CN115061220A - Day and night dual-purpose atmospheric turbulence parameter estimation method based on optical flow calculation - Google Patents
Day and night dual-purpose atmospheric turbulence parameter estimation method based on optical flow calculation Download PDFInfo
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Abstract
The invention provides a day and night dual-purpose atmospheric turbulence parameter estimation method based on optical flow calculation. The estimation method comprises an absolute median deviation algorithm and a Lucas-Kanad pyramid optical flow algorithm, and the system comprises a hardware system platform and a system software control interface written by adopting PyQt. The method comprises the steps of shooting continuous multiframe target images through a prepared Cassegrain type optical telescope system, calculating optical flows of pixel points of adjacent multiframe images through the optical flows to further obtain corresponding arrival angle fluctuation variance, and calculating corresponding near-ground and high-altitude atmospheric turbulence parameters. Meanwhile, the compiled system software has an automatic networking function, can inquire the weather conditions of the observation place on the same day and in the next several days, and provides weather reference conditions for subsequent relevant external field experiments.
Description
Technical Field
The invention belongs to the field of computer vision technology and image processing, and particularly relates to a day and night dual-purpose atmospheric turbulence parameter estimation method based on optical flow calculation.
Background
As the earth atmosphere is heated and cooled day and night, the refractive index of the atmosphere can be randomly changed, so that the earth atmosphere can move irregularly. This phenomenon is commonly referred to as atmospheric turbulence. The atmospheric turbulence is a basic parameter closely related to the design and application of a photoelectric engineering system. While it has a significant impact on long-range imaging and laser transmission in the atmosphere. At present, atmospheric optical turbulence parameter measurement is an important means for analyzing the change rule of atmospheric turbulence. But due to the structural constant of the refractive index of the atmosphere
And length of coherence of atmospherer 0 And the like do not belong to the conventional observation parameters, and the currently common measurement methods comprise measuring the whole-layer and single-layer atmospheric turbulence parameters by using a turbulence sonde, an atmospheric coherence length meter and the like. It is certain that these methods are limited by various conditions such as manpower, material resources, financial resources, etc., and the observation results are disturbed by various regions and environmental factors. Therefore, in recent years, inversion of atmospheric turbulence parameters by directly capturing an image of a target using an optical telescope system has become a new research method. Such as the literature (S.R. Bose-Pilai, J.E.McCrae, et al.estimation of atmospheric structural using differential motion of extended defects in time-lag image [ J.]. opt.Eng57(10),104108 (2018)). The method has the advantages that the method can acquire the target image by depending on a common optical telescope system without an excessively complicated hardware acquisition system and simultaneously does not need to be provided withAnd a target light source is arranged, and a target image can be shot by depending on natural light. However, how to perform effective image inversion on the acquired target image becomes the core of the method for achieving better effect.
Disclosure of Invention
The invention provides a day and night dual-purpose atmospheric turbulence parameter estimation method based on optical flow calculation, which aims to solve the problems that a special hardware system is required to be built for measurement in the atmospheric turbulence parameter calculation process, and the observation result is disturbed by a plurality of regional and environmental factors. The system comprises in sequence: the system comprises a hardware platform and software, wherein the hardware platform is a set of complete Cassegrain type optical telescope system, and the software is a system control interface written by PyQt. The pixel displacement of two remote adjacent frames of images is calculated by using a visual tracking algorithm (Lucas-Kanad pyramid optical flow), and outliers are removed by combining an Absolute Median Deviation (MAD) mechanism. The invention discloses a method for calculating single-layer atmosphere and whole-layer atmosphere turbulence parameters by using fluctuation variance of arrival angles, which is suitable for inverting the atmosphere turbulence parameters related to the daytime and the night by continuously shooting real atmosphere turbulence degraded images.
In order to achieve the purpose, the invention adopts the technical scheme that:
a day and night dual-purpose atmospheric turbulence parameter estimation method based on optical flow calculation comprises the following steps:
step 1, shooting continuous multi-frame target turbulence degradation images through a Cassegrain type optical telescope system;
firstly, judging whether the calculated image frame is the last frame image at the moment of image shooting, if not, calculating the light stream values of pixel points of adjacent multi-frame target turbulence degradation images through a Lucas-Kanad pyramid light stream algorithm so as to obtain the corresponding arrival angle fluctuation variance
(ii) a Lucas-Kanad pyramid optical flow computationIntroducing an absolute median deviation processing mechanism in the method to eliminate unreasonable fluctuation values of the arrival angle;
the obtained fluctuation variance of the arrival angle
Substituting the following formulas to respectively obtain a plurality of atmospheric turbulence parameters:
wherein the content of the first and second substances,Dthe aperture of the telescope system is the aperture,Lthe horizontal distance between the telescope system and the observation target,λk is wave number, and the atmospheric turbulence parameter comprises the structural constant of the refractive index of the atmosphere
Atmospheric coherence lengthr 0 Degree of harmonyε，hIs the height;
and respectively calculating the average values of the plurality of atmospheric turbulence parameters, wherein the average values are the output results of the finally estimated atmospheric turbulence parameters.
Further, the pixel points are calculated by the following formulaiOptical flow value of (2):
wherein the content of the first and second substances,x i and
respectively representing the same pixel pointiThe abscissa on the previous and next frame images,y i and
respectively representing the same pixel pointiOrdinate on previous and next frame images.
Further, the arrival angle fluctuation variance
Obtained by the following formula:
wherein the content of the first and second substances,α i the total wavefront tilt angle, i.e. the angle of arrival fluctuation,
the average value of fluctuation of arrival angles of a plurality of pixel points of two adjacent frames of images is obtained, and n is the number of the same target images shot at the same moment;
wherein the content of the first and second substances,
，pis the pixel size of the imaging camera in the telescope system,fis the focal length of the imaging camera;
further, the algorithm of the absolute median deviation processing mechanism is as follows:
calculating median of all arrival angle fluctuation estimated values
(ii) a Calculating the absolute deviation value of each estimated value from the median
(ii) a Obtaining the median of the absolute deviation:
(ii) a Determining a parameter m, m representing a threshold value when
In time keeping the original estimated value
。
Further, the cassegrain-type optical telescope system includes an optical system, an automatic tracking system, and an imaging camera.
Further, the resolution of the continuous multiple frames of target turbulence degradation images is 4944x3284, the daytime shooting exposure time is less than 10ms, and the nighttime shooting exposure time is less than 30 ms.
Has the advantages that:
(1) compared with the traditional system for observing the parameters of the atmospheric turbulence, the system has simpler hardware device, and the hardware platform only needs one Cassegrain type optical telescope system;
(2) in the estimation process, a beacon light source is not required to be arranged, and the estimation can be carried out by depending on the image shot by natural light;
(3) the matched software is simple to operate, and a plurality of atmospheric turbulence parameters can be estimated respectively in the daytime and at night by setting the parameters of the observation system;
(4) the system software provided by the invention has an automatic networking function, can query weather condition parameters of China mainland and the areas of harbor and Australia, and is convenient for providing accurate weather reference conditions in an outfield experiment.
The invention utilizes the proposed optical flow calculation method to estimate the single-layer atmospheric turbulence parameters including the atmospheric refractive index structural constant, the atmospheric coherence length and the night whole-layer atmospheric turbulence parameters including the atmospheric coherence length and the vergence by only depending on one Cassegrain type optical telescope system, and lays a foundation for inverting the atmospheric turbulence parameters based on continuous multiframe turbulence degraded images.
Drawings
FIG. 1 is a schematic diagram of the pyramid optical flow calculation of the present invention;
FIG. 2 is a schematic view of a Cassegrain-type optical telescope system used in the diurnal experiments of the present invention;
FIG. 3 is a block diagram of an implementation of the MAD optical flow calculation proposed by the day and night dual-purpose atmospheric turbulence parameter estimation method based on the optical flow calculation of the present invention;
fig. 4a, fig. 4b, fig. 4c, fig. 4d, fig. 4e, and fig. 4f are graphs comparing the atmospheric refractive index structure constant estimated by the estimation method of the present invention with the measured value of the temperature pulsator during the day, wherein fig. 4a is a graph comparing the estimated value of the algorithm at 3 months and 5 days of 2022 with the measured value of the temperature pulsator; FIG. 4b is the comparison of the estimated value of the algorithm at 3/6/2022 and the measured value of the instrument; FIG. 4c is the comparison of the estimated value of the algorithm at 3/7/2022 and the measured value of the instrument; FIG. 4d is the comparison of the estimated value of the algorithm at 3.8.2022 and the measured value of the instrument; FIG. 4e is the comparison of the estimated value of the algorithm at 3 months and 27 days in 2022 with the measured value of the instrument; fig. 4f shows the estimated value of the algorithm at 3/28/2022 compared with the measured value of the instrument.
Fig. 5a and 5b are graphs for estimating two night atmospheric turbulence parameter curves by using designed software, wherein fig. 5a is a graph of an estimated atmospheric coherence length, and fig. 5b is a graph of an estimated atmospheric seeing.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by those of ordinary skill in the art without inventive labor are within the scope of the present invention based on the embodiments of the present invention.
The invention mainly adopts a Lucas-Kanada optical flow calculation method to estimate the atmospheric turbulence parameter, but the Lucas-Kanada optical flow algorithm has two constraints of (I) and (II) and simultaneously requires the region consistency of two frames of images, which is not easy to meet under the common condition. Therefore, the tracking accuracy of the Lucas-Kanada algorithm is improved by adding an image pyramid.
Referring to fig. 1, the Lucas-Kanada pyramid optical flow algorithm of the present invention is configured such that an image frame (time T1) and an image frame (time T2) respectively represent two image frames captured at adjacent times, and optical flows corresponding to feature points at the adjacent times can be calculated using the two adjacent image frames. Specifically, the image frame at the time of T1 is used as a reference frame, and the optical flow of the feature points corresponding to the feature points of the image frame at the time of T2 is calculated by combining the pyramid.
The conditions for optical flow calculation mainly include: (I) the brightness is constant; (II) the temporal continuity or movement is "small movement". The partial constraint expression is:
I(x,y,t)=I(x+dx,y+dy,t+dt) (1)
that is, for a certain pixel point (x, y, t) in the image, the light intensity in the first frame isI(x, y, t), t represents the time dimension. It moves(dx, dy)To the next frame, using dtTime. The light intensity of the pixel before and after the motion is constant, as the previous assumption is fulfilled. Taylor expansion is performed on the right end of the formula (1), and the following can be obtained:
(2) in the formula (I), the compound is shown in the specification,
represents a second order infinitesimal term which can be ignored. Substituting the formula (2) into the formula (1) and dividing dtThe following can be obtained:
order to
，
The velocity vectors of the optical flow along the x-axis and the y-axis, respectively,
, 
, 
respectively representing the partial derivatives of the gray levels of pixel points in the image along the X, Y and T directions. Therefore, the above formula (3) can be written as:
I x u+I y v+I t =0 (4)
wherein:I x ,I y ,I t all can be obtained from the image data, equation (a)u,v) I.e. the optical flow vector sought. Calculating the light stream vector of the same pixel point in two adjacent frames of images to obtain the light stream of the pixel point of the two frames of images before and after the pixel point, and recording the light stream as∆w i The expression is shown as the formula (5):
x i and
respectively represent the same pixel pointiThe abscissa on the previous and next frame images,y i and
respectively representing the same pixel pointiOrdinate on previous and next frame images. Therefore, the pixel point can be calculated by the formula (5)iThe optical flow value of (a). (6) In the formula (I), the compound is shown in the specification,α i the method is used for expressing the condition of the arrival angle, and the arrival angle is characterized in that the light beam is influenced by the atmosphere during the propagation process to generate wavefront distortion, so that the integral wavefront inclination angle of the front end of the receiving apertureα i And (3) changing, namely, the arrival angle fluctuation, which causes deviation of the imaged pixel points. p represents the pixel size of the imaging camera in the telescopic system,frepresenting the focal length of the imaging camera, and obtaining the arrival angle fluctuation corresponding to the pixel point i according to an arrival angle formula. Since two adjacent frames of images capture a plurality of pixel points to calculate their corresponding optical flows, a plurality of arrival angles of the two adjacent frames of images can be obtained by formula (6). (7) In the formula (I), the compound is shown in the specification,
and representing the average value of fluctuation of arrival angles of a plurality of pixel points of the two adjacent frames of images, wherein n represents the number of the same target images shot at the same moment. Then combining with the formula (8) to obtain the corresponding fluctuation variance of the arrival angle of the plane wave
. When the turbulence intensity on the horizontal path is regarded as uniform distribution, the fluctuation variance of the arrival angle of the plane wave
Structural constant of refractive index of atmospheric turbulence
Can be expressed as:
k=2π/λ (10)
(9) in the formula (I), the compound is shown in the specification,Dthe aperture of the telescope system is the aperture,Lthe horizontal distance between the telescope system and the observation target,λthe wavelength is generally 550nm, and h is the height. The atmospheric refractive index structure constant corresponding to the specified two adjacent frames of images can be calculated by the expression (9). (10) The formula gives the formula for calculating the wave number k, and the formula (11) and the formula (12) respectively give the atmospheric coherence lengthr 0 And calculating the vergence using the atmospheric coherence lengthεThe formula (2).
The invention is based on a conventional 30 cm-caliber Cassegrain-type optical telescope system as an image acquisition platform, and as shown in figure 2 in the specification, the Cassegrain-type optical telescope system comprises an optical system, an automatic tracking system and an imaging camera. The optical system adopts an RC 12 telescope tube, the automatic tracking system adopts a starred-Lang CGX-Lde equatorial telescope, the imaging camera adopts an ASI071MC Pro semiconductor refrigeration camera, and the automatic tracking system further comprises two heavy hammers, a balance rod and a tripod.
A day and night dual-purpose atmospheric turbulence parameter estimation method based on optical flow calculation is provided, and simple and practical atmospheric turbulence parameter estimation system software is designed for facilitating the use of subsequent external field experiments. The atmospheric turbulence parameter estimation system software is written by PyQt, and two interfaces for calculating atmospheric turbulence parameters in a daytime mode and a nighttime mode are set according to the time for shooting a target image. The system parameters of the daytime mode are set to be 5, and the parameters are pixel (um), focal length (m), wavelength (nm), aperture (m) and observation distance (m); the night mode telescope system is characterized in that 4 system parameters are set, wherein the parameters are pixel (um), focal length (m), wavelength (nm), aperture (m), and the parameters of the day mode telescope system and the night mode telescope system are set as shown in the following tables 1 and 2. The atmospheric turbulence parameter estimation system software can realize the query of meteorological conditions, and the weather conditions of the current day and the next days of the observation place can be checked through manually inputting the place name of the observation place (accurate to a district-level administrative unit). Determining the position of a shooting place, and inquiring weather conditions of the area on the same day and four days in the future by using atmospheric turbulence parameter estimation system software to determine whether the requirements of shooting conditions are met; according to the shooting target and the shooting time, the method supports the estimation of a daytime single-layer atmospheric turbulence parameter and a nighttime whole-layer atmospheric turbulence parameter; a telescope system is used to capture images of a fixed target. And then opening atmospheric turbulence parameter estimation system software to set parameters of an observation system, selecting a folder directory of observation image data needing to be calculated and storing the position of a calculation result, and then starting to operate the atmospheric turbulence parameter estimation system software. The resolution of the shooting target image is as follows: 4944x3284, the exposure time for daytime shooting is less than 10ms, and the exposure time for night time shooting is less than 30 ms.
TABLE 1 telescope optical system parameter configuration (daytime mode parameter set)
TABLE 2 telescope optical system parameter configuration (night mode parameter set)
As shown in FIG. 3, the method for estimating day and night atmospheric turbulence parameters based on optical flow calculation according to the present invention is implemented by the following steps:
step 1, firstly, acquiring the serial number of the current image frame. The image frames mainly refer to serial numbers of continuous target images shot through a telescope system, the target images are disturbed by real atmospheric turbulence, the images are distorted, and the image distortion problem caused by the atmospheric turbulence is related to a theoretical model of fluctuation and variance of the arrival angle of the light wave.
And 2, when the image is not the last frame image, calculating the optical flow values of the current frame image and the next frame image. According to the formula, the jitter information of the image disturbed by the atmosphere can be fully captured by calculating the optical flows of the images of the front frame and the back frame. Since a plurality of target images are continuously captured at a certain time, optical flow values of a plurality of adjacent two-frame images are obtained. At this point, it is necessary to add a decision that the selected image is not the last image, since the last image cannot calculate the optical flow value with the next image.
And 3, calculating the corresponding fluctuation variance of the arrival angle through the calculated light flow value. In the last step, a plurality of optical flow values of the image at the same time can be obtained, and a plurality of arrival angle fluctuation values can be obtained by substituting the plurality of optical flow values into the formula (6).
And 4, since the fluctuation value of the arrival angle calculated by the Lucas-Kanada (L-K) pyramid optical flow algorithm inevitably has an outlier value which is beyond a normal range, the accuracy of the estimation of the atmospheric turbulence parameter is greatly influenced. Therefore, a reasonable arrival angle fluctuation value is screened by using an MAD mechanism. And then, respectively substituting the obtained reasonable arrival angle fluctuation values into a formula (7) and a formula (8) to obtain corresponding arrival angle fluctuation mean values and arrival angle fluctuation variance values.
The MAD mechanism is realized by the following steps: calculating median of all arrival angle fluctuation estimated values
(ii) a Calculating the absolute deviation value of each estimated value from the median
(ii) a Obtaining the median of the absolute deviation:
(ii) a Determining the parameter m when
In time keeping the original estimated value
。
And 5, respectively substituting the arrival angle fluctuation variance values obtained by the formula (8) into a formula (9) and a formula (11) to respectively obtain an atmospheric refractive index structural constant value and an atmospheric coherence length value corresponding to the arrival angle fluctuation variance, and simultaneously substituting the obtained atmospheric coherence length value into a formula (12) to obtain a corresponding seeing value when estimating the night mode. During daytime mode estimation, the vision acuity value does not need to be calculated, and during nighttime mode estimation, the atmospheric refractive index structural constant value does not need to be calculated.
And 6, when the image is judged to be the last frame of image, respectively calculating the average values of all the refractive index structure constants, the atmospheric coherence length and the seeing degree which are calculated before, and using the average values as the atmospheric turbulence parameter estimation values calculated by the algorithm at the current moment. By the continuous execution of the algorithm, the trend curves of the different atmospheric turbulence parameters can be plotted for all observation periods.
In order to prove the accuracy of the estimation method provided by the invention on the estimation of the atmospheric turbulence parameter. The temperature pulsation instrument equipped in a laboratory is used for comparing with the atmospheric refractive index structural constant estimated in the daytime by using the estimation method of the invention. In the experiment process, firstly, clear and cloudless weather is selected for carrying out the experiment, a telescope system (the optical parameter configuration condition of the telescope system is shown in table 1) shown in fig. 2 is used for horizontally shooting a target spot building inside and outside a public place by using an indoor window positioned on a 5-th floor (about 16 meters away from the ground), a temperature pulsator is placed on an outdoor roof which is positioned on a horizontal measurement path and is about 100m away from the telescope system, and data such as wind direction, temperature, atmospheric pressure temperature, relative humidity and the like on the path are collected in real time, and the temperature pulsator can calculate the atmospheric refractive index structural constant in real time by using the meteorological parameters
. At the moment, the telescope system synchronously acquires the image of the target point of one kilometer, but the telescope system acquires the image of the target point once every 3 minutes, and the image of the target point is acquired every timeThe set time is about 30 seconds, and a temperature pulsator used in a laboratory measures a group of data every 5 seconds, so that the time resolution of data acquired by the temperature pulsator is obviously higher than that of a telescope system in the experimental process, and in order to ensure that the time resolution of two types of data in later comparative analysis is the same, only the data at the same sampling time as that of the telescope system is reserved for the time sequence acquired by the temperature pulsator, namely, the time resolution of the two methods is 3 minutes. The observation experiment was performed approximately 8 a.m. to 6 a.m. each day. The specific results are shown in fig. 4a, 4b, 4c, 4d, 4e and 4f, the gray box curves represent the measured values of the daily temperature pulsator, and the black circle curves represent the estimated values of the proposed algorithm; in the daytime experiment process of 3 and 5 days in 2022, 3 and 6 days in 2022, 3 and 7 days in 2022, 3 and 8 days in 2022, 3 and 27 days in 2022, and 28 days in 2022, 3 and 28 days in 2022, the estimated value of the algorithm of the invention is compared with the daily variation trend of the atmospheric refractive index structural constant value (logarithmic value) actually measured by the temperature pulsator, so that the estimated value of the algorithm of the invention is very close to the actual measured value of the instrument, and the variation trend is consistent, wherein the horizontal coordinate in the graph represents the time of shooting the target image every day.
For night experiments, a telescope system is positioned on the roof of a 4 th building of an experimental building, a space target shot at night is a moon, after the moon target is found through the telescope system, an automatic tracking system of an instrument is arranged, continuous multiframe turbulence degraded moon images can be shot, corresponding observation parameters are arranged by using a night mode of writing software, a plurality of night atmospheric turbulence parameters can be calculated, and the night shooting time is generally about 23 o 'clock after 20 o' clock in night. The partial night turbulence parameter estimation results are shown in the graph in the software of fig. 5. Since the measured value cannot be obtained by the instrument for comparison with the algorithm estimated value temporarily in the night mode, fig. 5a and 5b only show the variation of two atmospheric turbulence parameter curves estimated by the algorithm, where fig. 5a is an estimated atmospheric coherence length graph and fig. 5b is an estimated atmospheric seeing graph.
Those skilled in the art will appreciate that the details of the invention not described in detail herein are well within the skill of those in the art.
The present invention is not limited to the above preferred embodiments, and any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (6)
1. A day and night dual-purpose atmospheric turbulence parameter estimation method based on optical flow calculation is characterized by comprising the following steps:
step 1, shooting continuous multi-frame target turbulence degradation images through a Cassegrain type optical telescope system;
step 2, estimating atmospheric turbulence parameters by using an optical flow algorithm through the multi-frame target turbulence degradation image, and specifically comprises the following steps:
firstly, judging whether the calculated image frame is the last frame image at the moment of image shooting, if not, calculating the light stream values of pixel points of adjacent multi-frame target turbulence degradation images through a Lucas-Kanad pyramid light stream algorithm so as to obtain the corresponding arrival angle fluctuation variance
(ii) a Introducing an absolute median deviation processing mechanism into the Lucas-Kanad pyramid optical flow algorithm to remove unreasonable arrival angle fluctuation values;
the obtained fluctuation variance of the arrival angle
Substituting the following formulas to respectively obtain a plurality of atmospheric turbulence parameters:
wherein the content of the first and second substances,Dthe aperture of the telescope system is the aperture,Lthe horizontal distance between the telescope system and the observation target,λis wavelength, k is wavenumber, said is largeThe air turbulence parameter comprises the structural constant of the refractive index of the atmosphere
Atmospheric coherence lengthr 0 Degree of harmonyε，hIs the height;
and respectively calculating the average values of the plurality of atmospheric turbulence parameters, wherein the average values are the output results of the finally estimated atmospheric turbulence parameters.
2. The method for estimating day and night air turbulence parameters based on optical flow calculation as claimed in claim 1, wherein:
calculating pixel points byiOptical flow value of (2):
wherein the content of the first and second substances,x i and
respectively representing the same pixel pointiThe abscissa on the previous and next frame images,y i and
respectively representing the same pixel pointiOrdinate on previous and next frame images.
3. The method for estimating day and night air turbulence parameters based on optical flow calculation as claimed in claim 2, wherein:
the variance of arrival angle fluctuation
Obtained by the following formula:
wherein the content of the first and second substances,α i the total wavefront tilt angle, i.e. the angle of arrival fluctuation,
the average value of fluctuation of arrival angles of a plurality of pixel points of two adjacent frames of images is obtained, and n is the number of the same target images shot at the same moment;
wherein the content of the first and second substances,
，pis the pixel size of the imaging camera in the telescope system,fis the focal length of the imaging camera;
4. the method for estimating day and night air turbulence parameters based on optical flow calculation as claimed in claim 3, wherein: the algorithm of the absolute median deviation processing mechanism is as follows:
calculating median of all arrival angle fluctuation estimated values
(ii) a Calculating the absolute deviation value of each estimated value from the median
(ii) a Obtaining the median of the absolute deviation:
(ii) a Determining a parameter m, m representing a threshold value when
In time keeping the original estimated value
。
5. The method for estimating day and night air turbulence parameters based on optical flow calculation as claimed in claim 1, wherein: the Cassegrain-type optical telescope system comprises an optical system, an automatic tracking system and an imaging camera.
6. The method for estimating day and night air turbulence parameters based on optical flow calculation as claimed in claim 1, wherein: the resolution of the shot continuous multi-frame target turbulence degradation images is 4944x3284, the daytime shooting exposure time is less than 10ms, and the nighttime shooting exposure time is less than 30 ms.
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| 陈宏烨: "海域条件下大气折射率结构常数估算方法研究", 《智能计算机与应用》 * |
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