阅读说明：本技术 一种视频流星检测和航迹分析方法 (Video meteor detection and track analysis method ) 是由 张静 李彦志 于 2020-12-30 设计创作，主要内容包括：一种视频流星检测和航迹分析方法。是为了解决空间覆盖范围和角度分辨率的角度来看是有益的,但较大的图像尺寸却给处理工作带来了压力,摩尔定律以及采用更大容量的CPU都部分抵消了计算问题,但这在多相机系统中可能会受到限制的问题。本发明包括如下步骤：对流星进行识别；前沿位置的细化；流星检测；使用恒定或指数动态速度模型,计算集合中剩余聚合轨迹的轨迹解,在给定单个轨迹解决方案的情况下,通过在所有投影轨道之间执行三维共对准和共线性测试,使分析人员复查步骤自动化,从而消除HIL；大气轨迹估计。本发明用于视频流星检测和航迹分析。(A video meteor detection and track analysis method. It is beneficial from the perspective of spatial coverage and angular resolution, but the larger image size puts pressure on the processing effort, moore's law and the use of larger CPUs partially offset the computational problem, which may be limited in a multi-camera system. The invention comprises the following steps: identifying the meteor; refining the position of the front edge; meteor detection; using a constant or exponential dynamic velocity model, computing a trajectory solution for the remaining aggregated trajectories in the set, and automating analyst review steps by performing three-dimensional co-alignment and co-linearity tests among all projection trajectories given a single trajectory solution, thereby eliminating HIL; and (4) estimating an atmospheric track. The method is used for video meteor detection and track analysis.)

1. A video meteor detection and track analysis method is characterized by comprising the following steps:

(1) identifying the meteor;

(2) refining the position of the front edge;

once meteor is detected, the position of the orbit needs to be measured as a function of time in focal plane coordinates. The measurement of the rows and columns is converted into inertia coordinates later for track estimation, a simpler measurement method is to estimate the mass center of a meteor line segment in a frame, but because the change of meteor intensity during frame acquisition or the obvious trail behind the meteor and the long-time comet tail can generate deviation, a better method is to estimate the front edge position of the meteor by using a point spread function of an imaging system;

(3) meteor detection;

using a constant or exponential dynamic velocity model, computing a trajectory solution for the remaining aggregated trajectories in the set, and automating analyst review steps by performing three-dimensional co-alignment and co-linearity tests among all projection trajectories given a single trajectory solution, thereby eliminating HIL;

(4) estimating an atmospheric track;

the particle swarm optimizer attempts to minimize the angular separation of the measurement rays along the radial direction from the linear trajectory solution and minimize the misalignment between the measurements pointing from each camera to multiple points along the unwrapped 3D trajectory to optimize the velocity portion of the solution.

2. The video meteor detection and flight path analysis method according to claim 1, wherein the specific process of the step (2) is as follows: to improve the estimation of the leading edge pickup point, after the meteor streak is found, the initial position and velocity state vector is perturbed using a particle swarm optimizer, and the maximum likelihood estimation of the matched filter is used as shown in the formula:

MLE＝log₁₀{0.5∑[(s-<s>)R^-1T^t]²/∑TR^-1T^t} (1)

adding a simple acceleration term scaled by the projection velocity vector, which improves both effects to the level of human accuracy when selecting the leading edge position, mathematical expressions for motion are given in equations (2) and (3) for the X-column and Y-column coordinates of the focal plane, respectively, where X is₀，y₀，V_x，V_yAnd A is the five MF fitting coefficients, time t is the time relative to the starting position (X0, Y0), and is

X＝X₀+V_xt+(V_x/V)At²/2 (2)

Y＝Y₀+V_yt+(V_y/V)At²/2 (3)

An estimate is generated using a two-dimensional gaussian point spread function that is convolved with the MF line segment motion assumption across the focal plane and takes into account the intensity variation of the meteor trajectory from one frame to the next, assuming a fixed intensity model frame that captures the light curve characteristics of most meteors at the video rate of 17 frames per second used by EMCCD systems and does not match only the case of extreme meteor bursts during the frame, in which rare cases the average intensity during the frame must be sufficient, otherwise an intra-frame flare model would need to be introduced, thereby increasing the size of the matched filter assembly.

3. The video meteor detection and flight path analysis method according to claim 2, wherein the specific process of the step (3) is as follows: using a constant or exponential dynamic velocity model, computing a trajectory solution for the remaining aggregated trajectories in the set, and automating analyst review steps by performing three-dimensional co-alignment and co-linearity tests among all projection trajectories given a single trajectory solution, thereby eliminating HIL; constraints are specified by the user, with typical values being a maximum of 3 degrees for the track crossing angle, 0.5km offset between tracks, similar to how a human reviewer visually screens good tracks, to find highly overlapping projected measurement maps that are coded in latitude/longitude and altitude/lower limits, and color-coded for each station's track, and final tests are performed to ensure that the starting altitude is below the ending altitude, which can be relaxed in the very rare predator meteor scenario.

4. The video meteor detection and flight path analysis method according to claim 3, wherein the specific process of the step (4) is as follows: and (3) adopting a strategy of dynamically and adaptively changing the inertia weight:

in the formula (3) -formula (5)The corresponding objective function value for the ith particle at the kth iteration,calculating a for the corresponding objective function value of the optimal particle in the k iteration^kThe index is used for judging the flatness of the target function in the k iteration, and a is obtained in each iteration^kThe objective function values obtained by the indexes are changed so that the inertia weight w becomes w dynamically changed with the change of the search position^k。

5. The video meteor detection and track analysis method of claim 4 wherein the camera used in step (1) is an electron multiplying CCD camera, the trained CNN is used as an upstream meteor detector on the captured video image, matched filtering or template matching is used, and the EMCCD processing pipeline uses an upstream detector.

Technical Field

The invention relates to a video meteor detection and track analysis method.

Background

The processing flow of video meteor detection and track analysis has been developed to include several new algorithms that improve the efficiency and performance of each step in the meteor image processing chain. With the advent of larger pixel digital sensors, image processing techniques not only required the use of high-end processors, but also required the development of faster threshold, clustering, and tracking algorithms to detect to accommodate the computational load.

Meteor imaging communities have begun migrating to millions of pixels, line-by-line scanning digital sensors, and have migrated from traditional analog cameras with fewer than 50 thousand pixels per frame. Although this is beneficial from the point of view of reduced noise, image quality, higher bit depth, spatial coverage and angular resolution, the larger image size puts pressure on the processing effort. For example, the number of pixels of a full High Definition (HD)1080p image is about six times the number of pixels of NTSC or PAL video. Moore's law and the use of larger CPUs partially offset the computational problem, but this may be limited in multi-camera systems without resorting to costly PC systems or custom GPU implementations. In addition, the advent of an innovative meteor collection system tracking meteors for fragmentation studies and spectroscopy requires real-time response to these transient events, re-examining the entire image processing chain to improve computational efficiency, while also maintaining detection and analysis robustness.

Disclosure of Invention

In order to solve the defects in the prior art, the invention aims to provide a device for trimming the stem tip before the mature corn planting, so as to overcome the defects in the prior art.

In order to achieve the above object, the present invention provides a video meteor detection and track analysis method, which comprises the following steps:

(1) identifying the meteor;

(2) refining the position of the front edge;

once meteor is detected, the position of the orbit needs to be measured as a function of time in focal plane coordinates. These row and column measurements will be later converted to inertial coordinates for trajectory estimation. The simpler measurement method is to estimate the centroid of the meteor line segment in the frame, but because the change of meteor intensity during the frame acquisition or the obvious trail behind the meteor and the long-time comet tail can generate deviation, a better method is to estimate the front edge position of the meteor by using the point spread function of the imaging system;

(3) meteor detection;

using a constant or exponential dynamic velocity model, computing a trajectory solution for the remaining aggregated trajectories in the set, and automating analyst review steps by performing three-dimensional co-alignment and co-linearity tests among all projection trajectories given a single trajectory solution, thereby eliminating HIL;

(4) estimating an atmospheric track;

the particle swarm optimizer attempts to minimize the angular separation of the measurement rays along the radial direction from the linear trajectory solution and minimize the misalignment between the measurements pointing from each camera to multiple points along the unwrapped 3D trajectory to optimize the velocity portion of the solution.

The video meteor detection and track analysis method comprises the following specific processes in the step (2): to improve the estimation of the leading edge pickup point, after the meteor streak is found, the initial position and velocity state vector is perturbed using a particle swarm optimizer, and the maximum likelihood estimation of the matched filter is used as shown in the formula:

MLE＝log₁₀{0.5∑[(s-<s>)R^-1T^t]²/∑TR^-1T^t} (1)

adding a simple acceleration term scaled by the projection velocity vector, which improves both effects to the level of human accuracy when selecting the leading edge position, mathematical expressions for motion are given in equations (2) and (3) for the X-column and Y-column coordinates of the focal plane, respectively, where X is₀，y₀，V_x，V_yAnd a is the five MF fitting coefficients, time t is the time relative to the starting position (X0, Y0) and is V1/4sqrt (Vx ×)*Vy)。

X＝X₀+V_xt+(V_x/V)At²/2 (2)

Y＝Y₀+V_yt+(V_y/V)At²/2 (3)

An estimate is generated using a two-dimensional gaussian point spread function that is convolved with the MF line segment motion assumption across the focal plane and takes into account the intensity variation of the meteor trajectory from one frame to the next, assuming a fixed intensity model frame that captures the light curve characteristics of most meteors at the video rate of 17 frames per second used by EMCCD systems and does not match only the case of extreme meteor bursts during the frame, in which rare cases the average intensity during the frame must be sufficient, otherwise an intra-frame flare model would need to be introduced, thereby increasing the size of the matched filter assembly.

The video meteor detection and track analysis method comprises the following specific processes in the step (3): using a constant or exponential dynamic velocity model, computing a trajectory solution for the remaining aggregated trajectories in the set, and automating analyst review steps by performing three-dimensional co-alignment and co-linearity tests among all projection trajectories given a single trajectory solution, thereby eliminating HIL; constraints are specified by the user, with typical values being a maximum of 3 degrees for the track crossing angle, 0.5km offset between tracks, similar to how a human reviewer visually screens good tracks, to find highly overlapping projected measurement maps that are coded in latitude/longitude and altitude/lower limits, and color-coded for each station's track, and final tests are performed to ensure that the starting altitude is below the ending altitude, which can be relaxed in the very rare predator meteor scenario.

The video meteor detection and track analysis method comprises the following specific processes in the step (4): and (3) adopting a strategy of dynamically and adaptively changing the inertia weight:

in the formula (3) -formula (5)The corresponding objective function value for the ith particle at the kth iteration,calculating a for the corresponding objective function value of the optimal particle in the k iteration^kThe index is used for judging the flatness of the target function in the k iteration, and a is obtained in each iteration^kThe objective function values obtained by the indexes are changed so that the inertia weight w becomes w dynamically changed with the change of the search position^k。

The video meteor detection and track analysis method is characterized in that the camera adopted in the step (1) takes an electron multiplication charge-coupled device as a camera, a trained CNN is taken as an upstream meteor detector on an shot video image, matched filtering or template matching is used, and an upstream detector is adopted in an EMCCD processing pipeline.

The invention has the beneficial effects that:

1. the invention uses a small image chip centered on the meteor track to train and test on maxpixel because the upstream detector will indicate the position of the meteor in a larger field of view and important features can be spatially located. CNN extracted 20,000 meteors and false alarms for post-training independent testing with 99.94% recall for post-CAMS spatiotemporal images using upstream cluster/tracker detectors.

2. The present machine learning approach employing cyclic and convolutional deep neural networks has helped eliminate the "human-in-the-loop false alarm mitigation" step inherent in many meteor collection process flows. The application of the matched filtering algorithm helps to improve the accuracy of the measured position of the propagation meteor orbit for post-detection analysis. The use of improved multi-site track aggregation greatly reduces the occurrence of unrelated tracks that are not correlated in the process of combining into a single track. This results in a better meteor orbit solution when an improved minimization metric is incorporated in the multi-parameter fitting method of trajectory estimation. Finally, the concept proposed in using convolutional neural networks as meteor detectors and performing trajectory fitting through empirical propagation models suggests that more powerful meteor image processing and analysis is expected to be achieved in the near future.

Drawings

FIG. 1 is a diagram illustrating the fast integer indexing algorithm of the present invention accumulating clusters of excess pixels into NxN cells;

FIG. 2 is a plot of orbital parameters estimating eccentricity and geocentric velocity of a track;

FIG. 3 is a diagram of a meteor trail taken by a camera;

Detailed Description

To further understand the structure, characteristics and other objects of the present invention, the following detailed description is given with reference to the accompanying preferred embodiments, which are only used to illustrate the technical solutions of the present invention and are not to limit the present invention.

In a first specific embodiment, a method for video meteor detection and track analysis in this embodiment includes the following steps:

(1) identifying the meteor;

(2) refining the position of the front edge;

once meteor is detected, the position of the orbit needs to be measured as a function of time (number of frames) in the focal plane coordinates, and these row and column measurements will be later converted to inertial coordinates for trajectory estimation. The simpler measurement method is to estimate the centroid of the meteor line segment in the frame, but because the change of meteor intensity during the frame acquisition or the obvious trail behind the meteor and the long-time comet tail can generate deviation, a better method is to estimate the front edge position of the meteor by using the point spread function of the imaging system;

(3) meteor detection;

using a constant or exponential dynamic velocity model, computing a trajectory solution for the remaining aggregated trajectories in the set, and automating analyst review steps by performing three-dimensional co-alignment and co-linearity tests among all projection trajectories given a single trajectory solution, thereby eliminating HIL;

(4) estimating an atmospheric track;

the particle swarm optimizer attempts to minimize the angular separation of the measurement rays along the radial direction from the linear trajectory solution and minimize the misalignment between the measurements pointing from each camera to multiple points along the unwrapped 3D trajectory to optimize the velocity portion of the solution.

In a second embodiment, the present embodiment is a further description of the video meteor detection and flight path analysis method in the first embodiment, and the specific process of the step (2) is as follows: to improve the estimation of the leading edge pickup point, after the meteor streak is found, the initial position and velocity state vector is perturbed using a particle swarm optimizer, and the maximum likelihood estimation of the matched filter is used as shown in the formula:

MLE＝log₁₀{0.5∑[(s-<s>)R^-1T^t]²/∑TR^-1T^t} (1)

adding a simple acceleration term scaled by the projection velocity vector, which improves both effects to the level of human accuracy when selecting the leading edge position, mathematical expressions for motion are given in equations (2) and (3) for the X-column and Y-column coordinates of the focal plane, respectively, where X is₀，y₀，V_x，V_yAnd a is the five MF fitting coefficients, time t is the time relative to the starting position (X0, Y0) and is V1/4sqrt (Vx ×)*Vy)。

X＝X₀+V_xt+(V_x/V)At²/2 (2)

Y＝Y₀+V_yt+(V_y/V)At²/2 (3)

An estimate is generated using a two-dimensional gaussian point spread function that is convolved with the MF line segment motion assumption across the focal plane and takes into account the intensity variation of the meteor trajectory from one frame to the next, assuming a fixed intensity model frame that captures the light curve characteristics of most meteors at the video rate of 17 frames per second used by EMCCD systems and does not match only the case of extreme meteor bursts during the frame, in which rare cases the average intensity during the frame must be sufficient, otherwise an intra-frame flare model would need to be introduced, thereby increasing the size of the matched filter assembly.

In a third specific embodiment, the present embodiment is a further description of the video meteor detection and flight path analysis method in the first specific embodiment, and the specific process of step (3) is as follows: using a constant or exponential dynamic velocity model, computing a trajectory solution for the remaining aggregated trajectories in the set, and automating analyst review steps by performing three-dimensional co-alignment and co-linearity tests among all projection trajectories given a single trajectory solution, thereby eliminating HIL; constraints are specified by the user, with typical values being a maximum of 3 degrees for the track crossing angle, 0.5km offset between tracks, similar to the way a human reviewer visually screens good tracks, to find highly overlapping projected measurement maps that are coded in latitude/longitude and altitude/lower limits, and color coded for each station's track, a final test being performed to ensure that the starting altitude is below the ending altitude. Can relax in the rare case of skimming.

In a fourth specific embodiment, the present embodiment is a further description of the video meteor detection and flight path analysis method in the first specific embodiment, and the specific process of step (4) is as follows: and (3) adopting a strategy of dynamically and adaptively changing the inertia weight:

in the formula (3) -formula (5)The corresponding objective function value for the ith particle at the kth iteration,calculating a for the corresponding objective function value of the optimal particle in the k iteration^kThe index is used for judging the flatness of the target function in the k iteration, and a is obtained in each iteration^kThe objective function values obtained by the indexes are changed so that the inertia weight w becomes w dynamically changed with the change of the search position^k。

In a fifth embodiment, the present embodiment is a further description of the video meteor detection and flight path analysis method described in the first embodiment, the camera used in step (1) uses an electron multiplying charge coupled device as a camera, the trained CNN is used as an upstream meteor detector on the captured video image, matched filtering or template matching is used, and an upstream detector is used in the EMCCD processing pipeline.

It should be noted that the above summary and the detailed description are intended to demonstrate the practical application of the technical solutions provided by the present invention, and should not be construed as limiting the scope of the present invention. Various modifications, equivalent substitutions, or improvements may be made by those skilled in the art within the spirit and principles of the invention. The scope of the invention is to be determined by the appended claims.