Shooting time speculation method

Abstract

The invention provides a shooting time speculation method, and relates to the technical field of shooting time speculation. Comprising the steps of obtaining to-be-speculated video data; splitting the video data to be speculated to obtain data to be corrected; performing time correction on the to-be-corrected data to obtain initial speculation data; and adjusting the shooting time in the initial speculation data frame by frame by using an effective frame rate interval to obtain a speculation result of the shooting time. According to the invention, the problem in the prior art that massive observation data cannot be effectively studied due to the fact that the time service problem of folk observation video data is not solved is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of shooting time estimation, and in particular to a shooting time estimation method. Background Art

[0002] With the popularity of SLR cameras and other optical equipment, more and more non-professionals or amateurs are photographing or broadcasting the night scene of the starry sky. There are many targeted records, such as low-orbit satellite transits, fireballs, and transient luminous events (TLEs), an optical phenomenon produced above thunderstorms and directly or indirectly induced by lightning, including red sprites, naughty sprites, giant jets, blue jets, etc. This provides a lot of research materials for further scientific research. However, amateur observations are similar to those obtained by most other civilian scientists, and there is usually no accurate recording time, even for original photos, because the camera time is difficult to keep in real-time synchronization with the network time server or GPS. However, accurate time is crucial for various experimental observations, such as fireball transit events and the search for parent lightning corresponding to TLEs, and the study of meteors, TLEs and their physical and chemical effects is of great significance to the near-space environment. There is extensive research on timing methods and technologies both at home and abroad. For example, there are timing methods that use radio waves as carriers. For scientific experimental observations, there are generally professional synchronous timing systems (such as GPS, BeiDou, etc.). However, for video data from civilian observations, the timing problem has not yet been solved, which has resulted in a large amount of observation data being shelved and unable to be effectively studied. Summary of the invention

[0003] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a method for estimating the shooting time. The present invention solves the problem that the timing problem of video data of civilian observations in the prior art has not been solved, which leads to the problem that a large amount of observation data has been shelved and cannot be effectively studied.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A method for estimating shooting time, comprising:

[0006] Obtaining video data to be inferred;

[0007] Decomposing the video data to be estimated to obtain data to be corrected;

[0008] Performing time correction on the data to be corrected to obtain initial estimated data;

[0009] The shooting time in the initial estimation data is adjusted frame by frame using the effective frame rate interval to obtain an estimation result of the shooting time.

[0010] Preferably, the step of disassembling the video data to be inferred to obtain the data to be corrected includes:

[0011] Decomposing the video data to be inferred frame by frame and marking the time of each frame in the video to obtain marked data;

[0012] A method for extracting a maximum brightness value by using image superposition is used to obtain superposition data according to the marked data;

[0013] It is determined whether star tracks and satellite tracks appear in the superimposed data, and if so, the data to be corrected is obtained.

[0014] Preferably, the step of performing time correction on the data to be corrected to obtain initial estimated data includes:

[0015] According to the star tracks, satellite tracks and the first preset software in the data to be corrected, the data to be corrected are adjusted minute by minute to obtain minute-adjusted data;

[0016] The second preset software is determined, the track data is added to the second preset software, and the minute adjustment data is adjusted second by second to obtain initial guess data.

[0017] Preferably, the adjusting the shooting time in the initial estimation data frame by frame by using the effective frame rate interval to obtain the estimation result of the shooting time includes:

[0018] Determining the simulated angle of the star track and the simulated angle of the satellite trajectory in the second preset software;

[0019] Determine the observation angle of the star track and the observation angle of the satellite track in the initial inference data;

[0020] The shooting time in the initial inference data is adjusted frame by frame using the effective frame rate interval until the current observation angle of the star track and the observation angle of the satellite trajectory are the same as the simulation angle of the star track and the simulation angle of the satellite trajectory.

[0021] The present invention discloses the following technical effects:

[0022] The present invention provides a method for estimating shooting time, comprising: obtaining video data to be estimated; disassembling the video data to be estimated to obtain data to be corrected; time-correcting the data to be corrected to obtain initial estimated data; adjusting the shooting time in the initial estimated data frame by frame using an effective frame rate interval to obtain an estimated result of the shooting time. The present invention does not require other complex transmitting or receiving devices such as radio waves and satellites. On the basis of providing relatively easy-to-obtain data such as an approximate shooting location and date, a timing accuracy of less than 500 milliseconds (related to the number of effective frames of video shooting) can be achieved. The method can be applied to relatively accurate timing systems, and at the same time, a large amount of civilian observation data will be made available for scientific research, promoting joint observations by professional scholars and amateur enthusiasts, and promoting the integrated development of astronomy, atmospheric science and enthusiast circles. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1 A flow chart of a method for estimating shooting time provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] like Figure 1 As shown, the present invention provides a method for estimating shooting time, comprising:

[0028] Step 100: Obtain video data to be estimated;

[0029] Step 200: disassembling the video data to be estimated to obtain data to be corrected;

[0030] Step 300: performing time correction on the data to be corrected to obtain initial estimated data;

[0031] Step 400: adjusting the shooting time in the initial estimation data frame by frame using the effective frame rate interval to obtain an estimation result of the shooting time.

[0032] Specifically, this embodiment takes 2 videos as an example:

[0033] The first video A has an effective frame interval of 0.16s, and the second video B has an effective frame interval of 0.04s. The effective observation times of A are 32 minutes and 53 seconds and 57 minutes and 8 seconds respectively. Both videos contain twinkling stars and visible motion tracks of low-Earth orbit (LEO) satellites.

[0034] Furthermore, the step of disassembling the video data to be estimated to obtain the data to be corrected includes:

[0035] Decomposing the video data to be inferred frame by frame and marking the time of each frame in the video to obtain marked data;

[0036] A method for extracting a maximum brightness value by using image superposition is used to obtain superposition data according to the marked data;

[0037] It is determined whether star tracks and satellite tracks appear in the superimposed data, and if so, the data to be corrected is obtained.

[0038] Specifically, the two videos were disassembled frame by frame, and the time of each frame in the video was marked. The maximum brightness value was extracted through the image stack to determine whether star tracks and obvious satellite motion tracks appeared, identify whether they were satellite tracks, and eliminate meteors and other aircraft tracks (based on duration, flickering status, etc.).

[0039] Furthermore, the time correction of the data to be corrected to obtain initial estimated data includes:

[0040] According to the star tracks, satellite tracks and the first preset software in the data to be corrected, the data to be corrected are adjusted minute by minute to obtain minute-adjusted data;

[0041] Specifically, according to the positional relationship between the landscape and constellations, and between constellations in the video (because the two positional relationships are only related to time), Videos A and B use the constellations of Capricornus and Vela. The open software Stellarium (based on the DE430 ephemeris) is used to adjust the time so that the azimuth and altitude of the constellation of interest are basically consistent with the azimuth and altitude of the same constellation in the video. This time (point) can be used as the initial reference time of step 3 to narrow the time retrieval range.

[0042] The second preset software is determined, the track data is added to the second preset software, and the minute adjustment data is adjusted second by second to obtain initial guess data.

[0043] Specifically, add two lines of orbital data (Two Line Elements) to the software Stellarium, and add it directly in the artificial satellite module of the software. The software not only displays the star field and satellite motion, but also estimates the brightness (i.e., magnitude) of the satellite based on the reflection model and the position of the sun. By manually adjusting the time of Stellarium second by second to match the motion trajectory of the artificial satellite and the background star field similar to the video, it can be clearly seen that the video observation and the software simulation are almost completely consistent. The time error obtained is about a few seconds, further narrowing the time range.

[0044] Furthermore, the using of the effective frame rate interval to adjust the shooting time in the initial estimation data frame by frame to obtain the estimation result of the shooting time includes:

[0045] Determining the simulated angle of the star track and the simulated angle of the satellite trajectory in the second preset software;

[0046] Determine the observation angle of the star track and the observation angle of the satellite track in the initial inference data;

[0047] The shooting time in the initial inference data is adjusted frame by frame using the effective frame rate interval until the current observation angle of the star track and the observation angle of the satellite trajectory are the same as the simulation angle of the star track and the simulation angle of the satellite trajectory.

[0048] Specifically, Skyfield, a high-precision Python astronomical computing library based on the Simplified General Perturbations 4 (SGP4) model, is used to draw the star field and satellite motion tracks of a shorter time (4 seconds in both A and B) according to the effective frame interval resolution of the video. The angle α between the start and end of the 4-second track of the satellite Okean-O (NORD: 25860) in video A is exactly the same as the angle calculated using the Stellarium star field, and other stars or other video clips containing satellite tracks can be used for experiments with consistent results. For video B, although the horizontal angle of the shooting is adjusted by about 2° and there may be slight distortion at the edge of the wide-angle field of view, since the local distortion is always consistent, this does not affect the relative angle in a small range. Using the angle formed by the satellite track and the nearby bright stars as a reference for time correction can avoid errors caused by lens distortion and jitter. In video B, the 4-second track of the satellite DELTA 1R / B (1) (NORD: 10062) and the β angle with HIP53740 are consistent with the model-based drawing. By adjusting the time frame by frame according to the effective frame rate interval (i.e., 0.16 seconds and 0.04 seconds) (Video A is adjusted in steps of 0.16 seconds, and Video B is adjusted in steps of 0.04 seconds), the observed and simulated angles are completely consistent, and a relatively perfect reference time can be obtained, with an estimated error of less than 500 milliseconds (approximately the time span of 3 frames in Video A, and the error of Video B should be smaller because of the higher effective frame rate). If this time period is exceeded, the relative position and angle of the star field and the satellite track will change significantly. In addition, the distance between the satellite and the camera is 1000 to 3000 kilometers, and the transmission time of light is less than 10 milliseconds, which is much smaller than the frame interval, so the delay error caused by light propagation can be ignored. This method uses the relative angle between the local stars and the satellite track, while the atmospheric refractive index remains basically consistent.

[0049] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0050] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for estimating shooting time, characterized in that: include: Obtaining video data to be inferred; Decomposing the video data to be estimated to obtain data to be corrected; Performing time correction on the data to be corrected to obtain initial estimated data; The shooting time in the initial estimation data is adjusted frame by frame using the effective frame rate interval to obtain an estimation result of the shooting time.

2. A method for estimating shooting time according to claim 1, characterized in that: The step of disassembling the video data to be estimated to obtain the data to be corrected includes: Decomposing the video data to be inferred frame by frame and marking the time of each frame in the video to obtain marked data; A method for extracting a maximum brightness value by using image superposition is used to obtain superposition data according to the marked data; It is determined whether star tracks and satellite tracks appear in the superimposed data, and if so, the data to be corrected is obtained.

3. The method for estimating shooting time according to claim 1, characterized in that: The step of performing time correction on the data to be corrected to obtain initial estimated data includes: According to the star tracks, satellite tracks and the first preset software in the data to be corrected, the data to be corrected are adjusted minute by minute to obtain minute-adjusted data; The second preset software is determined, the track data is added to the second preset software, and the minute adjustment data is adjusted second by second to obtain initial guess data.

4. The method for estimating shooting time according to claim 1, characterized in that: The step of adjusting the shooting time in the initial estimation data frame by frame by using the effective frame rate interval to obtain an estimation result of the shooting time includes: Determining the simulated angle of the star track and the simulated angle of the satellite trajectory in the second preset software; Determine the observation angle of the star track and the observation angle of the satellite track in the initial inference data; The shooting time in the initial inference data is adjusted frame by frame using the effective frame rate interval until the current observation angle of the star track and the observation angle of the satellite trajectory are the same as the simulation angle of the star track and the simulation angle of the satellite trajectory.

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