Optical detection image fixed star discrimination method based on dimension transformation

Abstract

The invention relates to an optical detection image fixed star discrimination method based on dimension transformation, and the method comprises the following steps: obtaining an optical detection image at a moment k, and determining a three-dimensional pointing position of a target in a sensor coordinate system; based on the three-dimensional pointing position of the target in the sensor coordinate system, determining the three-dimensional pointing position of the target in the orbital coordinate system; based on the three-dimensional pointing position of the target in the orbital coordinate system, determining the three-dimensional pointing position of the target in the earth inertial coordinate system; repeating the steps to obtain the three-dimensional pointing position of the target in the earth inertial coordinate system at the sequence moments of k + 1, k + 2...; and judging whether the target is a fixed star or not based on the three-dimensional pointing positions of the target in the earth inertial coordinate system at the multiple moments. According to the method, the fixed star track can be effectively judged under the condition of no fixed star catalogue.

Description

Technical Field

[0001] The present invention relates to the field of target detection technology, and in particular to a star discrimination method of an optical detection image based on dimensional transformation. Background Art

[0002] In the field of modern optical detection, especially in the detection of space targets such as satellites in deep space, accurate target confirmation is crucial. Optical detection systems mostly use point targets as detection objects, and their main basis is the motion trajectory formed by the target in the sequence image. By analyzing these motion trajectories, the target can be confirmed and the interference source can be eliminated at the same time. This technology provides an important means for space target detection.

[0003] However, when the detection environment is set against the background of deep space, the situation becomes complicated. In this environment, stars become an interference factor that cannot be ignored in the target confirmation process. Stars also form motion trajectories in the sequence images obtained by the optical detection system. These trajectories are similar to the motion trajectories of space targets in visual characteristics, which greatly interferes with the target confirmation work.

[0004] At present, in order to deal with the problem of stellar interference, it is first necessary to determine which targets are stars. The commonly used method is to confirm them based on the star catalog. The star catalog is a collection of known star information, which contains key parameters such as the position and brightness of the star. This method can help distinguish stars from targets to a certain extent. By comparing the detected point targets with the information in the star catalog, the points that meet the characteristics of stars are eliminated from the target candidates. However, this method has obvious shortcomings. With the continuous development of astronomy, there are still a large number of stars in the universe that have not yet been discovered and included. For these stars that have not yet been included in the star catalog, the judgment method based on the star catalog has lost its effect and cannot effectively distinguish them from the real targets. This seriously affects the accuracy and reliability of the optical detection system in confirming space targets, and restricts the further development of optical detection technology in the field of deep space target detection. Summary of the invention

[0005] In order to solve the technical problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a star identification method for optical detection images based on dimensional transformation, which can achieve accurate judgment of stars in the absence of a star catalog.

[0006] To achieve the above-mentioned object of the invention, the present invention provides a method for distinguishing stars from optical detection images based on dimensionality transformation, comprising the following steps:

[0007] Step S1, obtaining an optical detection image at time k, and determining the three-dimensional pointing position of the target in the sensor coordinate system;

[0008] Step S2, determining the three-dimensional pointing position of the target in the track coordinate system based on the three-dimensional pointing position of the target in the sensor coordinate system;

[0009] Step S3, determining the three-dimensional pointing position of the target in the Earth's inertial coordinate system based on the three-dimensional pointing position of the target in the orbital coordinate system;

[0010] Step S4, repeatedly executing the steps S1 to S3 to obtain the three-dimensional pointing position of the target in the earth's inertial coordinate system at the sequence time k+1, k+2...;

[0011] Step S5: Based on the three-dimensional pointing position of the target in the Earth's inertial coordinate system at multiple moments, determine whether the target is a star.

[0012] According to a technical solution of the present invention, the step S1 specifically includes:

[0013] Step S11: Obtain the optical detection image at time k, assuming that the position coordinate of the target at time k in the detection image of the optical detection system is r foc,k =(x foc,k ,y foc,k ) T ;

[0014] Step S12: based on the position coordinate r of the target in the image detected by the optical detection system at time k foc,k , calculate the three-dimensional pointing position r of the target in the sensor coordinate system sen,k , the formula is:

[0015]

[0016] Where f is the focal length of the optical system, d foc is the pixel size; and ||r sen ||-1.

[0017] According to a technical solution of the present invention, in step S2, the three-dimensional pointing position r of the target in the orbital coordinate system is obit,k It is expressed as:

[0018]

[0019] in, θ k , k They represent the roll angle, pitch angle and yaw angle of the satellite attitude at time k respectively; R X (·), R Y (·), R Z (·) represent the rotation matrices around the X, Y and Z axes respectively,

[0020]

[0021] According to a technical solution of the present invention, in step S3, the three-dimensional pointing position r of the target in the earth's inertial coordinate system is calculated. eci,k It is expressed as:

[0022]

[0023] Among them, ||r eci,k ||=1, that is cos(α 1,k ), cos(β 1,k ), cos(γ 1,k ) are the orbital coordinate system X at time k orb Axis and the Earth's inertial coordinate system X eci Axis, Y eci Axis and Z eci The cosine of the angle between the axes, cos(α 2,k ), cos(β 2,k ), cos(γ 2,k ) are the orbital coordinate system Y at time k orb Axis and the Earth's inertial coordinate system X eci Axis, Y eci Axis and Z eci The cosine of the angle between the axes, cos(α 3,k ), cos(β 3,k ), cos(γ 3,k ) are the orbital coordinate system Z at time k orb Axis and the Earth's inertial coordinate system X eci Axis, Y eci Axis and Z eci The cosine of the angle between the axes.

[0024] According to a technical solution of the present invention, the step S5 specifically includes:

[0025] Compare eci,k 、r eci,k+1 、r eci,k+2 ...relationship, when r eci,k =r eci,k+1 =r eci,k+2 =......, it is determined that the target is a star.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention proposes a star discrimination method for optical detection images based on dimensional transformation. By converting the two-dimensional position of the target in the detection image into a three-dimensional pointing position in the Earth's inertial coordinate system, the three-dimensional pointing position of the star in the Earth's inertial coordinate system is kept constant for a short time. In the absence of a star catalog, effective judgment of the star trajectory is achieved, thereby ensuring the accuracy and reliability of the optical detection system in confirming space targets, and facilitating the further development of optical detection technology in the field of deep space target detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 A flowchart schematically showing a method for identifying stars in an optical detection image based on dimensional transformation according to an embodiment of the present invention;

[0030] Figure 2 The target trajectory in the detection image (image plane coordinate system) before transformation according to one embodiment of the present invention is schematically shown;

[0031] Figure 3 Schematically showing the transformed XOY plane target position trajectory of the earth inertial coordinate system according to one embodiment of the present invention;

[0032] Figure 4 Schematically showing the transformed XOZ plane target position trajectory of the earth inertial coordinate system according to one embodiment of the present invention;

[0033] Figure 5 The transformed YOZ plane target position trajectory of the earth inertial coordinate system according to one embodiment of the present invention is schematically shown. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] like Figure 1As shown, a star identification method of an optical detection image based on dimensional transformation of the present invention comprises the following steps:

[0036] Step S1, obtaining an optical detection image at time k, and determining the three-dimensional pointing position of the target in the sensor coordinate system, specifically includes:

[0037] Step S11: Obtain the optical detection image at time k, assuming that the position coordinate of the target at time k in the detection image of the optical detection system is r foc,k =(x foc,k ,y foc,k ) T ;

[0038] Step S12: based on the position coordinate r of the target in the image detected by the optical detection system at time k foc,k , calculate the three-dimensional pointing position r of the target in the sensor coordinate system sen,k , the formula is:

[0039]

[0040] Where f is the focal length of the optical system, d foc is the pixel size; and ||r sen ||=1.

[0041] Step S2: Determine the three-dimensional pointing position r of the target in the track coordinate system based on the three-dimensional pointing position of the target in the sensor coordinate system. obit,k It is expressed as:

[0042]

[0043] in, θ k , k They represent the roll angle, pitch angle and yaw angle of the satellite attitude at time k respectively; R X (·), R Y (·), R Z (·) represent the rotation matrices around the X, Y and Z axes respectively,

[0044]

[0045] Step S3: Determine the three-dimensional pointing position r of the target in the Earth's inertial coordinate system based on the three-dimensional pointing position of the target in the orbital coordinate system. eci,k It is expressed as:

[0046]

[0047] Among them, ||r eci,k ||=1, that is cos(α1,k ), cos(β 1,k ), cos(γ 1,k ) are the orbital coordinate system X at time k orb Axis and the Earth's inertial coordinate system X eci Axis, Y eci Axis and Z eci The cosine of the angle between the axes, cos(α 2,k ), cos(β 2,k ), cos(γ 2,k ) are the orbital coordinate system Y at time k orb Axis and the Earth's inertial coordinate system X eci Axis, Y eci Axis and Z eci The cosine of the angle between the axes, cos(α 3,k ), cos(β 3,k ), cos(γ 3,k ) are the orbital coordinate system Z at time k orb Axis and the Earth's inertial coordinate system X eci Axis, Y eci Axis and Z eci The cosine of the angle between the axes.

[0048] Step S4, repeating the steps S1 to S3, according to the position coordinates of the target (space target or star) in the image detected by the optical detection system at time k+1 as r foc,k+1 =(x foc,k+1 ,y foc,k+1 ) T , then the corresponding position coordinate at time k+2 is r foc,k+2 =(x foc,k+2 ,y foc,k+2 ) T , get the three-dimensional pointing position of the target in the Earth's inertial coordinate system at the time sequence k+1, k+2...;

[0049] Step S5, judging whether the target is a star based on the three-dimensional pointing position of the target in the Earth's inertial coordinate system at multiple moments, specifically includes:

[0050] Compare eci,k 、r eci,k+1 、r eci,k+2 ...relationship, when r eci,k =r eci,k+1 =r eci,k+2 =......, it is determined that the target is a star.

[0051] Since the three-dimensional pointing position of a star in the Earth's inertial coordinate system remains constant over time, while the three-dimensional pointing position of a space target in the Earth's inertial coordinate system changes over time, by comparing the changes in the three-dimensional pointing position of the target in the Earth's inertial coordinate system at sequential moments such as k, k+1, k+2, ..., effective judgment of the stars in the detected image can be achieved without the support of a star catalog.

[0052] The following takes a low-orbit satellite operating at an altitude of 1,200 kilometers as an example.

[0053] The detection targets include 3 stars and 3 space targets. Figure 2 In the detection image (image plane coordinate system) shown in the figure, there are 6 target tracks; after dimensional transformation, Figures 3 to 5 As shown, the positions of the three stars remain unchanged, but are significantly different from the trajectories of the three space targets, so the star trajectories can be quickly eliminated without the support of a star catalog.

[0054] The present invention discloses a method for distinguishing stars from optical detection images based on dimensional transformation, comprising the following steps: obtaining an optical detection image at time k, determining the three-dimensional pointing position of a target in a sensor coordinate system; determining the three-dimensional pointing position of a target in an orbital coordinate system based on the three-dimensional pointing position of the target in the sensor coordinate system; determining the three-dimensional pointing position of a target in an earth inertial coordinate system based on the three-dimensional pointing position of the target in the orbital coordinate system; repeating the above steps to obtain the three-dimensional pointing position of the target in the earth inertial coordinate system at sequential times k+1, k+2, etc.; judging whether the target is a star based on the three-dimensional pointing position of the target in the earth inertial coordinate system at multiple times. The present invention realizes effective judgment of star trajectories without a star catalog, ensures the accuracy and reliability of the optical detection system in confirming space targets, and is conducive to the further development of optical detection technology in the field of deep space target detection.

[0055] It should be noted that although the embodiments of the present invention described above are illustrative, they are not intended to limit the present invention, and therefore the present invention is not limited to the above specific embodiments. Without departing from the principles of the present invention, any other embodiments obtained by those skilled in the art under the guidance of the present invention are deemed to be within the protection of the present invention.

Claims

1. A method for identifying stars in optical detection images based on dimensionality transformation, characterized in that: The following steps are involved: Step S1, obtaining an optical detection image at time k, and determining the three-dimensional pointing position of the target in the sensor coordinate system; Step S2, determining the three-dimensional pointing position of the target in the track coordinate system based on the three-dimensional pointing position of the target in the sensor coordinate system; Step S3, determining the three-dimensional pointing position of the target in the Earth's inertial coordinate system based on the three-dimensional pointing position of the target in the orbital coordinate system; Step S4, repeatedly executing the steps S1 to S3 to obtain the three-dimensional pointing position of the target in the earth's inertial coordinate system at the sequence time k+1, k+2...; Step S5: Based on the three-dimensional pointing position of the target in the Earth's inertial coordinate system at multiple moments, determine whether the target is a star.

2. The method for identifying stars in optical detection images based on dimensional transformation according to claim 1, characterized in that: The step S1 specifically includes: Step S11, obtain the optical detection image at time k, and assume that the position coordinates of the target in the detection image of the optical detection system at time k are Step S12: based on the position coordinate r of the target in the image detected by the optical detection system at time k foc,k , calculate the three-dimensional pointing position r of the target in the sensor coordinate system sen，k , the formula is: Where f is the focal length of the optical system, d foc is the pixel size; and ||r sen ||=1.

3. The method for identifying stars in optical detection images based on dimensional transformation according to claim 2, characterized in that: In step S2, the three-dimensional pointing position r of the target in the orbital coordinate system obi,k It is expressed as: in, θ k , k They represent the roll angle, pitch angle and yaw angle of the satellite attitude at time k respectively; R X (·), R Y (·), R Z (·) represent the rotation matrices around the X, Y and z axes respectively, 4. The method for identifying stars in optical detection images based on dimensional transformation according to claim 3, characterized in that: In step S3, the three-dimensional pointing position r of the target in the earth's inertial coordinate system is calculated. eci，k It is expressed as: Among them, ||r eci，t ||=1, that is cos(α 1，k ), cos(β 1，k ), cos(γ 1，k ) are the orbital coordinate system X at time k orb Axis and the Earth's inertial coordinate system X eci Axis, Y eci Axis and Z eci The cosine of the angle between the axes, cos(α 2，k ), cos(β 2，k ), cos(γ 2，k ) are the orbital coordinate system Y at time k orb Axis and the Earth's inertial coordinate system X eci Axis, Y eci Axis and Z eci The cosine of the angle between the axes, cos(α 3，k ), cos(β 3，k ), cos(γ 3，k ) are the orbital coordinate system Z at time k orb Axis and the Earth's inertial coordinate system X eci Axis, Y eci Axis and Z eci The cosine of the angle between the axes.

5. The method for identifying stars in optical detection images based on dimensional transformation according to claim 3, characterized in that: The step S5 specifically includes: Compare eci，k 、r eci，k+1 、r eci,k+2 ...relationship, when r eci，k =r eci,k+1 =r eci,k+2 =……, it is determined that the target is a star.

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