A method and system for calculating the area of ​​marine Enteromorpha based on a photoelectric platform

Abstract

The present invention relates to the field of marine enteromorpha monitoring technology, and is a marine enteromorpha area measurement method and system based on a photoelectric platform. The specific method includes: obtaining initial video data of a calibration plate under a plurality of viewing angles; extracting the initial video data, and selecting key frame image data of the calibration plate; calculating and obtaining the actual focal length; fitting the relationship between the actual focal length and the viewing angle according to the key frame image data and the actual focal length, completing the orthophoto correction of the key frame image data through the fitting relationship, obtaining an orthophoto image data set, and evaluating the actual marine enteromorpha area. The present invention ensures the basis for the accuracy of subsequent image data by calibrating the photoelectric platform for shooting marine enteromorpha images. The purpose of the calibration is to obtain the precise relationship between the actual focal length and the viewing angle of the photoelectric platform, thereby improving the accuracy of area measurement.

Description

Technical Field

[0001] The invention relates to the technical field of marine enteromorpha monitoring, and is a marine enteromorpha area calculation method and system based on a photoelectric platform. Background Art

[0002] Given the severity and complexity of the Enteromorpha green tide, the need for methods and systems to measure the area of ​​Enteromorpha at sea is becoming increasingly urgent. Accurately estimating the coverage area of ​​Enteromorpha is not only an important indicator for assessing the extent of its outbreak, but also a scientific basis for formulating effective prevention and control measures and resource allocation.

[0003] Manned or unmanned aircraft optoelectronic platforms have a huge application market as aerial emergency monitoring equipment, and there are many types of optoelectronic pods, including optical, near-infrared, and thermal infrared. In order to improve the observation capability of optoelectronic pods, in addition to mechanical zoom, there will also be digital zoom methods.

[0004] In order to accurately measure the area of ​​Enteromorpha on the sea surface, the recording equipment of the optoelectronic pod needs to project the internal and external orientation elements of the image and the average elevation onto the sea surface. The existing optoelectronic pod provides parameters such as field of view angle, pixel size, and sensor size. However, due to the variable focal length of the recording equipment and the existence of digital zoom, the field of view angle parameter error is very large during actual use, which cannot meet the needs of actual area and size measurement.

[0005] In the existing disclosed invention technology, for example, the patent with publication number CN112712553A discloses a method for estimating the amount of Enteromorpha reaching the shore, comprising the following steps: 1) selecting a research sea area for estimating the amount of Enteromorpha reaching the shore; 2) extracting the location of the Enteromorpha reaching the shore near the coastline of the research sea area in 1); 3) obtaining a remote sensing image of the research sea area in 1); 4) interpreting the Enteromorpha distribution data based on the remote sensing image obtained in 3); 5) obtaining the hydrological and meteorological data such as the ocean current and wind speed of the research sea area in 1); 6) calculating the coordinates of the Enteromorpha reaching the location of the Enteromorpha reaching the shore in 2) after a given time based on the hydrological and meteorological data obtained in 5); 7) determining the area between the connecting line of the Enteromorpha coordinates in 6) and the connecting line of the location of the Enteromorpha reaching the shore in 2); 8) calculating the Enteromorpha distribution area in the target area in 7); 9) quantifying the Enteromorpha unit area quality parameter of the research sea area in 1); 10) estimating the amount of Enteromorpha reaching the shore within a given time period.

[0006] The above patent has the problem of large errors in obtaining accurate remote sensing images and interpreting Ulva distribution data. Summary of the invention

[0007] The purpose of the present invention is to provide a method and system for calculating the area of ​​marine Enteromorpha based on a photoelectric platform.

[0008] In order to achieve the above-mentioned object, the technical solution of a method for calculating the area of ​​marine Enteromorpha based on a photoelectric platform of the present invention comprises the following steps:

[0009] S1: extract multiple sets of calibration plates, synchronously fix the distance between the calibration plates and the optoelectronic pod on the optoelectronic platform, adjust the field of view of the optoelectronic pod on the optoelectronic platform to shoot the calibration plates, and obtain initial video data of the calibration plates under different field of view angles;

[0010] S2: extracting initial video data, preprocessing the initial video data, and selecting key frame image data of the calibration plate;

[0011] S3: Calculate and obtain the actual focal length according to the key frame image data of the calibration plate;

[0012] S4: fitting the relationship between the actual focal length and the field of view angle according to the key frame image data and the actual focal length, completing the orthophoto correction of the key frame image data through the fitting, and obtaining an orthophoto image data set;

[0013] S5: Assess the actual marine Enteromorpha area based on the orthophoto dataset.

[0014] Specifically, in S2, the step of selecting the key frame image data of the calibration plate includes the following specific steps:

[0015] S21: reading the initial video data and extracting frames, and preprocessing each frame of the initial image, wherein the preprocessing includes: removing noise in each frame of the initial image by Gaussian filtering;

[0016] S22: converting the color image into the HSV color space, and marking the Enteromorpha region in each frame of the initial image using a color filter according to the hue and saturation range of the Enteromorpha;

[0017] S23: Convert each marked initial image frame into a grayscale image to form an initial image set, and establish a two-dimensional coordinate system with the lower left corner of each grayscale image frame as the origin, extract the coordinates of each pixel point in the Enteromorpha region, and evaluate the distribution fidelity of Enteromorpha in each initial image frame. The evaluation of the distribution fidelity of Enteromorpha in each initial image frame is specifically as follows:

[0018] ;

[0019] Where n is a subscript, indicating the nth frame of the initial image, and there are a total of N frames of initial images in the initial image set;

[0020] is the distribution fidelity of Enteromorpha in the initial image of the nth frame;

[0021] are the distribution characteristic coefficients of the initial images of the nth frame, the n-1th frame and the n+1th frame respectively;

[0022] S24: Preset a distribution fidelity threshold of the Enteromorpha in the initial image. When the distribution fidelity of the Enteromorpha in the n-th frame initial image is greater than or equal to the distribution fidelity threshold, select the n-th frame initial image as the key frame image of the calibration plate, traverse the initial image set to screen and obtain multiple key frame images of the calibration plate, and constitute the key frame image data of the calibration plate.

[0023] Specifically, in S23, the calculation strategy of the distribution characteristic coefficient is as follows:

[0024] ;

[0025] in, is a subscript, indicating the e-th pixel point in the Enteromorpha region in the n-th frame of the initial image. is the total number of pixels in the Enteromorpha region in the nth frame of the initial image;

[0026] are respectively the horizontal and vertical coordinates of the e-th pixel point in the Enteromorpha area in the n-th frame of the initial image.

[0027] Specifically, S3 includes the following specific steps:

[0028] S31: Extracting geometric feature data of the calibration plate, wherein the geometric feature data of the calibration plate includes: the number of sides M of each polygon in the calibration plate, the total area Ar of each polygon, the length of each side , the angle of each interior angle And the total number of pixels U on the calibration plate;

[0029] S32: Importing the geometric feature data of the calibration plate into the calibration plate corner coefficient calculation strategy, and calculating and obtaining the calibration plate corner coefficient. The calibration plate corner coefficient zl calculation strategy is:

[0030] ;

[0031] S33: extracting the key frame image data of the calibration plate, and calculating the resolution switching coefficient Gs of the key frame image data. The specific calculation strategy of the resolution switching coefficient of the key frame image data is: ;

[0032] S34: According to S31-S33, the actual focal length is calculated and obtained. The calculation strategy of the actual focal length f is specifically as follows: , where H is the distance between the center of the calibration plate and the optoelectronic pod on the optoelectronic platform; is the pixel size.

[0033] Specifically, S4 includes the following specific steps:

[0034] S41: extracting field of view angle data and the actual focal length corresponding to the field of view angle;

[0035] S42: construct multiple function fitting models, evaluate the fitting model parameters by the least square method, calculate the mean square error to evaluate the fitting results, and arrange the mean square errors in order; S43: select the function fitting model with the smallest mean square error as the final function fitting model, and fit the relationship between the actual focal length and the field of view angle by the final function fitting model, and obtain the functional relationship between the actual focal length and the field of view angle after the fitting is completed, wherein the functional relationship between the actual focal length and the field of view angle is: , a and b are the model parameters of the final function fitting model, a=341.02, b=-0.945.

[0036] Specifically, S4 also includes the following specific steps:

[0037] S44: Obtain the internal orientation element and the external orientation element of the camera of the optoelectronic pod on the optoelectronic platform, wherein the internal orientation element includes: the focal length of the camera in the horizontal direction , the vertical focal length of the camera , radial distortion and tangential distortion coefficients; the external orientation elements include: rotation matrix R and translation vector T;

[0038] S45: extracting the actual focal lengths at different field angles, and using the camera internal orientation elements to convert the image coordinates into camera coordinates, wherein the conversion method is:

[0039] ;

[0040] in, is the image coordinate, is the depth value of the camera coordinate system;

[0041] is the image coordinate The transformed camera coordinates;

[0042] is the coordinate of the principal point in the camera's internal orientation element;

[0043] S46: Convert the camera coordinates to world coordinates using the exterior orientation elements, wherein the conversion method is:

[0044] ;

[0045] in, is the camera coordinate The transformed world coordinates.

[0046] Specifically, S4 also includes the following specific steps:

[0047] S47: Extract the average sea surface elevation and calculate the actual sea surface elevation Gh. The specific calculation strategy is:

[0048] ;

[0049] Among them, Xh is the height of the camera of the optoelectronic pod on the optoelectronic platform from the sea surface;

[0050] is the camera coordinate The height coordinate in the transformed world coordinates;

[0051] S48: According to S41-S47, the image coordinates Convert to coordinates on the orthophoto , where the conversion strategy is specifically:

[0052] ;

[0053] in, are the sensor sizes in the horizontal and vertical directions, respectively;

[0054] S49: Obtain an orthophoto data set.

[0055] Specifically, S5 includes the following specific steps:

[0056] S51: extracting the area of ​​the Enteromorpha region in the orthoimage data set by a threshold segmentation algorithm to form an orthoimage Enteromorpha area data set;

[0057] S52: Evaluate the actual area of ​​Enteromorpha at sea, wherein the actual area of ​​Enteromorpha at sea is the average of each data amount in the orthophoto image Enteromorpha area data set.

[0058] Specifically, the calibration pattern of the calibration plate includes: a first color block and a second color block, the first color block and the second color block have the same shape, both are polygons, the first color block and the second color block have different colors, and the first color block and the second color block are arranged at intervals.

[0059] In addition, the present invention provides a system for calculating the area of ​​marine Enteromorpha based on a photoelectric platform, which includes the following modules:

[0060] Video data acquisition module, key frame image selection module, actual focal length calculation module, orthophoto acquisition module and Enteromorpha area calculation module;

[0061] The video data acquisition module is used to extract multiple sets of calibration plates, synchronously fix the distance between the calibration plates and the optoelectronic pod on the optoelectronic platform, adjust the field of view of the optoelectronic pod on the optoelectronic platform to shoot the calibration plates, and obtain initial video data of the calibration plates under different field of view angles;

[0062] The key frame image selection module is used to extract the initial video data, pre-process the initial video data, and select the key frame image data of the calibration plate;

[0063] The actual focal length calculation module calculates and obtains the actual focal length according to the key frame image data of the calibration plate;

[0064] The orthophoto acquisition module fits the relationship between the actual focal length and the field of view angle according to the key frame image data and the actual focal length, completes the orthophoto correction of the key frame image data through the fitting, and obtains the orthophoto image data set;

[0065] The enteromorpha area calculation module calculates the actual enteromorpha area at sea according to the orthophoto image data set.

[0066] A storage medium stores instructions, and when a computer reads the instructions, the computer executes the method for calculating the area of ​​marine Enteromorpha based on a photoelectric platform.

[0067] An electronic device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the above-mentioned method for calculating the area of ​​marine enteromorpha based on a photoelectric platform is implemented.

[0068] Compared with the prior art, the present invention can be directly implemented outside the field of Enteromorpha operation, greatly saving time and cost, and meeting the emergency measurement when disasters occur. The present invention calibrates the optoelectronic platform for shooting images of Enteromorpha at sea to ensure the basis for the accuracy of subsequent image data. The purpose of the calibration is to obtain the precise relationship between the actual focal length and the field angle of the optoelectronic platform. The focal length and the field angle are two important parameters for camera imaging. Theoretically, the two can be directly converted. In actual application, the recording equipment of the optoelectronic pod has a large error. The accurate functional relationship between the two fitted in the present invention is crucial for the correction and area calculation of subsequent images, which improves the accuracy of Enteromorpha measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. 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 creative labor. Among them:

[0070] Figure 1 It is a schematic flow chart of a method for calculating the area of ​​marine Enteromorpha based on a photoelectric platform of the present invention;

[0071] Figure 2 A schematic diagram of a square calibration plate of the present invention;

[0072] Figure 3 It is a schematic diagram of the image of the calibration plate under several viewing angles of the present invention;

[0073] Figure 4 It is a schematic diagram of an image of a calibration plate of the present invention;

[0074] Figure 5 The image data diagram corresponding to the image of the calibration plate under several viewing angles of the present invention;

[0075] Figure 6 A diagram showing the relationship between an actual focal length and a field of view angle of the present invention;

[0076] Figure 7 It is a correction effect verification diagram of performing orthophoto correction on key frame image data according to the present invention;

[0077] Figure 8 It is a structural schematic diagram of a system for calculating the area of ​​marine enteromorpha based on a photoelectric platform according to the present invention. DETAILED DESCRIPTION

[0078] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0079] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0080] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0081] Embodiment 1:

[0082] like Figure 1 As shown, a method for calculating the area of ​​marine Enteromorpha based on a photoelectric platform in an embodiment of the present invention is as follows: Figure 1 As shown, the specific steps are as follows:

[0083] S1: extract multiple sets of calibration plates, synchronously fix the distance between the calibration plates and the optoelectronic pod on the optoelectronic platform, adjust the field of view of the optoelectronic pod on the optoelectronic platform to shoot the calibration plates, and obtain initial video data of the calibration plates under different field of view angles;

[0084] The calibration pattern of the calibration plate includes: a first color block and a second color block, the first color block and the second color block have the same shape, both are polygons, the first color block and the second color block have different colors, and the first color block and the second color block are arranged at intervals.

[0085] S2: extracting initial video data, preprocessing the initial video data, and selecting key frame image data of the calibration plate;

[0086] In S2, the step of selecting the key frame image data of the calibration plate includes the following specific steps:

[0087] S21: reading the initial video data and extracting frames, and preprocessing each frame of the initial image, wherein the preprocessing includes: removing noise in each frame of the initial image by Gaussian filtering;

[0088] S22: converting the color image into the HSV color space, and marking the Enteromorpha region in each frame of the initial image using a color filter according to the hue and saturation range of the Enteromorpha;

[0089] S23: Convert each marked initial image frame into a grayscale image to form an initial image set, and establish a two-dimensional coordinate system with the lower left corner of each grayscale image frame as the origin, extract the coordinates of each pixel point in the Enteromorpha region, and evaluate the distribution fidelity of Enteromorpha in each initial image frame. The evaluation of the distribution fidelity of Enteromorpha in each initial image frame is specifically as follows:

[0090] ;

[0091] Where n is a subscript, indicating the nth frame of the initial image, and there are a total of N frames of initial images in the initial image set;

[0092] is the distribution fidelity of Enteromorpha in the initial image of the nth frame;

[0093] are the distribution characteristic coefficients of the initial images of the nth frame, the n-1th frame and the n+1th frame respectively;

[0094] S24: Preset a distribution fidelity threshold of the Enteromorpha in the initial image. When the distribution fidelity of the Enteromorpha in the n-th frame initial image is greater than or equal to the distribution fidelity threshold, select the n-th frame initial image as the key frame image of the calibration plate, traverse the initial image set to screen and obtain multiple key frame images of the calibration plate, and constitute the key frame image data of the calibration plate.

[0095] In S23, the calculation strategy of the distribution characteristic coefficient is as follows:

[0096] ;

[0097] in, is a subscript, indicating the e-th pixel point in the Enteromorpha region in the n-th frame of the initial image. is the total number of pixels in the Enteromorpha region in the nth frame of the initial image;

[0098] are respectively the horizontal and vertical coordinates of the e-th pixel point in the Enteromorpha area in the n-th frame of the initial image.

[0099] S3: Calculate and obtain the actual focal length according to the key frame image data of the calibration plate;

[0100] For example, in this embodiment, Figure 2 FIG. 1 shows a schematic diagram of a calibration board according to an embodiment of the present invention. Figure 2 As shown, a uniform pattern is arranged on the surface of the calibration plate, and the pattern includes blue squares and white squares, the blue squares and the white squares are of the same size, and the blue squares and the white squares are arranged at intervals. The pattern on the calibration plate consists of blue squares and white squares. The selection of these two colors is based on the high contrast between them, which helps to more easily identify and distinguish the squares during image processing. Blue and white can maintain good visibility under various lighting conditions, reducing the influence of ambient light on the calibration results; the size of the blue squares and the white squares are designed to be the same, which is to ensure that the number of pixels occupied by each square in the image is consistent, thereby simplifying the subsequent calculation process. The size of the square should be determined according to the resolution of the optoelectronic platform and the expected field of view range to ensure that the squares can be clearly seen at all field of view angles. The blue squares and the white squares are arranged at intervals, that is, each blue square is surrounded by white squares (or vice versa), forming a regular grid pattern. This spacing setting not only helps to enhance the recognition of the pattern, but also facilitates the determination of the image scaling and distortion by finding the boundaries of adjacent squares in image processing. Furthermore, in this embodiment, the size of a single blue square or white square is 20 cm×20 cm, and the total length of the calibration plate is 2 m×4 m. During the calibration process, ensure that the position of the calibration plate is fixed to avoid errors caused by position movement.

[0101] The distance between the calibration plate and the photoelectric platform is fixed, and the field of view of the photoelectric platform is adjusted to shoot the calibration plate, so as to obtain images of the calibration plate under several field of view angles.

[0102] S3 includes the following specific steps:

[0103] S31: Extracting geometric feature data of the calibration plate, wherein the geometric feature data of the calibration plate includes: the number of sides M of each polygon in the calibration plate, the total area Ar of each polygon, the length of each side , the angle of each interior angle And the total number of pixels U on the calibration plate;

[0104] S32: Importing the geometric feature data of the calibration plate into the calibration plate corner coefficient calculation strategy, and calculating and obtaining the calibration plate corner coefficient. The calibration plate corner coefficient zl calculation strategy is:

[0105] ;

[0106] S33: extracting the key frame image data of the calibration plate, and calculating the resolution switching coefficient Gs of the key frame image data. The specific calculation strategy of the resolution switching coefficient of the key frame image data is: ;

[0107] For example, in this embodiment, Figure 3 Schematic diagrams of images of a calibration plate under several viewing angles of an embodiment of the present invention are shown. Figure 4 FIG. 1 is a schematic diagram of an image of a calibration plate according to an embodiment of the present invention. Figure 3 and Figure 4 As shown; Use accurate measuring tools (such as laser rangefinder, tape measure, etc.) to measure and fix the distance between the calibration plate and the optoelectronic platform; This distance should be determined based on the performance parameters of the optoelectronic platform and the shooting requirements to ensure that clear images of the calibration plate can be captured at all field of view angles. The calibration plate is firmly fixed on a stable bracket or platform to prevent movement caused by factors such as vibration or wind during shooting. The field of view angle is gradually changed through the control software of the optoelectronic platform or the manual adjustment structure. The control software interface has a slider, knob or digital input box for field of view adjustment, allowing the user to accurately set the required field of view angle. Optionally, you can start from the minimum field of view angle and gradually increase to the maximum field of view angle, or vice versa. Before taking images at each field of view angle, ensure that the optoelectronic platform has been stably adjusted to the new field of view angle setting. During the process of adjusting the field of view angle, record the setting parameters corresponding to each field of view angle for subsequent data analysis and processing. When shooting, ensure that the focus system of the optoelectronic platform is correctly aligned with the calibration plate to capture a clear image.

[0108] Obtain image data corresponding to the image of the calibration plate at several field of view angles, Figure 5 FIG. 4 shows image data corresponding to the image of the calibration plate under several viewing angles of an embodiment of the present invention, such as Figure 5As shown, in this embodiment, the single-frame image data includes: the field of view angle, pixel size, distance between the calibration plate and the optoelectronic platform (H), pixel length, pixel width, calibration plate cell length and number of pixels of the calibration plate cell corresponding to the image of the calibration plate under several field of view angles. The field of view angle refers to the angle of the maximum scene range that the optoelectronic platform can capture at a certain focal length. For each captured calibration plate image, the corresponding field of view angle is recorded; the pixel size refers to the actual physical size corresponding to each pixel point on the optoelectronic platform sensor. The smaller the pixel size, the higher the spatial resolution of the image; the flight height is the fixed distance between the calibration plate and the optoelectronic platform; the calibration plate cell length is the data obtained during production, and the calibration plate cell pixel number is the number of pixels occupied by each calibration plate cell, which is measured by image processing software and obtained by identifying the boundaries of the cells and calculating the number of pixels crossing these boundaries.

[0109] S34: According to S31-S33, the actual focal length is calculated and obtained. The calculation strategy of the actual focal length f is specifically as follows: , where H is the distance between the center of the calibration plate and the optoelectronic pod on the optoelectronic platform; is the pixel size.

[0110] S4: fitting the relationship between the actual focal length and the field of view angle according to the key frame image data and the actual focal length, completing the orthophoto correction of the key frame image data through the fitting, and obtaining an orthophoto image data set;

[0111] S4 includes the following specific steps:

[0112] S41: extracting field of view angle data and the actual focal length corresponding to the field of view angle;

[0113] S42: construct multiple function fitting models, evaluate the fitting model parameters by the least square method, calculate the mean square error to evaluate the fitting results, and arrange the mean square errors in order; S43: select the function fitting model with the smallest mean square error as the final function fitting model, and fit the relationship between the actual focal length and the field of view angle by the final function fitting model, and obtain the functional relationship between the actual focal length and the field of view angle after the fitting is completed, wherein the functional relationship between the actual focal length and the field of view angle is: , a and b are the model parameters of the final function fitting model, a=341.02, b=-0.945;

[0114] Figure 6 is a graph showing the relationship between the actual focal length and the field of view angle of an embodiment of the present invention; Figure 6 As shown, the relationship between the actual focal length and the field of view angle is .

[0115] S44: Obtain the internal orientation element and the external orientation element of the camera of the optoelectronic pod on the optoelectronic platform, wherein the internal orientation element includes: the focal length of the camera in the horizontal direction , the vertical focal length of the camera , radial distortion and tangential distortion coefficients; the external orientation elements include: rotation matrix R and translation vector T;

[0116] S45: extracting the actual focal lengths at different field angles, and using the camera internal orientation elements to convert the image coordinates into camera coordinates, wherein the conversion method is:

[0117] ;

[0118] in, is the image coordinate, is the depth value of the camera coordinate system;

[0119] is the image coordinate The transformed camera coordinates;

[0120] is the coordinate of the principal point in the camera's internal orientation element;

[0121] S46: Convert the camera coordinates to world coordinates using the exterior orientation elements, wherein the conversion method is:

[0122] ;

[0123] in, is the camera coordinate The transformed world coordinates.

[0124] S47: Extract the average sea surface elevation and calculate the actual sea surface elevation Gh. The specific calculation strategy is:

[0125] ;

[0126] Among them, Xh is the height of the camera of the optoelectronic pod on the optoelectronic platform from the sea surface;

[0127] is the camera coordinate The height coordinate in the transformed world coordinates;

[0128] S48: According to S41-S47, the image coordinates Convert to coordinates on the orthophoto , where the conversion strategy is specifically:

[0129] ;

[0130] in, are the sensor sizes in the horizontal and vertical directions, respectively;

[0131] S49: Obtain an orthophoto data set.

[0132] S5: Assess the actual marine Enteromorpha area based on the orthophoto dataset.

[0133] S5 includes the following specific steps:

[0134] S51: extracting the area of ​​the Enteromorpha region in the orthoimage data set by a threshold segmentation algorithm to form an orthoimage Enteromorpha area data set;

[0135] S52: Evaluate the actual area of ​​Enteromorpha at sea, wherein the actual area of ​​Enteromorpha at sea is the average of each data amount in the orthophoto image Enteromorpha area data set.

[0136] Embodiment 2:

[0137] For example, Figure 7 As shown, in this embodiment, a correction effect verification diagram is provided for performing orthophoto correction on key frame image data through the fitting relationship. The actual length of the detected target is consistent with the measured length after correction, indicating the practicality of the measurement method of this embodiment.

[0138] Embodiment three:

[0139] like Figure 8 As shown, a system for calculating the area of ​​marine Enteromorpha based on a photoelectric platform according to an embodiment of the present invention is as follows: Figure 8 As shown, it includes the following modules:

[0140] Video data acquisition module, key frame image selection module, actual focal length calculation module, orthophoto acquisition module and Enteromorpha area calculation module;

[0141] The video data acquisition module is used to extract multiple sets of calibration plates, synchronously fix the distance between the calibration plates and the optoelectronic pod on the optoelectronic platform, adjust the field of view of the optoelectronic pod on the optoelectronic platform to shoot the calibration plates, and obtain initial video data of the calibration plates under several field of view angles;

[0142] The key frame image selection module is used to extract the initial video data, pre-process the initial video data, and select the key frame image data of the calibration plate;

[0143] The actual focal length calculation module calculates and obtains the actual focal length according to the key frame image data of the calibration plate;

[0144] The orthophoto acquisition module fits the relationship between the actual focal length and the field of view angle according to the key frame image data and the actual focal length, completes the orthophoto correction of the key frame image data through the fitting, and obtains the orthophoto image data set;

[0145] The enteromorpha area calculation module calculates the actual enteromorpha area at sea according to the orthophoto image data set.

[0146] Embodiment 4:

[0147] This embodiment provides an electronic device, including: a processor and a memory, wherein the memory stores a computer program that can be called by the processor;

[0148] The processor executes the above-mentioned method for calculating the area of ​​marine Enteromorpha based on a photoelectric platform by calling a computer program stored in the memory.

[0149] The electronic device may have relatively large differences due to different configurations or performances, and may include one or more processors (Central Processing Units, CPU) and one or more memories, wherein the memory stores at least one computer program, and the computer program is loaded and executed by the processor to implement a method for calculating the area of ​​marine Enteromorpha based on a photoelectric platform provided in the above method embodiment. The electronic device may also include other components for realizing the functions of the device, for example, the electronic device may also have components such as a wired or wireless network interface and an input and output interface to input and output data. This embodiment will not be described in detail here.

[0150] Embodiment five:

[0151] This embodiment provides a computer-readable storage medium having a rewritable computer program stored thereon;

[0152] When the computer program runs on a computer device, the computer device executes the above-mentioned method for calculating the area of ​​marine Enteromorpha based on a photoelectric platform.

[0153] For example, the computer readable storage medium can be a read-only memory (ROM), a random access memory (RAM), a compact disc (CD-ROM), a magnetic tape, a floppy disk, an optical data storage device, etc.

[0154] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0155] It should be understood that determining B based on A does not mean determining B only based on A. B can also be determined based on A and / or other information.

[0156] The above embodiments can be implemented in whole or in part by software, hardware, firmware or any other combination. When implemented by software, the above embodiments can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When a computer instruction or computer program is loaded or executed on a computer, a process or function according to an embodiment of the present invention is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. Computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, computer instructions can be transmitted from one website site, computer, server or data center to another website site, computer, server or data center through a wired network or / and a wireless network. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that contains one or more available media sets. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium. The semiconductor medium can be a solid-state hard disk.

[0157] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in the present invention can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0158] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0159] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of units is only one, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0160] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0161] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0162] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0163] In summary, compared with the prior art, the present invention can be directly implemented in the field of Enteromorpha operation, which greatly saves time and cost and meets the emergency measurement when disasters occur. The present invention calibrates the optoelectronic platform for shooting images of Enteromorpha at sea to ensure the accuracy of subsequent image data. The purpose of the calibration is to obtain the precise relationship between the actual focal length and the field angle of the optoelectronic platform. The focal length and the field angle are two important parameters for camera imaging. Theoretically, the two can be directly converted. In actual application, the recording equipment of the optoelectronic pod has a large error. The accurate functional relationship between the two fitted in the present invention is crucial for the correction and area calculation of subsequent images, which improves the accuracy of Enteromorpha measurement.

[0164] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for calculating the area of ​​marine Enteromorpha based on an optoelectronic calibration platform, characterized in that: The method comprises the following specific steps: S1: extract multiple sets of calibration plates, synchronously fix the distance between the calibration plates and the optoelectronic pod on the optoelectronic platform, adjust the field of view of the optoelectronic pod on the optoelectronic platform to shoot the calibration plates, and obtain initial video data of the calibration plates under different field of view angles; S2: extracting initial video data, preprocessing the initial video data, and selecting key frame image data of the calibration plate; S3: Calculate and obtain the actual focal length according to the key frame image data of the calibration plate; S4: fitting the relationship between the actual focal length and the field of view angle according to the key frame image data and the actual focal length, completing the orthophoto correction of the key frame image data through the fitting, and obtaining an orthophoto image data set; S5: Assess the actual marine Enteromorpha area based on the orthophoto dataset.

2. According to claim 1, a method for calculating the area of ​​marine Enteromorpha based on a photoelectric calibration platform is characterized in that: In S2, the step of selecting the key frame image data of the calibration plate includes the following specific steps: S21: reading the initial video data and extracting frames, and preprocessing each frame of the initial image, wherein the preprocessing includes: removing noise in each frame of the initial image by Gaussian filtering; S22: converting the color image into the HSV color space, and marking the Enteromorpha region in each frame of the initial image using a color filter according to the hue and saturation range of the Enteromorpha; S23: Convert each marked initial image frame into a grayscale image to form an initial image set, and establish a two-dimensional coordinate system with the lower left corner of each grayscale image frame as the origin, extract the coordinates of each pixel point in the Enteromorpha region, and evaluate the distribution fidelity of Enteromorpha in each initial image frame. The evaluation of the distribution fidelity of Enteromorpha in each initial image frame is specifically as follows: ； Where n is a subscript, indicating the nth frame of the initial image, and there are a total of N frames of initial images in the initial image set; is the distribution fidelity of Enteromorpha in the initial image of the nth frame; are the distribution characteristic coefficients of the initial images of the nth frame, the n-1th frame and the n+1th frame respectively; S24: Preset a distribution fidelity threshold of the Enteromorpha in the initial image. When the distribution fidelity of the Enteromorpha in the n-th frame initial image is greater than or equal to the distribution fidelity threshold, select the n-th frame initial image as the key frame image of the calibration plate, traverse the initial image set to screen and obtain multiple key frame images of the calibration plate, and constitute the key frame image data of the calibration plate.

3. The method for calculating the area of ​​marine Enteromorpha based on a photoelectric calibration platform according to claim 2, characterized in that: In S23, the calculation strategy of the distribution characteristic coefficient is as follows: ； in, is a subscript, indicating the e-th pixel point in the Enteromorpha region in the n-th frame of the initial image. is the total number of pixels in the Enteromorpha region in the nth frame of the initial image; are respectively the horizontal and vertical coordinates of the e-th pixel point in the Enteromorpha area in the n-th frame of the initial image.

4. The method for calculating the area of ​​marine Enteromorpha based on a photoelectric calibration platform according to claim 3, characterized in that: S3 includes the following specific steps: S31: Extracting geometric feature data of the calibration plate, wherein the geometric feature data of the calibration plate includes: the number of sides M of each polygon in the calibration plate, the total area Ar of each polygon, the length of each side , the angle of each interior angle And the total number of pixels U on the calibration plate; S32: Importing the geometric feature data of the calibration plate into the calibration plate corner coefficient calculation strategy, and calculating and obtaining the calibration plate corner coefficient. The calibration plate corner coefficient zl calculation strategy is: ； S33: extracting the key frame image data of the calibration plate, and calculating the resolution switching coefficient Gs of the key frame image data. The specific calculation strategy of the resolution switching coefficient of the key frame image data is: ; S34: According to S31-S33, the actual focal length is calculated and obtained. The calculation strategy of the actual focal length f is specifically as follows: , where H is the distance between the center of the calibration plate and the optoelectronic pod on the optoelectronic platform; is the pixel size.

5. The method for calculating the area of ​​marine Enteromorpha based on a photoelectric calibration platform according to claim 4, characterized in that: S4 includes the following specific steps: S41: extracting field of view angle data and the actual focal length corresponding to the field of view angle; S42: construct multiple function fitting models, evaluate the fitting model parameters by the least square method, calculate the mean square error to evaluate the fitting results, and arrange the mean square errors in order; S43: Selecting the function fitting model with the smallest mean square error as the final function fitting model, and fitting the relationship between the actual focal length and the field of view angle through the final function fitting model, and obtaining the functional relationship between the actual focal length and the field of view angle after the fitting is completed, wherein the functional relationship between the actual focal length and the field of view angle is: , a and b are the model parameters of the final function fitting model, a=341.02, b=-0.

945.

6. The method for calculating the area of ​​marine Enteromorpha based on a photoelectric calibration platform according to claim 5, characterized in that: S4 also includes the following specific steps: S44: Obtain the internal orientation element and the external orientation element of the camera of the optoelectronic pod on the optoelectronic platform, wherein the internal orientation element includes: the focal length of the camera in the horizontal direction , the vertical focal length of the camera , radial distortion and tangential distortion coefficients; the external orientation elements include: rotation matrix R and translation vector T; S45: extracting the actual focal lengths at different field angles, and using the camera internal orientation elements to convert the image coordinates into camera coordinates, wherein the conversion method is: ； in, are image coordinates, is the depth value of the camera coordinate system; is the image coordinate The transformed camera coordinates; is the coordinate of the principal point in the camera's internal orientation element; S46: Convert the camera coordinates to world coordinates using the exterior orientation elements, wherein the conversion method is: ； in, is the camera coordinate The transformed world coordinates.

7. The method for calculating the area of ​​marine Enteromorpha based on a photoelectric calibration platform according to claim 6, characterized in that: S4 also includes the following specific steps: S47: Extract the average sea surface elevation and calculate the actual sea surface elevation Gh. The specific calculation strategy is: ； Among them, Xh is the height of the camera of the optoelectronic pod on the optoelectronic platform from the sea surface is the camera coordinate The height coordinate in the transformed world coordinates; S48: According to S41-S47, the image coordinates Convert to coordinates on the orthophoto , where the conversion strategy is specifically: ； in, are the sensor sizes in the horizontal and vertical directions, respectively; S49: Obtain an orthophoto data set.

8. The method for calculating the area of ​​marine Enteromorpha based on a photoelectric calibration platform according to claim 7, characterized in that: S5 includes the following specific steps: S51: extracting the area of ​​the Enteromorpha region in the orthoimage data set by a threshold segmentation algorithm to form an orthoimage Enteromorpha area data set; S52: Evaluate the actual area of ​​Enteromorpha at sea, wherein the actual area of ​​Enteromorpha at sea is the average of each data amount in the orthophoto image Enteromorpha area data set.

9. The method for calculating the area of ​​marine Enteromorpha based on a photoelectric calibration platform according to claim 8, characterized in that: The calibration pattern of the calibration plate includes: a first color block and a second color block, the first color block and the second color block have the same shape, both are polygons, the first color block and the second color block have different colors, and the first color block and the second color block are arranged at intervals.

10. A system for calculating the area of ​​Enteromorpha at sea based on a photoelectric calibration platform, used to implement a method for calculating the area of ​​Enteromorpha at sea based on a photoelectric calibration platform as claimed in any one of claims 1 to 9, characterized in that: The system includes the following modules: Video data acquisition module, key frame image selection module, actual focal length calculation module, orthophoto acquisition module and Enteromorpha area calculation module; The video data acquisition module is used to extract multiple sets of calibration plates, synchronously fix the distance between the calibration plates and the optoelectronic pod on the optoelectronic platform, adjust the field of view of the optoelectronic pod on the optoelectronic platform to shoot the calibration plates, and obtain initial video data of the calibration plates under different field of view angles; The key frame image selection module is used to extract the initial video data, pre-process the initial video data, and select the key frame image data of the calibration plate; The actual focal length calculation module calculates and obtains the actual focal length according to the key frame image data of the calibration plate; The orthophoto acquisition module fits the relationship between the actual focal length and the field of view angle according to the key frame image data and the actual focal length, completes the orthophoto correction of the key frame image data through the fitting, and obtains the orthophoto image data set; The enteromorpha area calculation module calculates the actual enteromorpha area at sea according to the orthophoto image data set.

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