High-frame-frequency light deflection effect distortion image correction method

Abstract

The invention discloses a high-frame-frequency light deflection effect distortion image correction method. The method comprises the following steps: establishing an ideal initial light wave surface model; establishing a light deflection transmission model; establishing a light deflection model after the light is transmitted through the standard ambient atmosphere; establishing a light deflection model after the light is transmitted through the atmospheric wind field; establishing a light deflection model after the light is transmitted through the flow field outside the motion platform body; taking the ideal initial light wave surface as incident light to obtain a whole-process wave surface distortion model and a whole-process light deflection model; subtracting the ideal initial wavefront model from the whole-process wavefront distortion model to obtain a whole-process wavefront distortion model; subtracting the initial propagation direction of the light wave from the whole-process light deflection model to obtain a whole-process light deflection variation model; obtaining a high-frame-frequency image; and removing negative influence from the high-frame-frequency image by using the whole-process wavefront distortion model and the whole-process light deflection variation model to obtain a corrected high-frame-frequency image.

Description

Technical Field

[0001] The invention relates to a high frame rate light deflection effect distortion image correction method, which can be used for improving the image quality of a high-speed optical imaging device located inside a moving platform and belongs to the technical field of image correction. Background Art

[0002] The high frame rate optical imaging device is located inside the motion platform and monitors other moving targets through the optical window. When the motion platform flies at high speed in the atmosphere, the complex flow field around its head will change at high frequency. The complex flow field with high frequency changes will cause the target image to shift, jitter, and blur due to the light deflection effect. The light deflection effect will affect the imaging effect of the high frame rate optical imaging device.

[0003] The existing methods for correcting images distorted by the light deflection effect mainly correct the image quality, but fail to include the light transmission process in the complex flow field area into the image correction, resulting in poor image correction effect. The present invention models the light deflection effect based on the relationship between the optical refractive index and the flight parameters, and uses the ray tracing method to calculate the wavefront distortion and Stirr ratio caused by the aerodynamic flow field, and then analyzes the image distortion caused by the light deflection effect on the image of the high frame rate optical imaging device, thereby performing image correction. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and propose a high frame rate light deflection effect distortion image correction method to solve the problem that the existing light deflection effect distortion image correction method does not incorporate the transmission process of light in a complex flow field area into the image correction, resulting in poor image correction effect.

[0005] The present invention starts from the relationship between the optical refractive index and the flight parameters, models the light deflection effect, uses the ray tracing method to calculate the wavefront distortion caused by the aerodynamic flow field, and then analyzes the image distortion caused by the light deflection effect of the image of the high frame rate optical imaging device, thereby performing image correction. The problem of poor image correction effect of the traditional light deflection effect distortion image correction method can be solved.

[0006] The technical solution of the present invention is: a method for correcting image distortion caused by light deflection effect at a high frame rate, comprising:

[0007] Establish an ideal initial light wavefront model; use the ideal initial light wavefront model as incident light to establish a light deflection transmission model;

[0008] Establish an environmental standard atmosphere transmission model, obtain the standard atmosphere refractive index distribution, substitute the standard atmosphere refractive index distribution into the light deflection transmission model, and obtain the wavefront distortion model and light deflection model after the light passes through the standard environmental atmosphere;

[0009] An atmospheric wind field model is established to obtain the atmospheric wind field refractive index distribution, and the atmospheric wind field refractive index distribution is substituted into the light deflection transmission model to obtain the wavefront distortion model and light deflection model after the light passes through the atmospheric wind field;

[0010] Establishing an in vitro flow field model of a moving platform, obtaining the refractive index distribution of the in vitro flow field of the moving platform, substituting the refractive index distribution of the in vitro flow field of the moving platform into the light deflection transmission model, obtaining a wavefront distortion model and a light deflection model after light passes through the in vitro flow field of the moving platform;

[0011] The whole-process wavefront distortion model and the whole-process light deflection model are obtained after the coupled light is transmitted through the standard environment atmosphere, the wavefront distortion model and the light deflection model after the light is transmitted through the atmospheric wind field, and the wavefront distortion model and the light deflection model after the light is transmitted through the flow field in vitro of the moving platform in sequence; the ideal initial light wavefront model is subtracted from the whole-process wavefront distortion model to obtain the whole-process wavefront distortion quantity model; the initial propagation parameters of the light wave are subtracted from the whole-process light deflection model to obtain the whole-process light deflection variation quantity model;

[0012] The high-speed imaging device located in the moving platform images the ground through the moving platform light window to obtain high frame rate images. The full-process wavefront distortion model and the full-process light deflection change model are used to remove the influence of the standard ambient atmosphere, atmospheric wind field, and moving platform flow field in the light transmission path from the high frame rate images to obtain corrected high frame rate images.

[0013] The step of establishing an ideal initial light wavefront comprises:

[0014] The light waves emitted by an ideal point light source are spherical light waves, and the equiphase surface is a concentric sphere centered on the point light source that gradually expands with the increase of distance; then

[0015] The wave function of a spherical wave is:

[0016]

[0017] Among them, v is the phase propagation velocity of the spherical wave along the radial direction of the sphere in the medium; r is the distance from the spherical wave to the central point light source, expressed in polar coordinates; t is the propagation time of the spherical wave in the medium; B is the amplitude function of the spherical wave, which describes the change of amplitude with time and distance;

[0018] When the wave function is in the form of sine or cosine, the ideal initial light wave surface model is:

[0019]

[0020] A 1 is the amplitude at r = 1; k is the wave number; is the initial phase;

[0021] Convert E(r,t) to E(x,y,z,t) by performing polar and Cartesian coordinate conversion.

[0022] The method of establishing a light deflection transmission model using an ideal initial light wavefront model as incident light includes:

[0023] The combination of the ambient standard atmospheric flow field, the atmospheric wind field, and the motion platform flow field is regarded as a flow field with a velocity of V com , refractive index n com (x, y, z, t); the incident light E(r, t) is at a refractive index of n 0 (x, y, z, t) undisturbed flow field propagation, through the flow velocity V com , refractive index n com (x, y, z, t) flow field, due to the various gas movements in the flow field deflecting the light, when leaving the flow field, the distorted wavefront model E′(x, y, z, t) is:

[0024] E′(x,y,z,t)=exp[imOPL]

[0025]

[0026] Where L is the flow field thickness, i represents an imaginary number, m = 2π / λ is the wave number, λ represents the wavelength of the spherical wave; OPL is the optical length of the light path through the flow field, n com (x, y, z, t) is the refractive index of the spherical wave in the medium, ρ is the medium density, K G-D is the Glaston-Dyer constant data; (x, y, z) represents the location of the spherical wave propagation, and t represents the spherical wave propagation time;

[0027] Then the light deflection transmission model is:

[0028]

[0029] ε x is the deflection angle of the light in the x direction, ε y is the deflection angle of the light in the y direction.

[0030] The method of establishing an environmental standard atmosphere transmission model to obtain a standard atmosphere refractive index distribution and using a light deflection transmission model to obtain a light deflection model after light is transmitted through the standard environmental atmosphere includes:

[0031] The environmental standard atmospheric transmission model is established as:

[0032] Troposphere 0 <h<11km:

[0033] T atom_h (h) = T0 -αh

[0034]

[0035] Stratosphere 11 <h<20km:

[0036] T atom_h =216.65K

[0037]

[0038] Among them, T atom_h 、p atom_h They represent the temperature and pressure of the standard atmosphere respectively; h is the height from sea level, T 0 is the ground temperature, p 0 is the ground pressure, α is the annual average temperature lapse rate of 6.5℃ / km, R=287J / (kg·K) is the gas constant, and g is the gravitational acceleration;

[0039] Then the density change of the standard atmosphere is:

[0040]

[0041] ρ 0 The air density at 0°C and 0.1013MPa is ρ 0 =1.293kg / m 3 ;

[0042] Indicates the relative humidity of the air; p atom_b represents the partial pressure of water vapor in saturated air at temperature T; then the standard atmospheric refractive index distribution is:

[0043] n′ atom_h (h,t)=1+K G-D ρ′ atom_h (h,t)

[0044] Substituting the standard atmospheric refractive index distribution into the distorted wavefront model E′(x, y, z, t), the wavefront distortion caused by the ambient standard atmospheric transmission is obtained as:

[0045]

[0046] Among them, L atom It represents the path length of light propagation in the standard ambient atmosphere;

[0047] Substituting the standard atmospheric refractive index distribution into the light deflection transmission model, the light deflection model after the light passes through the standard ambient atmosphere is obtained:

[0048]

[0049]

[0050] ε atom_x Represents the light deflection model in the x direction after the light passes through the standard ambient atmosphere; ε atom_y Represents the light deflection model in the y direction after light is transmitted through the standard ambient atmosphere.

[0051] The atmospheric wind field model is established to obtain the atmospheric wind field refractive index distribution, and the light deflection transmission model is used to obtain the light deflection model after the light passes through the atmospheric wind field, including:

[0052] The atmospheric wind field model includes a standard atmospheric wind field model and an atmospheric turbulent flow field model;

[0053] A standard atmospheric wind field model is established to obtain the refractive index distribution of the standard atmospheric wind field. The specific process is as follows:

[0054] Standard atmospheric pressure is the sum of dynamic pressure and static pressure. v is the pressure caused by the movement of the atmospheric wind field, static pressure p h is the standard atmospheric pressure; standard atmospheric wind field model P wind (x,y,h,t) is:

[0055] P wind (x,y,h,t)=p v +p h (x,y,h,t)

[0056] The dynamic pressure p v =0.5ρV 2 , V is the atmospheric velocity in the wind field; ρ represents the standard atmospheric density;

[0057] The atmospheric density formed by the standard atmospheric wind field is:

[0058]

[0059] The standard atmospheric wind field refractive index distribution is:

[0060] n wind (x,y,h,t)=1+K G-D ρ wind (x,y,h,t)

[0061] An atmospheric turbulent flow field model is established to obtain the atmospheric turbulent refractive index distribution. The specific process is as follows:

[0062] The atmospheric turbulence flow field model is:

[0063]

[0064] where Γ is the gamma function, 0 < p < 2, κ is the turbulence wave number, is the refractive index structure constant;

[0065] The refractive index distribution of atmospheric turbulence is:

[0066]

[0067] where represents the refractive index structure constant;

[0068]

[0069] represents the root mean square wind speed of the vertical path, V g is the near-surface wind speed;

[0070] Substituting the refractive index distribution of the standard atmospheric wind field and the refractive index distribution of atmospheric turbulence into the wavefront model E′(x, y, z, t) that generates distortion, the wavefront distortion caused by the transmission of the atmospheric wind field is:

[0071]

[0072] L wind represents the propagation path length of light in the atmospheric wind field; L turb represents the propagation path length of light in atmospheric turbulence;

[0073] Substituting the refractive index distribution of the standard atmospheric wind field and the refractive index distribution of atmospheric turbulence into the light deflection transmission model, the light deflection model after the light passes through the atmospheric wind field transmission is:

[0074]

[0075] ε win_x represents the light deflection model in the x direction after the light passes through the atmospheric wind field transmission, ε win_y represents the light deflection model in the y direction after the light passes through the atmospheric wind field transmission.

[0076] The establishment of the external flow field model of the moving platform, obtaining the refractive index distribution of the external flow field of the moving platform, and using the light deflection transmission model to obtain the light deflection result after the light passes through the external flow field of the moving platform, including:

[0077] Establish a three-dimensional model of the high-speed moving platform and establish a flow field analysis grid around the platform; establish an external flow field model of the moving platform, and obtain the density ρ(x, y, z) of each grid in the external flow field of the moving platform according to the flight speed, flight altitude, and flight attitude of the moving platform;

[0078] Using the Gladstone-Dale formula, calculate the refractive index of each point in the grid:

[0079] n(x,y,z)=K G-D ρ(x,y,z)+1

[0080] Taking any point o in space as the center, calculate the refractive index n of point o through the 8 adjacent grid points o_obj (x, y, z); then the refractive index distribution of the flow field outside the moving platform is:

[0081]

[0082] Among them, n i is the refractive index of the space point adjacent to point o, i is the x-coordinate of the space point, and j is the y-coordinate of the space point;

[0083] is a spatial point (x j ,y j ,z j ) and the distance between point o(x,y,z);

[0084] Substituting the refractive index distribution of the flow field outside the moving platform into the wavefront model that produces distortion is E′(x, y, z, t), the wavefront distortion caused by the light transmission of the flow field outside the moving platform is obtained as:

[0085]

[0086] L obj It represents the propagation path length of light in the flow field outside the moving platform;

[0087] Substituting the refractive index distribution of the motion platform's in vitro flow field into the light deflection transmission model, the light deflection model after the light passes through the motion platform's in vitro flow field is obtained as follows:

[0088]

[0089] In the formula, ε obj_x represents the light deflection model in the x direction after the light passes through the flow field outside the moving platform, ε obj_y Represents the light deflection model in the y direction after the light passes through the flow field outside the moving platform.

[0090] Taking the ideal initial light wavefront as the incident light, the wavefront distortion model and the light deflection model after the light passes through the standard environment atmosphere, the wavefront distortion model and the light deflection model after the light passes through the atmospheric wind field, and the wavefront distortion model and the light deflection model after the light passes through the flow field in vitro of the moving platform are obtained in sequence, and the whole process wavefront distortion model and the whole process light deflection model are obtained; the ideal initial light wavefront model is subtracted from the whole process wavefront distortion model to obtain the whole process wavefront distortion quantity model; the initial propagation direction of the light wave is subtracted from the whole process light deflection model to obtain the whole process light deflection variation quantity model; including:

[0091] The whole process wavefront distortion model is:

[0092] E′(x,y,z,t)=E atom ′(h,t)+E win ′(x,y,h,t)+E obj ′(x,y,z,t)

[0093] The whole process wavefront distortion model is:

[0094] ΔE(x,y,z,t)=E′(x,y,z,t)-E(x,y,z,t)

[0095] The whole process light deflection model is:

[0096] ε x =ε atom_x +ε win_x +ε obj_x

[0097] ε y =ε atom_y +ε win_y +ε obj_y

[0098] The initial propagation parameters of the light wave are: ε x_0 , ε y_0 ;

[0099] After the whole process of light deflection, the whole process light deflection change model is:

[0100] Δε x =ε x -ε x_0 , Δε y =ε y -ε y_0 .

[0101] The whole-process wavefront distortion model and the whole-process light deflection variation model are used to remove the influence of the standard ambient atmosphere, the atmospheric wind field, and the motion platform flow field in the light transmission path on the image from the high frame rate image to obtain a corrected high frame rate image, including:

[0102] The high frame rate image is regarded as a two-dimensional function, defined as I(x,y);

[0103] The light intensity at a certain point in the undistorted high frame rate image is I in (x in ,y in ), the initial incident direction is (θ in_x ,θ in_y ), the wavefront is E(x,y,z,t), the light is not deflected, and an image is formed at point W on the image plane;

[0104] After the whole process of transmission, the change of light deflection Δε occurs x , Δε y , the transmission direction becomes (θ in_x +Δε x ,θ in_y +Δε y ), the wavefront is E′(x,y,z,t), then the light intensity becomes I out (x out ,y out ), after the light is deflected, an image is formed at point G on the image plane;

[0105] After the high frame rate image is distorted, the intensity of points W and G changes;

[0106] The wavefront change E′(x,y,z,t)-E(x,y,z,t) and the transmission parameter change (θ in_x +Δε x ,θ in_y +Δε y ), and then obtain the light intensity change I at a certain point on the high frame rate image out (x out ,y out )-I in (x in ,y in ), and finally obtain the corrected high frame rate image.

[0107] The advantages of the present invention over the prior art are: when the high frame rate optical imaging device located inside the motion platform uses downward or oblique downward viewing to image the ground object, the present invention couples the effects of standard ambient atmospheric transmission, light transmission through the atmospheric wind field, and light transmission through the flow field outside the motion platform on light deflection to model the wavefront distortion model, remove the influence of the entire imaging link process on the high frame rate image imaging effect, and improve the imaging quality. The problem of poor image correction effect caused by the use of traditional light deflection effect distortion image correction methods in the image distortion correction of high-speed imaging equipment inside the motion platform is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0108] Figure 1 This is a flow chart of a method for correcting distorted images caused by light deflection effects at high frame rates according to the present invention.

[0109] Figure 2 It is a schematic diagram of light transmission analysis of a method for correcting distorted images due to light deflection effects at high frame rates according to the present invention.

[0110] Figure 3 It is a schematic diagram of the photosensitivity change of the image plane after light deflection in a method for correcting distorted images due to light deflection effect at a high frame rate according to the present invention. DETAILED DESCRIPTION

[0111] like Figure 1 As shown, the present invention provides a method for correcting a distorted image due to light deflection effect at a high frame rate, comprising:

[0112] Establish an ideal initial light wavefront model; use the ideal initial light wavefront model as incident light to establish a light deflection transmission model;

[0113] Establish an environmental standard atmosphere transmission model, obtain the standard atmosphere refractive index distribution, substitute the standard atmosphere refractive index distribution into the light deflection transmission model, and obtain the wavefront distortion model and light deflection model after the light passes through the standard environmental atmosphere;

[0114] An atmospheric wind field model is established to obtain the atmospheric wind field refractive index distribution, and the atmospheric wind field refractive index distribution is substituted into the light deflection transmission model to obtain the wavefront distortion model and light deflection model after the light passes through the atmospheric wind field;

[0115] Establishing an in vitro flow field model of a moving platform, obtaining the refractive index distribution of the in vitro flow field of the moving platform, substituting the refractive index distribution of the in vitro flow field of the moving platform into the light deflection transmission model, obtaining a wavefront distortion model and a light deflection model after light passes through the in vitro flow field of the moving platform;

[0116] The whole-process wavefront distortion model and the whole-process light deflection model are obtained after the coupled light is transmitted through the standard environment atmosphere, the wavefront distortion model and the light deflection model after the light is transmitted through the atmospheric wind field, and the wavefront distortion model and the light deflection model after the light is transmitted through the flow field in vitro of the moving platform in sequence; the ideal initial light wavefront model is subtracted from the whole-process wavefront distortion model to obtain the whole-process wavefront distortion quantity model; the initial propagation parameters of the light wave are subtracted from the whole-process light deflection model to obtain the whole-process light deflection variation quantity model;

[0117] The high-speed imaging device located in the moving platform images the ground through the moving platform light window to obtain high frame rate images. The full-process wavefront distortion model and the full-process light deflection change model are used to remove the influence of the standard ambient atmosphere, atmospheric wind field, and moving platform flow field in the light transmission path from the high frame rate images to obtain corrected high frame rate images.

[0118] The step of establishing an ideal initial light wavefront comprises:

[0119] The light waves emitted by an ideal point light source are spherical light waves, and the equiphase surface is a concentric sphere centered on the point light source that gradually expands with the increase of distance; then

[0120] The wave function of a spherical wave is:

[0121]

[0122] Among them, v is the phase propagation velocity of the spherical wave along the radial direction of the sphere in the medium; r is the distance from the spherical wave to the central point light source, expressed in polar coordinates; t is the propagation time of the spherical wave in the medium; B is the amplitude function of the spherical wave, which describes the change of amplitude with time and distance;

[0123] When the wave function is in the form of sine or cosine, the ideal initial light wave surface model is:

[0124]

[0125] A 1 is the amplitude at r = 1; k is the wave number; is the initial phase;

[0126] Convert E(r,t) to E(x,y,z,t) by performing polar and Cartesian coordinate conversion.

[0127] The method of establishing a light deflection transmission model using an ideal initial light wavefront model as incident light includes:

[0128] The combination of the ambient standard atmospheric flow field, the atmospheric wind field, and the motion platform flow field is regarded as a flow field with a velocity of V com , refractive index n com (x, y, z, t); the incident light E(r, t) is at a refractive index of n 0 (x, y, z, t) undisturbed flow field propagation, through the flow velocity V com , refractive index n com (x, y, z, t) flow field, due to the various gas movements in the flow field deflecting the light, when leaving the flow field, the distorted wavefront model E′(x, y, z, t) is:

[0129] E′(x,y,z,t)=exp[imOPL]

[0130] OPL = ∫ 0 L n com (x,y,z,t)dy=∫ 0 L [1+K G-D ρ(x,y,z,t)]dy

[0131] E′(x,y,z,t)=exp[im·K G-D ∫ 0 L ρ(x,y,z,t)dy]

[0132] Where L is the flow field thickness, i represents an imaginary number, m = 2π / λ is the wave number, λ represents the wavelength of the spherical wave; OPL is the optical length of the light path through the flow field, ncom (x, y, z, t) is the refractive index of the spherical wave in the medium, ρ is the medium density, K G-D is the Glaston-Dyer constant data; (x, y, z) represents the location of the spherical wave propagation, and t represents the spherical wave propagation time;

[0133] Then the light deflection transmission model is:

[0134]

[0135] ε x is the deflection angle of the light in the x direction, ε y is the deflection angle of the light in the y direction.

[0136] The method of establishing an environmental standard atmosphere transmission model to obtain a standard atmosphere refractive index distribution and using a light deflection transmission model to obtain a light deflection model after light is transmitted through the standard environmental atmosphere includes:

[0137] The environmental standard atmospheric transmission model is established as:

[0138] Troposphere 0 <h<11km:

[0139] T atom_h (h) = T 0 -αh

[0140]

[0141] Stratosphere 11 <h<20km:

[0142] T atom_h =216.65K

[0143]

[0144] Among them, T atom_h 、p atom_h They represent the temperature and pressure of the standard atmosphere respectively; h is the height from sea level, T 0 is the ground temperature, p 0 is the ground pressure, α is the annual average temperature lapse rate of 6.5℃ / km, R=287J / (kg·K) is the gas constant, and g is the gravitational acceleration;

[0145] Then the density change of the standard atmosphere is:

[0146]

[0147] ρ 0 The air density at 0°C and 0.1013MPa is ρ 0 =1.293kg / m 3 ;

[0148] Indicates the relative humidity of the air; p atom_b represents the partial pressure of water vapor in saturated air at temperature T; then the standard atmospheric refractive index distribution is:

[0149] n′ atom_h (h,t)=1+K G-D ρ′ atom_h (h,t)

[0150] Substituting the standard atmospheric refractive index distribution into the distorted wavefront model E′(x, y, z, t), the wavefront distortion caused by the ambient standard atmospheric transmission is obtained as:

[0151]

[0152] Among them, L atom It represents the path length of light propagation in the standard ambient atmosphere;

[0153] Substituting the standard atmospheric refractive index distribution into the light deflection transmission model, the light deflection model after the light passes through the standard ambient atmosphere is obtained:

[0154]

[0155] ε atom_x Represents the light deflection model in the x direction after the light passes through the standard ambient atmosphere; ε atom_y Represents the light deflection model in the y direction after light is transmitted through the standard ambient atmosphere.

[0156] The atmospheric wind field model is established to obtain the atmospheric wind field refractive index distribution, and the light deflection transmission model is used to obtain the light deflection model after the light passes through the atmospheric wind field, including:

[0157] The atmospheric wind field model includes a standard atmospheric wind field model and an atmospheric turbulent flow field model;

[0158] A standard atmospheric wind field model is established to obtain the refractive index distribution of the standard atmospheric wind field. The specific process is as follows:

[0159] Standard atmospheric pressure is the sum of dynamic pressure and static pressure. v is the pressure caused by the movement of the atmospheric wind field, static pressure p h is the standard atmospheric pressure; standard atmospheric wind field model P wind (x,y,h,t) is:

[0160] P wind (x,y,h,t)=p v +p h (x,y,h,t)

[0161] The dynamic pressure p v = 0.5ρV 2 , where V is the atmospheric velocity in the wind field; ρ represents the standard atmospheric density;

[0162] Then the atmospheric density formed by the standard atmospheric wind field is:

[0163]

[0164] The refractive index distribution of the standard atmospheric wind field is:

[0165] n wind (x,y,h,t) = 1 + K G-D ρ wind (x,y,h,t)

[0166] Establish an atmospheric turbulence flow field model to obtain the refractive index distribution of atmospheric turbulence. The specific process is as follows:

[0167] The atmospheric turbulence flow field model is:

[0168]

[0169] where Γ is the gamma function, 0 < p < 2, κ is the turbulence wave number, is the refractive index structure constant;

[0170] The refractive index distribution of atmospheric turbulence is:

[0171]

[0172] where, represents the refractive index structure constant;

[0173]

[0174] represents the root mean square vertical path wind speed, V g is the near-surface wind speed;

[0175] Substitute the refractive index distribution of the standard atmospheric wind field and the refractive index distribution of atmospheric turbulence into the wavefront model with distortion E′(x,y,z,t) to obtain the wavefront distortion caused by the transmission of the atmospheric wind field as:

[0176]

[0177] L wind represents the propagation path length of light in the atmospheric wind field; L turb represents the propagation path length of light in atmospheric turbulence;

[0178] Substitute the refractive index distribution of the standard atmospheric wind field and the refractive index distribution of atmospheric turbulence into the light deflection transmission model to obtain the light deflection model after the light passes through the atmospheric wind field transmission as:

[0179]

[0180] ε win_x represents the light deflection model in the x direction after the light passes through the atmospheric wind field, ε win_y Represents the light deflection model in the y direction after the light passes through the atmospheric wind field.

[0181] The method of establishing the in vitro flow field model of the motion platform, obtaining the refractive index distribution of the in vitro flow field of the motion platform, and using the light deflection transmission model to obtain the light deflection result after the light passes through the in vitro flow field of the motion platform, includes:

[0182] Establish a three-dimensional model of the high-speed motion platform and establish a flow field analysis grid around the platform; establish an in vitro flow field model of the motion platform, and calculate the density ρ(x, y, z) of each grid at the in vitro flow field of the motion platform according to the flight speed, flight altitude, and flight posture of the motion platform;

[0183] Using the Gladstone-Dyer formula, calculate the refractive index at each point in the grid:

[0184] n(x,y,z)=K G-D ρ(x,y,z)+1

[0185] Taking any point o in space as the center, calculate the refractive index n of point o through the 8 adjacent grid points o_obj (x, y, z); then the refractive index distribution of the flow field outside the moving platform is:

[0186]

[0187] Among them, n i is the refractive index of the space point adjacent to point o, i is the x-coordinate of the space point, and j is the y-coordinate of the space point;

[0188] is a spatial point (x j ,y j ,z j ) and the distance between point o(x,y,z);

[0189] Substituting the refractive index distribution of the flow field outside the moving platform into the wavefront model that produces distortion is E′(x, y, z, t), the wavefront distortion caused by the light transmission of the flow field outside the moving platform is obtained as:

[0190]

[0191] L obj It represents the propagation path length of light in the flow field outside the moving platform;

[0192] Substituting the refractive index distribution of the motion platform's in vitro flow field into the light deflection transmission model, the light deflection model after the light passes through the motion platform's in vitro flow field is obtained as follows:

[0193]

[0194] In the formula, ε obj_x represents the light deflection model in the x direction after the light passes through the flow field outside the moving platform, ε obj_y Represents the light deflection model in the y direction after the light passes through the flow field outside the moving platform.

[0195] Taking the ideal initial light wavefront as the incident light, the wavefront distortion model and the light deflection model after the light passes through the standard environment atmosphere, the wavefront distortion model and the light deflection model after the light passes through the atmospheric wind field, and the wavefront distortion model and the light deflection model after the light passes through the in vitro flow field of the moving platform are successively obtained to obtain the whole process wavefront distortion model and the whole process light deflection model; the ideal initial light wavefront model is subtracted from the whole process wavefront distortion model to obtain the whole process wavefront distortion quantity model; the initial propagation direction of the light wave is subtracted from the whole process light deflection model to obtain the whole process light deflection variation quantity model, including:

[0196] The whole process wavefront distortion model is:

[0197] E′(x,y,z,t)=E atom v(h,t)+E win ′(x,y,h,t)+E obj ′(x,y,z,t)

[0198] The whole process wavefront distortion model is:

[0199] ΔE(x,y,z,t)=E′(x,y,z,t)-E(x,y,z,t)

[0200] The whole process light deflection model is:

[0201] ε x =ε atom_x +ε win_x +ε obj_x

[0202] ε y =ε atom_y +ε win_y +ε obj_y

[0203] The initial propagation parameters of the light wave are: ε x_0 , ε y_0 ;

[0204] After the whole process of light deflection, the whole process light deflection change model is:

[0205] Δε x =ε x -ε x_0 , Δε y =ε y -ε y_0 .

[0206] The whole-process wavefront distortion model and the whole-process light deflection variation model are used to remove the influence of the standard ambient atmosphere, the atmospheric wind field, and the motion platform flow field in the light transmission path on the image from the high frame rate image to obtain a corrected high frame rate image, including:

[0207] The high frame rate image is regarded as a two-dimensional function, defined as I(x,y);

[0208] The light intensity at a certain point in the undistorted high frame rate image is I in (x in ,y in ), the initial incident direction is (θ in_x ,θ in_y ), the wavefront is E(x,y,z,t), the light is not deflected, and an image is formed at point W on the image plane;

[0209] After the whole process of transmission, the change of light deflection Δε occurs x , Δε y , the transmission direction becomes (θ in_x +Δε x ,θ in_y +Δε y ), the wavefront is E′(x,y,z,t), then the light intensity becomes I out (x out ,y out ), after the light is deflected, an image is formed at point G on the image plane;

[0210] After the high frame rate image is distorted, the intensity of points W and G changes;

[0211] The wavefront change E′(x,y,z,t)-E(x,y,z,t) and the transmission parameter change (θ in_x +Δε x ,θ in_y +Δε y ), and then obtain the light intensity change I at a certain point on the high frame rate image out (x out ,y out )-I in (x in ,y in ), and finally obtain the corrected high frame rate image.

[0212] like Figure 2As shown, the present invention uses downward or oblique downward viewing to image the ground object. The light intensity at a certain point is I in (x in ,y in ), the initial incident direction is θ in , the wave surface is E(x,y,z,t), named as ray 0. Ray 1 is the transmission process of ray 0 in the ambient atmosphere, ray 2 is the transmission of ray 1 in atmospheric turbulence, ray 3 is the transmission of ray 2 in the atmospheric wind field, ray 4 is the transmission of ray in the ambient atmosphere, and ray 5 is the transmission of ray 4 in the flow field outside the moving platform. Among them, the ambient atmosphere transmission exists in the whole transmission process, and the atmospheric turbulence transmission and the atmospheric wind field transmission exist in the same height range.

[0213] like Figure 3 As shown, the light intensity at a certain point is I in (x in ,y in ), the initial incident direction is θ in The wavefront is E(x,y,z,t), and after passing through the transmission path, it is deflected by Δε x , Δε y , the light intensity becomes I out (x out ,y out ), the transmission direction becomes θ in_x +Δε x ,θ in_y +Δε y , the wavefront is E′(x,y,z,t). The incident light passes through the transmission path without being deflected, and forms an image at point W on the image plane; after being deflected, it forms an image at point G on the image plane; at this time, the intensities of both point W and point G change. The wavefront change E′(x,y,z,t)-E(x,y,z,t) and intensity change I obtained by the present invention are out (x out ,y out )-I in (x in ,y in ), the influence of the standard ambient atmosphere, atmospheric wind field, and motion platform flow field on light deflection in the optical transmission path can be analyzed, and these influences can be removed from the high frame rate image to obtain the corrected high frame rate image.

[0214] The motion platform of the present invention can be a high-speed motion platform or a low-speed motion platform.

[0215] The light transmission process described in the present invention analyzes the intensity effect caused by the light deflection, and does not elaborate on the effect of scattering, absorption, etc. on the intensity during the light transmission process. The mature scattering and absorption analysis methods during the light transmission process can be used to obtain the effect of scattering, absorption, etc. on the intensity, and analyze it together with the intensity effect caused by the light deflection.

[0216] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solution of the present invention by using the above disclosed methods and technical contents without departing from the spirit and scope of the present invention. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall belong to the protection scope of the technical solution of the present invention. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments can be combined with each other.

[0217] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A method for correcting image distortion caused by light deflection effect at high frame rate, characterized in that: include: Establish an ideal initial light wavefront model; use the ideal initial light wavefront model as incident light to establish a light deflection transmission model; Establish an environmental standard atmosphere transmission model, obtain the standard atmosphere refractive index distribution, substitute the standard atmosphere refractive index distribution into the light deflection transmission model, and obtain the wavefront distortion model and light deflection model after the light passes through the standard environmental atmosphere; An atmospheric wind field model is established to obtain the atmospheric wind field refractive index distribution, and the atmospheric wind field refractive index distribution is substituted into the light deflection transmission model to obtain the wavefront distortion model and light deflection model after the light passes through the atmospheric wind field; Establishing an in vitro flow field model of a moving platform, obtaining the refractive index distribution of the in vitro flow field of the moving platform, substituting the refractive index distribution of the in vitro flow field of the moving platform into the light deflection transmission model, obtaining a wavefront distortion model and a light deflection model after light passes through the in vitro flow field of the moving platform; Taking the ideal initial light wavefront as the incident light, the whole-process wavefront distortion model and the whole-process light deflection model are obtained after the light passes through the standard environment atmosphere, the wavefront distortion model and the light deflection model after the light passes through the atmospheric wind field, and the wavefront distortion model and the light deflection model after the light passes through the flow field in vitro of the moving platform in sequence; the ideal initial light wavefront model is subtracted from the whole-process wavefront distortion model to obtain the whole-process wavefront distortion quantity model; the initial propagation direction of the light wave is subtracted from the whole-process light deflection model to obtain the whole-process light deflection variation quantity model; The high-speed imaging device located in the motion platform images the ground objects through the motion platform light window to obtain high frame rate images; By using the full-process wavefront distortion model and the full-process light deflection variation model, the influence of the standard ambient atmosphere, atmospheric wind field and moving platform flow field in the light transmission path on the image is removed from the high frame rate image to obtain the corrected high frame rate image.

2. The method for correcting image distortion caused by light deflection effect at high frame rate according to claim 1, characterized in that: The step of establishing an ideal initial light wavefront comprises: The light waves emitted by an ideal point light source are spherical light waves, and the equiphase surface is a concentric sphere centered on the point light source that gradually expands with the increase of distance; then The wave function of a spherical wave is: Among them, v is the phase propagation velocity of the spherical wave along the radial direction of the sphere in the medium; r is the distance from the spherical wave to the central point light source, expressed in polar coordinates; t is the propagation time of the spherical wave in the medium; B is the amplitude function of the spherical wave, which describes the change of amplitude with time and distance; When the wave function is in the form of sine or cosine, the ideal initial light wave surface model is: A1 is the amplitude at r = 1; k is the wave number; is the initial phase; Convert E(r,t) to E(x,y,z,t) by performing polar and Cartesian coordinate conversion.

3. The method for correcting image distortion caused by light deflection effect at high frame rate according to claim 2, characterized in that: The method of establishing a light deflection transmission model using an ideal initial light wavefront model as incident light includes: The combination of the ambient standard atmospheric flow field, the atmospheric wind field, and the motion platform flow field is regarded as a flow field with a velocity of V com , refractive index n com (x, y, z, t); the incident light E(r, t) propagates in an undisturbed flow field with a refractive index of n0(x, y, z, t), passing through a flow with a velocity of V com , refractive index n com (x, y, z, t) flow field, due to the various gas movements in the flow field deflecting the light, when leaving the flow field, the distorted wavefront model E′(x, y, z, t) is: E′(x,y,z,t)=exp[imOPL] Where L is the flow field thickness, i represents an imaginary number, m = 2π / λ is the wave number, λ represents the wavelength of the spherical wave; OPL is the optical length of the light path through the flow field, n com (x, y, z, t) is the refractive index of the spherical wave in the medium, ρ is the medium density, K G-D is the Gladstone-Dyer constant data; (x, y, z) represents the location of the spherical wave propagation, and t represents the spherical wave propagation time; Then the light deflection transmission model is: ε x is the deflection angle of the light in the x direction, ε y is the deflection angle of the light in the y direction.

4. The method for correcting image distortion caused by light deflection effect at high frame rate according to claim 3, characterized in that: The method of establishing an environmental standard atmosphere transmission model to obtain a standard atmosphere refractive index distribution and using a light deflection transmission model to obtain a light deflection model after light is transmitted through the standard environmental atmosphere includes: The environmental standard atmospheric transmission model is established as: Troposphere 0 <h<11km: T atom_h (h)=T0-αh Stratosphere 11 <h<20km: T atom_h =216.65K Among them, T atom_h 、p atom_h Respectively represent the temperature and pressure of the standard atmosphere; h is the height calculated from sea level, T0 is the ground temperature, p0 is the ground pressure, α is the annual average temperature lapse rate of 6.5℃ / km, R is the gas constant, and g is the acceleration of gravity; Then the density change of the standard atmosphere is: ρ0 is the air density at 0℃ and pressure of 0.1013MPa; Indicates the relative humidity of the air; p atom_b represents the partial pressure of water vapor in saturated air at temperature T; then the standard atmospheric refractive index distribution is: n′ atom_h (h,t)=1+K G-D ρ′ atom_h (h,t) Substituting the standard atmospheric refractive index distribution into the distorted wavefront model E′(x, y, z, t), the wavefront distortion caused by the ambient standard atmospheric transmission is obtained as: Among them, L atom It represents the path length of light propagation in the standard ambient atmosphere; Substituting the standard atmospheric refractive index distribution into the light deflection transmission model, the light deflection model after the light passes through the standard ambient atmosphere is obtained: ε atom_x Represents the light deflection model in the x direction after the light passes through the standard ambient atmosphere; ε atom_y Represents the light deflection model in the y direction after light is transmitted through the standard ambient atmosphere.

5. The method for correcting image distortion caused by light deflection effect at high frame rate according to claim 4, characterized in that: The atmospheric wind field model is established to obtain the atmospheric wind field refractive index distribution, and the light deflection transmission model is used to obtain the light deflection model after the light passes through the atmospheric wind field, including: The atmospheric wind field model includes a standard atmospheric wind field model and an atmospheric turbulent flow field model; A standard atmospheric wind field model is established to obtain the refractive index distribution of the standard atmospheric wind field. The specific process is as follows: Standard atmospheric pressure is the sum of dynamic pressure and static pressure. v is the pressure caused by the movement of the atmospheric wind field, static pressure p h is the standard atmospheric pressure; standard atmospheric wind field model P wind (x,y,h,t) is: P wind (x,y,h,t)=p v +p h (x,y,h,t) The dynamic pressure p v =0.5ρV 2 , V is the atmospheric velocity in the wind field; ρ represents the standard atmospheric density; The atmospheric density formed by the standard atmospheric wind field is: The standard atmospheric wind field refractive index distribution is: n wind (x,y,h,t)=1+K G-D ρ wind (x,y,h,t) An atmospheric turbulent flow field model is established to obtain the atmospheric turbulent refractive index distribution. The specific process is as follows: The atmospheric turbulence flow field model is: where Γ is the gamma function, 0 < p < 2, κ is the turbulence wave number, and is the refractive index structure constant; The atmospheric turbulence refractive index distribution is: in, represents the refractive index structure constant; V RMS represents the vertical path RMS wind speed; Substituting the standard atmospheric wind field refractive index distribution and the atmospheric turbulence refractive index distribution into the distorted wavefront model E′(x, y, z, t), the wavefront distortion caused by atmospheric wind field transmission is obtained as: L wind Indicates the length of the light propagation path in the atmospheric wind field; L turb It represents the path length of light propagation in atmospheric turbulence; Substituting the standard atmospheric wind field refractive index distribution and the atmospheric turbulence refractive index distribution into the light deflection transmission model, the light deflection model after the light passes through the atmospheric wind field is obtained: ε win_x represents the light deflection model in the x direction after the light passes through the atmospheric wind field, ε win_y Represents the light deflection model in the y direction after the light passes through the atmospheric wind field.

6. The method for correcting image distortion caused by light deflection effect at high frame rate according to claim 5, characterized in that: The method of establishing the in vitro flow field model of the motion platform, obtaining the refractive index distribution of the in vitro flow field of the motion platform, and using the light deflection transmission model to obtain the light deflection result after the light passes through the in vitro flow field of the motion platform, includes: Establish a three-dimensional model of the high-speed motion platform and establish a flow field analysis grid around the platform; establish an in vitro flow field model of the motion platform, and calculate the density ρ(x, y, z) of each grid at the in vitro flow field of the motion platform according to the flight speed, flight altitude, and flight posture of the motion platform; Using the Gladstone-Dyer formula, calculate the refractive index at each point in the grid: n(x,y,z)=K G-D ρ(x,y,z)+1 Taking any point o in space as the center, calculate the refractive index n of point o through the 8 adjacent grid points o_obj (x, y, z); then the refractive index distribution of the flow field outside the moving platform is: Among them, n i is the refractive index of the space point adjacent to point o, i is the x-coordinate of the space point, and j is the y-coordinate of the space point; is a spatial point (x j ,y j ,z j ) and the distance between point o(x,y,z); Substituting the refractive index distribution of the flow field outside the moving platform into the wavefront model that produces distortion is E′(x, y, z, t), the wavefront distortion caused by the light transmission of the flow field outside the moving platform is obtained as: L obj It represents the propagation path length of light in the flow field outside the moving platform; Substituting the refractive index distribution of the motion platform's in vitro flow field into the light deflection transmission model, the light deflection model after the light passes through the motion platform's in vitro flow field is obtained as follows: In the formula, ε obj_x represents the light deflection model in the x direction after the light passes through the flow field outside the moving platform, ε obj_y Represents the light deflection model in the y direction after the light passes through the flow field outside the moving platform.

7. The method for correcting image distortion caused by light deflection effect at high frame rate according to claim 6, characterized in that: The method uses the ideal initial light wavefront as the incident light, and sequentially obtains the wavefront distortion model and light deflection model after the light passes through the standard ambient atmosphere, the wavefront distortion model and light deflection model after the light passes through the atmospheric wind field, and the wavefront distortion model and light deflection model after the light passes through the flow field outside the body of the moving platform, thereby obtaining the full-process wavefront distortion model and the full-process light deflection model; subtracts the ideal initial light wavefront model from the full-process wavefront distortion model to obtain the full-process wavefront distortion model; Subtract the initial propagation direction of the light wave from the whole process light deflection model to obtain the whole process light deflection change model, including: The whole process wavefront distortion model is: E′(x,y,z,t)=E atom ′(h,t)+E win ′(x,y,h,t)+E obj ′(x,y,z,t) The whole process wavefront distortion model is: ΔE(x,y,z,t)=E′(x,y,z,t)-E(x,y,z,t) The whole process light deflection model is: e x =e atom_x +e win_x +e obj_x e y =e atom_y +e win_y +e obj_y The initial propagation parameters of the light wave are: ε x_0 , ε y_0 ; After the whole process of light deflection, the whole process light deflection change model is: No x =e x -e x_0 、No y =e y -e y_0 。 8. The method for correcting image distortion caused by light deflection effect at high frame rate according to claim 7, characterized in that: The whole-process wavefront distortion model and the whole-process light deflection variation model are used to remove the influence of the standard ambient atmosphere, the atmospheric wind field, and the motion platform flow field in the light transmission path on the image from the high frame rate image to obtain a corrected high frame rate image, including: The high frame rate image is regarded as a two-dimensional function, defined as I(x,y); The light intensity at a certain point in the undistorted high frame rate image is I in (x in ,y in ), the initial incident direction is (θ in_x ,θ in_y ), the wavefront is E(x,y,z,t), the light is not deflected, and an image is formed at point W on the image plane; After the whole process of transmission, the change of light deflection Δε occurs x , Δε y , the transmission direction becomes (θ in_x +Δε x ,θ in_y +Δε y ), the wavefront is E′(x,y,z,t), then the light intensity becomes I out (x out ,y out ), after the light is deflected, an image is formed at point G on the image plane; After the high frame rate image is distorted, the intensity of points W and G changes; The wavefront change E′(x,y,z,t)-E(x,y,z,t) and the transmission parameter change (θ in_x +Δε x ,θ in_y +Δε y ), and then obtain the light intensity change I at a certain point on the high frame rate image out (x out ,y out )-I in (x in ,y in ), and finally obtain the corrected high frame rate image.

Images