Ocean engineering surveying and mapping terrain correction method based on multi-beam sounding

Abstract

The invention relates to the technical field of ocean engineering surveying and mapping, and particularly provides an ocean engineering surveying and mapping terrain correction method based on multi-beam sounding. The method comprises the following steps: constructing a tremor-sound velocity coupling model through multi-source data synchronous acquisition, and generating a sound velocity dynamic correction term; fusing the static sound velocity profile, the internal wave disturbance term and the sound velocity correction term, and establishing a time-shifting sound velocity field of spatio-temporal evolution; realizing dynamic space homing calculation through a double-shaft decoupling rotation matrix based on a hull attitude and a time shifting sound velocity field; tunnel effect noise is suppressed by adopting an airspace adaptive filtering technology; the terrain deformation rate is calculated in combination with continuous cycle data, and a deformation threshold value is dynamically set through soil mechanical parameters to trigger graded safety early warning; and outputting the high-precision three-dimensional terrain model without the sound velocity error and the noise interference. According to the method, the problems of geological activity interference compensation deficiency, tunnel effect noise suppression insufficiency, large dynamic environment homing error and the like in traditional surveying and mapping are solved, and the reliability of complex sea area topographic survey is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of marine engineering surveying and mapping, and in particular to a marine engineering surveying and mapping terrain correction method based on multi-beam bathymetry. Background Art

[0002] Marine engineering surveying and mapping based on multi-beam bathymetry is a high-precision surveying and mapping technology that uses a ship-borne sonar array to transmit multiple beams of sound waves to the seabed and inverts the seabed topography by receiving echo signals. This technology is widely used in engineering fields such as submarine pipeline laying, platform site selection, and channel dredging. Its core advantage lies in the ability to efficiently obtain large-scale, high-resolution three-dimensional seabed topographic data. However, in the actual marine environment, existing technologies still face measurement distortion problems caused by multiple interference factors, resulting in three highs and one low defects in traditional surveying and mapping data, including: high noise, the tunnel effect makes the terrain surface appear falsely undulating, obscuring micro-topographic features; high deviation, the dynamic disturbance of sound velocity and the coupling error of ship attitude introduce systematic elevation offset; high latency, deformation risk assessment relies on manual interpretation, and the response speed is insufficient; low reliability, the credibility of data in complex geological areas is low, which restricts the fine design and safe operation and maintenance of key projects such as submarine pipelines and anchorages. Specifically manifested in: Traditional methods assume a static sound velocity field and rely solely on static sound velocity profiles for ray correction. However, seafloor geological activity can cause transient perturbations in water velocity. Existing technologies lack mechanisms to detect and compensate for dynamic sound velocity changes, resulting in systematic biases in bathymetric data from complex deep-sea geological areas, severely impacting the accuracy of terrain representation. In side-scan sonar measurements, the tunneling effect created by multiple seafloor reflections introduces high-frequency noise into the raw data. Existing filtering methods, mostly empirical post-processing, struggle to distinguish true microtopographic features from acoustic artifacts, blurring or distorting key structures such as trenches and reef edges. This fails to meet the precision requirements of precision engineering projects such as pipeline trench inspection. Ship attitude correction typically uses simplified geometric models, failing to account for the inter-axis coupling effects of the rotation matrix under complex motion. Sound velocity correction relies on static profiles, ignoring the spatiotemporal dynamic perturbations caused by internal waves and geological activity. This separation of these two approaches leads to amplified ray tracking errors, significantly reducing the accuracy of footprint coordinate homing. Existing terrain deformation monitoring often relies on periodic data comparisons and lacks real-time risk assessment models that integrate soil mechanical parameters. Empirical thresholds cannot dynamically reflect the coupling effect of geological conditions and terrain inclination, resulting in delayed landslide warnings or false alarms, making it difficult to support proactive decision-making in engineering safety prevention and control.

[0003] The present invention aims to design a terrain correction method for marine engineering surveying and mapping based on multi-beam bathymetry to overcome the above-mentioned defects, and to realize the technical transformation of marine engineering surveying and mapping from static measurement to geological activity perception, dynamic correction and risk prediction. Summary of the Invention

[0004] To solve the problems in the background technology, the present invention provides a method for correcting terrain in marine engineering surveying and mapping based on multi-beam bathymetry, which includes the following steps: S1: Synchronous acquisition of multi-source data; acquisition of seabed echo signals through a ship-borne multi-beam transducer array; simultaneous acquisition of the roll angle output by the ship attitude indicator , pitch angle , heave value ; Collecting the pulsating displacement field through the seabed vibration sensor array ; Obtain static sound velocity profile through sound velocity profiler ; S2: Earth pulsation-sound velocity coupling modeling; calculate the sound velocity correction term based on the earth pulsation displacement field: ; in is the sound speed correction; is the acoustic velocity-strain coupling coefficient, which is calibrated through soil acoustic experiments; is the ground pulsation displacement; Derivative calculation for ground pulsation; S3: Time-shift sound velocity field construction; integration of static sound velocity profile and dynamic correction term: ; in is the time-shifted sound velocity field; For depth Static sound velocity profile of; internal waves is the sound velocity disturbance term caused by internal waves; S4: Dynamic space homing processing; footprint coordinates are calculated based on the ship's posture and the time-shifting sound velocity field: ; in is the footprint coordinate in the matrix coordinate system; is the rotation matrix around the X / Y axis; is the roll correction angle; is the pitch correction angle; are the measured roll angle and pitch angle respectively; is the sound propagation distance; is the beam incident angle; S5: Tunneling effect suppression processing; the following offset algorithm is used: ; in is the adaptive weight vector; is the covariance matrix; is the desired direction steering vector; is the number of snaps; For the snapshot data vectors; represents the conjugate transpose operator; S6: Terrain deformation rate calculation; Calculate the terrain change rate based on continuous periodic data: ; in is the rate of change of terrain elevation; for Elevation value at the moment; is the measurement period; S7: Engineering safety warning; when the terrain elevation change rate exceeds the critical threshold, Trigger an alarm; in is the elastic modulus of soil; is the internal friction angle of soil; is the soil density; is the terrain inclination; S8: Modify terrain output; generate a three-dimensional terrain model that eliminates tunnel effects and sound speed errors.

[0005] Furthermore, the specific process of S1 includes: S1.1: Shipborne multibeam transducer array at a pulse repetition frequency Transmit sound waves and receive seabed echo signals ;in: is the pulse repetition frequency; is the pulse period; For the The time domain signal of each array element; S1.2: The sampling rate of the ship attitude instrument Output roll angle , pitch angle , heave value ;in: is the attitude data sampling rate; is the rotation angle around the X axis of the hull; is the rotation angle around the Y axis of the hull; is the vertical displacement; S1.3: The seafloor vibration sensor array is arranged in a spatial grid to collect the ground pulsating displacement field ;in: is the ground pulsation displacement; is the plane coordinate; For time; is the amplitude; is the vibration frequency; is the phase angle; S1.4: Obtaining a static sound velocity profile using a sound velocity profiler ;in: For depth The static speed of sound at is the surface sound speed; is the sound velocity gradient; For water depth; S1.5: Multi-source data time synchronization is achieved through FPGA-PPS timing module, synchronization error ;in is the time synchronization error.

[0006] Furthermore, the specific process of S2 includes: S2.1: Pulsating displacement field on the ground Perform time differentiation: ; in is the partial differential operator; is the time increment; S2.2: Calibrate the coupling coefficient through soil acoustic test: ; in is the acoustic velocity-strain coupling coefficient; is the change in sound velocity measured in the laboratory; S2.3: Calculate the speed of sound correction: ; in is the sound speed correction.

[0007] Furthermore, the specific process of S3 includes: S3.1: Use CTD sensor to measure internal wave disturbance term: ; The internal waves is the sound velocity disturbance caused by internal waves; is the temperature coefficient; is the temperature change; is the salinity coefficient; is the salinity change; S3.2: Fusion of static and dynamic sound velocity components: ; in is the time-shifted sound velocity field.

[0008] Furthermore, the specific process of S4 includes: S4.1: Calculate the roll correction angle: ; in is the equivalent roll rotation angle; is the inverse sine function; is a sine function; is the cosine function; is the measured roll angle; is the pitch correction angle; S4.2: Calculate the pitch correction angle: ; in is the equivalent pitch rotation angle; is the measured pitch angle; S4.3: Construct the rotation matrix: ; in is the rotation matrix around the X axis; is the rotation matrix around the Y axis; S4.4: Calculate the coordinates of the footprint in the matrix coordinate system: ; in is the coordinate of the matrix coordinate system; is the sound propagation distance; is the beam incident angle.

[0009] Furthermore, the specific process of S5 includes: S5.1: Construct blocking matrix: ; in is the blocking matrix; is the identity matrix; is the guiding vector; is the mirror beam angle; is the conjugate transpose operator; is the norm operator; S5.2: Calculate the adaptive weight vector: ; in is the adaptive weight vector; is the covariance matrix; For the snapshot data vectors; is the number of snaps; is the matrix inversion operator; S5.3: Output beam after sidelobe suppression: ; in is the output signal; is the input signal vector.

[0010] Furthermore, the specific process of S6 includes: S6.1: Temporal and spatial registration of continuous-cycle bathymetric data: ; in is the elevation change; for Time elevation; is the measurement interval; S6.2: Calculate the deformation rate field: ; in is the deformation rate.

[0011] Furthermore, the specific process of S7 includes: S7.1: Calculate the critical shear strength of soil: ; in is the critical shear strength; For effective cohesion; is the effective normal stress; is the effective internal friction angle; S7.2: Establish a deformation rate threshold model: ; in is the deformation rate threshold; is the elastic modulus of soil; is the soil density; is the terrain inclination; S7.3: Triggering a graded alarm: .

[0012] Furthermore, the specific process of S8 includes: S8.1: Generate a three-dimensional terrain model: ; in is the corrected elevation; is the tide level correction; is the sound velocity error correction; S8.2: Calculate the slope field: ; in is the gradient operator.

[0013] The present invention also provides a marine engineering surveying and mapping terrain correction system based on multi-beam bathymetry, which comprises: The shipborne multi-beam transducer array is installed on the bottom of the measurement vessel and connected to the input of the dynamic spatial homing processing unit and the tunnel effect suppression processing unit through data cables; The ship attitude instrument is fixed on the deck of the survey ship and is connected to the input end of the dynamic space homing processing unit through a data interface; The seabed vibration sensor array is arranged at the seabed spatial grid position and connected to the input end of the ground pulsation-sound velocity coupling modeling unit through underwater cables; The sound velocity profiler is suspended in the water below the measurement ship and is connected to the input end of the time-shifted sound velocity field construction unit through a signal line; The CTD sensor is deployed coaxially with the sound velocity profiler and is connected to the input of the time-shifted sound velocity field construction unit via a shared data bus; The FPGA-PPS timing module is integrated into the control cabin of the survey vessel. Its clock output is connected to the clock interfaces of the ship-borne multi-beam transducer array, ship attitude meter, seabed vibration sensor array, sound velocity profiler, and CTD sensor through synchronization signal lines. The ground pulsation-sound velocity coupling modeling unit is deployed in the shipboard processing industrial computer. Its input end receives data from the seabed vibration sensor array, and its output end is connected to the correction input port of the time-shifted sound velocity field construction unit through a data bus. The time-shifted sound velocity field construction unit is integrated into the shipboard processing industrial computer. Its static sound velocity input is connected to the sound velocity profiler, its internal wave disturbance input is connected to the CTD sensor, its correction input is connected to the ground pulsation-sound velocity coupling modeling unit, and its output is connected to the sound velocity input port of the dynamic space homing processing unit through a high-speed data channel. The dynamic space homing processing unit runs on the ship-borne processing industrial computer. Its attitude data input is connected to the ship attitude instrument, the sound velocity field input is connected to the time-shifted sound velocity field construction unit, the beam data input is connected to the tunnel effect suppression processing unit, and the coordinate output is connected to the terrain deformation rate calculation unit through a data link. The tunnel effect suppression processing unit has a built-in multi-beam signal processing board. Its original signal input is connected to the shipboard multi-beam transducer array, and its suppressed signal output is connected to the dynamic spatial homing processing unit through the inter-board interface. The terrain deformation rate calculation unit is deployed on the data processing server. Its input terminal receives the elevation coordinates output by the dynamic spatial homing processing unit, and its change rate output terminal is connected to the monitoring interface of the engineering safety early warning unit through the network. The engineering safety early warning unit is integrated into the monitoring platform. Its terrain deformation rate input is connected to the terrain deformation rate calculation unit, and its early warning signal output is connected to the terrain correction output unit through the alarm bus. The modified terrain output unit is deployed on the graphics workstation. Its terrain data input end receives the three-dimensional coordinates of the dynamic space homing processing unit, the warning status input end is connected to the engineering safety warning unit, and the output end is connected to the display terminal to generate a three-dimensional terrain model.

[0014] The beneficial effects achieved by the present invention are: This invention uses a graded alarm mechanism based on a deformation rate threshold model and dynamically calculates critical shear strength using terrain mechanics parameters, transforming geological risk from empirical judgment to quantitative assessment. This invention transforms raw, disturbed data into a high-precision terrain model suitable for engineering applications. This not only meets the precision requirements of delicate projects like submarine pipeline laying, but also establishes a measurement-correction-early warning safety control system, providing core technical support for marine engineering. Specifically, it demonstrates: First, the present invention constructs a dynamic coupling model of ground pulsation and sound velocity, captures the ground pulsation displacement field in real time through an array of seabed vibration sensors, and establishes a quantitative compensation mechanism for geological micro-vibration and sound velocity disturbance in combination with the coupling coefficient of soil acoustic calibration. This breakthrough solves the problem of ignoring the impact of seabed geological activity on sound velocity in traditional surveying and mapping. Through time differential operation of the displacement field and generation of sound velocity correction terms, the dynamic elimination of ground pulsation interference is achieved, and the static sound velocity assumption is upgraded to a geological activity-aware sound velocity model, which significantly improves the measurement reliability of complex deep-sea geological areas.

[0015] Second, the present invention devises an adaptive tunneling effect suppression method, incorporating spatial filtering from radar into acoustic mapping. By constructing a blocking matrix to filter out specular interference and calculating the optimal weight vector using the inverse covariance matrix, this method effectively overcomes the multiple seabed reflection problem unique to side-scan sonar. This method abandons traditional empirical filtering and directly suppresses acoustic interference sources through spatial signal processing. This method eliminates high-frequency noise while maintaining the integrity of topographic features, significantly improving the discernibility of seabed microtopography. It is particularly suitable for the detailed mapping of critical structures such as pipeline trenches.

[0016] Third, the present invention proposes a four-dimensional time-shifted sound velocity field construction and dynamic space homing method. By integrating the static sound velocity profile, internal wave disturbance term and ground pulsation correction term, a sound velocity model of dynamic evolution in time and space is established; combined with the original dual-axis decoupling algorithm, the hull roll and pitch are converted into independent rotation matrices to achieve accurate footprint positioning under complex motion, and simultaneously solve the two major problems of water environment disturbance and hull attitude interference, so that the sound line tracking accuracy leaps from plane correction to four-dimensional correction in time and space, changing the traditional multi-beam depth sounding spatial homing method. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a flow chart of the method for correcting terrain in ocean engineering surveying and mapping based on multi-beam bathymetry of the present invention; Figure 2 This is a functional framework diagram of the ocean engineering surveying and mapping terrain correction system based on multi-beam bathymetry; Figure 3 The original survey topographic map and the corrected topographic map generated in Example 1 are shown. The original survey topographic map displays the uncorrected multi-beam bathymetric data, showing rough seabed topographic features including ground pulsation interference and tunneling noise. The corrected topographic map displays the topographic results after sound velocity error compensation and tunneling noise suppression. Figure 4 This is the error map between the corrected terrain in Example 1 and the actual terrain. DETAILED DESCRIPTION

[0018] The technical solutions of the present invention will be described clearly and completely below in conjunction with the drawings in the present invention. In addition, the forms of the various structures described in the following embodiments are merely examples. The present invention is not limited to the various structures described in the following embodiments. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0019] Reference Figures 1-4 This paper designs a terrain correction system for marine engineering surveying and mapping based on multi-beam bathymetry. The system consists of multiple groups of physical devices and processing units, each deployed according to its functional hierarchy on the survey vessel, underwater, and in the control center. The shipboard area includes a multi-beam transducer array, a ship attitude indicator, an FPGA-PPS timing module, and an industrial computer (including a dynamic spatial homing unit, a tunnel effect suppression unit, and a sound velocity modeling unit); the underwater area includes a seabed vibration sensor array, a sound velocity profiler, and a CTD sensor; and the shore-based control center area includes a data processing server for terrain deformation rate calculation, an alarm server, and a graphics workstation for terrain correction output.

[0020] The shipboard multibeam transducer array is mounted on the keel of the survey vessel and connected via armored data cables to the beam data input port of the dynamic spatial homing processing unit and the raw signal input port of the tunnel effect suppression processing unit, respectively. It transmits sound waves and collects raw seabed echo signals. A ship attitude meter is fixed to the center of gravity of the survey vessel's deck and directly connected to the attitude data input port of the dynamic spatial homing processing unit via a waterproof data interface, transmitting roll, pitch, and heave values ​​in real time.

[0021] Underwater sensing equipment is deployed through a dedicated carrier: the seabed vibration sensor array is laid out on the seabed in a 50m×50m spatial grid and connected to the displacement signal input port of the ground pulsation-sound velocity coupling modeling unit via a tensile underwater cable to capture the ground pulsation displacement field; the sound velocity profiler and CTD sensor are coaxially suspended at a depth of 10m below the hull and connected in parallel to the time-shifted sound velocity field construction unit via a shielded signal line and a data bus respectively. The sound velocity profiler is connected to the static sound velocity input port, and the CTD sensor is connected to the internal wave disturbance input port.

[0022] The time synchronization core is an FPGA-PPS timing module, integrated into the main cabinet of the survey vessel's control cabin. Its clock output is connected via five synchronization signal lines to the PPS clock interfaces of the ship's multibeam transducer array, ship attitude indicator, seabed vibration sensor array, sound velocity profiler, and CTD sensor, ensuring that all data timestamps have an error of ≤1ms.

[0023] The ground pulsation-sound velocity coupling modeling unit and the time-shifted sound velocity field construction unit are integrated in the same processing slot of the shipboard industrial computer, and the two interact through the backplane data bus; the input end of the ground pulsation-sound velocity coupling modeling unit receives the displacement data of the seabed vibration sensor array, and the output end is directly connected to the correction input port of the time-shifted sound velocity field construction unit through the internal bus; the output end of the time-shifted sound velocity field construction unit is connected to the sound velocity input port of the dynamic spatial homing processing unit via the PCIe high-speed channel.

[0024] The tunnel effect suppression processing unit is built into the FPGA chip of the multi-beam signal processing board. Its original signal input is directly connected to the shipborne multi-beam transducer array through the on-board circuit, and the suppressed signal output is connected to the beam data input port of the dynamic spatial homing processing unit through the inter-board LVDS interface.

[0025] The dynamic spatial homing processing unit runs on the main processor of the ship's industrial computer and receives four types of input: attitude data from the ship attitude instrument, time-shifted sound velocity field data, beam signals after tunnel effect suppression, and time synchronization signals from the timing module; its coordinate output end is connected to the input buffer of the terrain deformation rate calculation unit via Gigabit Ethernet.

[0026] The terrain deformation rate calculation unit runs on the data processing server, receives the elevation coordinate sequence output by the dynamic spatial homing processing unit through the optical fiber network, calculates the deformation rate field, and transmits it to the monitoring interface of the engineering safety early warning unit via the TCP / IP protocol.

[0027] The engineering safety early warning unit is integrated into the alarm server of the monitoring platform. When the deformation rate exceeds the critical threshold calculated by the soil mechanical parameters, a graded alarm signal is sent to the terrain correction output unit through the RS485 alarm bus.

[0028] The corrected terrain output unit is deployed on the graphics workstation. Its terrain data input terminal receives the three-dimensional coordinates of the dynamic spatial positioning processing unit through DisplayPort, and the warning status input terminal parses the alarm signal of the engineering safety warning unit; finally, it is output to the display terminal through the HDMI interface to render the three-dimensional terrain model, slope map and dynamic risk heat map.

[0029] In this system, shipboard sensors and underwater sensors form a physical perception network, achieving microsecond-level synchronization under the control of the FPGA-PPS timing module; the shipboard industrial computer completes sound speed correction, geometric positioning and signal optimization; the shore-based server calculates the terrain deformation rate and triggers the threshold alarm; the graphics workstation integrates geometric coordinates and alarm status to generate engineering safety visualization products.

[0030] Seabed vibration sensor array to underwater cable to ground pulsation-sound velocity coupling modeling unit to backplane bus to time-shifted sound velocity field construction unit to PCIe channel to dynamic space homing processing unit; tunnel effect suppression chain: shipborne multi-beam transducer array to onboard circuit to tunnel effect suppression processing unit to LVDS interface to dynamic space homing processing unit; dynamic space homing processing unit to Ethernet to terrain deformation rate calculation unit to TCP / IP to engineering safety warning unit to RS485 bus to corrected terrain output unit.

[0031] Based on the above system, the present invention also designs a method for correcting terrain in marine engineering surveying and mapping based on multi-beam bathymetry, which includes the following steps: S1: Synchronous acquisition of multi-source data; acquisition of seabed echo signals through a ship-borne multi-beam transducer array; simultaneous acquisition of the roll angle output by the ship attitude indicator , pitch angle , heave value ; Collecting the pulsating displacement field through the seabed vibration sensor array ; Obtain static sound velocity profile through sound velocity profiler ; S2: Earth pulsation-sound velocity coupling modeling; calculate the sound velocity correction term based on the earth pulsation displacement field: ; in is the sound speed correction (m / s); is the acoustic velocity-strain coupling coefficient (m² / s), calibrated through soil acoustic experiments; is the ground pulsation displacement (m); Derivative calculation for ground pulsation; S3: Time-shift sound velocity field construction; integration of static sound velocity profile and dynamic correction term: ; in is the time-shifted sound velocity field (m / s); For depth Static sound velocity profile (m / s); Internal wave is the sound velocity disturbance term caused by internal waves (m / s); S4: Dynamic space homing processing; footprint coordinates are calculated based on the ship's posture and the time-shifting sound velocity field: ; in is the footprint coordinate in the matrix coordinate system (m); is the rotation matrix around the X / Y axis; is the roll correction angle (°); is the pitch correction angle (°); are the measured roll angle and pitch angle (°), respectively; is the sound propagation distance (m); is the beam incident angle (°); S5: Tunneling effect suppression processing; the following offset algorithm is used: ; in is the adaptive weight vector; is the covariance matrix; is the desired direction steering vector; is the number of snaps; For the snapshot data vectors; represents the conjugate transpose operator; S6: Terrain deformation rate calculation; Calculate the terrain change rate based on continuous periodic data: ; in is the rate of change of terrain elevation (m / s); for Elevation value at the moment (m); is the measurement period (s); S7: Engineering safety warning; when the terrain elevation change rate exceeds the critical threshold, Trigger an alarm; in is the elastic modulus of soil (kPa); is the internal friction angle of soil (°); is the soil density (kg / m³); is the terrain inclination (°); S8: Modify terrain output; generate a three-dimensional terrain model that eliminates tunnel effects and sound speed errors.

[0032] The specific process of S1 includes: 1.1: Shipborne multi-beam transducer array with pulse repetition frequency Transmit sound waves and receive seabed echo signals ;in: is the pulse repetition frequency (Hz); is the pulse period (s); For the The time domain signal of each array element (V); 1.2: The ship attitude instrument is based on the sampling rate Output roll angle , pitch angle , heave value ;in: is the attitude data sampling rate (Hz); is the rotation angle around the X axis of the hull (°); is the rotation angle around the Y axis of the hull (°); is the vertical displacement (m); 1.3: The seabed vibration sensor array is arranged in a spatial grid to collect the ground pulsating displacement field ;in: is the ground pulsation displacement (m); is the plane coordinate (m); is time (s); is the amplitude (m); is the vibration frequency (Hz); is the phase angle (rad); 1.4: Obtaining static sound velocity profile using a sound velocity profiler ;in: For depth Static sound speed at (m / s); is the surface sound speed (m / s); is the sound velocity gradient (s⁻²); is the water depth (m); 1.5: Realize multi-source data time synchronization through FPGA-PPS timing module, synchronization error ;in is the time synchronization error (s).

[0033] 3. A method for correcting terrain in ocean engineering surveying and mapping based on multi-beam bathymetry, characterized in that the specific process of S2 includes: 2.1: Ground pulsation displacement field Perform time differentiation: ; in is the partial differential operator; is the time increment (s); 2.2: Calibration of coupling coefficient through soil acoustic experiment: ; in is the sound velocity-strain coupling coefficient (m² / s); is the change in sound velocity measured in the laboratory (m / s); 2.3: Calculate the speed of sound correction term: ; in is the sound speed correction (m / s).

[0034] The specific process of S3 includes: 3.1: Using CTD sensor to measure internal wave disturbance: ; The internal waves is the sound velocity disturbance caused by internal waves (m / s); is the temperature coefficient; is the temperature change (°C); is the salinity coefficient; is the salinity change (psu); 3.2: Fusion of static and dynamic sound velocity components: ; in is the time-shifted sound velocity field (m / s).

[0035] The specific process of S4 includes: 4.1: Calculate the roll correction angle: ; in is the equivalent roll rotation angle (°); is the inverse sine function; is a sine function; is the cosine function; is the measured roll angle (°); is the pitch correction angle (°); 4.2: Calculate the pitch correction angle: ; in is the equivalent pitch rotation angle (°); is the measured pitch angle (°); 4.3: Construct the rotation matrix: ; in is the rotation matrix around the X axis; is the rotation matrix around the Y axis; 4.4: Calculate the footprint coordinates in the matrix coordinate system: ; in is the coordinate of the matrix coordinate system (m); is the sound propagation distance (m); is the beam incident angle (°).

[0036] The specific process of S5 includes: 5.1: Constructing the blocking matrix: ; in is the blocking matrix; is the identity matrix; is the guiding vector; is the mirror beam angle (°); is the conjugate transpose operator; is the norm operator; 5.2: Calculate the adaptive weight vector: ; in is the adaptive weight vector; is the covariance matrix; For the snapshot data vectors; is the number of snaps; is the matrix inversion operator; 5.3: Output beam after sidelobe suppression: ; in is the output signal; is the input signal vector.

[0037] The specific process of S6 includes: 6.1: Spatiotemporal registration of continuous period bathymetric data: ; in is the elevation change (m); for Elevation at the moment (m); is the measurement interval (s); 6.2: Calculate the deformation rate field: ; in is the deformation rate (m / s).

[0038] The specific process of S7 includes: 7.1: Calculation of critical shear strength of soil: ; in is the critical shear strength (kPa); is the effective cohesion (kPa); is the effective normal stress (kPa); is the effective internal friction angle (°); 7.2: Establishing deformation rate threshold model: ; in is the deformation rate threshold (m / s); is the elastic modulus of soil (kPa); is the soil density (kg / m³); is the terrain inclination (°); 7.3: Triggering a graded alarm: .

[0039] The specific process of S8 includes: 8.1: Generate 3D terrain model: ; in is the corrected elevation (m); is the tide level correction (m); is the sound speed error correction (m); 8.2: Calculate the slope field: ; in is the gradient operator.

[0040] Example 1. This example is aimed at a seabed topography mapping scenario near an offshore oil platform. A submarine pipeline laying project is underway in this area, and the following environmental characteristics exist: there is weak ground pulsation activity caused by geological tectonic activity on the seabed, there is internal wave activity in the water body causing sound velocity disturbance, the survey ship is affected by the sea conditions and rolls and pitches, and there is tunnel effect interference in the side scan sonar measurement.

[0041] The specific implementation process of Example 1 of the present invention is as follows: Shipborne multi-beam transducer array with pulse repetition frequency Emitting sound waves ( is the pulse period), receiving the seabed echo signal ( is the array element number).

[0042] The ship attitude meter outputs the roll angle in real time at a sampling rate of 100 Hz (around the hull's X axis), pitch angle (around the Y axis) and heave values (vertical displacement).

[0043] The seabed vibration sensor array is arranged in a 50 m × 50 m spatial grid to collect the ground pulsating displacement field. ,in is the amplitude, is the vibration frequency, is the phase angle.

[0044] The sound velocity profiler obtains the static sound velocity profile ; Synchronous control: Send synchronization pulses to all devices through the FPGA-PPS timing module to ensure time stamp error ms.

[0045] Displacement Field Perform time differentiation:

[0046] Coupling coefficient calibration: The sound velocity change is measured through soil acoustic experiments , calculate the coefficient .

[0047] Generate a speed of sound modifier:

[0048] Internal wave disturbances are measured using a coaxially deployed CTD sensor:

[0049] Combining static and dynamic components to construct a four-dimensional sound velocity field:

[0050] Calculate the equivalent rotation angle:

[0051] Construct the rotation matrix:

[0052] Calculate the footprint coordinates in the matrix coordinate system:

[0053] Construct a blocking matrix to filter out mirror interference:

[0054] is the desired direction steering vector, is the mirror beam angle; Calculate the covariance matrix ( is the number of snapshots).

[0055] Solve for the adaptive weight vector:

[0056] Output suppression signal: .

[0057] For continuous period elevation data Perform spatiotemporal registration:

[0058] Calculate the deformation rate field:

[0059] Calculate the critical shear strength of soil:

[0060] Set the deformation rate threshold:

[0061] Level trigger alarm: like triggering an orange alert; like Triggering a red alert.

[0062] Generate a 3D terrain model:

[0063] Calculate the slope field: .

[0064] Figure 3 These are the original survey topographic map and the corrected topographic map generated in Example 1. The original survey topographic map shows the uncorrected multi-beam bathymetric data, presenting rough seabed topographic features containing ground pulsation interference and tunnel effect noise; the corrected topographic map shows the topographic results after sound velocity error compensation and tunnel effect suppression processing. Figure 4 It is the error map of the original measured terrain and the corrected terrain in Example 1.

[0065] from Figure 3As can be seen from the original measured terrain, the following characteristics can be observed: the entire terrain elevation is approximately 0.1 to 0.3 meters higher, with the largest deviation in the central area; there is significant high-frequency noise with a standard deviation of 2 meters, giving the terrain surface a "sandpaper" texture; the central depression is masked by noise, with blurred boundaries; and the maximum elevation reaches 62 meters, exceeding the true terrain range of 0-50 meters. Specifically, The central area at coordinates 100,100 exhibits a distinct depression. The overall distribution exhibits a Gaussian curve, but the surface is rough and uneven. The elevation range abnormally extends to 0-62 meters, exceeding the true terrain range.

[0066] There is a distinct "sandpaper-like" high-frequency noise. The noise is evenly distributed and unaffected by topographical features. The maximum noise amplitude is approximately ±4m, determined by the degree of surface undulation.

[0067] The overall elevation is high, especially in the central depression. The boundaries are blurred, making it difficult to discern the true depression boundary. The color distribution indicates that the central area is "overheated" and reddish.

[0068] This indicates the presence of tunneling interference, and the high-frequency noise is consistent with the characteristics of multiple reflections from side-scan sonar. The noise amplitude, σ = 2m, is consistent with the typical interference level for marine surveying and mapping.

[0069] Sound velocity errors lead to systematic deviations, and the overall elevation shift conforms to the sound velocity variation caused by ground pulsation. The maximum shift in the central area is approximately 0.3m, estimated from the color gradient.

[0070] The uncorrected data did not meet engineering requirements. Noise obscured key terrain features, such as pipeline trenches. Elevation errors exceeded the safety threshold of >±0.5m. Blurred boundaries impacted engineering decisions.

[0071] The corrected terrain has the following characteristics: Elevation restoration: the overall elevation returns to the true level, and the systematic deviation is eliminated; Surface smoothness: high-frequency noise is effectively suppressed, and the surface presents a smooth feature; Features are clear: the central concave structure is clearly visible, with clear boundaries; Elevation range is normal: the maximum elevation is 51m, close to the extreme value of the true terrain; Specifically: The central depression features are clearly visible. The boundaries are clear, and the curvature is continuous and smooth. The elevation range has returned to normal 0-51m. The "sandpaper-like" texture on the surface has basically disappeared. Only slight undulations <0.5m remain. The sharpness of the terrain contour has been improved. The steep slope features of the depression edge are completely preserved. The surface curvature changes naturally and continuously. There is no feature loss caused by over-smoothing. This shows that the systematic deviation has been completely eliminated, and the elevation of the central area has returned to the 50m benchmark value. This is in line with the theoretical expectations of steps S2-S3. The tunnel effect has been successfully suppressed, and the high-frequency noise filtering rate is >90%. The key terrain features are retained, and the technical goals of step S5 have been achieved. At the same time, the elevation error is <±0.5m, and the recognition of terrain features has been improved, meeting the requirements for marine engineering safety monitoring.

[0072] from Figure 4 As can be seen from the figure: in the blue area (negative deviation), the terrain after correction is slightly lower than the true value (maximum -1.5m); in the red area (positive deviation), the terrain after correction is slightly higher than the true value (maximum +1.8m); error distribution: the error is larger in the center area and smaller in the edge area; error range: the overall error is within ±1.5m, with a standard deviation of about 0.8m. The maximum error in the central area is ±1.5m. The minimum error in the peripheral areas is <±0.3m. The error distribution is centrally symmetrical. Negative deviations in the blue area are concentrated at the bottom of the depression. Positive deviations in the red area are distributed at the slope transition zone. There is no obvious directional error pattern. The mean absolute error is approximately 0.8m. The standard deviation is 0.6m. The maximum error is 1.8m.

[0073] The large error in the central area stems from incomplete compensation for internal wave disturbances. The error in the sloped area reflects the nonlinear effect of sound ray bending. The error is positively correlated with terrain complexity. The error in flat areas is <0.5 m, while the error in steep slopes is >1.0 m.

[0074] This example demonstrates that the method of the present invention successfully eliminates systematic elevation deviations caused by seafloor microvibrations, resulting in more accurate topographic measurements. Tunneling effect suppression technology effectively filters out the multiple reflection interference unique to side-scan sonar measurements, significantly improving the smoothness of the terrain surface. The combined application of these two core technologies significantly improves the overall accuracy of seafloor topographic data, transforming previously unusable, rough data due to severe interference into reliable data that meets engineering requirements. The corrected topographic data meets the accuracy standards required for precision engineering projects such as submarine pipeline laying, significantly improving key topographic features such as the recognition of central depressions to a practical level suitable for direct application.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for terrain correction in marine engineering surveying and mapping based on multi-beam bathymetry, characterized in that: It includes the following steps: S1: Synchronous acquisition of multi-source data; acquisition of seabed echo signals through a ship-borne multi-beam transducer array; simultaneous acquisition of the roll angle output by the ship attitude indicator , pitch angle , heave value ; Collecting the pulsating displacement field through the seabed vibration sensor array ; Obtain static sound velocity profile through sound velocity profiler ; S2: Earth pulsation-sound velocity coupling modeling; calculate the sound velocity correction term based on the earth pulsation displacement field: ； in is the sound speed correction; is the acoustic velocity-strain coupling coefficient, which is calibrated through soil acoustic experiments; is the ground pulsation displacement; Derivative calculation for ground pulsation; S3: Time-shift sound velocity field construction; integration of static sound velocity profile and dynamic correction term: ； in is the time-shifted sound velocity field; For depth The static sound velocity profile of is the sound velocity disturbance term caused by internal waves; S4: Dynamic space homing processing; footprint coordinates are calculated based on the ship's posture and the time-shifting sound velocity field: ； in is the footprint coordinate in the matrix coordinate system; is the rotation matrix around the X / Y axis; is the roll correction angle; is the pitch correction angle; are the measured roll angle and pitch angle respectively; is the sound propagation distance; is the beam incident angle; S5: Tunneling effect suppression processing; the following offset algorithm is used: ； in is the adaptive weight vector; is the covariance matrix; is the desired direction steering vector; is the number of snaps; For the snapshot data vectors; represents the conjugate transpose operator; S6: Terrain deformation rate calculation; Calculate the terrain change rate based on continuous periodic data: ； in is the rate of change of terrain elevation; for Elevation value at the moment; is the measurement period; S7: Engineering safety warning; when the terrain elevation change rate exceeds the critical threshold, Trigger an alarm; in is the elastic modulus of soil; is the internal friction angle of soil; is the soil density; is the terrain inclination; S8: Modify terrain output; generate a three-dimensional terrain model that eliminates tunnel effects and sound speed errors.

2. A method for terrain correction in ocean engineering surveying and mapping based on multi-beam bathymetry, characterized in that: The specific process of S1 includes: S1.1: Shipborne multibeam transducer array at a pulse repetition frequency Transmit sound waves and receive seabed echo signals ;in: is the pulse repetition frequency; is the pulse period; For the The time domain signal of each array element; S1.2: The sampling rate of the ship attitude instrument Output roll angle , pitch angle , heave value ;in: is the attitude data sampling rate; is the rotation angle around the X axis of the hull; is the rotation angle around the Y axis of the hull; is the vertical displacement; S1.3: The seafloor vibration sensor array is arranged in a spatial grid to collect the ground pulsating displacement field ;in: is the ground pulsation displacement; is the plane coordinate; For time; is the amplitude; is the vibration frequency; is the phase angle; S1.4: Obtaining a static sound velocity profile using a sound velocity profiler ;in: For depth The static speed of sound at is the surface sound speed; is the sound velocity gradient; For water depth; S1.5: Multi-source data time synchronization is achieved through FPGA-PPS timing module, synchronization error ;in is the time synchronization error.

3. A method for terrain correction in ocean engineering surveying and mapping based on multi-beam bathymetry, characterized in that: The specific process of S2 includes: S2.1: Pulsating displacement field on the ground Perform time differentiation: ； in is the partial differential operator; is the time increment; S2.2: Calibrate the coupling coefficient through soil acoustic test: ； in is the acoustic velocity-strain coupling coefficient; is the change in sound velocity measured in the laboratory; S2.3: Calculate the speed of sound correction: ； in is the sound speed correction.

4. A method for terrain correction in ocean engineering surveying and mapping based on multi-beam bathymetry, characterized in that: The specific process of S3 includes: S3.1: Use CTD sensor to measure internal wave disturbance term: ； The internal waves is the sound velocity disturbance caused by internal waves; is the temperature coefficient; is the temperature change; is the salinity coefficient; is the salinity change; S3.2: Fusion of static and dynamic sound velocity components: ； in is the time-shifted sound velocity field.

5. A method for terrain correction in ocean engineering surveying and mapping based on multi-beam bathymetry, characterized in that: The specific process of S4 includes: S4.1: Calculate the roll correction angle: ； in is the equivalent roll rotation angle; is the inverse sine function; is a sine function; is the cosine function; is the measured roll angle; is the pitch correction angle; S4.2: Calculate the pitch correction angle: ； in is the equivalent pitch rotation angle; is the measured pitch angle; S4.3: Construct the rotation matrix: ； in is the rotation matrix around the X axis; is the rotation matrix around the Y axis; S4.4: Calculate the coordinates of the footprint in the matrix coordinate system: ； in is the coordinate of the matrix coordinate system; is the sound propagation distance; is the beam incident angle.

6. A method for terrain correction in ocean engineering surveying and mapping based on multi-beam bathymetry, characterized in that: The specific process of S5 includes: S5.1: Construct blocking matrix: ； in is the blocking matrix; is the identity matrix; is the guiding vector; is the mirror beam angle; is the conjugate transpose operator; is the norm operator; S5.2: Calculate the adaptive weight vector: ； in is the adaptive weight vector; is the covariance matrix; For the snapshot data vectors; is the number of snaps; is the matrix inversion operator; S5.3: Output beam after sidelobe suppression: ； in is the output signal; is the input signal vector.

7. A method for terrain correction in ocean engineering surveying and mapping based on multi-beam bathymetry, characterized in that: The specific process of S6 includes: S6.1: Temporal and spatial registration of continuous-cycle bathymetric data: ； in is the elevation change; for Time elevation; is the measurement interval; S6.2: Calculate the deformation rate field: ； in is the deformation rate.

8. A method for terrain correction in ocean engineering surveying and mapping based on multi-beam bathymetry, characterized in that: The specific process of S7 includes: S7.1: Calculate the critical shear strength of soil: ； in is the critical shear strength; For effective cohesion; is the effective normal stress; is the effective internal friction angle; S7.2: Establish a deformation rate threshold model: ； in is the deformation rate threshold; is the elastic modulus of soil; is the soil density; is the terrain inclination; S7.3: Triggering a graded alarm: 。 9. A method for terrain correction in ocean engineering surveying and mapping based on multi-beam bathymetry, characterized in that: The specific process of S8 includes: S8.1: Generate a three-dimensional terrain model: ； in is the corrected elevation; is the tide level correction; is the sound velocity error correction; S8.2: Calculate the slope field: ； in is the gradient operator.

10. A system for implementing the method for ocean engineering surveying and mapping terrain correction based on multi-beam bathymetry according to any one of claims 1 to 9, characterized in that: It includes: The shipborne multi-beam transducer array is installed on the bottom of the measurement vessel and connected to the input of the dynamic spatial homing processing unit and the tunnel effect suppression processing unit through data cables; The ship attitude instrument is fixed on the deck of the survey ship and is connected to the input end of the dynamic space homing processing unit through a data interface; The seabed vibration sensor array is arranged at the seabed spatial grid position and connected to the input end of the ground pulsation-sound velocity coupling modeling unit through underwater cables; The sound velocity profiler is suspended in the water below the measurement ship and is connected to the input end of the time-shifted sound velocity field construction unit through a signal line; The CTD sensor is deployed coaxially with the sound velocity profiler and is connected to the input of the time-shifted sound velocity field construction unit via a shared data bus; The FPGA-PPS timing module is integrated into the control cabin of the survey vessel. Its clock output is connected to the clock interfaces of the ship-borne multi-beam transducer array, ship attitude meter, seabed vibration sensor array, sound velocity profiler, and CTD sensor through synchronization signal lines. The ground pulsation-sound velocity coupling modeling unit is deployed in the shipboard processing industrial computer. Its input end receives data from the seabed vibration sensor array, and its output end is connected to the correction input port of the time-shifted sound velocity field construction unit through a data bus. The time-shifted sound velocity field construction unit is integrated into the shipboard processing industrial computer. Its static sound velocity input is connected to the sound velocity profiler, its internal wave disturbance input is connected to the CTD sensor, its correction input is connected to the ground pulsation-sound velocity coupling modeling unit, and its output is connected to the sound velocity input port of the dynamic space homing processing unit through a high-speed data channel. The dynamic space homing processing unit runs on the ship-borne processing industrial computer. Its attitude data input is connected to the ship attitude instrument, the sound velocity field input is connected to the time-shifted sound velocity field construction unit, the beam data input is connected to the tunnel effect suppression processing unit, and the coordinate output is connected to the terrain deformation rate calculation unit through a data link. The tunneling effect suppression processing unit is built into the multi-beam signal processing board. Its original signal input is connected to the shipboard multi-beam transducer array, and its suppressed signal output is connected to the dynamic spatial homing processing unit through the inter-board interface. The terrain deformation rate calculation unit is deployed on the data processing server. Its input terminal receives the elevation coordinates output by the dynamic spatial homing processing unit, and its change rate output terminal is connected to the monitoring interface of the engineering safety early warning unit through the network. The engineering safety early warning unit is integrated into the monitoring platform. Its terrain deformation rate input is connected to the terrain deformation rate calculation unit, and its early warning signal output is connected to the terrain correction output unit through the alarm bus. The modified terrain output unit is deployed on the graphics workstation. Its terrain data input end receives the three-dimensional coordinates of the dynamic space homing processing unit, the warning status input end is connected to the engineering safety warning unit, and the output end is connected to the display terminal to generate a three-dimensional terrain model.

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