A reconfigurable underwater 3D laser scanning system and method

Abstract

This invention relates to a reconfigurable underwater 3D laser scanning system and method, belonging to the field of underwater robot underwater environment 3D scanning technology. It solves the problems of non-reconfigurable underwater laser scanning systems, such as fixed structure, inability to change the scanning beam and form according to actual needs, leading to sparse point cloud data, insufficient information acquisition, slow scanning speed, and small detection range. The system includes an underwater camera module, a laser emitter module, a parallel circuit module, and a data processing center module unit. The laser emitter module is electrically connected to the parallel circuit module, and the underwater camera module, parallel circuit module, and data processing center module unit are electrically connected. This invention allows for the addition of underwater camera modules and laser emitter modules according to the needs of the underwater robot, expanding the scanning range and increasing the field of view. It has advantages such as simple structure, flexible scanning mode, dense point cloud data, and accurate imaging.

Description

Technical Field

[0001] This invention relates to a reconfigurable three-dimensional laser scanning system and method, belonging to the field of underwater robot underwater environment three-dimensional scanning technology. Background Technology

[0002] With the increasing development of marine resources, the demand for underwater imaging technology is also growing. Underwater imaging technology provides visual images for underwater robots, creates underwater topographic maps, and provides geomorphological information for underwater energy extraction, facilitating the detection of underwater targets. Currently, underwater detection technology widely employs acoustic methods, represented by multibeam echo sounders. Generally, optical detection methods offer higher measurement accuracy than acoustic methods. Light and sound waves differ significantly in their propagation characteristics. Lasers are characterized by directional emission, high brightness, pure color, and high energy density, and can effectively reduce the influence of water (absorption and scattering). In applications requiring accurate and rapid positioning and target identification, light waves have a clear advantage.

[0003] Traditional underwater laser scanning systems are non-reconfigurable, with fixed structures that cannot be modified according to actual needs, resulting in sparse point cloud data, insufficient information acquisition, slow scanning speed, and small detection range.

[0004] Therefore, there is an urgent need to propose a reconfigurable underwater three-dimensional laser scanning system and method to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to address the problems of non-reconfigurable underwater laser scanning systems, such as fixed structures that prevent the modification of scanning beams and forms according to actual needs, leading to sparse point cloud data, insufficient information acquisition, slow scanning speed, and small detection range. This invention provides a reconfigurable underwater 3D laser scanning system and method. A brief overview of the invention is given below to provide a basic understanding of certain aspects of the invention. It should be understood that this overview is not an exhaustive summary of the invention. It is not intended to identify key or essential parts of the invention, nor is it intended to limit the scope of the invention.

[0006] The technical solution of this invention:

[0007] A reconfigurable underwater 3D laser scanning system includes an underwater camera module, a laser emitter module, a parallel circuit module, and a data processing center module unit. The laser emitter module is electrically connected to the parallel circuit module, and the underwater camera module, the parallel circuit module, and the data processing center module unit are electrically connected.

[0008] Preferably, the underwater camera module and the laser emitter module are both modules. The upper and right sides of the module are respectively provided with an upper slot and a right slot, and the lower and left sides of the module are respectively provided with a lower buckle and a left buckle. The upper slot of one adjacent module is connected to the lower buckle of another module, and the right slot of one adjacent module is connected to the left buckle of another module.

[0009] Preferably, several laser emitting modules are connected in a "line" shape to form an array laser cluster for scanning, and several laser emitting modules are connected in a "cross" shape to form a grid light for scanning. The line shape includes a single-beam mode and a multi-beam mode. The single-beam mode of the line shape includes one laser emitting module, and the multi-beam mode of the line shape includes two or more linearly arranged laser emitting modules. The cross shape is a grid light mode, and the cross shape consists of several laser emitting modules arranged in a cross shape.

[0010] Preferably, the underwater camera module includes single-view, dual-view, and multi-view modes. When the underwater camera module is set at one end of a straight line, it is in single-view mode. When the underwater camera module is set at both ends of a straight line or a cross, it is in dual-view mode. When the underwater camera module is set at both ends, the middle of a straight line, or the end of a cross, it is in multi-beam mode.

[0011] A reconfigurable underwater 3D laser scanning method includes the following steps:

[0012] Step 1: Assemble and connect the underwater camera module and laser emitter module according to requirements;

[0013] Step 2: The data processing center module unit identifies the number of underwater camera modules and laser emitter modules to determine the working scanning mode;

[0014] Step 3: The 3D laser scanning system scans the underwater target, preprocesses the image, segments the laser lines, and extracts the center of the laser lines;

[0015] Step 4: Match laser lines, match laser pixel pairs, calculate 3D coordinates, and transform to the coordinate system of the first underwater camera module.

[0016] Preferred method: In step one, insert the buckle into the adjacent slot to connect and complete the assembly.

[0017] Preferably, in step two, the scanning modes include array laser cluster scanning mode and grid light scanning mode; the array laser cluster scanning modes include single-view single-beam mode, dual-view single-beam mode, single-view multi-beam mode, dual-view multi-beam mode and multi-view multi-beam mode; the grid light scanning modes include dual-view grid light mode and multi-view grid light mode.

[0018] Single-vision, single-beam mode: An underwater camera module and a linear laser emission module are interconnected;

[0019] Dual-vision single-beam mode: Two underwater camera modules and one laser emission module are fixedly connected;

[0020] The multi-beam mode consists of a certain number of underwater camera modules and multiple laser emitters arranged in a "line" configuration. Depending on the number of underwater camera modules, it can be classified as single-vision multi-beam mode, dual-vision multi-beam mode, or multi-vision multi-beam mode.

[0021] Single-view multi-beam mode: The underwater camera module is located at one end of the "one" or at a certain position in the middle of the "one";

[0022] Dual-vision multi-beam mode: There is an underwater camera module at each end of the "one" shape, and multiple laser emitter modules can be arbitrarily assembled in the middle;

[0023] Multi-vision, multi-beam mode: It consists of three or more underwater camera modules and multiple laser emitter modules;

[0024] The grid light mode is assembled by connecting laser emitter modules in a "cross" shape. Depending on whether there are two or four underwater camera modules, it can be a dual-vision grid light mode or a multi-vision grid light mode.

[0025] Dual-vision grid light mode: underwater camera modules are assembled at both ends of the horizontal or vertical direction of the "cross";

[0026] Multi-view grid light mode: Underwater camera modules are assembled at both ends of the horizontal direction and the endpoints of the vertical direction of the "cross". The horizontal direction is a set of binocular cameras, and the vertical direction is a set of binocular cameras.

[0027] Preferred: Step 3 includes the following steps:

[0028] Step 31: The 3D laser scanning system scans the underwater target, and the underwater camera module captures photos which are then transmitted to the data processing center module for photo preprocessing.

[0029] Step 32: Extract the center of the laser line from the preprocessed photo, and divide the image into a foreground region and a background region. The pixel value of the point in the foreground region is 1, and the pixel value of the point in the background region is 0.

[0030] The state of the point to be measured is determined according to the following constraints: if the eight neighborhoods of the point to be measured satisfy the constraints.

[0031]

[0032] Among them, P iP represents the pixel value of the point to be measured and its eight neighboring points in the image (i = 1, 2, ..., 9). i The value of N(P) is 0 or 1; i ) represents the number of pixels with a value of 1 in the eight neighborhood of point P1; A(P1) represents the number of times the pixel value changes from 0 to 1 in the eight neighborhood template of point P1, starting from point P2 and rotating clockwise around point P2.

[0033] The state of the test point P1 is determined according to the following constraints. Test points that meet the judgment conditions are marked and not deleted temporarily. When the current iteration ends, that is, after traversing all pixels in the image, the marked foreground points are deleted uniformly. The loop is continuously iterated until all pixels in the image no longer meet the above conditions, then the loop ends.

[0034] Preferred method: In step four, single-vision single-beam mode: extract the laser line and the pixel coordinates [u, v, 1] of any point on the line. T Using the intrinsic parameter matrix, pixel coordinates can be transformed into the coordinates [x, y, 1] of a point with a focal length of 1 in camera coordinates. T =K -1 [u, v, 1] T The light plane AX is calculated using the least squares fitting plane principle. C +BY C +CZ C +D=0, the three-dimensional coordinates of the laser line are obtained as follows:

[0035]

[0036] Binocular single-beam mode: Extract the center of the laser line in the binocular image, perform geometric constraint matching on the pixels in the binocular image, and subtract the right image from the left image to obtain the disparity d = x. l -x r Calculate the three-dimensional coordinates (X,Y,Z):

[0037]

[0038] Single-vision multi-beam mode: Number multiple laser lines and calculate the light plane separately. Following the same steps as the single-vision single-beam mode described above, calculate the three-dimensional coordinates of each laser line.

[0039] Binocular multi-beam mode: The binocular image is searched from bottom to top and from left to right, starting with the first white pixel as the origin and center point, and continuing to search for adjacent points within an 8-neighborhood. When a new point is found, its pixel coordinates are immediately recorded and then erased from the image. This search process is repeated until there are no other adjacent points in the neighborhood of the other end of the stripe. At the end of the search, the coordinate data of all lines are recorded. Lines smaller than M pixels are removed, and the remaining laser lines are labeled P based on the y-value of the first pixel of each line. L [L1, L2, ..., L n ], P R [L1, L2, ..., L n The system performs pixel matching on multiple laser beams with matching numbers and calculates three-dimensional coordinates using parallax.

[0040] Dual-vision multi-beam mode: The binocular vision of adjacent cameras calculates disparity and extracts 3D point cloud coordinates through the same steps as described in the dual-vision multi-beam mode; each underwater camera corresponds to a coordinate system: O1-x1y1z1, O2-x2y2z2...O i -x i y i z i Calculate the extrinsic parameter matrix between adjacent cameras. This represents the transformation matrix from the coordinate system of the i-th camera to the coordinate system of the j-th camera, uniformly transforming to the first camera coordinate system;

[0041] Dual-vision grid light mode: The dual-vision grid light mode can be divided into two modes depending on whether the binocular camera module is installed horizontally or vertically. The binocular grid light image is refined by laser lines. "Cross-shaped node", "T-shaped node" and "L-shaped node" are set as grid node search templates. The grid nodes are encoded from left to right as (1,1), (1,2)...(1,n). Along the vertical direction, the grid is aligned with the vertical direction of the grid skeleton. The grid nodes are encoded from top to bottom as (2,1), (3,1)...(n,1). The binocular grid nodes are matched, and the laser lines are segmented and matched. After the above dual-vision multi-beam mode disparity calculation steps, the three-dimensional point cloud coordinates are extracted.

[0042] Multi-vision grid light mode: Multiple laser emitter modules are installed in a "cross" shape, with vision modules installed at both ends in the horizontal and vertical directions. The horizontal and vertical camera modules, as binocular images, pass through the matching node of the dual-vision grid light mode to calculate the three-dimensional coordinates relative to the left camera. After the vertical camera module calculates the three-dimensional coordinates, the three-dimensional coordinates are transformed to the coordinate system of the horizontal left camera.

[0043] The present invention has the following beneficial effects:

[0044] This invention allows for the addition of underwater camera modules and laser emitter modules as needed, depending on the requirements of the underwater robot. The number and configuration of each module can be adjusted as required.

[0045] This invention enables high-precision scanning of underwater targets, effectively solving problems such as information loss, sparse point clouds, narrow scanning range, and non-scalable structure caused by the fixed structure underwater laser scanning system's beam and single scanning mode. It expands the scanning range, increases the field of view, and features simple structure, flexible scanning mode, dense point cloud data, and accurate imaging. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of a reconfigurable underwater 3D laser scanning system.

[0047] Figure 2 This is a module connection diagram;

[0048] Figure 3 is a schematic diagram of the single-beam scanning mode;

[0049] Figure 3-1 This is a schematic diagram of a single-vision, single-beam scanning mode;

[0050] Figure 3-2 This is a schematic diagram of a dual-vision single-beam scanning mode;

[0051] Figure 4 is a schematic diagram of the multi-beam scanning mode;

[0052] Figure 4-1 This is a schematic diagram of a single-view multi-beam scanning mode;

[0053] Figure 4-2 This is a schematic diagram of a dual-vision multi-beam scanning mode;

[0054] Figure 4-3 This is a schematic diagram of a multi-view, multi-beam scanning mode;

[0055] Figure 5 is a schematic diagram of the grid beam scanning mode;

[0056] Figure 5-1 This is a schematic diagram of a dual-vision grid beam scanning mode;

[0057] Figure 5-2 This is a schematic diagram of a multi-view grid beam scanning mode;

[0058] Figure 6 This is a schematic diagram illustrating the pose transfer principle of a multi-camera system coordinate system.

[0059] In the diagram, 1-underwater camera module, 2-laser emitter module, 3-parallel circuit module, 4-data processing center module unit, 51-upper slot, 52-right slot, 61-lower buckle, 62-left buckle. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0061] Specific implementation method one: Combining Figure 1-2 This embodiment describes a reconfigurable underwater 3D laser scanning system, comprising an underwater camera module 1, a laser emitter module 2, a parallel circuit module 3, and a data processing center module unit 4. The laser emitter module 2 is electrically connected to the parallel circuit module 3, and the underwater camera module 1, the parallel circuit module 3, and the data processing center module unit 4 are electrically connected. Parallel connection is a connection method between components, connecting to the circuit for stable power supply, providing the same voltage to each laser. This invention allows for the addition of the underwater camera module 1 and the laser emitter module 2 according to the needs of the underwater robot, expanding the scanning range and increasing the field of view. It has advantages such as simple structure, flexible scanning mode, dense point cloud data, and accurate imaging.

[0062] Specific Implementation Method Two: Combining Figure 1-2This embodiment describes a reconfigurable underwater 3D laser scanning system. The underwater camera module 1 and laser emitter module 2 are both modules. Each module has an upper slot 51 and a right slot 52 fixedly mounted on its upper and right sides, respectively. A lower latch 61 and a left latch 62 are fixedly mounted on the lower and left sides, respectively. The upper slot 51 of one adjacent module connects to the lower latch 61 of another module, and the right slot 52 of one adjacent module connects to the left latch 62 of another module. Both the upper slot 51 and right slot 52 have rectangular insertion holes, and snap-fit ​​holes are provided on both sides of the mounting holes. The lower latch 61 and left latch 62 are U-shaped. 2. It is elastic, and the lower buckle 61 and the left buckle 62 have protrusions on both sides corresponding to the buckle holes, which are designed to mate with the buckle holes. One side of the protrusion is chamfered, and the other side is a square corner, which facilitates the buckle insertion into the buckle hole and ensures a stable connection after the protrusion enters the buckle hole. The two sides of the buckle are fixedly connected to the module through the end structure of the buckle. The structure is simple and easy to operate. With a reasonable buckle and slot layout, several underwater camera modules and laser emitter modules can be quickly assembled and modified as needed, which is highly efficient. The structure can be reconfigured according to actual needs, which is convenient for structural expansion, scanning beam and form changes, increasing the detection range, improving scanning efficiency, and facilitating the sufficient acquisition of point cloud data information.

[0063] Specific implementation method three: Combining Figure 1 -5 Description of this embodiment: This embodiment provides a reconfigurable underwater three-dimensional laser scanning system in which several laser emitting modules are connected in a "line" configuration to form an array laser cluster for scanning, and several laser emitting modules are connected in a "cross" configuration to form a grid light for scanning. The line configuration includes a single-beam mode and a multi-beam mode. The single-beam mode of the line configuration includes one laser emitting module 2, and the multi-beam mode of the line configuration includes two or more linearly arranged laser emitting modules 2. The cross configuration is a grid light mode, which consists of several laser emitting modules 2 arranged in a cross or T-shape. The laser emitting module 2 is a line laser transmitting module.

[0064] Specific implementation method four: Combination Figure 1-5 Description of this embodiment: This embodiment provides a reconfigurable underwater 3D laser scanning system. The underwater camera module 1 includes single-view, dual-view, and multi-view modes. The underwater camera module 1 is in single-view mode when positioned at one end or the middle of a straight line; in dual-view mode when positioned at the symmetrical ends of a straight line or a cross; and in multi-beam mode when positioned at the ends, middle, or four ends of a straight line or a cross. Specifically, the single-view single-beam mode consists of an underwater camera module and a straight-line laser emission module interconnected to scan underwater targets and calculate the light level. The binocular vision single-beam mode consists of two underwater camera modules and one laser emission module connected together. It performs geometric constraint matching on the binocular images to match pixel pairs and calculates the three-dimensional coordinates of the matched point pairs. The single-beam vision mode can be further divided into endpoint single-beam vision mode and intermediate single-beam vision mode according to the position of the underwater camera module. It uses one underwater camera module and multiple linear laser emission modules to label multiple lasers and calculate the light plane separately to obtain the three-dimensional coordinates. The two ends of the binocular vision multi-beam mode are vision modules (underwater camera modules), and multiple laser emission modules are arbitrarily installed in the middle part.

[0065] Specific Implementation Method Five: Combining Figure 1 -5 This embodiment describes a reconfigurable underwater three-dimensional laser scanning method based on a reconfigurable underwater three-dimensional laser scanning system (hereinafter referred to as the three-dimensional laser scanning system), which includes the following steps:

[0066] Step 1: Assemble the underwater camera module 1 and laser emitter module 2 according to the requirements. The modules are connected by using slots and buckles.

[0067] Step 2: The data processing center module unit 4 determines the working scanning mode by identifying the number of underwater camera modules 1 and laser emitter modules 2 in the device connection status information identification device;

[0068] Step 3: The 3D laser scanning system scans the underwater target, preprocesses the image, segments the laser lines, and extracts the center of the laser lines;

[0069] Step 4: Match laser lines, match laser pixel pairs, calculate 3D coordinates, and transform to the coordinate system of the first underwater camera module 1; This invention is installed on an underwater robot. The data processing center module identifies the scanning mode, preprocesses the photos to match laser lines, performs pixel matching on the laser lines, calculates the parallax of the paired points to obtain the 3D coordinates, and uses the pose transformation matrix to transform the acquired 3D point cloud data to the coordinate system of the first camera to realize 3D scanning of the underwater environment.

[0070] Specific Implementation Method Six: Combination Figure 1 -5 This embodiment describes a reconfigurable underwater 3D laser scanning method. In step one, the buckles are inserted into adjacent slots to connect and complete the assembly. This includes the following steps:

[0071] Step 11: The underwater camera module and the linear laser emission module are provided with slots on the top and left side, and buckles are provided on the bottom and right side. The top slot and the bottom buckle are fixedly connected, and the left buckle and the right buckle are fixedly connected.

[0072] Step 12: Modules can be combined arbitrarily according to requirements. The number and configuration of each module can be adjusted as needed. This can be achieved by constructing single-beam scanning, multiple laser emission modules connected in a straight line to form an array laser cluster for scanning, or multiple laser emission modules connected in a cross shape to form a grid beam for scanning. Multiple laser emitters are connected to a parallel circuit module and then to the data processing center module. Independent underwater camera modules and independent linear laser emission modules can be combined arbitrarily according to requirements, with the number and configuration of each module adjustable as needed. The underwater camera module and laser emission module are assembled to form an underwater 3D laser scanning system for high-precision scanning of underwater targets. This effectively solves the problems of information loss, sparse point clouds, narrow scanning range, and non-scalable structure caused by the fixed structure underwater laser scanning system's linear beam and single scanning mode. It is less affected by water quality when scanning underwater targets and has advantages such as wide scanning range, high efficiency, flexible and varied modes, dense point cloud data, and accurate imaging.

[0073] Specific implementation method seven: Combining Figure 1 -5 This embodiment describes a reconfigurable underwater three-dimensional laser scanning method. In step two, the scanning modes include array laser cluster scanning mode and grid light scanning mode. The array laser cluster scanning mode includes single-view single-beam mode, dual-view single-beam mode, single-view multi-beam mode, dual-view multi-beam mode, and multi-view multi-beam mode. The grid light scanning mode includes dual-view grid light mode and multi-view grid light mode.

[0074] Single-vision, single-beam mode: An underwater camera module and a linear laser emission module are interconnected to scan underwater targets and calculate the linear laser plane equation. It features a simple structure, low cost, and ease of integration and maintenance. Suitable for basic distance measurement tasks, especially in applications where high accuracy is not required.

[0075] Dual-vision single-beam mode: Two underwater camera modules and one laser emission module are fixedly connected to perform geometric constraint matching of pixel pairs on the binocular images and calculate the three-dimensional coordinates of the matching point pairs; by using two cameras, more accurate depth information can be provided, which is suitable for applications that require higher precision and can better handle some complex scenes;

[0076] The multi-beam mode consists of a certain number of underwater camera modules and multiple laser emitters arranged in a "line" configuration. Depending on the number of underwater camera modules, it can be classified as single-vision multi-beam mode, dual-vision multi-beam mode, or multi-vision multi-beam mode.

[0077] Single-view multi-beam mode: The underwater camera module, positioned at either the end of the "one" shape or somewhere in the middle of the "one," numbers multiple beams and calculates the light plane separately. Compared to single-line fringes, multi-line fringes provide more spatial information, thereby improving measurement accuracy and reliability. Suitable for scenarios requiring moderate precision.

[0078] Dual-vision multi-beam mode: There is an underwater camera module at each end of the "I" shape, and multiple laser emitter modules can be arbitrarily assembled in the middle; combining the advantages of binocular vision and multi-line stripes, it can provide very high accuracy and reliability; suitable for professional-grade applications with extremely high accuracy requirements, such as advanced robot navigation.

[0079] Multi-view, multi-beam mode: Composed of three or more underwater camera modules and multiple laser emitter modules, adjacent cameras perform laser line matching and pixel pair matching to calculate 3D coordinates; multiple laser sources can provide more spatial information, thus greatly improving measurement accuracy and resolution. The multi-view system can capture targets from different angles, providing more comprehensive 3D information, which is particularly useful in complex or occluded scenes, adapting to various complex measurement tasks.

[0080] The grid light mode is assembled by connecting laser emitter modules in a "cross" shape. Depending on whether there are two or four underwater camera modules, it can be a dual-vision grid light mode or a multi-vision grid light mode.

[0081] Dual-vision grid light mode: Underwater camera modules are assembled at both ends of the horizontal or vertical direction of the "cross" to match the grid nodes of the binocular images and calculate the three-dimensional coordinates by matching laser lines; a single frame image can obtain rich spatial information, which helps to improve measurement accuracy;

[0082] Multi-view grid light mode: Underwater camera modules are assembled at both ends of the horizontal direction and the vertical end of the "cross". One set of binocular cameras is positioned horizontally, and another set vertically. The 3D coordinates of the binocular images are calculated and transformed to the coordinate system of the camera at the left end of the horizontal direction. It offers extremely high accuracy and resolution, can capture targets from different angles, reduces occlusion and blind spots, and provides more comprehensive 3D information. It can be adjusted as needed to adapt to different measurement tasks. It helps to capture subtle differences on the target surface.

[0083] Specific implementation method eight: Combination Figure 1-5 This embodiment describes a reconfigurable underwater three-dimensional laser scanning method. Step three includes the following steps:

[0084] Step 31: The 3D laser scanning system scans the underwater target, and the underwater camera module takes pictures and transmits them to the data processing center module for picture preprocessing. The preprocessing includes distortion correction, limit constraints, laser line segmentation, grayscale conversion, binarization, etc.

[0085] Step 32: Extract the laser line center from the preprocessed photo, dividing the image into foreground and background regions. Pixels in the foreground region have a value of 1, while pixels in the background region have a value of 0. The algorithm iterates continuously to find foreground points that meet specific conditions, marks them, and then deletes them to achieve image thinning. The eight-neighborhood of a foreground point P1 (the point to be measured) in the foreground region is shown in the table below:

[0086] <![CDATA[P9]]> <![CDATA[P2]]> <![CDATA[P3]]> <![CDATA[P8]]> <![CDATA[P1]]> <![CDATA[P4]]> <![CDATA[P7]]> <![CDATA[P6]]> <![CDATA[P5]]>

[0087] The state of the test point is determined according to the following constraints. If the eight neighbors of the test point meet the constraints, the state of the test point is set to be deleted. If the conditions are not met, it is temporarily retained. During the judgment process, the test points that meet the conditions are not deleted. Instead, the test points are marked first. When each iteration ends, all the marked test points are deleted uniformly. After the uniform deletion, each laser line changes from a thick line to a single pixel laser line.

[0088]

[0089] Among them, P i P represents the pixel value of the point to be measured and its eight neighboring points in the image (i = 1, 2, ..., 9). i The value of N(P) is 0 or 1; i ) represents the number of pixels with a value of 1 in the eight neighborhood of point P1; A(P1) represents the number of times the pixel value changes from 0 to 1 in the eight neighborhood template of point P1, starting from point P2 and rotating clockwise around point P2.

[0090] The state of the test point P1 is determined according to the following constraints. Test points that meet the judgment conditions are marked and not deleted temporarily. When the current iteration ends, that is, after traversing all pixels in the image, the marked foreground points are deleted uniformly. The loop is continuously iterated until all pixels (test points) in the image no longer meet the above conditions, then the loop ends.

[0091] Specific Implementation Method Nine: Combining Figure 1-5 This embodiment describes a reconfigurable underwater three-dimensional laser scanning method. In step four, the single-beam mode is divided into a single-vision single-beam mode and a dual-vision single-beam mode.

[0092] Single-vision, single-beam mode: Extracts the laser line and the pixel coordinates [u, v, 1] of any point on the line. T Using the intrinsic parameter matrix, pixel coordinates can be transformed into the coordinates [x, y, 1] of a point with a focal length of 1 in camera coordinates. T =K -1 [u, v, 1] T K is the intrinsic parameter matrix during camera calibration, and ABCD are parameters describing the characteristics of the light plane, where the light plane AX is calculated using the least squares fitting principle. C +BY C +CZ C +D=0, the three-dimensional coordinates of the laser line are obtained as follows:

[0093]

[0094] Where A, B, and C are the components of the plane's normal vector; the normal vector is a vector perpendicular to the plane, indicating the plane's direction; D is a position parameter, which is related to the distance from the plane to the origin; Xc, Yc, and Zc represent the coordinates of any point in space.

[0095] Binocular single-beam mode: Extract the center of the laser line in the binocular image, perform geometric constraint matching on the pixels in the binocular image, and subtract the right image from the left image to obtain the disparity d = x. l -x r Calculate the three-dimensional coordinates (X,Y,Z):

[0096]

[0097] Among them, X l It is the horizontal coordinate of a specific feature point in the left camera view; X r It is the horizontal coordinate of the same feature point in the right camera view as in the left camera view;

[0098] Multibeam mode is divided into single-vision multibeam mode, dual-vision multibeam mode, and multi-vision multibeam mode;

[0099] Single-vision multi-beam mode: Number multiple laser lines and calculate the light plane separately. Following the same steps as the single-vision single-beam mode described above, calculate the three-dimensional coordinates of each laser line.

[0100] Binocular multi-beam mode: The binocular image is searched from bottom to top and from left to right, starting with the first white pixel as the origin and center point, and continuing to search for adjacent points within an 8-neighborhood. When a new point is found, its pixel coordinates are immediately recorded and then erased from the image. This search process is repeated until there are no other adjacent points in the neighborhood of the other end of the stripe. At the end of the search, the coordinate data of all lines are recorded. Lines smaller than M pixels are removed, and the remaining laser lines are labeled P based on the y-value of the first pixel of each line. L [L1, L2, ..., L n ], P R [L1, L2, ..., L n ], pixel-by-pixel matching is performed on multiple laser beams with matching numbers, and three-dimensional coordinates are calculated using parallax, where P L Photo taken with the left camera, P R Photographs from the camera, L n Meaning: The laser line number in the photo;

[0101] Dual-vision multi-beam mode: The binocular vision of adjacent cameras calculates disparity and extracts 3D point cloud coordinates through the same steps as described in the dual-vision multi-beam mode; each underwater camera corresponds to a coordinate system: O1-x1y1z1, O2-x2y2z2...Q i -x i y i z i Calculate the extrinsic parameter matrix between adjacent cameras. This represents the transformation matrix from the coordinate system of the i-th camera to the coordinate system of the j-th camera, uniformly transforming to the coordinate system of the first camera (underwater camera module);

[0102] The grid light mode, depending on the number of underwater camera modules installed at both ends of the "cross", is a dual-vision grid light mode or a multi-vision grid light mode;

[0103] Dual-vision raster light mode: The dual-vision raster light mode can be divided into two modes depending on whether the binocular camera module is installed horizontally or vertically. Laser lines are refined in the binocular raster light image. "Cross-shaped nodes," "T-shaped nodes," and "L-shaped nodes" are set as raster node search templates. The raster nodes are encoded from left to right as (1,1), (1,2)...(1,n). Along the vertical direction, the raster is aligned with the vertical direction of the grid skeleton, and the grid nodes are encoded from top to bottom as (2,1), (3,1)...(n,1). The binocular raster nodes are matched, and the laser lines are segmented and matched. After the disparity calculation steps of the dual-vision multi-beam mode described above, the 3D point cloud coordinates are extracted. After laser line refinement in the raster image, each node (at the intersection of horizontal and vertical lines) is not a complete cross, but rather has "cross," "T," and "L" shapes. Using these shapes as search templates facilitates obtaining the node positions and quantities, which is convenient for the next step of matching and calculating 3D information.

[0104] Multi-vision grid light mode: Multiple laser emitter modules are installed in a "cross" shape, with vision modules installed at both ends in the horizontal and vertical directions. The horizontal and vertical camera modules, as binocular images, pass through the matching node of the dual-vision grid light mode to calculate the three-dimensional coordinates relative to the left camera. After the vertical camera module calculates the three-dimensional coordinates, the three-dimensional coordinates are transformed to the coordinate system of the horizontal left camera.

[0105] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutation and combination. Therefore, the present invention will not describe the technical solutions after permutation and combination one by one, but it should be understood that the technical solutions after permutation and combination have been disclosed by the present invention.

[0106] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A scanning method for a reconfigurable underwater three-dimensional laser scanning system, characterized in that: The system includes an underwater camera module (1), a laser emitter module (2), a parallel circuit module (3), and a data processing center module unit (4). The laser emitter module (2) is electrically connected to the parallel circuit module (3), and the underwater camera module (1), the parallel circuit module (3), and the data processing center module unit (4) are electrically connected. The method includes the following steps: Step 1: Assemble the underwater camera module (1) and laser emitter module (2) according to requirements and connect them; Step 2: The data processing center module unit (4) identifies the number of underwater camera modules (1) and laser emitter modules (2) to determine the working scanning mode; In step two, the scanning modes include array laser cluster scanning mode and grid light scanning mode; the array laser cluster scanning modes include single-view single-beam mode, dual-view single-beam mode, single-view multi-beam mode, dual-view multi-beam mode and multi-view multi-beam mode; the grid light scanning modes include dual-view grid light mode and multi-view grid light mode. Single-vision, single-beam mode: An underwater camera module and a linear laser emission module are interconnected; Dual-vision single-beam mode: Two underwater camera modules and one laser emission module are fixedly connected; The multi-beam mode consists of a certain number of underwater camera modules and multiple laser emitters arranged in a "line" configuration. Depending on the number of underwater camera modules, it can be classified as single-vision multi-beam mode, dual-vision multi-beam mode, or multi-vision multi-beam mode. Single-view multi-beam mode: The underwater camera module is located at one end of the "one" or at a certain position in the middle of the "one"; Dual-vision multi-beam mode: There is an underwater camera module at each end of the "one" shape, and multiple laser emitter modules can be arbitrarily assembled in the middle; Multi-vision, multi-beam mode: It consists of three or more underwater camera modules and multiple laser emitter modules; The grid light mode is assembled by connecting laser emitter modules in a "cross" shape. Depending on whether there are two or four underwater camera modules, it can be a dual-vision grid light mode or a multi-vision grid light mode. Dual-vision grid light mode: underwater camera modules are assembled at both ends of the horizontal or vertical direction of the "cross"; Multi-view grid light mode: Underwater camera modules are assembled at both ends of the horizontal direction and the endpoints of the vertical direction of the "cross". The horizontal direction is a set of binocular cameras, and the vertical direction is a set of binocular cameras. Step 3: The 3D laser scanning system scans the underwater target, preprocesses the image, segments the laser lines, and extracts the center of the laser lines; Step three includes the following steps: Step 31: The 3D laser scanning system scans the underwater target, and the underwater camera module captures photos which are then transmitted to the data processing center module for photo preprocessing. Step 32: Extract the center of the laser line from the preprocessed photo, and divide the image into a foreground region and a background region. The pixel value of the point in the foreground region is 1, and the pixel value of the point in the background region is 0. The state of the point to be measured is determined according to the following constraints: if the eight neighborhoods of the point to be measured satisfy the constraints. in, The pixel values ​​of the point to be measured and its eight neighboring points in the image. , The value can be 0 or 1; express The number of pixels with a value of 1 in the eight neighborhood of a point; Indicates in In the eight-neighbor template of a point, from Click to start The pixel value changes from 0 to 1 once in a clockwise circular motion, centered on the point. The test point is subject to the following constraints. The state is determined, and the test points that meet the judgment conditions are marked and not deleted temporarily; when the current iteration ends, that is, after traversing all the pixels in the image, the marked foreground points are deleted uniformly; the loop is continuously iterated until all the pixels in the image no longer meet the above conditions, then the loop ends. Step 4: Match laser lines, match laser pixel pairs, calculate three-dimensional coordinates, and transform to the coordinate system of the first underwater camera module (1); In step four, the single-vision single-beam mode extracts the laser line and the pixel coordinates of any point on the line. Using the intrinsic parameter matrix, pixel coordinates can be transformed into coordinates at focal length 1 in camera coordinates. The light plane is calculated using the least squares fitting plane principle. The three-dimensional coordinates of the laser line are obtained as follows: ； Binocular single-beam mode: Extract the center of the laser line in the binocular image, perform geometric constraint matching on the pixels in the binocular image, and subtract the right image from the left image to obtain the disparity. Calculate three-dimensional coordinates : Single-vision multi-beam mode: Number multiple laser lines and calculate the light plane separately. Following the same steps as the single-vision single-beam mode described above, calculate the three-dimensional coordinates of each laser line. Binocular multi-beam mode: The binocular image is searched from bottom to top and from left to right, starting with the first white pixel as the origin and center point, and continuing to search for adjacent points within an 8-neighborhood. When a new point is found, its pixel coordinates are immediately recorded and then erased from the image. This search process is repeated until there are no other adjacent points in the neighborhood of the other end of the stripe. At the end of the search, the coordinate data of all lines are recorded. Lines smaller than M pixels are removed, and the remaining laser lines are labeled with the y-value of the first pixel of each line. Pixel matching is performed on multiple laser beams of the matching number, and the three-dimensional coordinates are calculated using parallax. Dual-vision multi-beam mode: The binocular vision of adjacent cameras calculates disparity and extracts 3D point cloud coordinates through the same steps as described in the dual-vision multi-beam mode; each underwater camera corresponds to a coordinate system. , ... Calculate the extrinsic matrix between adjacent cameras. , Indicates the first Camera coordinate system transferred to the first The transformation matrix of the camera coordinate system is used to uniformly transform the system to the first camera coordinate system. Dual-vision raster light mode: The dual-vision raster light mode can be further divided into two modes depending on whether the binocular camera module is installed horizontally or vertically. Laser lines are used to refine the binocular raster light image. "Cross-shaped nodes," "T-shaped nodes," and "L-shaped nodes" are set as raster node search templates. The raster nodes are coded sequentially from left to right. Along the vertical direction, the grid is aligned with the vertical direction of the grid skeleton, and the grid nodes are encoded sequentially from top to bottom. The binocular grid nodes are matched, the laser lines are segmented and matched, and the three-dimensional point cloud coordinates are extracted through the above-mentioned dual-vision multi-beam mode disparity calculation steps. Multi-vision grid light mode: Multiple laser emitter modules are installed in a "cross" shape, with vision modules installed at both ends in the horizontal and vertical directions. The horizontal and vertical camera modules, as binocular images, are passed through matching nodes similar to the dual-vision grid light mode to calculate the three-dimensional coordinates relative to the left camera. After the vertical camera module calculates the three-dimensional coordinates, the three-dimensional coordinates are transformed to the coordinate system of the horizontal left camera.

2. The scanning method for a reconfigurable underwater three-dimensional laser scanning system according to claim 1, characterized in that: The underwater camera module (1) and the laser emitter module (2) are both modules. The upper and right sides of the modules are respectively provided with an upper slot (51) and a right slot (52). The lower and left sides of the modules are respectively provided with a lower buckle (61) and a left buckle (62). The upper slot (51) of one module is connected to the lower buckle (61) of another module, and the right slot (52) of one module is connected to the left buckle (62) of another module.

3. A scanning method for a reconfigurable underwater three-dimensional laser scanning system according to claim 1 or 2, characterized in that: Several laser emitting modules are connected in a "line" to form an array of laser clusters for scanning, and several laser emitting modules are connected in a "cross" to form a grid light for scanning. The line type includes single-beam mode and multi-beam mode. The single-beam mode of the line type includes one laser emitting module (2), and the multi-beam mode of the line type includes two or more linearly arranged laser emitting modules (2). The cross type is a grid light mode, and the cross type consists of several laser emitting modules (2) arranged in a cross shape.

4. The scanning method for a reconfigurable underwater three-dimensional laser scanning system according to claim 3, characterized in that: The underwater camera module (1) includes single vision, dual vision and multi-vision modes. When the underwater camera module (1) is set at one end of the straight line, it is in single vision mode. When the underwater camera module (1) is set at both ends of the straight line and cross shape, it is in dual vision mode. When the underwater camera module (1) is set at both ends, the middle of the straight line and the end of the cross shape, it is in multi-beam mode.

5. A scanning method for a reconfigurable underwater three-dimensional laser scanning system according to claim 4, characterized in that: In step one, insert the buckle into the adjacent slot to connect and complete the assembly.

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