Underwater laser scanning device and underwater target three-dimensional reconstruction system

Abstract

The invention discloses an underwater laser scanning device and an underwater target three-dimensional reconstruction system, and relates to the technical field of underwater measurement, and the underwater laser scanning device comprises a laser assembly, an image acquisition assembly and a control module. The laser assembly comprises three line laser emitting devices, line laser beams emitted by the three line laser emitting devices intersect at the same target point, and the optical axis of any one line laser emitting device is not located in the plane determined by the optical axes of the other two line laser emitting devices. The image acquisition assembly is used for acquiring a target feature image formed by projecting the linear laser beam to the surface of the underwater stepped structure; the control module is used for driving the line laser emitting device to emit a line laser beam and obtaining a target feature image collected by the image collection assembly. According to the scheme, the crossed three-line lasers serve as signal sources, it can be guaranteed that at least one line laser beam can intersect with the step interface, with the step, of the step type structure, and therefore the step depth of the step type structure can be accurately measured under the condition that no measurement blind area exists.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of underwater measurement, in particular to an underwater laser scanning device and an underwater target three-dimensional reconstruction system. BACKGROUND

[0002] With the implementation of the strategy of building a strong maritime country, the utilization and development of marine resources gradually show the development trend of green ocean, transparent ocean and smart ocean. In different underwater scene requirements such as fine mapping of seabed exploration, feature target identification in underwater search and rescue, equipment shape reconstruction in marine engineering maintenance, and object size measurement in marine ranching, underwater target shape three-dimensional reconstruction and stereoscopic space reconstruction are technical problems to be solved. Through underwater shape three-dimensional reconstruction and stereoscopic space reconstruction technology, the underwater target (seabed topography, search and rescue target, engineering equipment, breeding object, etc.) in the actual marine scene is scanned and depth information is obtained. The three-dimensional information is converted by superimposing the scanning pose data, and the virtual reality simulation under water is realized by combining deep learning and data twin technologies, which can provide visual, panoramic, stereoscopic and real-time intelligent sensing technology for the utilization and development of marine resources.

[0003] At present, underwater target shape three-dimensional reconstruction and stereoscopic space reconstruction technology mainly includes underwater acoustic three-dimensional measurement and underwater optical three-dimensional measurement. The underwater acoustic three-dimensional measurement mainly includes the hardware form of two-dimensional image sonar vertical group and three-dimensional imaging sonar, which has the advantages of long action distance and the limitations of short distance measurement and low measurement accuracy. The underwater optical three-dimensional measurement mainly includes the hardware form of underwater binocular camera and underwater laser scanner; the underwater action distance of binocular camera is limited by water turbidity, and a larger distance between the imaging centers of the two cameras is required to obtain smaller depth estimation error; underwater laser scanner has the advantages of moderate action distance, high signal resolution, high measurement accuracy and low image data calculation, which is suitable for underwater near-field fine three-dimensional measurement scene requirements.

[0004] However, the existing underwater laser scanner mainly uses a single line laser or a parallel line array laser as a signal source. In the case that the measured underwater target has a stepped structure and the stepped structure has an interface parallel to the direction of the line laser, the stepped depth of the stepped structure cannot be measured, that is, the underwater laser scanner using a single line laser or a parallel line array laser as a signal source has a measurement blank area when measuring the stepped structure. SUMMARY

[0005] The main purpose of the present application is to provide an underwater laser scanning device, which aims to solve the technical problem of the existing underwater laser scanner having a measurement blank area when measuring underwater stepped structures.

[0006] To achieve the above object, the underwater laser scanning device provided by the present application comprises:

[0007] The laser assembly comprises three linear laser emitting devices, the linear laser beams emitted by the three linear laser emitting devices converge at the same target point, and the optical axis of any one of the linear laser emitting devices is not located in the plane determined by the optical axes of the other two linear laser emitting devices.

[0008] The image acquisition assembly is used to acquire the target feature image formed by the linear laser beams emitted by the linear laser emitting devices and projected onto the surface of the underwater stepped structure.

[0009] The control module is electrically connected with the laser assembly and the image acquisition assembly; the control module is used to drive the linear laser emitting devices to emit linear laser beams, and the control module is used to acquire the target feature image acquired by the image acquisition assembly.

[0010] In an embodiment, the linear laser emitting device comprises a linear laser, a signal cabin pipe and a first light-transmitting structure; the linear laser is packaged inside the signal cabin pipe, the first light-transmitting structure is sealingly arranged at the front end of the signal cabin pipe to form an exit window, and the linear laser is used to project linear laser beams onto the underwater stepped structure through the exit window.

[0011] In an embodiment, the image acquisition assembly comprises a point cloud camera, a texture camera, an acquisition cabin pipe and a second light-transmitting structure; the point cloud camera and the texture camera are packaged inside the acquisition cabin pipe, the second light-transmitting structure is sealingly arranged at the front end of the acquisition cabin pipe to form an acquisition window, the point cloud camera is used to acquire the laser stripe signals reflected by the underwater stepped structure through the acquisition window, and the texture camera is used to acquire the high-order texture information of the underwater stepped structure through the acquisition window.

[0012] In an embodiment, the material of the first light-transmitting structure is quartz glass.

[0013] In an embodiment, the material of the second light-transmitting structure is quartz glass.

[0014] In an embodiment, the material of the signal cabin pipe is one of aluminum alloy, stainless steel and titanium alloy.

[0015] In an embodiment, the material of the acquisition cabin pipe is one of aluminum alloy, stainless steel and titanium alloy.

[0016] In an embodiment, the line laser emitting device further comprises a secondary water-tight connector, which is connected to the rear end of the signal cabin pipe, the inner end of the secondary water-tight connector is connected to the line laser, and the outer end of the secondary water-tight connector is connected to the control module through a first water-tight cable.

[0017] In an embodiment, the image acquisition assembly further comprises a primary water-tight connector, which is connected to the rear end of the acquisition cabin pipe, the inner end of the primary water-tight connector is connected to the control module, and the outer end of the primary water-tight connector is used to be connected to a host computer through a second water-tight cable.

[0018] In an embodiment, the image acquisition assembly further comprises a filter, which is arranged on the second light-transmitting structure, and the filter is located at the front end of the point cloud camera.

[0019] In an embodiment, the image acquisition assembly further comprises an auxiliary light, which is arranged on the second light-transmitting structure, and the auxiliary light is symmetrically arranged on both sides of the texture camera.

[0020] In an embodiment, the underwater laser scanning device further comprises a support fixing member and three angle fixing members, the support fixing member is clamped and fixed to the acquisition cabin pipe, one end of each of the three angle fixing members is connected to the support fixing member, and the other end of each of the three angle fixing members is connected to one of the three signal cabin pipes.

[0021] In an embodiment, the three line laser emitting devices are respectively referred to as a first emitting device, a second emitting device, and a third emitting device.

[0022] The optical axis of the point cloud camera, the optical axis of the first emitting device, and the optical axis of the second emitting device are located on a first plane, the optical axis of the point cloud camera and the optical axis of the third emitting device are located on a second plane, and the second plane is perpendicular to the first plane.

[0023] The normal line of the exit window forms an angle of 7°-27° with the normal line of the acquisition window, and the shortest straight line distance between the center point of the exit window and the center point of the acquisition window is 240 mm-260 mm.

[0024] In an embodiment, the line laser beam emitted by the first emitting device is orthogonal to the line laser beam emitted by the second emitting device, and the line laser beam emitted by the third emitting device is perpendicular to the second plane; the intersection point between the line laser beam emitted by the first emitting device, the line laser beam emitted by the second emitting device, and the line laser beam emitted by the third emitting device is located on the optical axis of the point cloud camera.

[0025] Correspondingly, the application also provides an underwater target three-dimensional reconstruction system, which comprises the underwater laser scanning device as described above.

[0026] The underwater laser scanning device provided by the application is provided with three linear laser emitting devices, three linear laser beams emitted by the three linear laser emitting devices intersect at the same target point, and the optical axis of any one linear laser emitting device is not located in the plane determined by the optical axes of the other two linear laser emitting devices, so as to form a spatial structure of "two-axis coplanar and third-axis orthogonal". When three mutually intersecting linear laser beams emitted by the three linear laser emitting devices are projected to the underwater ladder-shaped structure surface, no matter the direction of the ladder interface of the underwater ladder-shaped structure, at least one linear laser beam can intersect with the ladder interface, so that the problem of the blind area of the step depth measurement of the traditional single linear laser or parallel linear array laser due to the parallel direction of the ladder interface can be avoided, the omnidirectional depth information of the complex underwater ladder-shaped structure can be captured, and the target feature image formed by the linear laser beam projected to the underwater ladder-shaped structure surface is collected by the image acquisition component, so as to provide accurate original data for the three-dimensional reconstruction operation of the rear end, and the integrity and accuracy of the subsequent coordinate conversion and model reconstruction can be ensured. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only constitute some embodiments of the application, and for those skilled in the art, other drawings can also be obtained according to the structures shown in the drawings without creative labor.

[0028] Figure 1 The three-dimensional structure schematic diagram of the underwater laser scanning device provided by an embodiment of the application;

[0029] Figure 2 The top view structure schematic diagram of the underwater laser scanning device provided by an embodiment of the application;

[0030] Figure 3 The schematic diagram of the linear laser beam projected to the underwater ladder-shaped structure surface in the underwater laser scanning device provided by an embodiment of the application.

[0031] Explanation of the reference signs:

[0032] 100, first plane; 200, second plane; 300, underwater ladder-shaped structure;

[0033] 1, laser component; 11, linear laser emitting device; 11a, first emitting device; 11b, second emitting device; 11c, third emitting device;

[0034] 111, linear laser; 112, signal cabin pipe; 113, first light-transmissive structure; 114, secondary water-tight connector;

[0035] 2, image acquisition assembly; 21, point cloud camera; 22, texture camera; 23, acquisition cabin pipe; 24, second light-transmissive structure; 25, primary water-tight connector; 26, filter; 27, auxiliary fill light;

[0036] 3, first water-tight cable; 4, second water-tight cable; 5, support fixing piece; 6, angle fixing piece.

[0037] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0039] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative positional relationship, movement condition, etc. between the components in a certain posture, and if the certain posture changes, the directional indications also change accordingly.

[0040] In addition, if the embodiments of the present application involve descriptions of "first", "second", etc., the descriptions of "first", "second", etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first" and "second" can explicitly or implicitly include at least one of the features. In addition, "and / or" or "and / or" appearing throughout the text means that the three parallel schemes are included, for example, "A and / or B" includes A scheme, or B scheme, or A and B simultaneously satisfy the scheme. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it, and when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the scope of protection claimed by the present application.

[0041] With the implementation of the strategy of building a maritime power, the utilization and development of marine resources gradually show the trend of green ocean, transparent ocean and smart ocean. Under different underwater scene requirements such as fine mapping of seabed terrain, feature target identification in underwater search and rescue, equipment shape reconstruction in marine engineering maintenance, and object size measurement in marine ranching, underwater target shape three-dimensional reconstruction and stereo space reconstruction are technical problems to be solved urgently. Through underwater shape three-dimensional reconstruction and stereo space reconstruction technology, the underwater target (seabed terrain, search and rescue target, engineering equipment, breeding object, etc.) in the actual marine scene is scanned and the depth information is obtained. The scanning pose data is superimposed to convert three-dimensional information. Combined with deep learning and data twin technology, virtual reality simulation under water is realized, which can provide visual, panoramic, three-dimensional and real-time intelligent perception technology for the utilization and development of marine resources.

[0042] At present, underwater target shape three-dimensional reconstruction and stereo space reconstruction technology mainly includes underwater acoustic three-dimensional measurement and underwater optical three-dimensional measurement. The underwater acoustic three-dimensional measurement mainly includes the hardware form of two-dimensional image sonar vertical group and three-dimensional imaging sonar, which has the advantages of long action distance and the limitations of short distance measurement and low measurement accuracy. The underwater optical three-dimensional measurement mainly includes the hardware form of underwater binocular camera and underwater laser scanner; the underwater action distance of binocular camera is limited by water turbidity, and a larger distance between the imaging centers of the two cameras is required to obtain smaller depth estimation error; underwater laser scanner has the advantages of moderate action distance, high signal resolution, high measurement accuracy and low image data calculation, which is suitable for underwater near-field fine three-dimensional measurement scene requirements.

[0043] However, the existing underwater laser scanner mainly uses a single line laser or a parallel line array laser as a signal source. In the case that the measured underwater target has a stepped structure and the stepped structure has an interface parallel to the direction of the line laser, the step depth of the stepped structure cannot be measured, that is, the underwater laser scanner using a single line laser or a parallel line array laser as a signal source has a measurement blank area when measuring the stepped structure.

[0044] In order to solve the above problems, the underwater laser scanning device provided by the present application uses three mutually intersecting line lasers as a signal source, which can ensure that at least one line laser beam emitted by the underwater laser scanning device can intersect with the stepped interface of the stepped structure in any cross-sectional direction, so that the step depth of the stepped structure can be accurately measured, and thus the fine three-dimensional measurement of the complex structure of the underwater target can be realized without measurement blank area.

[0045] Please refer to Figures 1 to 3 The underwater laser scanning device provided by the present application comprises:

[0046] The laser assembly 1 comprises three linear laser emitting devices 11, linear laser beams emitted by the three linear laser emitting devices 11 intersect at a same target point O, and the optical axis of any one of the linear laser emitting devices 11 is not located in a plane determined by the optical axes of the other two linear laser emitting devices 11;

[0047] The image acquisition assembly 2 is configured to acquire a target feature image formed by the linear laser beams emitted by the linear laser emitting devices 11 being projected onto the surface of the underwater stepped structure 300;

[0048] A control module (not shown in the figure) is electrically connected with the laser assembly 1 and the image acquisition assembly 2. The control module is configured to drive the linear laser emitting devices 11 to emit linear laser beams, and the control module is configured to acquire the target feature image acquired by the image acquisition assembly 2.

[0049] In the embodiment, the laser assembly 1 comprises three linear laser emitting devices 11, and the design core is that the linear laser beams emitted by the three linear laser emitting devices 11 intersect at a same target point O, and the optical axis of any one of the linear laser emitting devices 11 is not located in a plane determined by the optical axes of the other two linear laser emitting devices 11. In the specific implementation process, the three linear laser emitting devices 11 are arranged in a three-dimensional spatial cross layout, and the optical axes of the three linear laser emitting devices 11 form a spatial structure of “two axes in the same plane and the third axis being orthogonal”. For example, the optical axis of the first linear laser emitting device 11 and the optical axis of the second linear laser emitting device 11 are arranged in a 90° cross layout in a plane, and the optical axis of the third linear laser emitting device 11 is perpendicular to the plane. The three linear laser layout has the beneficial effect that when the underwater target to be measured has a stepped structure, at least one linear laser beam will intersect with the stepped interface of the stepped structure, regardless of the direction of the stepped interface. For example, as shown in FIG. 2, when the stepped interface X of the underwater stepped structure 300 is parallel to the first linear laser beam a1, the second linear laser beam a2 or the third linear laser beam a3 must intersect with the stepped interface X. Based on the above arrangement, the problem of the traditional single linear laser or parallel linear array laser having a blind area for stepped depth measurement due to the direction being parallel to the stepped interface can be avoided, and full-directional depth information of the complex underwater stepped structure 300 can be captured. Figure 3

[0050] ​The image acquisition component 2 can include an image sensor, an image preprocessing module, and supporting components, which are used to acquire a target feature image formed by the three linear laser beams emitted by the linear laser emitting device 11 and projected onto the surface of the underwater stepped structure 300. The target feature image can include a light spot reflection image, a texture image of the target surface, and the like. Specifically, when the linear laser beams are projected onto the surface of the underwater stepped structure 300, the characteristics such as light spots and stripes will differ at different positions due to the change in step depth. At this time, the image acquisition component 2 can record the difference information through high-resolution imaging, thereby providing original data for subsequent three-dimensional reconstruction operations.

[0051] The hardware structure of the control module can include a main control board on which a lower computer system is deployed, a multi-channel laser control board, a power module, and the like. In the working process, the main control board controls the multi-channel laser control board through a trigger signal to realize the start-stop of the three linear lasers in series or in parallel, and can adjust the laser emission frequency according to the measurement requirements. At the same time, the control module can receive the target feature image transmitted by the image acquisition component 2 through an Ethernet protocol interface, and perform preprocessing operations such as real-time noise reduction and key frame selection. The beneficial effects of this design are that, through timing synchronization control, the timestamps of laser emission and image acquisition are ensured to be consistent, thereby providing an accurate timing basis for subsequent three-dimensional coordinate conversion combined with spatial movement information, and avoiding reconstruction errors caused by data misplacement.

[0052] As can be seen, the underwater laser scanning device provided in the embodiment is provided with three linear laser emitting devices 11, the linear laser beams emitted by the three linear laser emitting devices 11 intersect at the same target point O, and the optical axis of any one linear laser emitting device 11 is not located in the plane determined by the optical axes of the other two linear laser emitting devices 11, so as to form a spatial structure of “two-axial coplanar and third-axial orthogonal”. When the three mutually intersecting linear laser beams emitted by the three linear laser emitting devices 11 are projected onto the surface of the underwater stepped structure 300, regardless of the direction of the stepped interface of the underwater stepped structure 300, at least one linear laser beam can intersect with the stepped interface, thereby avoiding the problem of the stepped depth measurement blind area of the traditional single linear or parallel linear array laser due to the parallel direction of the stepped interface, and enabling the full-directional depth information of the complex underwater stepped structure 300 to be captured. In combination with the image acquisition component 2, the target feature image formed by the linear laser beams projected onto the surface of the underwater stepped structure 300 is acquired, thereby providing accurate original data for the three-dimensional reconstruction operation of the rear end, and ensuring the integrity and accuracy of subsequent coordinate conversion and model reconstruction.

[0053] In an embodiment, with reference to Figure 1 and Figure 2The line laser emitting device 11 comprises a line laser 111, a signal cabin pipe 112 and a first light-transmitting structure 113; the line laser 111 is encapsulated inside the signal cabin pipe 112, and the first light-transmitting structure 113 is sealingly arranged at the front end of the signal cabin pipe 112 to form an exit window, and the line laser 111 is used to project a line laser beam to the underwater stepped structure 300 through the exit window.

[0054] Specifically, the signal cabin pipe 112 can be a cylindrical structure as shown in the figure; the three line lasers 111 can specifically be three line lasers of green wave band (for example, commonly used 532nm wavelength), and the three line lasers 111 are encapsulated one by one inside the three signal cabin pipes 112, so that damage of the line lasers 111 caused by the complex underwater environment can be avoided; one first light-transmitting structure 113 is arranged at the front end of each of the three signal cabin pipes 112, and the first light-transmitting structure 113 can be made of glass or other light-transmitting materials, so that the line lasers 111 can normally emit line laser beams outward while the signal cabin pipes 112 are capped and the line lasers 111 are protected.

[0055] In an embodiment, referring to Figure 1 and Figure 2 , the image acquisition assembly 2 comprises a point cloud camera 21, a texture camera 22, an acquisition cabin pipe 23 and a second light-transmitting structure 24; the point cloud camera 21 and the texture camera 22 are encapsulated inside the acquisition cabin pipe 23, and the second light-transmitting structure 24 is sealingly arranged at the front end of the acquisition cabin pipe 23 to form an acquisition window, the point cloud camera 21 is used to acquire a laser stripe signal reflected by the underwater stepped structure 300 through the acquisition window, and the texture camera 22 is used to acquire high-order texture information of the underwater stepped structure 300 through the acquisition window.

[0056] Specifically, the acquisition cabin pipe 23 can be a cylindrical structure as shown in the figure, and the point cloud camera 21 and the texture camera 22 are encapsulated inside the acquisition cabin pipe 23, so that damage of the point cloud camera 21 and the texture camera 22 caused by the complex underwater environment can be avoided; the second light-transmitting structure 24 can be made of glass or other light-transmitting materials, so that the point cloud camera 21 and the texture camera 22 can normally acquire external target image data while the acquisition cabin pipe 23 is capped and the point cloud camera 21 and the texture camera 22 are protected.

[0057] Through the cooperation of the point cloud camera 21 and the texture camera 22, high-precision three-dimensional reconstruction of the underwater target can be achieved. Specifically, the point cloud camera 21 is specially used to collect the three-line laser stripe signals reflected by the measured underwater target, and three-dimensional point cloud data is generated by analyzing the deformation of the laser stripe, so as to realize accurate measurement of the geometric structure of the underwater target; the texture camera 22 is responsible for collecting high-order texture information (such as surface color, texture, etc.) of the measured underwater target, and providing texture mapping data source for the three-dimensional point cloud through recording the visual features of the underwater target surface. Through the spatial synchronization and feature matching of the above three-dimensional point cloud data and high-order texture information, the reconstruction result can be upgraded from a simple geometric structure to a three-dimensional model with real visual features, so as to significantly improve the realism and application value of the three-dimensional reconstruction of the underwater target (such as seabed topography, engineering equipment, breeding equipment, etc.), and meet the requirements of fine and visual measurement in marine exploration, search and rescue identification and other scenes.

[0058] In an embodiment, referring to Figure 1 and Figure 2 , the material of the first light-transmitting structure 113 is quartz glass.

[0059] In an embodiment, referring to Figure 1 and Figure 2 , the material of the second light-transmitting structure 24 is quartz glass.

[0060] Specifically, quartz glass has high light transmittance, water pressure resistance and other excellent characteristics, which can ensure the normal penetration of the linear laser beam and the optical stability during image acquisition, and can provide good protection for the devices inside the signal cabin pipe 112 and the collection cabin pipe 23.

[0061] In an embodiment, referring to Figure 1 and Figure 2 , the material of the signal cabin pipe 112 is one of aluminum alloy, stainless steel and titanium alloy.

[0062] In an embodiment, referring to Figure 1 and Figure 2 , the material of the collection cabin pipe 23 is one of aluminum alloy, stainless steel and titanium alloy.

[0063] Specifically, the materials of the signal cabin pipe 112 and the collection cabin pipe 23 can be set according to different working water depths. Aluminum alloy can be used when the water depth is within 50 m, stainless steel can be used when the water depth is within 500 m, and titanium alloy can be used when the water depth is greater than 500 m. According to the pressure environment of different water depths, the materials with corresponding strength and corrosion resistance are matched, which can avoid deformation or water leakage of the signal cabin pipe 112 and the collection cabin pipe 23 caused by water pressure, so as to ensure the reliability of long-term underwater operation.

[0064] In an embodiment, referring toFigure 1 and Figure 2 The line laser emitting device 11 further comprises a secondary water-tight connector 114, which is plugged into the rear end of the signal cabin pipe 112, the inner end of the secondary water-tight connector 114 is connected with the line laser 111, and the outer end of the secondary water-tight connector 114 is connected with the control module through the first water-tight cable 3.

[0065] Specifically, one secondary water-tight connector 114 is arranged at the rear end of each of the three signal cabin pipes 112. By arranging the secondary water-tight connector 114, while realizing the electrical connection between the line laser 111 and the control module and ensuring normal signal transmission between the line laser 111 and the control module, water can be prevented from penetrating into the signal cabin pipe 112 to cause circuit failure.

[0066] In an embodiment, referring to Figure 1 and Figure 2 The image acquisition assembly 2 further comprises a primary water-tight connector 25, which is plugged into the rear end of the acquisition cabin pipe 23, the inner end of the primary water-tight connector 25 is connected with the control module, and the outer end of the primary water-tight connector 25 is used to be connected with the upper computer through the second water-tight cable 4.

[0067] By arranging the primary water-tight connector 25, while realizing the electrical connection between the control module and the upper computer and ensuring normal signal transmission between the control module and the upper computer, water can be prevented from penetrating into the acquisition cabin pipe 23 to cause circuit failure. The upper computer refers to an external computing device electrically connected with the control module. The upper computer can send control instructions (such as laser emitting frequency, image acquisition parameters, etc.) to the control module through the second water-tight cable 4, and supply power to the line laser 111 through the control module. The control module can also send the preprocessed target feature image data to the upper computer through the second water-tight cable 4 for subsequent three-dimensional reconstruction algorithm processing by the upper computer.

[0068] In an embodiment, referring to Figure 1 and Figure 2 The image acquisition assembly 2 further comprises a filter 26, which is arranged on the second light-transmitting structure 24 and located at the front end of the point cloud camera 21.

[0069] The passband wavelength of the filter 26 should be adapted to the wavelength of the line laser beam. In this way, other wavelengths of light in the ambient light can be effectively suppressed, so as to ensure that the point cloud camera 21 only receives the reflection signals of the selected wavelength light, to reduce background noise and improve signal-to-noise ratio, thereby improving the accuracy of subsequent point cloud reconstruction operation. Specifically, the filter 26 can adopt a 532nm narrowband filter, and the cutoff depth OD (Optical Density) of the filter 26 to other wavelengths of light is greater than 3.

[0070] In an embodiment, referring to Figure 1 and Figure 2 , the image acquisition assembly 2 further comprises an auxiliary light 27, which is arranged on the second light-transmitting structure 24 and symmetrically arranged on both sides of the texture camera 22.

[0071] In the scene where the underwater light is seriously attenuated, the auxiliary light 27 can compensate for the light intensity to ensure that the texture camera 22 acquires clear target surface texture details, avoids the blurring of texture features due to insufficient light, and improves the quality of subsequent underwater target three-dimensional reconstruction.

[0072] In an embodiment, referring to Figure 1 and Figure 2 , the underwater laser scanning device further comprises a support fixing member 5 and three angle fixing members 6, the support fixing member 5 is clamped and fixed on the acquisition cabin pipe 23, one end of the three angle fixing members 6 is connected to the support fixing member 5, and the other end of the three angle fixing members 6 is connected to the three signal cabin pipes 112 one by one.

[0073] By arranging the support fixing member 5 and the angle fixing member 6, the connection and fixation between the acquisition cabin pipe 23 and the three signal cabin pipes 112 can be conveniently realized. The angle fixing member 6 can act as an adapter between the support fixing member 5 and the signal cabin pipe 112, so that the signal cabin pipe 112 is deflected at a certain angle relative to the acquisition cabin pipe 23, so that the optical axis of the line laser emitting device 11 and the optical axis of the point cloud camera 21 form a certain angle, so as to meet the requirements of line laser beam emission and reflected spot image acquisition.

[0074] In an embodiment, referring to Figure 1 and Figure 2 , the three line laser emitting devices 11 are respectively referred to as a first emitting device 11a, a second emitting device 11b and a third emitting device 11c;

[0075] The optical axis of the point cloud camera 21, the optical axis of the first emitting device 11a and the optical axis of the second emitting device 11b are located on the first plane 100, and the optical axis of the point cloud camera 21 and the optical axis of the third emitting device 11c are located on the second plane 200, which is perpendicular to the first plane 100;

[0076] The normal line of the exit window forms an angle of 7°-27° with the normal line of the acquisition window, and the shortest straight line distance L between the center point of the exit window and the center point of the acquisition window is 240mm-260mm.

[0077] Preferably, as shown in Figure 2 , the shortest straight line distance L between the center point of the exit window and the center point of the acquisition window is 250mm.

[0078] Specifically, the normal lines of the three exit windows are all at an angle of 7°-27° with respect to the normal line of the collection window, that is, the optical axis of the first emitting device 11a, the optical axis of the second emitting device 11b, and the optical axis of the third emitting device 11c are all at an angle of 7°-27° with respect to the optical axis of the point cloud camera 21. Through the matching of the normal angles and the center point distances, it can be ensured that the three linear laser beams can be focused on the target point O within a range of 0.5 m-2 m from the lens of the point cloud camera 21, so that a clear intersection grid can be formed by the three linear laser beams within the target measurement range of the point cloud camera 21, which can not only ensure sufficient laser energy density, but also avoid problems such as deformation caused by excessive focusing, so as to further improve the accuracy and reliability of image data acquisition.

[0079] In the embodiment, the adjustable focusing range of the lenses corresponding to the point cloud camera 21 and the texture camera 22 should include the range of 0.5 m-2 m.

[0080] In an embodiment, referring to Figure 1 and Figure 2 , the linear laser beam emitted by the first emitting device 11a is orthogonal to the linear laser beam emitted by the second emitting device 11b, and the linear laser beam emitted by the third emitting device 11c is perpendicular to the second plane 200; the intersection point between the linear laser beam emitted by the first emitting device 11a, the linear laser beam emitted by the second emitting device 11b, and the linear laser beam emitted by the third emitting device 11c is located on the optical axis of the point cloud camera 21.

[0081] Specifically, as shown in Figure 2 , the angle α between the linear laser beam emitted by the first emitting device 11a and the first plane 100 can be 45°, and the angle β between the linear laser beam emitted by the second emitting device 11b and the first plane 100 can be 45°, so that the linear laser beam emitted by the first emitting device 11a is orthogonal to the linear laser beam emitted by the second emitting device 11b.

[0082] In the embodiment, when the intersection point of the three linear laser beams (i.e., the aforementioned target point O) is located on the optical axis of the point cloud camera 21, the pixel coordinates of the intersection point in the image coordinate system have a direct correspondence with the depth information of the intersection point in the world coordinate system, and at this time, the optical axis of the point cloud camera 21 can be used as the reference line for step depth measurement; such spatial alignment simplifies the coordinate conversion calculation, reduces the algorithm complexity, and improves the real-time processing efficiency. In addition, when there is a step depth change on the underwater target surface, since the intersection point of the three linear laser beams (i.e., the aforementioned target point O) is located on the optical axis of the point cloud camera 21, the point cloud camera 21 can sensitively capture the displacement of the light spot and the stripe at the intersection point, which can reduce the measurement error caused by the off-axis angle and maintain a relatively stable measurement reference.

[0083] Correspondingly, the embodiment of the present application also provides a three-dimensional reconstruction system of underwater target, please refer to Figures 1 to 3 The three-dimensional reconstruction system of underwater target comprises the underwater laser scanning device in any of the above embodiments.

[0084] The three-dimensional reconstruction system of underwater target in the embodiment can acquire the target feature image data transmitted by the image acquisition component 2 to the control module through the upper computer, and perform subsequent three-dimensional reconstruction algorithm processing based on the target feature image data, so as to establish a three-dimensional digital model of the underwater target, and provide visual, high-precision and intelligent sensing technology support for the development and utilization of marine resources.

[0085] The specific structure and working principle of the underwater laser scanning device can be referred to the above embodiments. Since the three-dimensional reconstruction system of underwater target adopts all the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, that is, by arranging three linear laser emitting devices 11, the linear laser beams emitted by the three linear laser emitting devices 11 intersect at the same target point O, and the optical axis of any one linear laser emitting device 11 is not located in the plane determined by the optical axes of the other two linear laser emitting devices 11, so as to form a spatial structure of “two-axes coplanar and third-axis orthogonal”; when the three mutually intersecting linear laser beams emitted by the three linear laser emitting devices 11 are projected onto the surface of the underwater stepped structure 300, no matter the direction of the stepped interface of the underwater stepped structure 300, at least one linear laser beam can intersect with the stepped interface, thereby avoiding the problem of the stepped depth measurement blind area of the traditional single linear or parallel linear array laser due to the parallel direction of the stepped interface, and realizing the full-directional depth information capture of the complex underwater stepped structure 300, and cooperating with the image acquisition component 2 to acquire the target feature image formed by the linear laser beams projected onto the surface of the underwater stepped structure 300, so as to provide accurate raw data for the three-dimensional reconstruction operation of the rear end, and guarantee the integrity and accuracy of the subsequent coordinate conversion and model reconstruction.

[0086] It should be noted that other contents of the underwater laser scanning device and the three-dimensional reconstruction system of underwater target disclosed in the present application can be referred to the prior art, which will not be repeated here.

[0087] The above is only an exemplary embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structural transformation made by referring to the content of the present application specification and drawings, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. An underwater laser scanning device, characterized in that: The underwater laser scanning device comprises: A laser assembly comprising three line laser emitting devices, wherein the line laser beams emitted by the three line laser emitting devices intersect at the same target point, and the optical axis of any one of the line laser emitting devices is not located in the plane defined by the optical axes of the other two line laser emitting devices; An image acquisition component is used to acquire a target feature image formed when the line laser beam emitted by the line laser emitting device is projected onto the surface of the underwater stepped structure; A control module is electrically connected to the laser assembly and the image acquisition assembly; the control module is used to drive the line laser emitting device to emit a line laser beam, and the control module is used to obtain the target feature image captured by the image acquisition assembly.

2. The underwater laser scanning device according to claim 1, characterized in that: The line laser emitting device includes a line laser, a signal cabin tube, and a first light-transmitting structure; the line laser is encapsulated inside the signal cabin tube, and the first light-transmitting structure is sealed at the front end of the signal cabin tube to form an exit window, and the line laser is used to project a line laser beam toward the underwater stepped structure through the exit window; And / or, the image acquisition component includes a point cloud camera, a texture camera, a collection cabin tube and a second light-transmitting structure; the point cloud camera and the texture camera are encapsulated inside the collection cabin tube, and the second light-transmitting structure is sealed at the front end of the collection cabin tube to form a collection window, the point cloud camera is used to collect the laser stripe signal reflected by the underwater stepped structure through the collection window, and the texture camera is used to collect high-order texture information of the underwater stepped structure through the collection window.

3. The underwater laser scanning device according to claim 2, characterized in that: The material of the first light-transmitting structure is set to be quartz glass; And / or, the material of the second light-transmitting structure is set to be quartz glass; And / or, the signal compartment tube is made of one of aluminum alloy, stainless steel, and titanium alloy; And / or, the material of the collection chamber tube is set to be one of aluminum alloy, stainless steel, and titanium alloy.

4. The underwater laser scanning device according to claim 2, characterized in that: The line laser emitting device further includes a secondary watertight connector, which is plugged into the rear end of the signal compartment pipe, an inner end of the secondary watertight connector is connected to the line laser, and an outer end of the secondary watertight connector is connected to the control module via a first watertight cable; And / or, the image acquisition component also includes a main watertight connector, which is plugged into the rear end of the acquisition cabin tube, the inner end of the main watertight connector is connected to the control module, and the outer end of the main watertight connector is used to connect to the host computer through a second watertight cable.

5. The underwater laser scanning device according to claim 2, characterized in that: The image acquisition component further includes a filter, which is arranged on the second light-transmitting structure and is located at the front end of the point cloud camera.

6. The underwater laser scanning device according to claim 2, characterized in that: The image acquisition component further includes auxiliary fill lights, which are arranged on the second light-transmitting structure and symmetrically arranged on both sides of the texture camera.

7. The underwater laser scanning device according to claim 2, characterized in that: The underwater laser scanning device also includes a supporting fixing member and three angle fixing members. The supporting fixing member is clamped and fixed on the collection cabin tube. One end of the three angle fixing members is connected to the supporting fixing member, and the other end of the three angle fixing members is connected to the three signal cabin tubes one by one.

8. The underwater laser scanning device according to claim 2, wherein: The three line laser emitting devices are respectively referred to as a first emitting device, a second emitting device and a third emitting device; The optical axis of the point cloud camera, the optical axis of the first transmitting device, and the optical axis of the second transmitting device are located in a first plane, the optical axis of the point cloud camera and the optical axis of the third transmitting device are located in a second plane, and the second plane is perpendicular to the first plane; The normal of the exit window forms an angle of 7° to 27° with respect to the normal of the collection window, and the shortest straight-line distance between the center point of the exit window and the center point of the collection window is 240 mm to 260 mm.

9. The underwater laser scanning device according to claim 8, characterized in that: The line laser beam emitted by the first emitting device and the line laser beam emitted by the second emitting device are orthogonal to each other, and the line laser beam emitted by the third emitting device is perpendicular to the second plane; the intersection of the line laser beam emitted by the first emitting device, the line laser beam emitted by the second emitting device, and the line laser beam emitted by the third emitting device is located on the optical axis of the point cloud camera.

10. A 3D reconstruction system for underwater targets, characterized in that: The underwater target three-dimensional reconstruction system includes the underwater laser scanning device according to any one of claims 1 to 9.

Images