the vacuum tank; after the vacuum tank door is closed, vacuuming is started, and after reaching the required vacuum degree, the blackbody controller is turned on and set to the required temperature point to control the temperature of the surface source blackbody, thereby emitting blackbody radiation energy at a specific temperature in a vacuum environment.

5. The multi-point dynamic calibration system for scanning cameras at different angles according to claim 4, characterized in that: The height of the surface source blackbody mounting base is consistent with the center height of the scanning mirror, ensuring that the scanning mirror can scan the surface of the surface source blackbody when rotating.

6. The multi-point dynamic calibration system for scanning cameras at different angles according to claim 4, characterized in that: The orientation of the blackbody mounting seat is adjusted to ensure that when the scanning mirror scans the surface of the surface source blackbody, the optical axis direction of the scanning mirror is consistent with the normal direction of the surface source blackbody.

7. The multi-point dynamic calibration system for scanning cameras at different angles according to claim 4, characterized in that: The distance between the surface source blackbody and the scanning mirror is adjusted to ensure that the effective aperture of the surface source blackbody completely covers the optical field of view of the scanning mirror.

8. A method for dynamic multi-point calibration of a scanning camera at different angles using any one of the systems of claims 1 to 7, characterized in that: include: Adjusting the two-dimensional turntable platform to a preset angle, setting the surface source blackbody to a preset temperature, and dynamically scanning the surface of the surface source blackbody with a scanning mirror to obtain the radiation energy of the surface source blackbody at different temperatures, thereby obtaining dynamic calibration image data at different scanning angles and different blackbody temperature values; The calibration coefficients for different scanning angles and blackbody temperature values ​​are calculated based on the data, and polynomial fitting is performed according to the angle to obtain dynamic calibration coefficients for multiple points at different angles.

9. The method according to claim 8, characterized in that The calibration coefficients for different scanning angles and different blackbody temperature values ​​are calculated, and polynomial fitting is performed according to the angle to obtain dynamic calibration coefficients for multiple points at different angles, including: Calculate the radiance L corresponding to different blackbody temperatures T; Calculate the DN value of the calibration image corresponding to the surface source blackbody at different blackbody temperatures T; The least squares fitting of multiple sets of data DN=K is performed on the calibration image DN value and radiance L of the area source blackbody at different blackbody temperatures T. w *L+C w , the external calibration coefficient K at a certain scanning angle A is obtained by linear fitting w 、C w ; The least squares fitting of multiple sets of data DN'=K is performed on the calibration image DN' value and radiance L' corresponding to the high-temperature blackbody and the low-temperature blackbody on the star. n *L`+C n , the internal calibration coefficient K at a certain scanning angle A is obtained by linear fitting n 、C n ; Establish a correlation between the high-temperature blackbody on the star, the low-temperature blackbody on the star and the surface source blackbody, and obtain the correlation relationship of the external calibration coefficient The correlation relationship between the internal calibration coefficient and R2=(C n -C w ) / K w ; A cubic polynomial fitting is performed on the relationship between R1, R2 and the scanning angle θ, and the calibration coefficients R1(θ) and R2(θ) at any angle position θ are calculated.

10. The method according to claim 9, characterized in that Calculate the radiance L as follows: Where: μ——blackbody emissivity; L——spectral radiance; T——absolute temperature; λ——wavelength; Constant c1=3.7415×10 8 ; Constant c2=1.43879×10 4 .

11. The method according to claim 9, characterized in that The calculation results in the calibration coefficients R1(θ) and R2(θ) at any angle position θ as follows: R1(θ)=a3θ 3 +a2θ 2 +a1θ+a0 R2(θ)=b3θ 3 +b2θ 2 +b1θ+b0 Where: θ is the scanning angle; a2, a1, a0, b3, b2, b1, and b0 are fitting coefficients respectively.

Images