A multi-beam sonar image gain compensation method
By performing frame-by-frame gain compensation on multi-beam sonar images, the problem of remote signal strength attenuation is solved, and efficient real-time generation and brightness enhancement of sonar images are achieved.
Patent Information
- Application Number
- CN202211737467.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-12-31
- Publication Date
- 2025-09-02
- Estimated Expiration
- 2042-12-31
AI Technical Summary
When multi-beam depth sounders generate underwater terrain images, the far-end signal intensity attenuates severely, and it is difficult for the prior art to effectively compensate for gain, resulting in insufficient image brightness.
By obtaining the effective data length of the beam sequence segment, normalizing calculation and sliding window average processing, the gain compensation curve is calculated, and multiplying it with the effective data point by the normalization result for data replacement, thereby realizing frame-by-frame gain compensation.
It effectively enhances the remote brightness of the sonar image and realizes efficient real-time generation of sonar images.
Smart Images
Figure CN116184415B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of signal processing, and in particular relates to a multi-beam sonar image gain compensation method. Background Art
[0002] Multi-beam echo sounders can perform strip sounding, thereby achieving efficient mapping of underwater terrain. Multi-beam echo data can be further used for underwater imaging to obtain underwater topographic information. The beam sequence fragment (small piece) method can calculate the backscatter intensity within the beam footprint of each multi-beam beam and generate a sonar image. It has the advantages of high resolution and high signal-to-noise ratio, but similar to conventional side-scan sonar, the far-end signal strength will be significantly attenuated. The correction method for the seabed echo scattering intensity mainly focuses on propagation loss, sound line bending and sound irradiation area correction. It is necessary to gain compensate the far-end signal strength. Conventional side-scan images perform gain compensation on the entire sonar image generated by multiple frames of signals, and multiple frames of signals need to be cached. Summary of the Invention
[0003] The object of the present invention is to provide a multi-beam sonar image gain compensation method to solve the problems raised in the above background technology.
[0004] To achieve the above object, the present invention provides the following technical solution: a multi-beam sonar image gain compensation method, comprising the following steps:
[0005] 1) Obtain beam sequence fragments;
[0006] 2) Extract the effective data length on the beam sequence segment and perform normalization calculation on the effective data of each data point;
[0007] 3) Divide the effective data length into several segments; the points in two adjacent segments are spliced into a sliding window;
[0008] 4) Calculate the average value of all valid data; calculate the average value of each sliding window data segment separately;
[0009] 5) Calculate the gain compensation curve;
[0010] 6) The gain compensation curve is multiplied by the valid data point at that point and normalized. The calculated result replaces the data corresponding to the position in the valid data segment to obtain the data after the beam sequence segment side scan gain compensation.
[0011] Preferably, the method for extracting the effective data length in step 2) is:
[0012] 2.1) Find the first non-zero valid value position A;
[0013] 2.2) Continue to find the last valid value position B that is not zero;
[0014] 2.3) Then the effective data length is N=B-A+1;
[0015] The position of each data point is denoted as n, where n=1, 2, ...N.
[0016] Preferably, the specific steps of step 3) are: the effective data length N is divided into M segments, each segment is numbered m, m = 1, 2, ..., M, the points in two adjacent segments are spliced into a sliding window, each sliding window is numbered k, k = 1, 2, ..., M-1.
[0017] Preferably, the formula for calculating the gain compensation curve in step 5) is as follows:
[0018]
[0019] in, W is the average value of N points, and the average value of the k-th sliding window data is recorded as
[0020] Preferably, the starting and ending positions in step 6) are effective value position A and effective value position B.
[0021] The technical effects and advantages of the present invention are as follows: the present invention performs frame-by-frame gain compensation based on the characteristics of small-piece side-scan data, which can effectively enhance the far-end brightness of the sonar image and efficiently realize the real-time generation of the sonar image. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 It is the segmentation of single frame signal sampling points and the generation of sliding windows;
[0023] Figure 2 This is the effect diagram of a single frame signal before gain compensation;
[0024] Figure 3 It is the gain compensation curve of single frame signal;
[0025] Figure 4 This is the effect diagram after gain compensation of a single frame signal;
[0026] Figure 5 It is the entire sonar image before gain compensation;
[0027] Figure 6 It is the entire sonar image after gain compensation. DETAILED DESCRIPTION
[0028] The following is a further description of specific embodiments of the present invention in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is intended to facilitate understanding of the present invention and does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
[0029] The present invention provides Figure 1 A multi-beam sonar image gain compensation method shown includes the following steps:
[0030] 1) Obtain a beam sequence segment of the starboard side of the side scan data with a length of L frames;
[0031] 2) Extract the effective data length on the beam sequence segment and normalize the effective data of each data point. The method for extracting the effective data length is:
[0032] 2.1) Find the first non-zero valid value position A;
[0033] 2.2) Continue to find the last valid value position B that is not zero;
[0034] 2.3) Then the effective data length is N=B-A+1;
[0035] The position of each data point is denoted as n, where n=1, 2, ...N.
[0036] 3) Divide the effective data length into several segments; the points in two adjacent segments are spliced into a sliding window;
[0037] The effective data length N is divided into M segments, each segment is numbered m, m = 1, 2, ..., M, the points in two adjacent segments are spliced into a sliding window, each sliding window is numbered k, k = 1, 2, ..., M-1; the average value of N points is recorded as W,
[0038] 4) Calculate the average value of all valid data; calculate the average value of each sliding window data separately
[0039] 5) Calculate the gain compensation curve; the formula is as follows:
[0040]
[0041] in, W is the average value of N points, and the average value of the k-th sliding window data is recorded as
[0042] 6) Set the gain compensation curve G mnThe result is multiplied by the valid data points of N points and normalized. The data of the corresponding position from position A to B is replaced by the calculated result to obtain the data after the side scan gain compensation of the beam sequence segment.
[0043] Figure 2 is a frame of normalized small-piece sidescan data on the starboard side, Figure 3 is the gain compensation curve calculated using the formula in step 5), where M = 4; Figure 4 for Figure 2 The effect of data gain compensation is shown in the figure. It can be seen from the figure that the remote data is significantly enhanced;
[0044] Figure 5 This is the effect before gain compensation, which is composed of 1000 frames of small side-scan data of the starboard side. Figure 6 This is the effect diagram after gain compensation; by comparison, it can be seen that gain compensation can effectively enhance the brightness of the far end of the sonar image and efficiently realize the real-time generation of sonar images.
[0045] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.
Claims
1. A multi-beam sonar image gain compensation method, characterized in that: The steps include: 1) Obtain beam sequence fragments; 2) Extract the effective data length on the beam sequence segment and normalize the effective data of each data point; 3) Divide the valid data length into several equal segments; the points in two adjacent segments are spliced into a sliding window; 4) Calculate the average value of all valid data; calculate the average value of each sliding window data segment separately; 5) Calculate the gain compensation curve; the formula is as follows: ； in, , is the average value of N points, and the average value of the k-th sliding window data is recorded as , N is the length of valid data, m is the index number of each small segment after the valid data of length N is divided into M segments; 6) The gain compensation curve is multiplied by the valid data point at that point and normalized. The calculated result replaces the corresponding data in the valid data segment to obtain the data after side scan gain compensation of the beam sequence segment.
2. The multi-beam sonar image gain compensation method according to claim 1, characterized in that: The method for extracting the effective data length in step 2) is: 2.1) Find the first non-zero valid value position A; 2.2) Continue to find the last valid non-zero value position B; 2.3) Then the effective data length is ; The position of each data point is denoted as n, where n=1,2,...N.
3. The multi-beam sonar image gain compensation method according to claim 2, characterized in that: The specific steps of step 3) are as follows: the effective data length N is divided into M segments, each segment is numbered m, m=1, 2, ..., M, the points in two adjacent segments are spliced into a sliding window, each sliding window is numbered k, k=1, 2, ..., M-1.
4. The multi-beam sonar image gain compensation method according to claim 2, characterized in that: The starting and ending positions in step 6) are the effective value position A and the effective value position B.