A method and system for simulating optical detection of a target against a stellar background

Abstract

The application belongs to the field of target optical detection, and discloses a target optical detection simulation method and system containing a star background, which simulates a scene containing a star background and a target by constructing an optical scene to be detected, establishes a detection model, converts star luminosity and target luminosity optical physical quantities into gray value DN in the field of digital images, and presents data collected by a detector in the form of an image, accurately identifies and removes star information from a complex image containing stars and targets, accurately obtains the position of the target and the miss distance, determines the deviation of the target relative to an ideal observation position, adjusts the observation angle in real time, continuously tracks the target, ensures that the target is always in the center or within the field of view, and obtains comprehensive and accurate detection information, solving the problem that existing target detection process simulation has relatively independent elements, does not have the capability of simultaneously constructing a target and a background and full-link modeling simulation, and lacks physical simulation modeling capability.

Description

Technical Field

[0001] This invention belongs to the field of target optical detection technology, and relates to a simulation method and system for target optical detection with a stellar background. Background Technology

[0002] The target optical detection simulation method describes the detection process of the optical detection system on the target through a digital model to generate target detection result images, which can provide an important basis for the capability evaluation, design optimization and efficient use of the optical detection system.

[0003] The simulation of the target detection process includes target (geometry, orbit, attitude, characteristics) modeling, background (deep space, stars) modeling, and detection process (relative motion, response, noise) modeling. Target modeling mainly establishes the photometric characteristics of the target under different orbits and attitudes; background modeling mainly establishes the detection scene, including the cold background of deep space, star positions, and photometric values; detection process modeling mainly establishes the optical detection system response, relative motion, and system noise. By modeling each element of the target, background, and detection process, the simulation of the final detection result is achieved.

[0004] Currently, target detection process simulations suffer from several limitations. The elements are relatively independent, lacking the ability to simultaneously construct the target and background and perform full-link modeling and simulation. Furthermore, they lack physical simulation capabilities. Most simulations rely on adding degradation functions to ideal images, resulting in simulations that lack true numerical significance. In particular, there are significant simplifications in target photometric and detection process modeling, rendering them unsuitable for target photometric and line-of-sight measurements, and unable to provide a data source for target tracking and pointing. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention aims to provide a simulation method and system for optical detection of targets with stellar backgrounds. By constructing an optical scene to be detected, a scene containing both stellar backgrounds and targets is simulated. A detection model is then established, converting the optical physical quantities of stellar luminosity and target luminosity into grayscale values ​​(DN) in the digital image domain. This allows the data collected by the detector to be presented intuitively in image form. Subsequently, stars are removed, accurately identifying and eliminating stellar information from complex images containing both stars and targets. This allows for precise determination of the target's position and miss distance, clarifying the target's deviation from the ideal observation position. Finally, the observation angle is adjusted in real time to continuously track the target, ensuring it remains at the center or within the field of view to obtain comprehensive and accurate detection information.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a simulation method for optical detection of targets with a stellar background, comprising the following steps: constructing a scene to be detected by an optical detection system; establishing a detection model based on the scene to be detected by the optical detection system, and converting the stellar luminosity and target luminosity into digital image grayscale values ​​(DN); removing stars to obtain the target position and miss distance; and tracking the target based on the target position and miss distance.

[0008] Furthermore, the detection model includes: a response model, a motion model, a sampling model, and a noise model; the response model is used to convert the illuminance of the target and the star into a light intensity distribution on the detector receiving surface according to the optical detection system; the motion model is used to describe the relative motion relationship between the target and the detection system during the exposure time of the detection process, so as to adjust or compensate for the change in light intensity distribution caused by relative motion; the sampling model is used to sample the continuous light intensity distribution on the detector receiving surface into discrete detector pixel values, i.e., digital image grayscale values ​​DN; the noise model is used to simulate and compensate for the noise introduced by the image detector during the sampling process.

[0009] Furthermore, after constructing the optical detection system for the scene to be detected, the following steps are also included: determining the coordinates of the star and the target on the image plane of the optical detection system; and determining the illuminance of the star and the target.

[0010] Furthermore, the scene to be detected by the optical detection system includes: establishing the star position and star luminosity; establishing the target position, target attitude, target geometry, and target luminosity.

[0011] Furthermore, the coordinates of the star and the target on the image plane of the optical detection system are determined through coordinate transformation.

[0012] Furthermore, determining the coordinates of the star and the target on the image plane of the optical detection system includes:

[0013]

[0014] in, For image pixels Axis coordinates For image pixels Axis coordinates This is the transformation matrix from image coordinates to pixel coordinates; This is the transformation matrix from camera coordinates to image coordinates. To bypass The rotation matrix of the axis. To bypass The rotation matrix of the axis. It is the azimuth angle. For pitch angle; calculate stars, , The right ascension of a star. The declination of a star; calculating the target, , For the target under J2000 Axis coordinates For the target under J2000 Axis coordinates For the target under J2000 Axis coordinates.

[0015] Furthermore, the winding Rotation matrix of axis for:

[0016]

[0017] in, It is the azimuth angle.

[0018] Furthermore, the illuminance of the star is:

[0019]

[0020] in, The apparent magnitude of a star. For the magnitude is The illuminance of the star, is the illuminance constant for zero magnitude stars.

[0021] Furthermore, the illuminance of the target is:

[0022]

[0023] in, Illuminance for the target For the target equivalent area, The solar irradiance within the detection wavelength range, The reflectivity of the target The angle of incidence of the sun relative to the target. The observation angle of the optical detection system relative to the target. The distance between the target and the optical detection system.

[0024] This invention also provides a target optical detection simulation system with a stellar background, comprising: a construction module for constructing the scene to be detected by the optical detection system; a conversion module for establishing a detection model based on the scene to be detected by the optical detection system, and converting stellar luminosity and target illuminance into digital image grayscale values ​​DN; a removal module for removing stars to obtain the target position and miss distance; and a tracking module for tracking the target based on the target position and miss distance.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects:

[0026] This invention discloses a simulation method for optical detection of targets with a stellar background. It constructs an optical scene to be detected, simulating a scene containing both a stellar background and the target. A detection model is then established, converting the optical physical quantities of stellar luminosity and target luminosity into grayscale values ​​(DN) in the digital image domain. This allows the data collected by the detector to be presented intuitively in image form. Stars are then removed; stellar information is accurately identified and removed from complex images containing both stars and the target, thereby precisely determining the target's position and miss distance. The deviation of the target from the ideal observation position is clarified. Finally, the observation angle is adjusted in real time to continuously track the target, ensuring that the target remains at the center or within the field of view to obtain comprehensive and accurate detection information.

[0027] This invention provides a target optical detection simulation method with a stellar background. The high-precision channel simulation can simulate the target detection process against a stellar background, accurately calculate the target's position and trajectory, and provide accurate information for the optical detection system.

[0028] This invention provides a target optical detection simulation method with a stellar background, which can simulate the stellar background and target in the scene, improve the adaptability of the optical detection system to environmental changes in different scenes, and enable it to work stably in more complex and variable environments.

[0029] This invention provides a target optical detection simulation method with a stellar background, which can accurately identify and track targets under complex and variable stellar backgrounds, thereby improving the robustness and adaptability of the optical detection system. Attached Figure Description

[0030] Figure 1 This is a flowchart of a target optical detection simulation method with a stellar background according to the present invention;

[0031] Figure 2 This is a schematic diagram of the simulation results of the optical detection system not tracking the target in an embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram of the target tracking simulation results of the optical detection system in an embodiment of the present invention;

[0033] Figure 4 This is a schematic diagram of the simulation results of the optical detection system tracking and pointing correction in an embodiment of the present invention. Detailed Implementation

[0034] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0035] Example 1

[0036] This invention provides a simulation method for optical detection of targets with a stellar background, comprising the following steps: constructing a scene to be detected by the optical detection system; establishing a detection model based on the scene to be detected by the optical detection system, and converting stellar luminosity and target luminosity into digital image grayscale values ​​(DN); removing stars to obtain the target position and miss distance; and tracking the target based on the target position and miss distance, such as... Figure 1 As shown.

[0037] The detection model includes mathematical models of stellar position, stellar luminosity, target position, target attitude, target geometry, and target luminosity. The stellar position is primarily based on star catalogs, transforming the right ascension and declination of stars within the optical detection system to the image plane coordinates of the optical detection system through coordinate transformation. Stellar luminosity is determined based on apparent magnitude. The target position is calculated by combining the target's orbit, attitude, and geometry, transforming it to the image plane coordinates of the optical detection system. The target luminosity is calculated using ray tracing based on the relative relationship between the Sun and the target, as well as the target's material properties.

[0038] By constructing the scene to be detected by the optical detection system, the environment faced during actual detection can be highly reproduced, making the simulation results more reliable and practical, and effectively guiding actual optical detection tasks.

[0039] Optical detection systems face complex environments in practical applications, including target characteristics, background noise, atmospheric disturbances, and the system's own performance limitations. By constructing a simulated optical detection scenario, these factors can be simulated, allowing for the testing and verification of the optical detection system in a virtual environment. Constructing such a scenario reduces costs and enhances reliability. Cost reduction: Simulation in a virtual environment avoids the high costs and resource consumption that may be encountered in actual testing. Enhanced reliability: Simulation results can provide reliable data support for actual tasks, ensuring a higher success rate.

[0040] A detection model is established to convert stellar luminosity and target illumination into digital image grayscale values ​​(DN). Specifically, the target and star in the optical detection system are observed, and raw image data is collected. The raw image data is collected by a camera, which consists of a lens and a detector. The lens mainly collects the energy of the star, target, and background. The light-gathering capability of the lens is determined by its aperture and focal length parameters. The detector performs photoelectric conversion on the illumination collected by the lens. After the photoelectric conversion is completed, the detector performs discrete sampling. Discrete sampling is similar to "cutting" a continuous electrical signal according to a certain rule, selecting specific points to represent the entire signal, and finally forming the grayscale image we see.

[0041] The acquired raw image data needs to be processed, including response model, motion model, sampling model, and noise model, and steps such as response correction, motion compensation, discrete sampling, and noise suppression are performed to convert the illumination values ​​of the target and stars into the image pixel grayscale values ​​DN.

[0042] Response correction converts the illuminance of stars and targets in an optical detection system to the light intensity distribution on the detector's receiving surface. There is a close and physically governed relationship between stellar luminosity and stellar illuminance. Stellar luminosity is the power of energy radiated outward by a star, reflecting the rate at which nuclear fusion reactions within the star produce and release energy. Stellar illuminance is the stellar radiation flux received per unit area, representing the brightness of a star as observed by the observer. Under the same observation conditions, stellar illuminance is directly proportional to luminosity and inversely proportional to the square of the distance from the observer to the star.

[0043] Stellar Illumination The calculation is as follows:

[0044]

[0045] in, The apparent magnitude of a star. For the magnitude is The illuminance of the star, is the illuminance constant for zero magnitude stars.

[0046] Target illuminance is primarily determined by spatial location, material properties, and solar illumination conditions. Spatial location is determined by orbital modeling results, while material properties characterize the target's reflection of sunlight. For a detection optical system, the illuminance of the target at the entrance pupil of the optical system is calculated as follows:

[0047]

[0048] in, Illuminance for the target For the target equivalent area, The solar irradiance within the detection wavelength range. The reflectivity of the target The angle of incidence of the sun relative to the target. The observation angle of the optical detection system relative to the target. The distance between the target and the optical detection system.

[0049] Before determining the illumination of stars and targets, the coordinates of the star and target image pixels need to be transformed into the image plane coordinates of the optical detection system. This avoids simulation errors caused by coordinate mismatch, thereby improving the overall accuracy of the simulation. Through precise coordinate positioning, we can more accurately simulate the imaging effect of stars and targets on the detector, providing a solid foundation for subsequent illumination calculations.

[0050] The coordinate transformation of a star in the image plane of an optical detection system is as follows:

[0051]

[0052] in, For image pixels Axis coordinates For image pixels Axis coordinates This is the transformation matrix from image coordinates to pixel coordinates; This is the transformation matrix from camera coordinates to image coordinates. To bypass The rotation matrix of the axis. To bypass The rotation matrix of the axis. It is the azimuth angle. The pitch angle;

[0053]

[0054] The right ascension of a star. The declination of a star.

[0055] The target's coordinates on the image plane of the optical detection system are transformed as follows:

[0056]

[0057] in, For image pixels Axis coordinates For image pixels Axis coordinates This is the transformation matrix from image coordinates to pixel coordinates; This is the transformation matrix from camera coordinates to image coordinates. To bypass The rotation matrix of the axis. To bypass The rotation matrix of the axis. It is the azimuth angle. The pitch angle;

[0058]

[0059] For the target under J2000 Axis coordinates For the target under J2000 Axis coordinates For the target under J2000 Axis coordinates.

[0060] The transformation matrix from camera coordinates to image coordinates for:

[0061]

[0062] in, For the focal length of the optical detection system, This represents the imaging distance.

[0063] The transformation matrix from image coordinates to pixel coordinates for:

[0064]

[0065] in, For pixel size, For the center pixel of the image plane Axis coordinates For the center pixel of the image plane Axis coordinates.

[0066] The response model is mainly determined by the aperture, integration time, quantum efficiency of the detector, and speckle size of the optical detection system; the motion model is mainly determined by the orbit of the optical detection system; the sampling model is mainly completed by discrete sampling of the detector, which is a discrete sampling of continuous energy; and the noise model adds noise on the basis of discrete sampling.

[0067] In summary, stellar luminosity and target luminosity are converted into digital image grayscale values ​​(DN).

[0068]

[0069] in, The grayscale value of the digital image obtained by the optical detection system; and It is a rectangle function, when or The rect function evaluates to 1 when the value is between -0.5 and 0.5; otherwise, it evaluates to 0. For the aperture of the optical detection system Integral Time quantum efficiency and the size of the diffuse spot The system response coefficients are jointly determined; relative velocity of the target The determined translation transformation System noise determined by the detector.

[0070] The detector converts the received light signals into electrical signals, and after quantization and other processing, represents the light intensity information of each pixel in the image with different grayscale values ​​(DN). The image composed of grayscale values ​​(DN) is the basic data source for star map matching and subsequent star removal operations. This enables precise tracking of the target, ensuring that the target is always at the center of the field of view or at least remains within the field of view.

[0071] The image composed of grayscale values ​​(DN) is compared and matched with existing standard star maps to effectively identify stars. After a successful match, the stars are removed from the image composed of grayscale values ​​(DN), resulting in an image containing only the target. This provides a simplified and crucial data foundation for subsequent target miss distance calculations.

[0072] When tracking a target, the grayscale value (DN) change of the target pixels is calculated based on the captured target image and the target miss distance. As the target moves within the field of view, the grayscale distribution of its corresponding pixels also changes. These changes allow for the calculation of the target's miss distance relative to the center of the field of view. The pointing direction is driven by the miss distance, and by adjusting the azimuth and elevation angles, a rapid and accurate response is made to ensure the target remains at the center of the field of view or at least within it. This not only improves the accuracy of target detection but also reduces the impact of background interference on data analysis, providing clear and accurate data for target tracking and processing.

[0073] Target miss distance calculation mainly involves calculating the centroid of an image containing the target to obtain the target's pixel coordinates. Centroid calculation is an important method for determining the precise location of a target in an image. By mathematically analyzing the pixel distribution of the target image, the centroid position of the target is calculated, thus obtaining the target's pixel position.

[0074] For example, the target is an artificial satellite traveling through space, appearing as an irregularly shaped spot of light with varying grayscale values ​​in the images generated by the detector. The optical detection system then analyzes all the pixels covered by this spot, considering the grayscale value of each pixel and its position in the image coordinate system. Pixels with higher grayscale values ​​are given relatively higher weight in the calculation because they contribute more to the overall features of the target. After a series of rigorous mathematical derivations and calculations, a pixel coordinate position representing the satellite's center of mass is finally determined.

[0075] Based on the difference between the target's pixel position and the image center pixel position, the angle value required for pointing correction is derived, i.e., the azimuth correction amount. and pitch correction amount Azimuth correction amount and pitch correction amount The adjustment direction and magnitude required by the pointing mechanism to bring the target back to the center of the field of view were clarified, ultimately achieving the goal of accurately placing the target in the center of the field of view and ensuring that the entire system can continuously and stably track and observe the target.

[0076] The optical detection system does not track the target, such as... Figure 2 As shown, the tracking results of the optical detection system on the target are as follows: Figure 3 As shown, the optical detection system tracks the target and places it at the center of the field of view. The result is as follows: Figure 4 As shown.

[0077] Azimuth correction for:

[0078]

[0079] in, For image pixels Axis coordinates For the focal length of the optical detection system, For image pixels Axis coordinates The pitch angle.

[0080] Pitch angle correction for:

[0081]

[0082] in, For the focal length of the optical detection system, The pitch angle, For image pixels Axis coordinates For image pixels Axis coordinates.

[0083] By acquiring target location and miss distance in real time and dynamically adjusting the tracking strategy, the system ensures accurate target tracking at all times, significantly improving target accuracy and stability, and enabling timely monitoring of target dynamics. Continuous monitoring of the target's position and movement status allows for the timely detection of abnormal target behavior or potential threats.

[0084] Example 2

[0085] The present invention provides a target optical detection simulation system with a stellar background, comprising a construction module, a conversion module, a rejection module, and a tracking module.

[0086] The module consists of: a model building module for establishing a detection model based on the scene to be detected by the optical detection system; a conversion module for establishing the detection model and converting stellar luminosity and target illuminance into digital image grayscale values ​​(DN); a removal module for removing stars to obtain the target position and miss distance; and a tracking module for tracking the target based on its position and miss distance.

[0087] The target optical detection simulation system with a stellar background provided by this invention can implement the same method steps as the above method, so it will not be described again.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A simulation method for optical detection of targets with a stellar background, characterized in that, Includes the following steps: Construct the scene to be detected by the optical detection system; The scenario to be detected by the optical detection system includes: establishing the star's position and luminosity; establishing the target's position, target attitude, target geometry, and target luminosity; Determine the coordinates of the star and the target on the image plane of the optical detection system; determine the illuminance of the star and the target; the coordinates of the star and the target on the image plane of the optical detection system are obtained through coordinate transformation; Determining the coordinates of the star and the target on the image plane of the optical detection system includes: in, For image pixels Axis coordinates For image pixels Axis coordinates This is the transformation matrix from image coordinates to pixel coordinates; This is the transformation matrix from camera coordinates to image coordinates. To bypass The rotation matrix of the axis. To bypass The rotation matrix of the axis. It is the azimuth angle. The pitch angle; Calculate stars, , The right ascension of a star. The declination of a star; Calculate the target, , For the target under J2000 Axis coordinates For the target under J2000 Axis coordinates For the target under J2000 Axis coordinates; A detection model is established based on the scene to be detected by the optical detection system, and the luminosity of stars and the luminosity of targets are converted into digital image grayscale values ​​DN. By removing stars, the target position and miss distance are obtained; The target is tracked based on its location and miss distance.

2. The target optical detection simulation method with stellar background according to claim 1, characterized in that: The detection model includes: a response model, a motion model, a sampling model, and a noise model; The response model is used to convert the illuminance of the target and the star into the light intensity distribution on the detector receiving surface based on the optical detection system. The motion model is used to describe the relative motion between the target and the detection system during the exposure time of the detection process, so as to adjust or compensate for the changes in light intensity distribution caused by the relative motion. The sampling model is used to sample the continuous light intensity distribution on the detector receiving surface into discrete detector pixel values, i.e., digital image grayscale values ​​DN. The noise model is used to simulate the noise introduced by the image detector during the sampling process.

3. The target optical detection simulation method with stellar background according to claim 1, characterized in that: The winding Rotation matrix of axis for: in, This is the azimuth angle.

4. The target optical detection simulation method with a stellar background according to claim 1, characterized in that: The illuminance of the star is: in, The apparent magnitude of a star. For the magnitude is The illuminance of the star, is the illuminance constant for zero magnitude stars.

5. The target optical detection simulation method with a stellar background according to claim 1, characterized in that: The illuminance of the target is: in, Illuminance for the target For the target equivalent area, The solar irradiance within the detection wavelength range. The reflectivity of the target The angle of incidence of the sun relative to the target. The observation angle of the optical detection system relative to the target. The distance between the target and the optical detection system.

6. A target optical detection simulation system with a stellar background, characterized in that, The target optical detection simulation method with stellar background described in any one of claims 1 to 5 is applied.

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