An underwater panoramic camera waterproof ball shell optimization method based on light path analysis

Abstract

The present application relates to underwater robot optical detection technology field, specifically speaking, it is a kind of underwater panoramic camera waterproof spherical shell optimization method based on light path analysis, including the following steps: the optical simulation model of panoramic camera without installing waterproof spherical shell is established, and simulation calculation is carried out, and the simulation imaging effect of panoramic camera in simulated air environment or seawater environment is obtained;The optical simulation model of underwater panoramic camera with waterproof spherical shell is established, different geometric size parameters of waterproof spherical shell are selected to establish multiple optical simulation models, and the multiple optical simulation models established are simulated, and the simulation imaging effect of underwater panoramic camera in simulated seawater environment is obtained;The simulation results of multiple groups are compared and analyzed, and the geometric size parameters of the waterproof spherical shell corresponding to the optimal imaging effect in the simulation results of multiple groups are obtained.The present application is finally achieved by light path analysis and optimization design of waterproof spherical shell The characteristics of high imaging clarity, large field of view and small distortion of underwater panoramic camera.

Description

Technical Field

[0001] This invention relates to the field of underwater robot optical detection technology, specifically an optimization method for the waterproof spherical shell of an underwater panoramic camera based on optical path analysis. Background Technology

[0002] Underwater robots are a crucial technological means for humans to enter, explore, and develop the ocean. Optical equipment (underwater cameras and lasers, etc.) and acoustic equipment (sonar, etc.) are the main devices used by underwater robots for ocean exploration. Currently, underwater cameras can be categorized into monocular or binocular underwater cameras based on the number of cameras. Underwater cameras acquire images of the underwater scene and feed them back to displays on the surface support vessel, allowing operators to monitor the real-time status of the underwater robot and its environment. The underwater environmental images acquired by underwater cameras can also be stored for later review and analysis, or combined with image processing algorithms to achieve autonomous identification and localization of underwater targets.

[0003] Because underwater cameras have a limited field of view, they are usually mounted on an underwater gimbal, and the rotation of the gimbal changes the direction of the underwater camera's field of view. However, this method can only change the direction of the underwater camera's field of view, but cannot increase the size of the field of view, making it impossible to comprehensively monitor or record underwater panoramic information. Furthermore, the use of an underwater gimbal also increases the complexity of underwater robot operation. Summary of the Invention

[0004] The purpose of this invention is to provide a method for enabling panoramic imaging in underwater environments by adding a waterproof spherical shell to a conventional panoramic camera used in the air. Through optical path analysis and optimization design of the waterproof spherical shell, the underwater panoramic camera achieves high image clarity, a large field of view, and low distortion.

[0005] The technical solution adopted by this invention to achieve the above objectives is: an optimization method for a waterproof spherical shell for an underwater panoramic camera based on optical path analysis, comprising the following steps:

[0006] 1-1) Based on the performance parameters of the panoramic camera, an optical simulation model of the panoramic camera without a waterproof spherical shell is established in the optical simulation software. Based on the model, simulation calculations are performed to obtain the simulated imaging effect of the panoramic camera in simulated air or seawater environments. The simulated imaging effect is used to compare with the simulation results of an underwater panoramic camera with a waterproof spherical shell installed.

[0007] 1-2) Based on the optical simulation model of the panoramic camera without the waterproof spherical shell established in step 1-1), and combining the geometric dimensions and material refractive index of the waterproof spherical shell, an optical simulation model of the underwater panoramic camera with the waterproof spherical shell is established. Multiple sets of optical simulation models are established by selecting different geometric parameters of the waterproof spherical shell to form a control group.

[0008] 1-3) Use optical simulation software to perform simulation calculations on the multiple sets of optical simulation models established in step 1-2) to obtain the simulated imaging effect of the underwater panoramic camera in a simulated seawater environment.

[0009] The simulated imaging effect includes: field of view, sharpness, and distortion;

[0010] 1-4) Compare and analyze the multiple sets of simulation results obtained in steps 1-1) and 1-3) to obtain the relationship between the panoramic camera imaging effect and whether or not a waterproof spherical shell is installed, as well as the size parameters of the waterproof spherical shell, and obtain the geometric size parameters of the waterproof spherical shell corresponding to the best comprehensive imaging effect in the multiple sets of simulation results, which are used as the optimal design parameters of the waterproof spherical shell.

[0011] In step 1-1), the optical simulation model of the panoramic camera without a waterproof dome housing is established in the optical simulation software. The specific modeling process is as follows:

[0012] 2-1) Establish a three-dimensional model of the panoramic camera using its geometric dimensions;

[0013] The geometric parameters of the panoramic camera include: camera dimensions, lens curvature, lens axis position, and photosensitive target axis position.

[0014] 2-2) Import the 3D model of the panoramic camera into the optical simulation environment, and input the camera focal length, aperture, field of view and refractive index of the ambient medium in sequence, and set the angle range of the incident light.

[0015] The refractive index parameters of the environmental medium include: refractive index parameters of seawater, air, and waterproof spherical shell;

[0016] 2-3) Design a visualization interface for the panoramic camera optical simulation model, set the content format and saving method of the simulation output data, and save the above process files to form the optical simulation model of the panoramic camera without the waterproof spherical shell installed.

[0017] In step 1-1), the simulation calculation based on the model is performed to obtain the simulated imaging effect of the panoramic camera in simulated air or seawater environments. The specific simulation calculation process is as follows:

[0018] 3-1) Call the established optical simulation model of the panoramic camera and check the correctness of the model in the visualization interface;

[0019] 3-2) Input the initial parameters for the simulation calculation, which include: visible light wavelength range, calculation accuracy, and simulation time;

[0020] 3-3) Based on Fermat's principle of light propagation in a medium, a simulation algorithm is designed using formula (1) to calculate the field of view data of the panoramic camera, namely:

[0021]

[0022] Among them, a e The field of view is indicated by: 'a' represents the field of view without the waterproof spherical shell, 'R' represents the outer diameter of the waterproof spherical shell, 'D' represents the wall thickness of the waterproof spherical shell, and 'n' represents the field of view without the waterproof spherical shell. p n represents the refractive index of the waterproof spherical shell. w Indicates the refractive index of seawater;

[0023] 3-4) Based on the principle of the equal-area small-area light spot imaging speckle algorithm, the imaging sharpness data results of the panoramic camera were obtained by simulation.

[0024] 3-5) Based on the principle of optical geometric analysis algorithm of optical path tracing, the imaging distortion data results of panoramic camera are obtained by simulating the imaging difference between actual image height and ideal image height.

[0025] 3-6) Complete the simulation calculation of this group of optical simulation models, return to step 3-1) to perform the next group of simulation calculations, until all optical simulation models have completed the simulation calculations.

[0026] In steps 1-2), based on the established optical simulation model of the panoramic camera without the waterproof spherical shell, and combining the geometric dimensions and material refractive index parameters of the waterproof spherical shell, an optical simulation model of the underwater panoramic camera with the waterproof spherical shell is established. The specific modeling process is as follows:

[0027] 4-1) Build a three-dimensional model of the underwater panoramic camera with the waterproof sphere installed using the geometric parameters of the waterproof sphere and the panoramic camera, and design to ensure that the center of the waterproof sphere coincides with the center of the panoramic camera.

[0028] 4-2) Import the 3D model of the underwater panoramic camera into the optical simulation environment, and input the camera focal length, aperture, field of view and refractive index parameters of the environmental medium in sequence, and set the angle range of the incident light.

[0029] 4-3) Design the visualization interface for the underwater panoramic camera optical simulation model, set the content format and saving method of the simulation output data, and save the above process files to form the optical simulation model of the underwater panoramic camera with the waterproof spherical shell installed.

[0030] In steps 1-2), the step of selecting different geometric parameters of the waterproof spherical shell to establish multiple sets of simulation models to form a control group is specifically as follows:

[0031] In an underwater scene, light passes sequentially through seawater, a waterproof spherical shell, and air inside the shell before entering the underwater panoramic camera. During this process, the light undergoes optical refraction at the interfaces of the seawater-outer surface of the spherical shell and the inner surface of the spherical shell-air. To obtain the relationship between the diameter and wall thickness parameters of the waterproof spherical shell and the imaging effect of the underwater panoramic camera, multiple simulation models are established by selecting different diameter and wall thickness parameters of the waterproof spherical shell.

[0032] The optical simulation software is used to perform simulation calculations on the multiple sets of optical simulation models established in steps 1-2). During the simulation calculation process, the diameter of the waterproof spherical shell is selected from 140mm to 180mm, and the wall thickness of the waterproof spherical shell is selected from 5mm to 10mm. Different diameters and wall thicknesses are arranged and combined to generate multiple sets of simulation models.

[0033] In steps 1-4), the comparison and analysis of multiple sets of simulation results obtained in steps 1-1) and 1-3) are performed to obtain the relationship between the panoramic camera imaging effect and whether or not a waterproof spherical shell is installed, as well as the size parameters of the waterproof spherical shell. Specifically:

[0034] 7-1) Compare and analyze the multiple sets of simulation results obtained in steps 1-1) and 1-3). The simulation imaging effect of the panoramic camera without waterproof shell obtained in step 1-1) is used as a blank control group, and the multiple sets of simulation imaging effects of the underwater panoramic camera with waterproof shell in simulated seawater environment obtained in step 1-3) are used as control groups.

[0035] 7-2) In the above multiple sets of simulated imaging effects, the three indicators of field of view, sharpness and distortion of the imaging were calculated for each set.

[0036] 7-3) Compare the field of view parameters in multiple sets of simulation results. The independent variables in the comparison are the diameter and wall thickness parameters of the waterproof spherical shell, and the dependent variable is the field of view parameter. The relationship between the imaging field of view of the underwater panoramic camera and the size parameters of the waterproof spherical shell is obtained through comparative analysis.

[0037] 7-4) Using the same method as step 7-3), obtain the relationship between sharpness and distortion indices and the size parameters of the waterproof spherical shell.

[0038] Step 7-4), specifically:

[0039] By utilizing the relationship between the obtained field of view, sharpness, and distortion and the size parameters of the waterproof spherical shell, the size parameters of the waterproof spherical shell corresponding to the simultaneous optimization of the three parameters are determined, and this size parameter is taken as the optimal design parameter of the waterproof spherical shell.

[0040] Specifically, determining the size parameters of the waterproof spherical shell corresponding to the simultaneous optimality of the three indicators, and using these size parameters as the optimal design parameters for the waterproof spherical shell, involves:

[0041] Based on the comparative analysis of the simulated imaging effects, the diameter and wall thickness of the waterproof spherical shell corresponding to the maximum field of view, highest clarity, and minimum distortion in the simulated imaging were selected. These diameter and wall thickness parameters of the waterproof spherical shell were then used as the final optimized design parameters for the waterproof spherical shell.

[0042] The relationship between the three indicators—field of view, sharpness, and distortion—and the size parameters of the waterproof spherical shell is as follows:

[0043] 9-1) When the diameter of the waterproof spherical shell is the same, the imaging field of view decreases as the wall thickness increases, while when the wall thickness remains constant, the field of view increases as the diameter increases.

[0044] 9-2) When the diameter of the waterproof spherical shell is the same, the image clarity decreases as the wall thickness increases, while when the wall thickness remains constant, the clarity increases as the diameter increases.

[0045] 9-3) The imaging distortion of the panoramic camera in the simulated seawater environment is significantly less than that in the air. The imaging distortion is not affected by whether a waterproof sphere is installed or by changes in the size parameters of the waterproof sphere.

[0046] The present invention has the following beneficial effects and advantages:

[0047] 1. The present invention provides an optical path analysis and optimization design method for a waterproof spherical shell for an underwater panoramic camera, which can replace the traditional combination of underwater camera and gimbal, and has the advantage of richer and more comprehensive underwater scene image acquisition.

[0048] 2. The optical path analysis and optimization design method for a waterproof spherical shell for an underwater panoramic camera of the present invention has the advantages of significantly improving the imaging effect of the underwater panoramic camera (large field of view, high clarity and small distortion), and has practical significance for improving the optical detection capability of underwater robots;

[0049] 3. The optical path analysis and optimization design method for a waterproof spherical shell for an underwater panoramic camera, as described in this invention, is practical and simple, and is applicable to most remotely operated underwater robots or autonomous underwater robots. Attached Figure Description

[0050] Figure 1 This is a flowchart of the method of the present invention;

[0051] Figure 2 This is a schematic diagram of the underwater panoramic camera of the present invention;

[0052] Figure 3 These are simulation results of the optical path and field of view of the waterproof spherical shells of different sizes and parameters according to the present invention;

[0053] Figure 4This invention relates the relationship between the waterproof spherical shell with different size parameters and the image clarity.

[0054] Figure 5 This relates the relationship between the waterproof spherical shells of different sizes and imaging distortion in this invention. Detailed Implementation

[0055] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0056] This invention improves the imaging effect of underwater panoramic cameras through optical path analysis and optimization design of a waterproof spherical shell, such as... Figure 1 The diagram shown is a flowchart of the method of the present invention. The present invention provides an optimization method for a waterproof spherical shell for an underwater panoramic camera based on optical path analysis, comprising the following steps:

[0057] 1) Based on the performance parameters of the panoramic camera, an optical simulation model of the panoramic camera without a waterproof spherical shell is established in the optical simulation software. Based on the model, simulation calculations are performed to obtain the simulated imaging effect of the panoramic camera in simulated air or seawater environments. The simulated imaging effect is used to compare with the simulation results of an underwater panoramic camera with a waterproof spherical shell installed.

[0058] 2) Based on the optical simulation model of the panoramic camera without the waterproof spherical shell established in step 1), and combining the geometric dimensions and material refractive index of the waterproof spherical shell, an optical simulation model of the underwater panoramic camera with the waterproof spherical shell is established. Multiple sets of optical simulation models are established by selecting different geometric parameters of the waterproof spherical shell to form a control group.

[0059] 3) Use optical simulation software to perform simulation calculations on the multiple sets of optical simulation models established in step 2) to obtain the simulated imaging effect of the underwater panoramic camera in a simulated seawater environment.

[0060] The simulated imaging effect includes: field of view, sharpness, and distortion;

[0061] 4) Compare and analyze the multiple sets of simulation results obtained in steps 1) and 3) to obtain the relationship between the panoramic camera imaging effect and whether or not a waterproof spherical shell is installed, as well as the size parameters of the waterproof spherical shell, and obtain the geometric size parameters of the waterproof spherical shell corresponding to the best comprehensive imaging effect in the multiple sets of simulation results, which are used as the optimal design parameters of the waterproof spherical shell.

[0062] I. Establishing an optical simulation model:

[0063] Specifically, regarding steps 1) and 2), an optical simulation model of a panoramic camera without a waterproof spherical shell is created in the optical simulation software, and an optical simulation model of a panoramic camera with a waterproof spherical shell is created.

[0064] The specific modeling process for the optical simulation model of the panoramic camera without a waterproof spherical shell is as follows:

[0065] (1) Establish a three-dimensional model of the panoramic camera using the geometric dimensions of the panoramic camera;

[0066] The geometric parameters of the panoramic camera include: camera dimensions, lens curvature, lens axis position, and photosensitive target axis position.

[0067] (2) Import the panoramic camera 3D model into the optical simulation environment, and input the camera focal length, aperture, field of view and refractive index of the environmental medium in sequence, and set the angle range of the incident light.

[0068] The refractive index parameters of the environmental medium include: refractive index parameters of seawater, air, and waterproof spherical shell;

[0069] (3) Design a visualization interface for the panoramic camera optical simulation model, set the content format and saving method of the simulation output data, and save the above process files to form an optical simulation model of the panoramic camera without the waterproof spherical shell installed.

[0070] The specific modeling process for the optical simulation model of the panoramic camera with a waterproof spherical shell is as follows:

[0071] (1) Use the geometric parameters of the waterproof spherical shell and the panoramic camera to establish a three-dimensional model of the underwater panoramic camera with the waterproof spherical shell installed, and design to ensure that the center of the waterproof spherical shell coincides with the center assembly position of the panoramic camera.

[0072] (2) Import the three-dimensional model of the underwater panoramic camera into the optical simulation environment, and input the camera focal length, aperture, field of view and refractive index of the environmental medium in sequence, and set the angle range of the incident light.

[0073] (3) Design the visualization interface of the underwater panoramic camera optical simulation model, set the content format and saving method of the simulation output data, and save the above process files to form the optical simulation model of the underwater panoramic camera with the waterproof spherical shell installed.

[0074] In establishing the optical simulation model of the panoramic camera with a waterproof spherical shell, multiple simulation models with different geometric parameters of the waterproof spherical shell were selected to form a control group. The working principle is as follows:

[0075] In an underwater environment, light passes sequentially through seawater, a waterproof spherical shell, and air inside the shell before entering the underwater panoramic camera. During this process, the light undergoes optical refraction at the interfaces of the seawater-outer surface of the spherical shell and the inner surface of the spherical shell-air. The diameter and wall thickness of the waterproof spherical shell directly affect the light propagation path. To obtain the relationship between the diameter and wall thickness of the waterproof spherical shell and the imaging effect of the underwater panoramic camera, multiple simulation models are established using different diameters and wall thicknesses of the waterproof spherical shell.

[0076] II. Optical Simulation Calculation

[0077] The simulation calculation methods for the optical models of underwater panoramic cameras without waterproof housings and underwater panoramic cameras with waterproof housings are as follows:

[0078] (1) Call the established optical simulation model of the panoramic camera and check the correctness of the model in the visualization interface;

[0079] (2) Input the initial parameters for simulation calculation, which include: visible light wavelength range, calculation accuracy and simulation time;

[0080] (3) Based on Fermat's principle of light propagation in a medium, a simulation algorithm is designed using formula (1) to calculate the field of view data of the panoramic camera, namely:

[0081]

[0082] Among them, a e The field of view is indicated by: 'a' represents the field of view without the waterproof spherical shell, 'R' represents the outer diameter of the waterproof spherical shell, 'D' represents the wall thickness of the waterproof spherical shell, and 'n' represents the field of view without the waterproof spherical shell. p n represents the refractive index of the waterproof spherical shell. w Indicates the refractive index of seawater;

[0083] (4) Based on the principle of the equal-area small-area light spot imaging diffusion pattern algorithm, the imaging sharpness data results of the panoramic camera are obtained by simulation.

[0084] (5) Based on the principle of optical geometric analysis algorithm of optical path tracing, the imaging distortion data results of panoramic camera are obtained by simulating the imaging difference between actual image height and ideal image height.

[0085] (6) Complete the simulation calculation of this group of optical simulation models, return to step (1) to perform the next group of simulation calculations, until all optical simulation models have completed the simulation calculations.

[0086] For underwater panoramic cameras with waterproof spherical shells, multiple optical simulation models were established for simulation calculations. During the simulation calculations, the diameter of the waterproof spherical shell was selected from 140mm to 180mm, and the wall thickness of the waterproof spherical shell was selected from 5mm to 10mm. Different diameters and wall thicknesses were arranged and combined to generate multiple simulation models.

[0087] III. Comparative Analysis: Obtaining the Correspondence between Panoramic Camera Imaging Effects and Waterproof Dome Size Parameters

[0088] In step 4), the multiple sets of simulation results obtained in steps 1) and 3) are compared and analyzed to obtain the relationship between the panoramic camera imaging effect and whether or not a waterproof spherical shell is installed, as well as the size parameters of the waterproof spherical shell. Specifically:

[0089] (1) Comparative analysis of multiple sets of simulation results obtained in step 1) and step 3), where the simulation imaging effect of the panoramic camera without waterproof shell obtained in step 1) is used as a blank control group, and the multiple sets of simulation imaging effects of the underwater panoramic camera with waterproof shell in simulated seawater environment obtained in step 3) are used as a control group.

[0090] (2) In the above multiple sets of simulated imaging effects, the three indicators of field of view, sharpness and distortion of the imaging are simulated and calculated for each set.

[0091] (3) Compare the field of view indexes in multiple sets of simulation results. The independent variables in the comparison process are the diameter and wall thickness parameters of the waterproof spherical shell, and the dependent variable is the field of view index. The relationship between the imaging field of view of the underwater panoramic camera and the size parameters of the waterproof spherical shell is obtained through comparative analysis.

[0092] (4) Using the same method as step (3), obtain the relationship between sharpness and distortion index and the size parameters of the waterproof spherical shell;

[0093] Step (4) is as follows:

[0094] The relationship between the obtained field of view, sharpness, and distortion as a function of the waterproof spherical shell size parameters is as follows:

[0095] (1) When the diameter of the waterproof spherical shell is the same, the imaging field of view decreases as the wall thickness increases, while when the wall thickness remains constant, the field of view increases as the diameter increases.

[0096] (2) When the diameter of the waterproof spherical shell is the same, the image clarity decreases as the wall thickness increases, while when the wall thickness remains constant, the clarity increases as the diameter increases.

[0097] (3) The imaging distortion of the panoramic camera in the simulated seawater environment is significantly less than that in the air. The imaging distortion is not affected by whether a waterproof sphere is installed or by changes in the size parameters of the waterproof sphere.

[0098] Based on the relationship between the three indices of field of view, sharpness, and distortion and the size parameters of the waterproof spherical shell, the size parameters of the waterproof spherical shell corresponding to the simultaneous optimality of the three indices are determined, and this size parameter is taken as the optimal design parameter of the waterproof spherical shell.

[0099] Specifically, determining the size parameters of the waterproof spherical shell corresponding to the simultaneous optimality of the three indicators, and using these size parameters as the optimal design parameters for the waterproof spherical shell, involves:

[0100] Based on the comparative analysis of the simulated imaging effects, the diameter and wall thickness of the waterproof spherical shell corresponding to the maximum field of view, highest clarity, and minimum distortion in the simulated imaging were selected. These diameter and wall thickness parameters of the waterproof spherical shell were then used as the final optimized design parameters for the waterproof spherical shell.

[0101] Example:

[0102] The panoramic camera involved in this embodiment is a product for use in conventional air environments and cannot be directly placed underwater. The main parameters of this panoramic camera are: focal length 2.3mm, single-camera field of view 190°, aperture 2.2, and lens curvature radius of 15mm. This panoramic camera uses four fisheye cameras to acquire 360° panoramic image information of the environment, and uses image stitching technology to stitch the images from the four cameras together, ultimately presenting a 360° panoramic view of the environment on a monitor or VR headset.

[0103] The present invention provides a waterproof spherical shell for an underwater panoramic camera. The waterproof spherical shell is installed around the four cameras of the panoramic camera and combined with components such as a metal sealing shell to achieve the waterproof function of the panoramic camera. The sealed panoramic camera can be placed underwater for operation.

[0104] like Figure 2 The diagram shows a schematic of an underwater panoramic camera. The panoramic camera, equipped with a waterproof spherical shell, is referred to as an underwater panoramic camera in this paper. The waterproof spherical shell isolates the panoramic camera from the seawater; the outside of the shell is seawater, and the inside contains the panoramic camera and air. Light from underwater scenes must pass through seawater, the waterproof spherical shell, and air in sequence, undergoing two refractions before reaching the panoramic camera. The geometry of the waterproof spherical shell directly affects the propagation and refraction path of light. Therefore, this invention patent improves the imaging effect of the underwater panoramic camera through optical path analysis and optimized design of the waterproof spherical shell, enabling it to play a better role in underwater optical detection.

[0105] The underwater panoramic camera includes: a waterproof spherical shell, a panoramic camera, a sealed housing, a camera base, a signal cable, and a sealed end cap.

[0106] The underwater panoramic camera has four cameras positioned in four directions, with a waterproof sphere covering the four cameras. A sealed housing is connected to the bottom of the waterproof sphere, which seals and protects the body of the panoramic camera and is fixed to the camera base. The underwater panoramic camera is mounted on the camera base, and the bottom of the camera base is sealed to the edge of the sealed housing through a sealing end cap. The signal cable is connected to an external controller or processor or other data processing unit in sequence through the camera base and the sealing end cap.

[0107] In this embodiment, the waterproof spherical shell material is polymethyl methacrylate (PMMA), which has a refractive index of 1.491, a dispersion coefficient Vd = 57.2, and a transmittance of approximately 92%. It is an optically non-metallic transparent material.

[0108] In this embodiment, when a panoramic camera equipped with a waterproof spherical shell operates underwater, the outside of the spherical shell is seawater, and the inside consists of air and the panoramic camera. When the underwater panoramic camera acquires environmental image information, ambient light passes through seawater, the waterproof spherical shell, and air before entering the camera and being captured. Because the refractive indices of seawater (1.33), the waterproof spherical shell (1.49), and air (1.00) are different, there is a significant refraction phenomenon in the propagation of ambient light on the outer and inner surfaces of the waterproof spherical shell. The diameter and wall thickness parameters of the waterproof spherical shell affect the refraction path of the light, thus affecting the final imaging effect of the panoramic camera.

[0109] The focus of this invention is on the optical path analysis and optimization design of the waterproof spherical shell. By analyzing the optical path of waterproof spherical shells with various size combinations of different diameters and wall thicknesses, the law of variation of the panoramic camera's imaging field of view, distortion, and sharpness with the size of the waterproof spherical shell is determined, and finally the optimal size parameters of the waterproof spherical shell are determined.

[0110] like Figure 3 The figure shows the optical path simulation and field of view calculation results for waterproof spherical shells of different sizes. It can be seen that the field of view of the panoramic camera without a waterproof spherical shell is 190° in air and 154.8° in water. This indicates that, under otherwise constant conditions, the field of view of the panoramic camera is significantly smaller in water than in air. After installing waterproof spherical shells of different diameters (140mm, 160mm, and 180mm) and wall thicknesses (5mm, 7.5mm, and 10mm) on the panoramic camera, the optical path simulation results show that, for the same diameter, the field of view decreases with increasing wall thickness, while when the wall thickness remains constant, the field of view increases with increasing diameter. Therefore, it can be concluded that the panoramic camera achieves the largest field of view when the waterproof spherical shell diameter is 180mm and the wall thickness is 5mm.

[0111] like Figure 4The figure shows the relationship between different sizes of waterproof spherical shells and image sharpness. The vertical axis represents the number of speckle points, indicating higher image sharpness for the panoramic camera. The horizontal axis represents the angle at which light enters the field of view. Simulation results were compared between cameras without and with waterproof spherical shells of different sizes (in this embodiment, nine sets of comparative simulation models were formed based on different combinations of the diameter and wall thickness of the waterproof spherical shells). It can be seen that the panoramic camera without a waterproof spherical shell has the smallest speckle point and the highest sharpness. Comparing the nine sets of simulation results with waterproof spherical shells, it can be seen that when the diameter of the waterproof spherical shell is 180mm and the wall thickness is 5mm, the speckle point is the smallest and the sharpness is the highest.

[0112] like Figure 5 The figure shows the relationship between the waterproof spherical shell with different dimensions and imaging distortion. The degree of deformation of the grid in the figure represents the degree of distortion in the underwater panoramic camera image under given simulation conditions. It can be seen from the figure that the panoramic camera without a waterproof spherical shell exhibits the most significant imaging distortion in an air environment, while the imaging distortion is minimal in an underwater environment. Simulation results for the panoramic camera with a waterproof spherical shell show that the influence of different sized waterproof spherical shells on imaging distortion is almost negligible.

[0113] Based on the above analysis, it can be concluded that in the optical path simulation of the waterproof spherical shell with different size parameters, the underwater panoramic camera has the best imaging clarity and field of view when the diameter of the waterproof spherical shell is 180mm and the wall thickness is 5mm. The size parameters of the waterproof spherical shell have a negligible impact on imaging distortion. Therefore, in the specific implementation of this invention, the waterproof spherical shell with a diameter of 180mm and a wall thickness of 5mm is the optimal size design result.

[0114] This invention addresses the need for a transparent, waterproof spherical shell to achieve watertightness when applying conventional air-based panoramic cameras underwater. Considering the impact of the waterproof spherical shell's diameter and wall thickness on the underwater panoramic camera's imaging performance, this invention analyzes the optical path transmission characteristics of the waterproof spherical shell and optimizes its diameter and wall thickness parameters with the goals of improving the imaging field of view, sharpness, and distortion.

[0115] This invention solves the problem that current underwater gimbals cannot increase the field of view and cannot comprehensively monitor or record underwater panoramic information by adding a waterproof spherical shell to the panoramic camera and optimizing the diameter and wall thickness parameters of the waterproof spherical shell.

[0116] Since the above-described optical path analysis and optimization design of the waterproof spherical shell for underwater panoramic cameras and the specific implementation steps are only specific implementation objects and methods of the present invention, and are not intended to limit the present invention, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An optimization method for a waterproof spherical shell of an underwater panoramic camera based on optical path analysis, characterized in that, Includes the following steps: 1-1) Based on the performance parameters of the panoramic camera, an optical simulation model of the panoramic camera without a waterproof spherical shell is established in the optical simulation software. Based on the model, simulation calculations are performed to obtain the simulated imaging effect of the panoramic camera in simulated air or seawater environments. The simulated imaging effect is used to compare with the simulation results of an underwater panoramic camera with a waterproof spherical shell installed. 1-2) Based on the optical simulation model of the panoramic camera without the waterproof spherical shell established in step 1-1), and combining the geometric dimensions and material refractive index of the waterproof spherical shell, an optical simulation model of the underwater panoramic camera with the waterproof spherical shell is established. Multiple sets of optical simulation models are established by selecting different geometric parameters of the waterproof spherical shell to form a control group. 1-3) Use optical simulation software to perform simulation calculations on the multiple sets of optical simulation models established in step 1-2) to obtain the simulated imaging effect of the underwater panoramic camera in a simulated seawater environment. The simulated imaging effect includes: field of view, sharpness, and distortion; 1-4) Compare and analyze the multiple sets of simulation results obtained in steps 1-1) and 1-3) to obtain the relationship between the panoramic camera imaging effect and whether or not a waterproof spherical shell is installed, as well as the size parameters of the waterproof spherical shell, and obtain the geometric size parameters of the waterproof spherical shell corresponding to the best comprehensive imaging effect in the multiple sets of simulation results, which are used as the optimal design parameters of the waterproof spherical shell.

2. The optimization method for a waterproof spherical shell of an underwater panoramic camera based on optical path analysis according to claim 1, characterized in that, In step 1-1), the optical simulation model of the panoramic camera without a waterproof dome housing is established in the optical simulation software. The specific modeling process is as follows: 2-1) Establish a three-dimensional model of the panoramic camera using its geometric dimensions; The geometric parameters of the panoramic camera include: camera dimensions, lens curvature, lens axis position, and photosensitive target axis position. 2-2) Import the 3D model of the panoramic camera into the optical simulation environment, and input the camera focal length, aperture, field of view and refractive index of the ambient medium in sequence, and set the angle range of the incident light. The refractive index parameters of the environmental medium include: refractive index parameters of seawater, air, and waterproof spherical shell; 2-3) Design a visualization interface for the panoramic camera optical simulation model, set the content format and saving method of the simulation output data, and save the above process files to form the optical simulation model of the panoramic camera without the waterproof spherical shell installed.

3. The optimization method for a waterproof spherical shell of an underwater panoramic camera based on optical path analysis according to claim 1, characterized in that, In step 1-1), the simulation calculation based on the model is performed to obtain the simulated imaging effect of the panoramic camera in simulated air or seawater environments. The simulation calculation process is as follows: 3-1) Call the established optical simulation model of the panoramic camera and check the correctness of the model in the visualization interface; 3-2) Input the initial parameters for the simulation calculation, which include: visible light wavelength range, calculation accuracy, and simulation time; 3-3) Based on Fermat's principle of light propagation in a medium, a simulation algorithm is designed using formula (1) to calculate the field of view data of the panoramic camera, namely: wherein a e represents the field of view after installing the waterproof spherical shell, a represents the field of view before installing the waterproof spherical shell, R represents the outer diameter of the waterproof spherical shell, D represents the wall thickness of the waterproof spherical shell, n p represents the refractive index of the waterproof spherical shell, n w represents the refractive index of seawater; 3-4) Based on the principle of the equal-area small-area light spot imaging speckle algorithm, the imaging sharpness data results of the panoramic camera were obtained by simulation. 3-5) Based on the principle of optical geometric analysis algorithm of optical path tracing, the imaging distortion data results of panoramic camera are obtained by simulating the imaging difference between actual image height and ideal image height. 3-6) Complete the simulation calculation of this group of optical simulation models, return to step 3-1) to perform the next group of simulation calculations, until all optical simulation models have completed the simulation calculations.

4. The optimization method for a waterproof spherical shell of an underwater panoramic camera based on optical path analysis according to claim 1, characterized in that, In steps 1-2), based on the established optical simulation model of the panoramic camera without the waterproof spherical shell, and combining the geometric dimensions and material refractive index parameters of the waterproof spherical shell, an optical simulation model of the underwater panoramic camera with the waterproof spherical shell is established. The specific modeling process is as follows: 4-1) Build a three-dimensional model of the underwater panoramic camera with the waterproof sphere installed using the geometric parameters of the waterproof sphere and the panoramic camera, and design to ensure that the center of the waterproof sphere coincides with the center of the panoramic camera. 4-2) Import the 3D model of the underwater panoramic camera into the optical simulation environment, and input the camera focal length, aperture, field of view and refractive index parameters of the environmental medium in sequence, and set the angle range of the incident light. 4-3) Design the visualization interface for the underwater panoramic camera optical simulation model, set the content format and saving method of the simulation output data, and save the above process files to form the optical simulation model of the underwater panoramic camera with the waterproof spherical shell installed.

5. The optimization method for a waterproof spherical shell of an underwater panoramic camera based on optical path analysis according to claim 1, characterized in that, In steps 1-2), the step of selecting different geometric parameters of the waterproof spherical shell to establish multiple sets of simulation models to form a control group is specifically as follows: In an underwater scene, light passes sequentially through seawater, a waterproof spherical shell, and air inside the shell before entering the underwater panoramic camera. During this process, the light undergoes optical refraction at the interfaces of the seawater-outer surface of the spherical shell and the inner surface of the spherical shell-air. To obtain the relationship between the diameter and wall thickness parameters of the waterproof spherical shell and the imaging effect of the underwater panoramic camera, multiple simulation models are established by selecting different diameter and wall thickness parameters of the waterproof spherical shell.

6. The optimization method for a waterproof spherical shell of an underwater panoramic camera based on optical path analysis according to claim 1, characterized in that, The optical simulation software is used to perform simulation calculations on the multiple sets of optical simulation models established in steps 1-2). During the simulation calculation process, the diameter of the waterproof spherical shell is selected from 140mm to 180mm, and the wall thickness of the waterproof spherical shell is selected from 5mm to 10mm. Different diameters and wall thicknesses are arranged and combined to generate multiple sets of simulation models.

7. The optimization method for a waterproof spherical shell of an underwater panoramic camera based on optical path analysis according to claim 1, characterized in that, In steps 1-4), the comparison and analysis of multiple sets of simulation results obtained in steps 1-1) and 1-3) are performed to obtain the relationship between the panoramic camera imaging effect and whether or not a waterproof spherical shell is installed, as well as the size parameters of the waterproof spherical shell. Specifically: 7-1) Compare and analyze the multiple sets of simulation results obtained in steps 1-1) and 1-3). The simulation imaging effect of the panoramic camera without waterproof shell obtained in step 1-1) is used as a blank control group, and the multiple sets of simulation imaging effects of the underwater panoramic camera with waterproof shell in simulated seawater environment obtained in step 1-3) are used as control groups. 7-2) In the above multiple sets of simulated imaging effects, the three indicators of field of view, sharpness and distortion of the imaging were calculated for each set. 7-3) Compare the field of view parameters in multiple sets of simulation results. The independent variables in the comparison are the diameter and wall thickness parameters of the waterproof spherical shell, and the dependent variable is the field of view parameter. The relationship between the imaging field of view of the underwater panoramic camera and the size parameters of the waterproof spherical shell is obtained through comparative analysis. 7-4) Using the same method as step 7-3), obtain the relationship between sharpness and distortion indices and the size parameters of the waterproof spherical shell.

8. The optimization method for a waterproof spherical shell of an underwater panoramic camera based on optical path analysis according to claim 7, characterized in that, Step 7-4), specifically: By utilizing the relationship between the obtained field of view, sharpness, and distortion and the size parameters of the waterproof spherical shell, the size parameters of the waterproof spherical shell corresponding to the simultaneous optimization of the three parameters are determined, and this size parameter is taken as the optimal design parameter of the waterproof spherical shell. Specifically, determining the size parameters of the waterproof spherical shell corresponding to the simultaneous optimality of the three indicators, and using these size parameters as the optimal design parameters for the waterproof spherical shell, involves: Based on the comparative analysis of the simulated imaging effects, the diameter and wall thickness of the waterproof spherical shell corresponding to the maximum field of view, highest clarity, and minimum distortion in the simulated imaging were selected. These diameter and wall thickness parameters of the waterproof spherical shell were then used as the final optimized design parameters for the waterproof spherical shell.

9. The optimization method for a waterproof spherical shell of an underwater panoramic camera based on optical path analysis according to claim 8, characterized in that, The relationship between the three indices—field of view, sharpness, and distortion—and the size parameters of the waterproof spherical shell is as follows: 9-1) When the diameter of the waterproof spherical shell is the same, the imaging field of view decreases as the wall thickness increases, while when the wall thickness remains constant, the field of view increases as the diameter increases. 9-2) When the diameter of the waterproof spherical shell is the same, the image clarity decreases as the wall thickness increases, while when the wall thickness remains constant, the clarity increases as the diameter increases. 9-3) The imaging distortion of the panoramic camera in the simulated seawater environment is significantly less than that in the air. The imaging distortion is not affected by whether a waterproof sphere is installed or by changes in the size parameters of the waterproof sphere.

Images