Artificial fish reef pile distribution characteristic analysis method based on echo detection

Abstract

The invention discloses an artificial fish reef pile distribution characteristic analysis method based on echo detection, and relates to the technical field of ecological environment monitoring, and the method comprises the following steps: data collection and preprocessing: selecting a multi-frequency echo detection device, and transmitting and receiving sound waves of different frequencies at the same time to adapt to detection demands of different water depths and fish reef types; all-directional cruise detection is carried out in a target sea area, it is ensured that all areas where artificial fish reefs possibly exist are covered, and echo signal data under different frequencies are recorded; according to the invention, an advanced signal processing algorithm is adopted, a multi-angle detection data synthesis technology is combined, a high-resolution three-dimensional model of the fish reef pile is constructed, the model is optimized and refined, and the characteristic parameters of the fish reef pile, such as echo intensity, reflection area and height difference, are extracted, so that the high-resolution three-dimensional model of the fish reef pile is obtained. The spatial distribution pattern of the fish reef pile, the relation between the fish reef pile and the marine environment and the dynamic change condition along with time can be deeply analyzed.

Description

Technical Field

[0001] The invention relates to the technical field of ecological environment monitoring, and in particular to a method for analyzing the distribution characteristics of artificial fish reef piles based on echo detection. Background Art

[0002] With the continuous improvement of awareness of marine ecological protection, the role of artificial reefs in marine ecological restoration and fishery resource proliferation has become increasingly prominent. Artificial reefs can provide a place for marine organisms to live, reproduce and forage, which helps to improve the marine ecological environment and increase the quantity and quality of fishery resources. However, in order to give full play to the ecological and economic benefits of artificial fish reefs, it is necessary to accurately grasp the distribution characteristics of artificial fish reef piles. Only by understanding the distribution of fish reef piles can we reasonably plan the location and number of fish reefs, evaluate their impact on the marine ecosystem, and formulate effective fishery management strategies;

[0003] At present, traditional methods for analyzing the distribution characteristics of artificial fish reefs have many defects. These methods are often not very accurate and cannot accurately determine key information such as the location, size and shape of the fish reefs. At the same time, they are time-consuming and require a lot of manpower and material resources, resulting in low analysis efficiency. Moreover, traditional methods are difficult to fully reflect the true distribution of fish reefs and may ignore some important distribution characteristics, such as the spatial aggregation degree of fish reefs, their relationship with marine environmental factors, and changes over time. These limitations seriously restrict the scientific management and effective utilization of artificial fish reefs.

[0004] In order to solve the above defects, a technical solution is now provided. Summary of the invention

[0005] The purpose of the present invention is to solve the problems that the traditional artificial fish reef pile distribution characteristic analysis method has low accuracy, long time consumption and difficulty in fully reflecting the actual distribution situation, and proposes an artificial fish reef pile distribution characteristic analysis method based on echo detection.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] The method for analyzing the distribution characteristics of artificial reef piles based on echo sounding includes the following steps:

[0008] S1. Data acquisition and preprocessing: Use multi-frequency echo detection equipment to cruise and detect in the target sea area, record echo signals of different frequencies and preprocess the data to improve data quality to meet different detection needs;

[0009] S2. Preliminary identification of fish reefs: Use multi-frequency echo signal differences and algorithms to preliminarily identify fish reef areas, and then eliminate interference factors to determine the preliminary range;

[0010] S3. Fine positioning and feature extraction of fish reef piles: Use high-resolution detection to build a three-dimensional model of the determined area and extract feature parameters for subsequent analysis;

[0011] S4. Analysis of distribution characteristics of fish reefs: Analyze the spatial distribution pattern of fish reefs, their relationship with the marine environment, and their changes over time based on location and parameters;

[0012] S5. Result output and application: Output the results in a visual way to provide suggestions for fish reef construction and management, and provide a basis for combining marine ecological protection and fishery resource management.

[0013] Furthermore, the specific steps of S4 are as follows:

[0014] Based on the location and characteristic parameters of fish reef piles, the spatial distribution pattern of fish reef piles was analyzed. Specifically, the density, aggregation and dispersion indexes of fish reef piles were calculated using spatial statistical analysis methods to describe the distribution characteristics of fish reef piles.

[0015] Analyze the changes in the distribution of fish reef piles over time. Specifically, by regularly conducting echo sounding, comparing the distribution of fish reef piles at different time points, and analyzing the stability and dynamic changes of fish reef piles. The specific process is as follows:

[0016] The stability of the fish reef pile is graded by determining the stability index, which includes displacement index, deformation index and characteristic parameter change rate index. The displacement index value, deformation index value and characteristic parameter change rate index value are obtained by analyzing the stability index respectively.

[0017] The obtained displacement index value Id, deformation index value If and characteristic parameter change rate index value Ic are normalized and then inserted into the following formula: S = W1*Id+W2*If+W3*Ic to obtain the comprehensive stability value S, where W1, W2, and W3 are respectively the preset weight coefficients of the displacement index value, the deformation index value and the characteristic parameter change rate index value;

[0018] The obtained comprehensive stability value S is compared with a plurality of preset comprehensive stability value intervals, and the plurality of comprehensive stability value intervals correspond to different stability levels. When the comprehensive stability value interval described by the comprehensive stability value is determined, the stability level of the fish reef pile is obtained;

[0019] Dynamic change analysis studies the dynamic changes of fish reef stacks, including the emergence of new fish reef stacks, the disappearance or changes of old fish reef stacks, and analyzes the causes of these changes, including natural factors, human activities or changes in the marine ecosystem.

[0020] Furthermore, the specific process of obtaining the displacement index value, the deformation index value and the characteristic parameter change rate index value by analyzing the stability index in S4 is as follows:

[0021] Displacement index: Calculate the Euclidean distance of the center position of the fish reef pile at different time points as the displacement D, normalize the displacement, and obtain the normalized displacement value Dn=D / Dmax, where Dmax is the maximum value of all fish reef pile displacements, and the displacement index value Id=1-Dn;

[0022] Deformation index: Compare the three-dimensional models of fish reef piles at different time points, calculate the change rate of the surface area and volume of the fish reef pile, record the surface area change rate as As, the volume change rate as Av, the comprehensive deformation index value Df = 1-(As+Av) / 2, after normalization, through the formula: Dfn = Df / Dfmax, where Dfmax is the maximum value of all fish reef pile deformation indicators, deformation index value If = 1-Dfn;

[0023] Characteristic parameter change rate index: calculate the change rate of echo intensity, reflection area, and height difference characteristic parameters at different time points, respectively recorded as: echo intensity change rate Ri, reflection area change rate Ar, height difference change rate Hc, comprehensive characteristic parameter change rate index value Cp = 1-(Ri + Ar + Hc) / 3, normalized, Cpn = Cp / Cpmax, where Cpmax is the maximum value of all fish reef pile characteristic parameter change rate indicators, characteristic parameter change rate index value Ic = 1-Cpn.

[0024] Furthermore, the specific operation steps of S1 are as follows:

[0025] Select multi-frequency echo sounder to transmit and receive sound waves of different frequencies at the same time to meet the detection requirements of different water depths and fish reef types;

[0026] Carry out all-round patrol detection in the target sea area to ensure coverage of all areas with artificial reefs, record echo signal data at different frequencies, and store the data in real time;

[0027] The collected data are preprocessed, including removing noise and correcting the sound speed error caused by changes in sea water temperature and salinity, to improve the quality and accuracy of the data.

[0028] Furthermore, the specific operation steps of preprocessing the collected data in S1 are as follows:

[0029] The process of removing noise is as follows:

[0030] Identify noise characteristics: Analyze the spectral characteristics of echo signal data to determine the frequency range and intensity distribution of noise. Due to the complex marine environment, noise comes from multiple sources, including ship navigation noise and marine biological activity noise, which have different frequency characteristics;

[0031] By analyzing the time series and spectrum of the data, the abnormal fluctuation parts that are different from the target echo signal are identified, and these parts are noise;

[0032] Select denoising method: According to the characteristics of the noise, select the corresponding denoising algorithm, including wavelet transform denoising and filter denoising;

[0033] Use a bandpass filter and set the corresponding cutoff frequency to allow only signals in the frequency range of the target echo signal to pass, thereby filtering out noise;

[0034] Wavelet transform denoising decomposes the signal into wavelet coefficients of different scales by performing wavelet decomposition on the signal. According to the characteristics of the wavelet coefficients, the wavelet coefficients corresponding to the noise are threshold processed, and then wavelet reconstruction is performed to obtain the denoised signal.

[0035] Verify the denoising effect: Evaluate the denoised signal to determine whether it meets the standard. Specifically, the denoising effect is measured by comparing the signal-to-noise ratio of the signal before and after denoising.

[0036] The process of sound velocity error correction is as follows:

[0037] Measuring seawater temperature and salinity: While conducting echo sounding, use a temperature-salinity-depth instrument to measure the temperature and salinity of seawater. The temperature-salinity-depth instrument measures at preset depth intervals to obtain vertical profile data of seawater temperature and salinity.

[0038] Calculate the change of sound speed: According to the temperature and salinity data of seawater, use the sound speed calculation formula to calculate the actual value of the sound speed. The formula is: C = 1448.96 + 4.591T - 5.304 × 10 -2 T 2 +2.374×10 -4 T 3 +1.340(S-35)+1.630×10 -2 (S-35)T, where C is the speed of sound, T is the temperature, and S is the salinity;

[0039] Substitute the measured temperature and salinity into the formula to calculate the difference between the actual sound speed and the standard sound speed, that is, the sound speed error:

[0040] Correct echo data: Correct echo data according to sound velocity error;

[0041] The sound speed error is known to be ΔC, the original echo propagation time is t, and the corrected propagation time t'=t×(C0 / (C0+ΔC)), where C0 is the standard sound speed. The distance parameter corresponding to the echo is recalculated according to the corrected propagation time to complete the sound speed error correction and improve the accuracy of the data.

[0042] Furthermore, the specific operation steps of S2 are as follows:

[0043] By using the characteristic differences of multi-frequency echo signals and combining signal processing algorithms, the artificial reef area can be preliminarily identified. By comparing the echo intensity and reflection characteristics at different frequencies, the area with reflection signals can be screened out.

[0044] Further analysis and verification of the initially identified areas were carried out to eliminate interference factors, including changes in seabed topography and natural reefs. Specifically:

[0045] For the initially selected areas, combined with the seabed topography data, determine whether there are situations where the same reflection signal is generated due to changes in the seabed topography. If so, exclude it;

[0046] By comparing the typical echo characteristics of natural reefs, the signal processing algorithm is used to distinguish the echo signals of the candidate area from those of natural reefs, eliminate the interference caused by natural reefs, and determine the final preliminary identification area of ​​the artificial fish reef pile.

[0047] Furthermore, the specific operation steps of S3 are as follows:

[0048] For the determined artificial reef area, echo detection technology is used to determine the location, size and shape of the reef. Through multi-angle detection and signal synthesis, a three-dimensional model of the reef is constructed. Specifically:

[0049] Use echo sounder to detect the artificial fish reef area, adjust the parameters of the detection equipment to ensure that clear and accurate echo signals can be obtained, detect the fish reef area from different angles, record the arrival time and direction of the echo signal, calculate the distance between the fish reef and the detection equipment by measuring the propagation time of the echo signal, and determine the position of the fish reef in three-dimensional space by combining the measurement results at different angles;

[0050] The echo signals obtained from multi-angle detection are synthesized, and the echo signals at different angles are fused using signal processing algorithms to construct a three-dimensional image of the fish reef pile. The three-dimensional image is optimized and refined, and the accuracy and clarity of the three-dimensional model are improved by removing noise and enhancing edge processing. Image processing technology, including filtering and edge detection, is used to further optimize the three-dimensional model.

[0051] The characteristic parameters of the fish reef piles are extracted, including echo intensity, reflection area, and height difference. The characteristic parameters are used for subsequent distribution characteristic analysis.

[0052] Furthermore, the specific operation steps of extracting the characteristic parameters of the fish reef pile in S3 are as follows:

[0053] Echo intensity extraction: Analyze the amplitude of the echo signal, determine the echo intensity of the fish reef pile, and calculate the average amplitude or peak amplitude of the echo signal as an indicator of echo intensity;

[0054] Reflection area calculation: According to the three-dimensional model, determine the reflection surface of the fish reef pile, calculate the area of ​​the reflection surface, obtain the reflection area parameters of the fish reef pile, and use three-dimensional modeling software or algorithms to automatically calculate the reflection area;

[0055] Height difference measurement: Use the three-dimensional model to measure the height difference of the fish reef pile, determine the highest and lowest points of the fish reef pile, calculate the height difference between them, and measure the height difference by comparing the arrival time of the echo signal at different positions or using the three-dimensional coordinate information;

[0056] Establish a data table or database to store the location, size, shape and characteristic parameter information of fish reef piles, back up and archive the data for subsequent distribution characteristic analysis and research, and ensure the security and accessibility of the data.

[0057] Furthermore, the specific operation steps of extracting the characteristic parameters of the fish reef pile in S5 are as follows:

[0058] Output the analysis results in a visual way, including drawing fish reef pile distribution maps and three-dimensional model display, so as to intuitively understand the distribution characteristics of fish reef piles;

[0059] The process of drawing the fish reef distribution map is as follows:

[0060] Data collation: collate the location data of the fish reef piles, including longitude and latitude coordinates;

[0061] Choose a mapping tool: Use GIS software or mapping tools;

[0062] Map settings: set the map scale, legend, and annotation elements to ensure that the map is clear and readable;

[0063] Mapping the location of fish reefs: The location data of fish reefs are represented on the map with icons or symbols. Different types or characteristics of fish reefs are distinguished by different colors or shapes;

[0064] Add marine environment information: When there is marine environment data such as water depth and current, it is displayed on the map in the form of contour lines and arrows to better understand the relationship between fish reefs and the marine environment;

[0065] The 3D model display process includes:

[0066] Data preparation: Prepare the 3D model data of the fish reef pile, and construct the 3D model by obtaining the fine positioning and feature extraction steps of the fish reef pile;

[0067] Choose presentation tools: Use 3D modeling software or visualization platforms;

[0068] Model import and settings: Import the 3D model of the fish reef pile into the display tool and set the lighting and material parameters;

[0069] Adding interactive functions: Adding interactive functions to the 3D model display, including rotation, zooming, and translation, so that users can observe the shape and structure of the fish reef pile from different angles;

[0070] Labeling and description: Add labels and descriptions to the 3D model to introduce the characteristic parameters and important information of the fish reef pile;

[0071] Based on the analysis results, provide scientific advice for the construction and management of artificial reefs, including determining the location of artificial reefs, optimizing the design and layout of artificial reefs, so as to improve the ecological and economic benefits of artificial reefs;

[0072] The results of the analysis of the distribution characteristics of fish reef piles are combined with marine ecological protection and fishery resource management to provide a basis for the formulation of marine protection policies and fishery development plans.

[0073] Compared with the prior art, the present invention has the following beneficial effects:

[0074] (1) The present invention adopts advanced signal processing algorithms and combines multi-angle detection data synthesis technology to construct a high-resolution three-dimensional model of fish reef piles, and optimizes and refines the model. By extracting characteristic parameters of fish reef piles, such as echo intensity, reflection area and height difference, it is possible to deeply analyze the spatial distribution pattern of fish reef piles and their relationship with the marine environment, as well as their dynamic changes over time;

[0075] (2) The present invention uses a multi-frequency echo sounder to conduct all-round cruise detection of artificial reefs, which can meet the detection requirements of different water depths and reef types. Through real-time data storage and preprocessing, including noise removal and sound speed error correction, the quality and accuracy of the data are significantly improved. This method not only improves the detection accuracy, but also greatly improves the detection efficiency due to the use of automated processing technology;

[0076] (3) The present invention provides analysis results that are output in a visual manner, including drawing a fish reef pile distribution map and a three-dimensional model display, so that decision makers can intuitively understand the distribution characteristics of the fish reef piles. In addition, by analyzing the stability and dynamic changes of the fish reef piles, it can provide a scientific basis for the construction and management of artificial fish reefs, optimize the placement and design of fish reefs, and thus improve the ecological and economic benefits of fish reefs. At the same time, these analysis results can also provide important decision-making support for marine ecological protection and fishery resource management. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] In order to facilitate understanding by those skilled in the art, the present invention is further described below in conjunction with the accompanying drawings;

[0078] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0079] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0080] It should be understood that the terms "include" and "comprising" used in the specification and claims of the present disclosure indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or collections thereof.

[0081] It should also be understood that the terms used in this disclosure are only for the purpose of describing specific embodiments and are not intended to limit the disclosure. As used in this disclosure and claims, the singular forms of "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It should also be further understood that the term "and / or" used in this disclosure and claims refers to any combination of one or more of the associated listed items and all possible combinations, including these combinations.

[0082] like Figure 1 As shown, the method for analyzing the distribution characteristics of artificial reef piles based on echo detection includes the following steps:

[0083] Data collection and preprocessing:

[0084] Select multi-frequency echo sounder equipment to simultaneously transmit and receive sound waves of different frequencies to meet the detection needs of different water depths and fish reef types; conduct all-round patrol detection in the target sea area to ensure that all areas where artificial fish reefs may exist are covered, record echo signal data at different frequencies, and store the data in real time; pre-process the collected data, including removing noise, correcting the sound speed error caused by changes in seawater temperature and salinity, etc., to improve the quality and accuracy of the data;

[0085] The process of removing noise is as follows:

[0086] Identify noise characteristics: Analyze the spectral characteristics of the echo signal data to determine the frequency range and intensity distribution of the noise. Due to the complex marine environment, noise comes from multiple sources, including ship navigation noise and marine biological activity noise, which have different frequency characteristics. By analyzing the time series and spectrum of the data, identify the abnormal fluctuation parts that are different from the target echo signal (i.e., the echo from the artificial reef), which are the noise. Select the denoising method: According to the characteristics of the noise, select the corresponding denoising algorithm, including wavelet transform denoising and filter denoising. When the noise is more concentrated in a specific frequency range, use a bandpass filter and set a suitable cutoff frequency to only allow the signal in the frequency range where the target echo signal is located to pass. The noise is filtered out by wavelet transform. For complex non-stationary noise, wavelet transform denoising is more suitable. The signal is decomposed into wavelet coefficients of different scales by wavelet decomposition. According to the characteristics of wavelet coefficients, the wavelet coefficients corresponding to the noise are threshold processed, and then wavelet reconstruction is performed to obtain the denoised signal. Verify the denoising effect: evaluate the denoised signal to observe whether it is closer to the ideal noise-free signal. Specifically, the denoising effect is measured by comparing the signal-to-noise ratio (SNR) of the signal before and after denoising. The formula for calculating the signal-to-noise ratio is: SNR = 10log10 (Ps / Pn), where Ps is the signal power and Pn is the noise power. If the signal-to-noise ratio is improved after denoising, it means that the denoising effect is good.

[0087] The process of sound velocity error correction is as follows:

[0088] Measuring seawater temperature and salinity: While conducting echo sounding, a temperature-salinity-depth (CTD) device is used to measure the temperature and salinity of seawater. These parameters may vary greatly at different depths and sea areas, and will have a significant impact on the speed of sound. The CTD device can measure at regular depth intervals to obtain vertical profile data of seawater temperature and salinity.

[0089] Calculate the change of sound speed: According to the temperature and salinity data of seawater, use the sound speed calculation formula to calculate the actual value of the sound speed. The sound speed calculation formula is: C = 1448.96 + 4.591T - 5.304 × 10 -2 T 2 +2.374×10 -4 T 3 +1.340(S-35)+1.630×10 -2(S-35)T, where C is the speed of sound (m / s), T is the temperature (℃), and S is the salinity (‰); substitute the measured temperature and salinity into the formula to calculate the difference between the actual speed of sound and the standard speed of sound (assuming the speed of sound under ideal conditions), i.e., the speed of sound error: Correct echo data: Correct echo data according to the speed of sound error. Since changes in the speed of sound will cause deviations in the propagation time and distance calculation of the echo signal, these data need to be corrected; if the speed of sound error is known to be ΔC and the original echo propagation time is t, then the corrected propagation time t'=t×(C0 / (C0+ΔC)), where C0 is the standard speed of sound, recalculate the distance and other parameters corresponding to the echo based on the corrected propagation time, thereby completing the speed of sound error correction and improving the accuracy of the data;

[0090] Preliminary identification of fish reef piles:

[0091] By using the characteristic differences of multi-frequency echo signals and combining signal processing algorithms, the artificial reef area is preliminarily identified. By comparing the echo intensity and reflection characteristics at different frequencies, the area with obvious reflection signals is screened out. The screening process is as follows:

[0092] Select a relatively stable area without artificial reefs as the control area, measure the echo intensity and reflection characteristics of the area at different frequencies, and establish a reference standard for the background signal. For example, the average echo intensity and typical values ​​of reflection characteristics of the control area at multiple measurement points can be calculated, such as the mean and variance of the reflection coefficient; set the echo intensity index and reflection characteristic index,

[0093] Set echo intensity index: calculate the threshold of echo intensity at different frequencies, and perform statistical analysis on the echo intensity of multiple control area samples. When the echo intensity of a certain area at a specific frequency exceeds the threshold, it is judged that the area has a strong echo signal at this frequency; define the echo intensity ratio, calculate the echo intensity ratio of the target area at different frequencies, that is, the ratio of the higher frequency echo intensity to the lower frequency echo intensity. When the ratio exceeds the preset value, it is judged that the echo intensity of the area at different frequencies has obvious differences, which may be the characteristics of artificial fish reef piles;

[0094] Reflection characteristic indicators: Reflection coefficient: The reflection coefficient is calculated according to the amplitude ratio of the reflected wave to the incident wave at different frequencies, and the threshold range of the reflection coefficient is set. When the reflection coefficient of the target area falls within the threshold range at a specific frequency, the area is considered to have obvious reflection characteristics; Reflection time difference: Compare the reflection time differences of echoes at different frequencies. At different frequencies, the reflection time difference of the target area is relatively stable and significantly different from that of the control area. This is used as the basis for judging whether it has obvious reflection characteristics. For example, a threshold of the reflection time difference is set. When the reflection time difference of the target area exceeds the threshold, it is considered to have obvious reflection characteristics; Combine the echo intensity index and the reflection characteristic index for comprehensive evaluation. Specifically, different weights are assigned to the echo intensity index and the reflection characteristic index. A comprehensive index value is obtained by weighted summation. When the comprehensive index value exceeds the preset threshold, the area is identified as an area with obvious reflection signals;

[0095] Further analysis and verification are carried out on the initially identified areas to eliminate interference factors, including changes in seabed topography and natural reefs. Specifically: for the initially screened areas, combined with the seabed topography data, it is determined whether there are similar reflection signals caused by changes in the seabed topography. If so, they are eliminated; by comparing the typical echo characteristics of natural reefs, the signal processing algorithm is used to distinguish the echo signals of the candidate areas from those of natural reefs, the interference caused by natural reefs is eliminated, and the final preliminary identification area of ​​the artificial fish reef pile is determined.

[0096] Fish reef location and feature extraction:

[0097] For the determined artificial reef area, high-resolution echo detection technology is used to accurately determine the location, size and shape of the reef. Through multi-angle detection and signal synthesis, a three-dimensional model of the reef is constructed. Specifically:

[0098] For the determined artificial fish reef area, use high-resolution echo detection equipment to conduct more detailed detection, adjust the parameters of the detection equipment to ensure that clear and accurate echo signals can be obtained, detect the fish reef area from different angles, record the arrival time and direction of the echo signal, and calculate the distance between the fish reef and the detection equipment by measuring the propagation time of the echo signal. Combining the measurement results at different angles, the position of the fish reef in three-dimensional space can be determined; synthesize the echo signals obtained from multi-angle detection, use signal processing algorithms to fuse the echo signals at different angles, construct a three-dimensional image of the fish reef, optimize and refine the three-dimensional image, and improve the accuracy and clarity of the three-dimensional model by removing noise, enhancing edges, etc. Use image processing techniques such as filtering and edge detection to further optimize the three-dimensional model;

[0099] Extract characteristic parameters of fish reef piles, including echo intensity, reflection area, and height difference. The characteristic parameters are used for subsequent distribution characteristic analysis;

[0100] Echo intensity extraction: Analyze the amplitude of the echo signal, determine the echo intensity of the fish reef pile, and calculate the average amplitude or peak amplitude of the echo signal as an indicator of echo intensity; Reflection area calculation: According to the three-dimensional model, determine the reflection surface of the fish reef pile, and obtain the reflection area parameters of the fish reef pile by calculating the area of ​​the reflection surface. Use three-dimensional modeling software or algorithms to automatically calculate the reflection area; Height difference measurement: Use the three-dimensional model to measure the height difference of the fish reef pile, determine the highest and lowest points of the fish reef pile, calculate the height difference between them, and measure the height difference by comparing the arrival time of the echo signals at different positions or using three-dimensional coordinate information;

[0101] Establish a data table or database to store information such as the location, size, shape, and characteristic parameters of fish reef piles, back up and archive the data for subsequent distribution characteristic analysis and research, and ensure the security and accessibility of the data.

[0102] Analysis of distribution characteristics of fish reef piles:

[0103] Based on the location and characteristic parameters of fish reef piles, the spatial distribution pattern of fish reef piles was analyzed. Specifically, the density, aggregation and dispersion indexes of fish reef piles were calculated using spatial statistical analysis methods to describe the distribution characteristics of fish reef piles. Specifically:

[0104] Select spatial statistical analysis methods, including kernel density estimation and nearest neighbor analysis; calculate density index: use the selected method to calculate the density of fish reef piles, reflecting the concentration of fish reef piles in space, and determine the density by calculating the number of fish reef piles or the sum of echo intensities per unit area; calculate aggregation index: use aggregation index, including Moran's I index or Geary's C index, to evaluate the spatial aggregation degree of fish reef piles. Aggregation index is used to measure the autocorrelation of fish reef piles in space and determine whether they present a clustered distribution; calculate dispersion index: use dispersion index, including standard deviation ellipse or mean center distance, to describe the dispersion degree of fish reef piles. Dispersion index is used to determine the distribution range and direction of fish reef piles;

[0105] Analyze the relationship between the distribution of fish reefs and marine environmental factors. Specifically, combine the water depth, ocean currents, and seabed topography data to study the impact of these factors on the distribution of fish reefs. Analyze the distribution patterns of fish reefs in different water depths, as well as the impact of ocean currents on the location and morphology of fish reefs.

[0106] Study the changes in the distribution of fish reef piles over time. Specifically, by regularly conducting echo sounding, comparing the distribution of fish reef piles at different time points, and analyzing the stability and dynamic changes of fish reef piles. The specific process is as follows:

[0107] The stability of the fish reef pile is graded and judged by determining the stability indicators, which include:

[0108] Displacement index: Calculate the Euclidean distance of the center position of the fish reef pile at different time points as the displacement D, normalize the displacement, and obtain the normalized displacement value Dn=D / Dmax, where Dmax is the maximum displacement of all fish reef piles, and the displacement index value Id=1-Dn; Deformation index: Compare the three-dimensional models of the fish reef pile at different time points, calculate the change rate of the surface area and volume of the fish reef pile, record the surface area change rate as As, the volume change rate as Av, and the comprehensive deformation index value Df=1-(As+Av) / 2. After normalization, Dfn=Df / Dfmax, where Dfmax is the maximum value of all fish reef pile deformation indicators, and the deformation index value If=1-Dfn; characteristic parameter change rate index: calculate the change rate of echo intensity, reflection area, and height difference characteristic parameters at different time points, echo intensity change rate Ri, reflection area change rate Ar, height difference change rate Hc, comprehensive characteristic parameter change rate index value Cp=1-(Ri+Ar+Hc) / 3, normalized, Cpn=Cp / Cpmax, where Cpmax is the maximum value of all fish reef pile characteristic parameter change rate indicators, and characteristic parameter change rate index value Ic=1-Cpn;

[0109] The obtained displacement index value Id, deformation index value If and characteristic parameter change rate index value Ic are normalized and then inserted into the following formula: S=W1*Id+W2*If+W3*Ic to obtain the comprehensive stability value S, wherein W1, W2, and W3 are respectively the preset weight coefficients of the displacement index value Id, the deformation index value If and the characteristic parameter change rate index value Ic, and W1+W2+W3=1; the obtained comprehensive stability value S is compared with several preset comprehensive stability value intervals, and the several comprehensive stability value intervals correspond to different stability levels. When the comprehensive stability value interval described in the comprehensive stability value is determined, the stability level of the fish reef pile is obtained;

[0110] Dynamic change analysis: Study the dynamic changes of fish reef piles, including the emergence of new fish reef piles, the disappearance or changes of old fish reef piles, etc., and analyze the reasons for these changes, such as natural factors, human activities or changes in marine ecosystems.

[0111] Result output and application:

[0112] The analysis results are output in a visual way, including drawing fish reef pile distribution maps and three-dimensional model display, so as to intuitively understand the distribution characteristics of fish reef piles; the process of drawing fish reef pile distribution maps is as follows:

[0113] Data collation: collate the location data of the fish reef piles, including latitude and longitude coordinates; select drawing tools: use geographic information system (GIS) software or drawing tools, such as ArcGIS, QGIS, etc.; map settings: set the scale, legend, and annotation elements of the map to ensure that the map is clear and readable; draw the location of the fish reef piles: represent the location data of the fish reef piles on the map with icons or symbols, and use different colors or shapes to distinguish fish reef piles of different types or characteristics; add marine environment information: if there is marine environment data such as water depth and current, display it on the map in the form of contour lines, arrows, etc., so as to better understand the relationship between the fish reef piles and the marine environment;

[0114] The 3D model display includes:

[0115] Data preparation: prepare the 3D model data of the fish reef pile, and construct the 3D model by obtaining the steps of fine positioning and feature extraction of the fish reef pile; select the display tool: use 3D modeling software or visualization platform, such as Blender, Unity, etc.; import and set the model: import the 3D model of the fish reef pile into the display tool, set the lighting, material and other parameters to make the model more realistic; add interactive functions: add interactive functions to the 3D model display, such as rotation, scaling, translation, etc., so that users can observe the shape and structure of the fish reef pile from different angles; mark and explain: add marks and explanations on the 3D model to introduce the characteristic parameters and important information of the fish reef pile.

[0116] Based on the analysis results, scientific advice is provided for the construction and management of artificial fish reefs, including determining the best location for fish reef placement and optimizing the design and layout of fish reefs to improve the ecological and economic benefits of fish reefs; the analysis results of the distribution characteristics of fish reefs are combined with marine ecological protection and fishery resource management to provide a basis for the formulation of marine protection policies and fishery development plans.

[0117] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for analyzing the distribution characteristics of artificial reefs based on echo sounding, characterized in that: The following steps are involved: S1. Data acquisition and preprocessing: Use multi-frequency echo detection equipment to cruise and detect in the target sea area, record echo signals of different frequencies and preprocess the data to improve data quality to meet different detection needs; S2. Preliminary identification of fish reefs: Use multi-frequency echo signal differences and algorithms to preliminarily identify fish reef areas, and then eliminate interference factors to determine the preliminary range; S3. Fine positioning and feature extraction of fish reef piles: Use high-resolution detection to build a three-dimensional model of the determined area and extract feature parameters for subsequent analysis; S4. Analysis of distribution characteristics of fish reefs: Analyze the spatial distribution pattern of fish reefs, their relationship with the marine environment, and their changes over time based on location and parameters; S5. Result output and application: Output the results in a visual way to provide suggestions for reef construction and management, and provide a basis for combining marine ecological protection and fishery resource management.

2. The method for analyzing the distribution characteristics of artificial reefs based on echo sounding according to claim 1, characterized in that: The specific steps of S4 are as follows: Based on the location and characteristic parameters of fish reef piles, the spatial distribution pattern of fish reef piles was analyzed. Specifically, the density, aggregation and dispersion indexes of fish reef piles were calculated using spatial statistical analysis methods to describe the distribution characteristics of fish reef piles. Analyze the changes in the distribution of fish reef piles over time. Specifically, by regularly conducting echo sounding, comparing the distribution of fish reef piles at different time points, and analyzing the stability and dynamic changes of fish reef piles. The specific process is as follows: The stability of the fish reef pile is graded by determining the stability index, which includes displacement index, deformation index and characteristic parameter change rate index. The displacement index value, deformation index value and characteristic parameter change rate index value are obtained by analyzing the stability index respectively. The obtained displacement index value Id, deformation index value If and characteristic parameter change rate index value Ic are normalized and then inserted into the following formula: S = W1*Id+W2*If+W3*Ic to obtain the comprehensive stability value S, where W1, W2, and W3 are respectively the preset weight coefficients of the displacement index value, the deformation index value and the characteristic parameter change rate index value; The obtained comprehensive stability value S is compared with a plurality of preset comprehensive stability value intervals, and the plurality of comprehensive stability value intervals correspond to different stability levels. When the comprehensive stability value interval described by the comprehensive stability value is determined, the stability level of the fish reef pile is obtained; Dynamic change analysis studies the dynamic changes of fish reef stacks, including the emergence of new fish reef stacks, the disappearance or changes of old fish reef stacks, and analyzes the causes of these changes, including natural factors, human activities or changes in the marine ecosystem.

3. The method for analyzing the distribution characteristics of artificial reefs based on echo sounding according to claim 2, characterized in that: The specific process of obtaining the displacement index value, the deformation index value and the characteristic parameter change rate index value by analyzing the stability index in S4 is as follows: Displacement index: Calculate the Euclidean distance of the center position of the fish reef pile at different time points as the displacement D, normalize the displacement, and obtain the normalized displacement value Dn=D / Dmax, where Dmax is the maximum value of all fish reef pile displacements, and the displacement index value Id=1-Dn; Deformation index: Compare the three-dimensional models of fish reef piles at different time points, calculate the change rate of the surface area and volume of the fish reef pile, record the surface area change rate as As, the volume change rate as Av, the comprehensive deformation index value Df = 1-(As+Av) / 2, after normalization, through the formula: Dfn = Df / Dfmax, where Dfmax is the maximum value of all fish reef pile deformation indicators, deformation index value If = 1-Dfn; Characteristic parameter change rate index: calculate the change rate of echo intensity, reflection area, and height difference characteristic parameters at different time points, respectively recorded as: echo intensity change rate Ri, reflection area change rate Ar, height difference change rate Hc, comprehensive characteristic parameter change rate index value Cp = 1-(Ri + Ar + Hc) / 3, normalized, Cpn = Cp / Cpmax, where Cpmax is the maximum value of all fish reef pile characteristic parameter change rate indicators, characteristic parameter change rate index value Ic = 1-Cpn.

4. The method for analyzing the distribution characteristics of artificial reefs based on echo sounding according to claim 1, characterized in that: The specific operation steps of S1 are as follows: Select multi-frequency echo sounder to transmit and receive sound waves of different frequencies at the same time to meet the detection requirements of different water depths and fish reef types; Carry out all-round patrol detection in the target sea area to ensure coverage of all areas with artificial reefs, record echo signal data at different frequencies, and store the data in real time; The collected data are preprocessed, including removing noise and correcting the sound speed error caused by changes in sea water temperature and salinity, to improve the quality and accuracy of the data.

5. The method for analyzing the distribution characteristics of artificial reefs based on echo sounding according to claim 4, characterized in that: The specific operation steps of preprocessing the collected data in S1 are as follows: The process of removing noise is as follows: Identify noise characteristics: Analyze the spectral characteristics of echo signal data to determine the frequency range and intensity distribution of noise. Due to the complex marine environment, noise comes from multiple sources, including ship navigation noise and marine biological activity noise, which have different frequency characteristics; By analyzing the time series and spectrum of the data, the abnormal fluctuation parts that are different from the target echo signal are identified, and these parts are noise; Select denoising method: According to the characteristics of the noise, select the corresponding denoising algorithm, including wavelet transform denoising and filter denoising; Use a bandpass filter and set the corresponding cutoff frequency to allow only signals in the frequency range of the target echo signal to pass, thereby filtering out noise; Wavelet transform denoising decomposes the signal into wavelet coefficients of different scales by performing wavelet decomposition on the signal. According to the characteristics of the wavelet coefficients, the wavelet coefficients corresponding to the noise are threshold processed, and then wavelet reconstruction is performed to obtain the denoised signal. Verify the denoising effect: Evaluate the denoised signal to determine whether it meets the standard. Specifically, the denoising effect is measured by comparing the signal-to-noise ratio of the signal before and after denoising. The process of sound velocity error correction is as follows: Measuring seawater temperature and salinity: While conducting echo sounding, use a temperature-salinity-depth instrument to measure the temperature and salinity of seawater. The temperature-salinity-depth instrument measures at preset depth intervals to obtain vertical profile data of seawater temperature and salinity. Calculate the change of sound speed: According to the temperature and salinity data of seawater, use the sound speed calculation formula to calculate the actual value of the sound speed. The formula is: C = 1448.96 + 4.591T - 5.304 × 10 -2 T 2 +2.374×10 -4 T 3 +1.340(S-35)+1.630×10 -2 (S-35)T, where C is the speed of sound, T is the temperature, and S is the salinity; Substitute the measured temperature and salinity into the formula to calculate the difference between the actual sound speed and the standard sound speed, that is, the sound speed error: Correct echo data: Correct echo data according to sound velocity error; The sound speed error is known to be ΔC, the original echo propagation time is t, and the corrected propagation time t'=t×(C0 / (C0+ΔC)), where C0 is the standard sound speed. The distance parameter corresponding to the echo is recalculated according to the corrected propagation time to complete the sound speed error correction and improve the accuracy of the data.

6. The method for analyzing the distribution characteristics of artificial reefs based on echo sounding according to claim 1, characterized in that: The specific operation steps of S2 are as follows: By using the characteristic differences of multi-frequency echo signals and combining signal processing algorithms, the artificial reef area can be preliminarily identified. By comparing the echo intensity and reflection characteristics at different frequencies, the area with reflection signals can be screened out. Further analysis and verification of the initially identified areas were carried out to eliminate interference factors, including changes in seabed topography and natural reefs. Specifically: For the initially selected areas, combined with the seabed topography data, determine whether there are situations where the same reflection signal is generated due to changes in the seabed topography. If so, exclude it; By comparing the typical echo characteristics of natural reefs, the signal processing algorithm is used to distinguish the echo signals of the candidate area from those of natural reefs, eliminate the interference caused by natural reefs, and determine the final preliminary identification area of ​​the artificial fish reef pile.

7. The method for analyzing the distribution characteristics of artificial reefs based on echo sounding according to claim 1, characterized in that: The specific operation steps of S3 are as follows: For the determined artificial reef area, echo detection technology is used to determine the location, size and shape of the reef. Through multi-angle detection and signal synthesis, a three-dimensional model of the reef is constructed. Specifically: Use echo sounder to detect the artificial fish reef area, adjust the parameters of the detection equipment to ensure that clear and accurate echo signals can be obtained, detect the fish reef area from different angles, record the arrival time and direction of the echo signal, calculate the distance between the fish reef and the detection equipment by measuring the propagation time of the echo signal, and determine the position of the fish reef in three-dimensional space by combining the measurement results at different angles; The echo signals obtained from multi-angle detection are synthesized, and the echo signals at different angles are fused using signal processing algorithms to construct a three-dimensional image of the fish reef pile. The three-dimensional image is optimized and refined, and the accuracy and clarity of the three-dimensional model are improved by removing noise and enhancing edge processing. Image processing technology, including filtering and edge detection, is used to further optimize the three-dimensional model. The characteristic parameters of the fish reef piles are extracted, including echo intensity, reflection area, and height difference. The characteristic parameters are used for subsequent distribution characteristic analysis.

8. The method for analyzing the distribution characteristics of artificial reefs based on echo sounding according to claim 7, characterized in that: The specific operation steps of extracting the characteristic parameters of the fish reef pile in S3 are as follows: Echo intensity extraction: Analyze the amplitude of the echo signal, determine the echo intensity of the fish reef pile, and calculate the average amplitude or peak amplitude of the echo signal as an indicator of echo intensity; Reflection area calculation: According to the three-dimensional model, determine the reflection surface of the fish reef pile, calculate the area of ​​the reflection surface, obtain the reflection area parameters of the fish reef pile, and use three-dimensional modeling software or algorithms to automatically calculate the reflection area; Height difference measurement: Use the three-dimensional model to measure the height difference of the fish reef pile, determine the highest and lowest points of the fish reef pile, calculate the height difference between them, and measure the height difference by comparing the arrival time of the echo signal at different positions or using the three-dimensional coordinate information; Establish a data table or database to store the location, size, shape and characteristic parameter information of fish reef piles, back up and archive the data for subsequent distribution characteristic analysis and research, and ensure the security and accessibility of the data.

9. The method for analyzing the distribution characteristics of artificial reefs based on echo sounding according to claim 1, characterized in that: The specific operation steps of extracting the characteristic parameters of the fish reef pile in S5 are as follows: Output the analysis results in a visual way, including drawing fish reef pile distribution maps and three-dimensional model display, so as to intuitively understand the distribution characteristics of fish reef piles; The process of drawing the fish reef distribution map is as follows: Data collation: collate the location data of the fish reef piles, including longitude and latitude coordinates; Choose a mapping tool: Use GIS software or mapping tools; Map settings: set the map scale, legend, and annotation elements to ensure that the map is clear and readable; Mapping the location of fish reefs: The location data of fish reefs are represented on the map with icons or symbols. Different types or characteristics of fish reefs are distinguished by different colors or shapes; Add marine environment information: When there is marine environment data such as water depth and current, it is displayed on the map in the form of contour lines and arrows to better understand the relationship between fish reefs and the marine environment; The 3D model display process includes: Data preparation: Prepare the 3D model data of the fish reef pile, and construct the 3D model by obtaining the fine positioning and feature extraction steps of the fish reef pile; Choose presentation tools: Use 3D modeling software or visualization platforms; Model import and settings: Import the 3D model of the fish reef pile into the display tool and set the lighting and material parameters; Adding interactive functions: Adding interactive functions to the 3D model display, including rotation, zooming, and translation, so that users can observe the shape and structure of the fish reef pile from different angles; Labeling and description: Add labels and descriptions to the 3D model to introduce the characteristic parameters and important information of the fish reef pile; Based on the analysis results, provide scientific advice for the construction and management of artificial reefs, including determining the location of artificial reefs, optimizing the design and layout of artificial reefs, so as to improve the ecological and economic benefits of artificial reefs; The results of the analysis of the distribution characteristics of fish reef piles are combined with marine ecological protection and fishery resource management to provide a basis for the formulation of marine protection policies and fishery development plans.

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