CN115014311B - Atmospheric polarization information-based light compass orientation method for eliminating sky occlusion - Google Patents

Atmospheric polarization information-based light compass orientation method for eliminating sky occlusion Download PDF

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CN115014311B
CN115014311B CN202210941420.4A CN202210941420A CN115014311B CN 115014311 B CN115014311 B CN 115014311B CN 202210941420 A CN202210941420 A CN 202210941420A CN 115014311 B CN115014311 B CN 115014311B
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atmospheric
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CN115014311A (en
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范晨
范颖
何晓峰
胡小平
张礼廉
黄靖
周文舟
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National University of Defense Technology
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C17/00—Compasses; Devices for ascertaining true or magnetic north for navigation or surveying purposes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C1/00—Measuring angles
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C21/00—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00
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    • G06V10/26—Segmentation of patterns in the image field; Cutting or merging of image elements to establish the pattern region, e.g. clustering-based techniques; Detection of occlusion
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Abstract

The invention discloses an optical compass orientation method for eliminating sky occlusion based on atmospheric polarization information, which comprises the following steps: obtaining an atmospheric polarization degree distribution image based on a sky polarization image acquired by a carrier; obtaining a neighborhood self-adaptive two-dimensional maximum entropy threshold value based on the atmospheric polarization degree distribution image; performing threshold segmentation on a sky area and an occlusion area in an atmospheric polarization degree distribution image based on a neighborhood self-adaptive two-dimensional maximum entropy threshold; and for the measuring points in the sky area, the course angle of the carrier is calculated by using a least square method in combination with time and geographic information. The invention is applied to the field of bionic polarized light navigation, can effectively remove the interference of shielding under the condition that the sky is shielded, extracts the sky area, improves the polarized light orientation efficiency and realizes the atmospheric polarized light orientation under the condition that the sky is shielded.

Description

Atmospheric polarization information-based light compass orientation method for eliminating sky occlusion
Technical Field
The invention relates to the technical field of bionic polarized light navigation, in particular to an optical compass orientation method for eliminating sky occlusion based on atmospheric polarization information.
Background
The bionic polarized light navigation is a novel navigation mode developed by inspiring of animals in nature, such as desert ants, crickets and the like, and is one of key technologies in the field of autonomous navigation. The bionic polarized light navigation uses an atmospheric polarization mode in nature as a navigation information source, has the characteristics of no error accumulation along with time, good autonomy, strong robustness and the like, can play a good role under the satellite rejection condition, and has wide application prospects in the military field and the civil field.
In practical applications, the atmospheric polarization mode is often affected by weather conditions, for example, when the weather conditions are cloudy, cloudy or shielded by obstacles, the effect of the bionic polarized light navigation is greatly reduced. The light compass orientation method based on atmospheric polarization information sky occlusion elimination adopts a two-dimensional maximum entropy threshold segmentation method to process collected polarization images, segments an occlusion region and a sky region, and then only processes the sky region.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides the light compass orientation method for eliminating sky occlusion based on the atmospheric polarization information, which can effectively remove occlusion interference under the condition that the sky is occluded, extract a sky area, improve the orientation efficiency of polarized light and realize the atmospheric polarized light orientation under the condition that the sky is occluded.
In order to achieve the purpose, the invention provides an optical compass orientation method for eliminating sky occlusion based on atmospheric polarization information, which comprises the following steps:
step 1, obtaining an atmospheric polarization degree distribution image based on a sky polarization image acquired by a carrier;
step 2, obtaining a neighborhood self-adaptive two-dimensional maximum entropy threshold value based on the atmospheric polarization degree distribution image;
step 3, performing threshold segmentation on a sky area and an occlusion area in the atmospheric polarization degree distribution image based on a neighborhood self-adaptive two-dimensional maximum entropy threshold;
and 4, calculating the course angle of the carrier by using a least square method for the measuring points in the sky area in combination with time and geographic information.
In one embodiment, in step 1, a Stokes method is used to obtain an atmospheric polarization degree distribution image, and the process is as follows:
the partially polarized light is represented by a Stokes vector, which contains four parametersS=[S 1,S 2,S 3,S 4]Wherein, in the step (A),S 1which represents the total light intensity of the light,S 2is a polarized light component in the 0 deg. direction,S 3is a polarization component in the 45 deg. direction,S 4is a circular polarization component, the light intensity of the polarized light after passing through the polarizer is:
Figure 544971DEST_PATH_IMAGE001
in the formula (I), the compound is shown in the specification,
Figure 915910DEST_PATH_IMAGE002
is the angle of the polarization of the light,
Figure 927728DEST_PATH_IMAGE003
is the included angle between the polarization direction of the sensor and the optical axis of the system;
the Stokes intensity equation is obtained by simplification as:
Figure 16907DEST_PATH_IMAGE004
when in use
Figure 139584DEST_PATH_IMAGE005
When 0 degree, 45 degrees and 90 degrees are respectively taken, the Stokes parameters of each pixel point on the image are obtained as follows:
Figure 630608DEST_PATH_IMAGE006
the polarization angle and the linear polarization degree of each pixel point can be obtained without considering the circularly polarized light as follows:
Figure 46283DEST_PATH_IMAGE007
Figure 357179DEST_PATH_IMAGE008
in the formula (I), the compound is shown in the specification,
Figure 283547DEST_PATH_IMAGE009
is the angle of the polarization of the light,dis the degree of linear polarization;
the collected sky polarization image is calculated by the formula, and then the sky polarization image can be converted into an atmosphere polarization degree distribution image.
In one embodiment, in step 2, the process of obtaining the neighborhood adaptive two-dimensional maximum entropy threshold is as follows:
obtaining the average value of the polarization degree of each pixel point in the atmospheric polarization degree distribution image, taking the average value as the polarization degree of the atmospheric polarization degree distribution image, and adaptively setting the neighborhood based on the polarization degree of the atmospheric polarization degree distribution imagek；
For pixel points in the polarization map image (x,y) Having a value of polarization ofd(x,y) The mean value of the neighborhood polarization degree is:
Figure 629077DEST_PATH_IMAGE010
in the formula (I), the compound is shown in the specification,D(x,y) Is a pixel point (x,y) Neighborhood of (2)kThe mean value of the degree of polarization of the neighborhood,d(x+m,y+n) Is a pixel point (x+m,y+n) A value of polarization of;
the pixels of the atmosphere polarization degree distribution image areM×NIs provided withf i j,Is a value of polarizationiAnd the mean value of the neighborhood polarization degree isjThe number of pixels of (2) is definedP i j,The probability of occurrence is noted as:
Figure 248278DEST_PATH_IMAGE011
defining a two-dimensional threshold vector of the segmented image as: (S,T) Wherein, in the step (A),Twhich represents the value of the degree of polarization,Srepresenting the mean value of the polarization degree of the pixel neighborhood;
to probabilityP i j,The two-dimensional entropy of the occlusion region after normalization processing is as follows:
Figure 46469DEST_PATH_IMAGE012
Figure 776528DEST_PATH_IMAGE013
Figure 976565DEST_PATH_IMAGE014
in the formula (I), the compound is shown in the specification,H occlusion for the two-dimensional entropy of the occlusion region,P 1to be the probability of the occurrence of a pixel in the occlusion region,H 1is the two-dimensional discrete entropy of the occlusion region;
to probabilityP i j,The two-dimensional entropy of the sky area after normalization processing is as follows:
Figure 2552DEST_PATH_IMAGE015
Figure 22461DEST_PATH_IMAGE016
Figure 821790DEST_PATH_IMAGE017
in the formula (I), the compound is shown in the specification,H sky is the two-dimensional entropy of the sky region,P 2is the probability of the occurrence of a pixel of the sky region,H 2is the two-dimensional discrete entropy of the sky region,Lis a degree of polarization series;
setting the sum of entropies of an occlusion area and a sky area in the whole atmospheric polarization degree distribution image as a target function
Figure 876333DEST_PATH_IMAGE018
(S,T) The method comprises the following steps:
Figure 571757DEST_PATH_IMAGE019
following the maximum entropy principle, there is a two-dimensional threshold vector that satisfies the condition:
Figure 344541DEST_PATH_IMAGE020
in the formula (I), the compound is shown in the specification, (ii) (S*,T* ) Namely the neighborhood self-adaptive two-dimensional maximum entropy threshold.
In one embodiment, the neighborhood is adaptively set based on the polarization degree size of the atmosphere polarization degree distribution imagekThe method specifically comprises the following steps:
Figure 416402DEST_PATH_IMAGE021
in the formula (I), the compound is shown in the specification,dop_meanthe polarization degree of the image is distributed to the atmospheric polarization degree.
In one embodiment, in step 3, the threshold segmentation is performed on the sky area and the occlusion area in the atmospheric polarization degree distribution image, specifically:
obtaining a binarization function based on a neighborhood self-adaptive two-dimensional maximum entropy threshold value, wherein the binarization function comprises the following steps:
Figure 325452DEST_PATH_IMAGE022
in the formula (I), the compound is shown in the specification,d A B,(x,y) =0 indicates that the pixel belongs to the occlusion region,d A B,(x,y) =1 indicates that the pixel belongs to the sky area;
and performing binarization processing on the atmospheric polarization degree distribution image based on a binarization function, namely completing threshold segmentation between a sky area and a shielding area in the atmospheric polarization degree distribution image.
In one embodiment, step 4 specifically includes:
based on all pixel points in the sky area, obtainingE-a vector matrix of:
Figure 955891DEST_PATH_IMAGE023
in the formula (I), the compound is shown in the specification,
Figure 950392DEST_PATH_IMAGE024
，wis the total number of pixel points in the sky area,
Figure 825944DEST_PATH_IMAGE025
is the angle of polarization;
according to the Rayleigh scattering model,Ethe geometric relationship between the vector and the vector perpendicular to the sun direction can be obtained as follows:
Figure 589501DEST_PATH_IMAGE026
the sun azimuth vector can be obtained by solving with the least square methodsBased on the sun's azimuth vectorsAnd combining the time and the geographic position to obtain the heading angle of the carrier.
Compared with the prior art, the invention has the following beneficial technical effects:
1. the polarization degree information is fully utilized, the method is different from the traditional image segmentation method for directly processing the original image, the original image is converted into an atmospheric polarization degree distribution image, and on the basis, the two-classification processing is carried out on the shielded sky area to segment the shielded area from the sky area; extracting a sky area and laying a foundation for subsequent polarized light orientation;
2. in the preprocessing stage, the shielded area is removed, shielded interference is avoided, the sky area is directly used for calculation, and the calculation efficiency is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a flow chart of a method for directing polarized sky light according to an embodiment of the present invention;
FIG. 2 is a schematic view of an original sky polarization image according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of an atmospheric polarization degree distribution graph in an embodiment of the invention;
FIG. 4 is a schematic diagram of an atmospheric polarization degree distribution image after two-dimensional maximum entropy processing in an embodiment of the present invention.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that all directional indicators (such as up, down, left, right, front, back \8230;) in the embodiments of the present invention are only used to explain the relative positional relationship between the components, the motion situation, etc. in a specific posture (as shown in the attached drawings), and if the specific posture is changed, the directional indicator is changed accordingly.
In addition, descriptions such as "first", "second", etc. in the present invention are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "connected," "secured," and the like are to be construed broadly, and for example, "secured" may be a fixed connection, a removable connection, or an integral part; the connection can be mechanical connection, electrical connection, physical connection or wireless communication connection; they may be directly connected or indirectly connected through intervening media, or they may be interconnected within two elements or in a relationship where two elements interact with each other unless otherwise specifically limited. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination of technical solutions should not be considered to exist, and is not within the protection scope of the present invention.
Fig. 1 shows a method for orienting an optical compass based on atmospheric polarization information to eliminate sky occlusion, which includes the following steps:
step 1, a sky polarization image shown in fig. 2 is acquired based on a polarized light sensor on a carrier, and an atmosphere polarization degree distribution image is obtained according to the sky polarization image.
In this embodiment, the Stokes method is used to obtain the atmospheric polarization degree distribution image, and the process is as follows:
the partially polarized light is represented by a Stokes vector, which contains four parametersS=[S 1,S 2,S 3,S 4]Wherein, in the step (A),S 1which represents the total light intensity of the light,S 2is a polarized light component in the 0 deg. direction,S 3is a polarization component in the 45 deg. direction,S 4is a circularly polarized component, the intensity of the polarized light after transmitting the polarizer is:
Figure 892306DEST_PATH_IMAGE027
in the formula (I), the compound is shown in the specification,
Figure 374103DEST_PATH_IMAGE028
is the angle of the polarization of the light,
Figure 787767DEST_PATH_IMAGE029
is the included angle between the polarization direction of the sensor and the optical axis of the system;
the Stokes intensity equation is obtained by simplification as:
Figure 671409DEST_PATH_IMAGE030
when in use
Figure 646581DEST_PATH_IMAGE031
When 0 degree, 45 degrees and 90 degrees are respectively taken, the Stokes parameters of each pixel point on the image are obtained as follows:
Figure 818936DEST_PATH_IMAGE032
the polarization angle and the linear polarization degree of each pixel point can be obtained without considering the circularly polarized light as follows:
Figure 36291DEST_PATH_IMAGE033
Figure 774440DEST_PATH_IMAGE034
in the formula (I), the compound is shown in the specification,
Figure 419048DEST_PATH_IMAGE035
is the angle of polarization of the light beam,dis the degree of linear polarization;
the collected sky polarization image is calculated by using the above formula, and then the sky polarization image can be converted into an atmospheric polarization degree distribution image shown in fig. 3.
Step 2, obtaining a neighborhood self-adaptive two-dimensional maximum entropy threshold value based on the atmospheric polarization degree distribution image, wherein the specific implementation process is as follows:
firstly, obtaining the average value of the polarization degree of each pixel point in the atmospheric polarization degree distribution image, taking the average value as the polarization degree of the atmospheric polarization degree distribution image, and adaptively setting the neighborhood based on the polarization degree of the atmospheric polarization degree distribution imagekThe method specifically comprises the following steps:
Figure 141016DEST_PATH_IMAGE036
in the formula (I), the compound is shown in the specification,dop_meanthe polarization degree of the image is distributed to the atmospheric polarization degree. The embodiment adaptively sets the neighborhood through the polarization degree size of the atmospheric polarization degree distribution imagekThe neighborhood most suitable for the image can be selected according to different shielding distribution conditionskBetter segmentation effect is realized;
then, for pixel points in the polarization diagram image (A), (B), and (C)x,y) Having a value of polarization ofd(x,y) In the neighborhood of which iskThe time neighborhood polarization mean is:
Figure 630903DEST_PATH_IMAGE037
in the formula (I), the compound is shown in the specification,D(x,y) Is a pixel point (x,y) The mean value of the degree of polarization of the neighborhood,d(x+m,y+n) Is a pixel point (x+m,y+n) A value of polarization of;
if the pixels of the atmosphere polarization degree distribution image areM×NIs provided withf i j,Is a value of polarizationiAnd the mean value of the neighborhood polarization degree isjThe number of pixel points of (2) is definedP i j,Is the probability of occurrence, noted as:
Figure 489138DEST_PATH_IMAGE038
defining a two-dimensional threshold vector of the segmented image as: (S,T) Wherein, in the process,Twhich represents the value of the degree of polarization,Srepresenting the mean value of the polarization degree of the pixel neighborhood; the two-dimensional discrete entropy is defined as:
Figure 39068DEST_PATH_IMAGE039
to probabilityP i j,The two-dimensional entropy of the occlusion region after normalization is as follows:
Figure 481288DEST_PATH_IMAGE040
Figure 40446DEST_PATH_IMAGE041
Figure 753187DEST_PATH_IMAGE042
in the formula (I), the compound is shown in the specification,H occlusion in order to obtain the two-dimensional entropy of the occlusion region,P 1to be the probability of the occurrence of a pixel in the occlusion region,H 1is the two-dimensional discrete entropy of the occlusion region;
to probabilityP i j,The two-dimensional entropy of the sky area after normalization processing is as follows:
Figure 739597DEST_PATH_IMAGE043
Figure 170579DEST_PATH_IMAGE016
Figure 267848DEST_PATH_IMAGE044
in the formula (I), the compound is shown in the specification,H sky is the two-dimensional entropy of the sky region,P 2is the probability of the occurrence of a pixel of the sky region,H 2is a two-dimensional discrete entropy of the sky region,Lis a polarization degree series;
setting the sum of entropies of a shielding region and a sky region in the whole atmospheric polarization degree distribution image as an objective function
Figure 100674DEST_PATH_IMAGE045
(S,T) The method comprises the following steps:
Figure 257986DEST_PATH_IMAGE046
following the maximum entropy principle, there is a two-dimensional threshold vector that satisfies the condition:
Figure 113947DEST_PATH_IMAGE047
wherein (A) isS*,T* ) Namely the neighborhood self-adaptive two-dimensional maximum entropy threshold.
Step 3, based on a neighborhood self-adaptive two-dimensional maximum entropy threshold, carrying out threshold segmentation on a sky area and an occlusion area in an atmospheric polarization degree distribution image, wherein the process is as follows:
obtaining a binarization function based on a neighborhood self-adaptive two-dimensional maximum entropy threshold value, wherein the function is as follows:
Figure 516371DEST_PATH_IMAGE048
in the formula (I), the compound is shown in the specification,d A B,(x,y) =0 indicates that the pixel belongs to the shielding areaI occlusion ，d A B,(x,y) =1 shows that the pixel belongs to sky areaI sky ；
And (3) performing binarization processing on the atmospheric polarization degree distribution image based on a binarization function, namely completing threshold segmentation between a sky area and a shielding area in the atmospheric polarization degree distribution image, namely as shown in fig. 4. In FIG. 4, the black part is the occlusion areaI occlusion The white part is the sky areaI sky 。
And 4, calculating the course angle of the carrier by combining time and geographic information for the measuring points in the sky area by using a least square method, wherein the specific implementation process comprises the following steps:
based on all pixel points in the sky area, obtainingE-a vector matrix of:
Figure 469284DEST_PATH_IMAGE049
in the formula (I), the compound is shown in the specification,
Figure 797497DEST_PATH_IMAGE050
，wis the total number of pixel points in the sky area,
Figure 140754DEST_PATH_IMAGE051
is the angle of polarization;
according to the Rayleigh scattering model,Ethe geometric relationship between the vector and the vector perpendicular to the sun direction can be obtained as follows:
Figure 579825DEST_PATH_IMAGE052
solving by least square methodThe sun azimuth vector can be obtainedsBased on the sun's azimuth vectorsThe course angle of the carrier can be obtained by combining the time and the geographic position, and the specific calculation process is a conventional means in the field, so the detailed description thereof is omitted in this embodiment.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (4)

1. An atmospheric polarization information-based light compass orientation method for eliminating sky occlusion is characterized by comprising the following steps:
step 1, obtaining an atmospheric polarization degree distribution image based on a sky polarization image acquired by a carrier;
step 2, obtaining a neighborhood self-adaptive two-dimensional maximum entropy threshold value based on the atmospheric polarization degree distribution image;
step 3, performing threshold segmentation on a sky area and an occlusion area in the atmospheric polarization degree distribution image based on a neighborhood self-adaptive two-dimensional maximum entropy threshold;
step 4, calculating the course angle of the carrier by using a least square method for the measuring points in the sky area in combination with time and geographic information;
in step 2, the obtaining process of the neighborhood self-adaptive two-dimensional maximum entropy threshold value is as follows:
obtaining the average value of the polarization degree of each pixel point in the atmospheric polarization degree distribution image, taking the average value as the polarization degree of the atmospheric polarization degree distribution image, and adaptively setting the neighborhood based on the polarization degree of the atmospheric polarization degree distribution imagek；
For pixel points in the polarization diagram image (A)x,y) Having a value of polarization ofd(x,y) The mean value of the neighborhood polarization degree is:
Figure 711590DEST_PATH_IMAGE001
in the formula (I), the compound is shown in the specification,D(x,y) Is a pixel point (x,y) Neighborhood of (2)kThe mean value of the degree of polarization of the neighborhood,d(x+m,y+n) Is a pixel point (x+m,y+n) A value of polarization of;
pixels of the atmospheric polarization degree distribution image areM×NIs provided withf i j,Is a value of polarizationiAnd the mean value of the neighborhood polarization degrees isjThe number of pixel points of (2) is definedP i j,The probability of occurrence is noted as:
Figure 388559DEST_PATH_IMAGE002
defining a two-dimensional threshold vector of a segmented image as (A), (B)S,T) Wherein, in the process,Twhich represents the value of the degree of polarization,Srepresenting the mean value of the polarization degrees of the neighborhood of the pixels;
to probabilityP i j,The two-dimensional entropy of the occlusion region after normalization is as follows:
Figure 810181DEST_PATH_IMAGE003
Figure 965219DEST_PATH_IMAGE004
Figure 172210DEST_PATH_IMAGE005
in the formula (I), the compound is shown in the specification,
Figure 754501DEST_PATH_IMAGE006
in order to obtain the two-dimensional entropy of the occlusion region,P 1to be the probability of the occurrence of a pixel in the occlusion region,H 1is the two-dimensional discrete entropy of the occlusion region;
to probabilityP i j,The two-dimensional entropy of the sky area after normalization is as follows:
Figure 414152DEST_PATH_IMAGE007
Figure 372881DEST_PATH_IMAGE008
Figure 168799DEST_PATH_IMAGE009
in the formula (I), the compound is shown in the specification,H sky is the two-dimensional entropy of the sky region,P 2is the probability of the occurrence of a pixel of the sky area,H 2is a two-dimensional discrete entropy of the sky region,Lis a degree of polarization series;
setting the sum of entropies of a shielding region and a sky region in the whole atmospheric polarization degree distribution image as an objective function
Figure 938303DEST_PATH_IMAGE010
(S,T) The method comprises the following steps:
Figure 85250DEST_PATH_IMAGE011
following the maximum entropy principle, there is a two-dimensional threshold vector that satisfies the condition:
Figure 847670DEST_PATH_IMAGE012
in the formula (I), the compound is shown in the specification, (ii) (S*,T* ) Namely, the two-dimensional maximum entropy threshold value is self-adaptive to the neighborhood;
degree of polarization of the atmospheric polarization degree-based distribution imageSize adaptive setting neighborhoodkThe method specifically comprises the following steps:
Figure 498094DEST_PATH_IMAGE013
in the formula (I), the compound is shown in the specification,dop_meanthe polarization degree of the image is distributed to the atmospheric polarization degree.
2. The atmospheric polarization information-based sky-covering-eliminated light compass orientation method according to claim 1, wherein in step 1, a Stokes method is used to obtain an atmospheric polarization degree distribution image, and the process is as follows:
the partially polarized light is represented by a Stokes vector, which contains four parametersS=[S 1,S 2,S 3,S 4]Wherein, in the step (A),S 1which represents the total light intensity of the light,S 2is a polarized light component in the 0 deg. direction,S 3is a polarization component in the direction of 45,S 4is a circular polarization component, the light intensity of the polarized light after passing through the polarizer is:
Figure 422188DEST_PATH_IMAGE014
in the formula (I), the compound is shown in the specification,θis the angle of polarization of the light beam,φis the included angle between the polarization direction of the sensor and the optical axis of the system;
the Stokes intensity equation is obtained by simplification as:
Figure 56431DEST_PATH_IMAGE015
when the temperature is higher than the set temperatureθWhen 0 degrees, 45 degrees and 90 degrees are respectively taken, the Stokes parameters of each pixel point on the image are obtained as follows:
Figure 356963DEST_PATH_IMAGE016
the polarization angle and the linear polarization degree of each pixel point can be obtained without considering the circularly polarized light as follows:
Figure 642319DEST_PATH_IMAGE017
Figure 471735DEST_PATH_IMAGE018
in the formula (I), the compound is shown in the specification,
Figure 593275DEST_PATH_IMAGE019
is the angle of polarization of the light beam,dis the degree of linear polarization;
the collected sky polarization image is calculated by the formula, and then the sky polarization image can be converted into an atmosphere polarization degree distribution image.
3. The light compass orientation method for removing sky occlusion based on atmospheric polarization information of claim 1, wherein in step 3, the threshold segmentation is performed on the sky area and the occlusion area in the atmospheric polarization degree distribution image, specifically:
obtaining a binarization function based on a neighborhood self-adaptive two-dimensional maximum entropy threshold value, wherein the function is as follows:
Figure 697497DEST_PATH_IMAGE020
in the formula (I), the compound is shown in the specification,d A B,(x,y) =0 indicates that the pixel belongs to the occlusion region,d A B,(x,y) =1 indicates that the pixel belongs to the sky area;
and (4) carrying out binarization processing on the atmospheric polarization degree distribution image based on a binarization function, namely completing threshold segmentation between a sky area and a shielding area in the atmospheric polarization degree distribution image.
4. The atmospheric polarization information-based sky-occlusion rejecting optical compass orientation method of any one of claims 1-3, wherein step 4 specifically comprises:
based on all pixel points in the sky area, obtainingE-a vector matrix of:
Figure 322514DEST_PATH_IMAGE021
in the formula (I), the compound is shown in the specification,
Figure 853989DEST_PATH_IMAGE022
，wis the total number of pixel points in the sky area,
Figure 197246DEST_PATH_IMAGE023
is the angle of polarization;
according to the Rayleigh scattering model,Ethe geometric relationship between the vector and the vector perpendicular to the sun direction can be obtained as follows:
Figure 864680DEST_PATH_IMAGE024
the sun azimuth vector can be obtained by solving by using a least square methodsBased on the sun's azimuth vectorsAnd combining the time and the geographic position to obtain the course angle of the carrier.
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