A wellbore casing cavity three-dimensional measurement method based on omni-directional speckle structured light

Abstract

The present application belongs to the technical field of oil and gas equipment detection, and particularly relates to a wellbore casing cavity three-dimensional measurement method based on omni-directional speckle structured light. The wellbore casing cavity three-dimensional measurement method based on omni-directional speckle structured light is simple to operate, high in measurement accuracy, capable of realizing accurate reproduction of the actual appearance of the wellbore casing cavity, simplifying the existing cavity measurement process, and suitable for appearance detection of wellbore casings and complex cavities. The wellbore casing cavity three-dimensional measurement method based on omni-directional speckle structured light comprises the following steps: constructing a cavity imaging model based on monocular speckle structured light; determining a calibration workpiece; three-dimensionally calibrating the cavity imaging model based on monocular speckle structured light; preparing a speckle image; collecting an omni-directional speckle image in the cavity; expanding the collected omni-directional speckle image; calculating the final parallax of each pixel to complete three-dimensional point cloud reconstruction of the wellbore casing cavity to be measured.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas equipment testing technology, and particularly relates to a three-dimensional measurement method for well casing cavity based on omnidirectional speckle structured light. Background Technology

[0002] In the field of petroleum engineering, well casing serves as a crucial support component in oil and gas well operations. It is subjected to complex downhole stress, corrosion, and high-temperature, high-pressure environments over extended periods, making it susceptible to wear, deformation, or perforation, potentially leading to damaged wells. Notably, damaged wells carry the risk of further leakage or even explosion. Therefore, it is essential for technicians to obtain timely three-dimensional morphological data of the well casing cavity to develop repair plans. However, the enclosed space and high length-to-diameter ratio of the well casing cavity present significant challenges to existing measurement methods.

[0003] Further research revealed that, compared to traditional two-dimensional image measurement methods (which have lower accuracy and are easily affected by ambient light), three-dimensional measurement technology has advantages such as non-contact operation, high precision, and high efficiency, thus showing significant potential in well casing cavity inspection. For example, patent application CN114529598A, "A Prism Speckle Monocular Real-Time Measurement Method Applicable to Three-Dimensional Deformation," provides a prism speckle monocular real-time measurement method suitable for three-dimensional deformation. This technical solution specifically constructs a binocular stereo vision system using a monocular camera and a prism, combining speckle images with feature matching algorithms to measure the three-dimensional deformation of material surfaces in industrial manufacturing. However, this method does not consider the influence of ambient light, has a limited effective field of view, and is difficult to cover large-scale or full-circumferential scenes, therefore it is not suitable for cavity measurement. Patent application CN103971405A, entitled "A 3D Reconstruction Method Based on Laser Speckle Structured Light and Depth Information," provides a monocular vision system that uses laser speckle structured light as an enhancement pattern and employs a support vector machine (SVM) to perform multi-class classification encoding on the speckle image to obtain depth information. However, the inventors found that this method relies on a large amount of training data, resulting in high computational complexity and low measurement efficiency. Furthermore, its measurement system also has a limited field of view, making it unsuitable for omnidirectional measurement of cavities. In addition, patent application CN117006974A, entitled "A 3D Laser Imaging Method and System for Dense Texture Projection," provides a high-precision 3D topography measurement method based on active structured light binocular stereo vision, suitable for 3D measurement of surfaces with high curvature and weak texture in open spaces. However, its system is complex and has a large structural size, making it unsuitable for cavity measurement as well.

[0004] In summary, existing measurement methods are insufficient for achieving high-precision and high-efficiency three-dimensional measurements of the inner wall of the well casing cavity. Therefore, there is an urgent need for those skilled in the art to design a three-dimensional measurement method suitable for confined spaces to meet the requirements for high-precision and high-efficiency three-dimensional topographic data detection of the well casing cavity. Summary of the Invention

[0005] This invention provides a three-dimensional measurement method for well casing cavities based on omnidirectional speckle structured light. This method is simple to operate, highly accurate, and can precisely reproduce the actual morphology of the well casing cavity, simplifying the existing cavity measurement process. It is suitable for morphological inspection of well casings and complex cavities.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A three-dimensional measurement method for well casing cavity based on omnidirectional speckle structured light includes the following steps:

[0008] Step S1: Construct a cavity imaging model based on monocular speckle structured light;

[0009] Step S2: Determine the calibration workpiece;

[0010] Step S3: Based on the calibrated workpiece, perform three-dimensional calibration of the cavity imaging model based on monocular speckle structured light;

[0011] Step S4: Use the local location random speckle algorithm to prepare a speckle image;

[0012] The prepared speckle image is omnidirectionally projected into the well casing cavity to be measured, and the omnidirectional speckle image inside the cavity is acquired.

[0013] Step S5: Expand the acquired omnidirectional speckle image inside the cavity;

[0014] A cavity imaging model based on monocular speckle structured light is applied to match the unfolded omnidirectional speckle image;

[0015] Calculate the final disparity of each pixel to complete the 3D point cloud reconstruction of the well casing cavity to be measured.

[0016] Preferably, the process of constructing a cavity imaging model based on monocular speckle structured light in step S1 is specifically described as follows:

[0017] Establish a spatial coordinate system; set the virtual projection optical center and the virtual imaging optical center, and determine the virtual image plane of the monocular speckle structured light based on the virtual projection optical center and the virtual imaging optical center;

[0018] The virtual image plane of monocular speckle structured light is unfolded to obtain a cavity imaging model based on monocular speckle structured light.

[0019] Preferably, the process of performing three-dimensional calibration of the cavity imaging model based on monocular speckle structured light based on the calibrated workpiece in step S3 is specifically described as follows:

[0020] Based on the calibrated workpiece, the camera parameters are calibrated to obtain the camera parameters;

[0021] The speckle pattern based on a cavity imaging model using monocular speckle structured light is omnidirectionally projected into a standard cylinder to obtain a reference speckle surface; an image of the reference speckle surface is acquired using a camera, and this image is unfolded into a virtual reference speckle image;

[0022] The speckle pattern of the cavity imaging model based on monocular speckle structured light is omnidirectionally projected onto the calibration workpiece by a projector. The calibration image with speckle features is acquired by a camera, the corner points of the ring imaging area are extracted, and they are converted into virtual plane coordinates.

[0023] The DIC algorithm based on ZNCC is used to calculate the displacement of the corner points of the annular imaging region relative to the virtual reference speckle image; the virtual optical center coordinates of the projector and the equation of the reference plane are solved to complete the calibration of the projector and the reference plane.

[0024] Preferably, the process of matching the unfolded omnidirectional speckle image using a cavity imaging model based on monocular speckle structured light in step S5 is specifically described as follows:

[0025] Within the projection space, the distance between speckles, speckle size, and distribution in the omnidirectional speckle image within the cavity are made consistent on different depth reflecting surfaces, and are offset only along the baseline direction. A cavity imaging model based on monocular speckle structured light is then applied.

[0026] A semi-global stereo matching algorithm is used to match the unfolded omnidirectional speckle image.

[0027] Preferably, in step S5, the final disparity of each pixel is calculated to complete the three-dimensional point cloud reconstruction of the well casing cavity to be measured, specifically described as follows:

[0028] The final disparity of each pixel satisfies: (1);

[0029] In equation (1), For depth information, For parallax, The length of the baseline between the projector and the camera. The focal length of the camera; For the column coordinates of the camera; The column coordinates of the camera's virtual principal point;

[0030] The reconstructed three-dimensional point cloud of the well casing cavity to be measured satisfies:

[0031] (2);

[0032] (3);

[0033] in, , , These are the coordinate components in the camera coordinate system; It is the depth information corresponding to the i-th pixel; , It is the pixel coordinate of the i-th pixel in the image plane; These are the row coordinates of the camera's virtual principal point; The coordinates of the cylindrical coordinate system of the three-dimensional point cloud of the well casing cavity to be measured are given. Using the radius of the reference cylinder, the unfolded image resolution is... .

[0034] This invention provides a method for three-dimensional measurement of well casing cavities based on omnidirectional speckle structured light. The method includes the following steps: Step S1: Constructing a cavity imaging model based on monocular speckle structured light; Step S2: Determining the calibration workpiece; Step S3: Performing three-dimensional calibration of the cavity imaging model based on monocular speckle structured light based on the calibration workpiece; Step S4: Preparing a speckle image using a local position random speckle algorithm; omnidirectionally projecting the prepared speckle image onto the well casing cavity to be measured, acquiring the omnidirectional speckle image within the cavity; Step S5: Unfolding the acquired omnidirectional speckle image within the cavity; Matching the unfolded omnidirectional speckle image using the cavity imaging model based on monocular speckle structured light; Calculating the final disparity of each pixel to complete the three-dimensional point cloud reconstruction of the well casing cavity to be measured.

[0035] The three-dimensional measurement method for well casing cavity based on omnidirectional speckle structured light, which has the above-mentioned step characteristics, has at least the following technical advantages compared with the existing technology:

[0036] 1) The present invention provides a three-dimensional measurement method for well casing cavity based on omnidirectional speckle structured light. Based on the monocular speckle structured light measurement principle, it utilizes a virtual optical center and image unfolding algorithm to convert the complex well casing cavity measurement scenario into a planar measurement mode, thereby realizing efficient three-dimensional reconstruction of a single cavity image and avoiding multiple measurements and complex registration operations.

[0037] 2) The present invention provides a three-dimensional measurement method for well casing cavity based on omnidirectional speckle structured light, which has many advantages such as high precision, full field of view, high efficiency and reliable detection results. It provides an efficient and feasible solution for well casing morphology measurement, simplifies the existing cavity measurement process, and is applicable to the detection process of various complex cavities such as well casing. Attached Figure Description

[0038] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the following drawings:

[0039] Figure 1 This is a flowchart illustrating a three-dimensional measurement method for well casing cavity based on omnidirectional speckle structured light, provided by the present invention.

[0040] Figure 2 This is a schematic diagram of the measurement system corresponding to the cavity imaging model;

[0041] Figure 3 for Figure 2 A schematic diagram of the structure of stacked hyperboloid mirrors;

[0042] Reference numerals: 1. Projector; 2. Camera; 3. Stacked hyperboloid mirror; 31. Projection hyperboloid; 32. Imaging hyperboloid; 4. Support. Detailed Implementation

[0043] This invention provides a three-dimensional measurement method for well casing cavities based on omnidirectional speckle structured light. This method is simple to operate, highly accurate, and can precisely reproduce the actual morphology of the well casing cavity, simplifying the existing cavity measurement process. It is suitable for morphological inspection of well casings and complex cavities.

[0044] like Figure 1 As shown, this invention provides a three-dimensional measurement method for well casing cavity based on omnidirectional speckle structured light, specifically including the following steps:

[0045] Step S1: Construct a cavity imaging model based on monocular speckle structured light.

[0046] First, a cavity imaging model based on monocular speckle structured light is constructed. It is worth noting that, for the convenience of those skilled in the art, a set of schematic diagrams of the measurement system corresponding to the cavity imaging model are provided here. References are as follows... Figure 2As shown, the measurement system corresponding to this cavity imaging model specifically consists of a projector 1 (with a resolution of 720P, i.e., 1280×720; a transmittance of 1.3, and mechanical dimensions of approximately 95×65×18mm), a camera 2 (with a resolution of 3840×2160 pixels, a field of view of approximately 90.03°, and mechanical dimensions of 8.5×8.5×5.3mm), a stacked hyperboloid mirror 3, and a support 4. Further references are provided below. Figure 3 As shown, where Figure 3 This is a schematic diagram of a stacked hyperboloid mirror structure, which consists of two parts: a projection hyperboloid 31 and an imaging hyperboloid 32.

[0047] Based on this, the cavity imaging model based on monocular speckle structured light is further supplemented as follows. As a preferred embodiment of the present invention, the process of constructing the cavity imaging model based on monocular speckle structured light in step S1 is specifically described as follows:

[0048] Establish a spatial coordinate system.

[0049] Set up a virtual projection optical center and a virtual imaging optical center, and determine the virtual image plane of the monocular speckle structured light based on the virtual projection optical center and the virtual imaging optical center.

[0050] The virtual image plane of monocular speckle structured light is unfolded to obtain a cavity imaging model based on monocular speckle structured light.

[0051] Specifically, the origin O is taken as the midpoint of the line connecting the two focal points of the projection hyperboloid 31, the Z-axis is the axis of the measurement system, and the X-axis is the inner diameter of the cavity. Then, the two internal focal points of the stacked hyperboloid mirror 3 are selected as the virtual projection optical center and the virtual imaging optical center, respectively. Next, based on the virtual projection optical center and the virtual imaging optical center, a cylindrical surface with a radius of twice the focal length and centered at the virtual imaging optical center is defined, and this is used as the virtual image plane for monocular speckle structured light. Finally, this virtual image plane is unfolded onto a plane to obtain the cavity imaging model based on monocular speckle structured light.

[0052] Step S2: Determine the calibration workpiece.

[0053] Based on step S1, step S2 is further implemented. Specifically, after constructing the cavity imaging model based on monocular speckle structured light, a specially designed calibration workpiece suitable for the three-dimensional measurement scenario of well casing cavity is determined and designed. This calibration workpiece is a standard cylindrical shape with a known radius, and a checkerboard array with a spacing of 10mm is evenly distributed along its axial and circumferential directions. Then, an image of the calibration workpiece is captured, and its corner points are extracted. The image of the calibration workpiece is then unfolded onto a virtual plane, through which the coordinates of the corner points can be measured.

[0054] Step S3: Based on the calibrated workpiece, perform three-dimensional calibration of the cavity imaging model based on monocular speckle structured light.

[0055] Based on completing step S2, step S3 is further implemented. In a preferred embodiment of the present invention, step S3, which involves three-dimensional calibration of the cavity imaging model based on monocular speckle structured light, based on the calibrated workpiece, is specifically described as follows:

[0056] Based on the calibrated workpiece, the camera parameters are calibrated to obtain the camera parameters.

[0057] Based on the camera imaging model, the relationship between the image coordinate system and the camera coordinate system can be described as follows:

[0058] ;

[0059] Wherein, coordinates (X) c Y c Z c (x, y) is a point in the camera coordinate system, and its projection point in the image coordinate system is point (x, y).

[0060] The transformation relationship between the camera coordinate system and the image coordinate system is represented by an intrinsic parameter matrix; specifically, the camera's intrinsic parameter matrix satisfies:

[0061] ;

[0062] Where, d x and d y This represents the actual physical distance between the centers of adjacent pixels in the x and y directions, where (u0, v0) are the coordinates of the origin in the pixel coordinate system, and f is the camera focal length.

[0063] The relationship between the world coordinate system and the camera coordinate system can be expressed as follows:

[0064] ;

[0065] The origin translation matrix t and the axis rotation matrix R together constitute the camera's external parameters.

[0066] Here, Zhang Zhengyou's checkerboard calibration method is used to calibrate the parameters of the cavity 3D measurement system for omnidirectional speckle structured light, determining the camera's intrinsic and extrinsic parameters. It is worth noting that the specific camera parameters can be found as follows:

[0067] ;

[0068] Table 1 Camera Parameters

[0069] in, The pixel size of the camera's focal length. Main point location, For radial distortion parameters, For tangential distortion parameters, This is the reprojection error.

[0070] The speckle pattern of the cavity imaging model based on monocular speckle structured light is omnidirectionally projected into a standard cylinder to obtain a reference speckle surface. An image of the reference speckle surface is acquired using a camera and unfolded into a virtual reference speckle image. Subsequently, the speckle pattern of the cavity imaging model based on monocular speckle structured light is omnidirectionally projected onto the calibration workpiece using a projector. The calibration image with speckle features is acquired by a camera, and the corner points of the annular imaging region are extracted and converted into virtual planar coordinates.

[0071] Next, the DIC algorithm based on ZNCC is used to calculate the displacement of the corner points of the annular imaging region relative to the virtual reference speckle image. Finally, the principle of monocular speckle structured light measurement is substituted into the reprojection error objective function for optimization, which yields the virtual optical center coordinates of the projector and the equation of the reference plane, thus completing the calibration of the projector and the reference plane.

[0072] Specifically, the calibrated parameters of the projector and reference plane can be found as follows:

[0073] ;

[0074] Table 2 Projector and Reference Plane Parameters

[0075] in, The virtual optical center coordinates of the projector. For reference plane parameters, This represents the reprojection error under speckle projection conditions.

[0076] Step S4: Use the local location random speckle algorithm to prepare a speckle image.

[0077] The prepared speckle image is omnidirectionally projected into the well casing cavity to be measured, and the omnidirectional speckle image inside the cavity is acquired.

[0078] Step S5: Expand the acquired omnidirectional speckle image inside the cavity.

[0079] A cavity imaging model based on monocular speckle structured light is applied to match the unfolded omnidirectional speckle image.

[0080] Calculate the final disparity of each pixel to complete the 3D point cloud reconstruction of the well casing cavity to be measured.

[0081] Based on completing steps S3 and S4, step S5 is further implemented. It is worth noting that after acquiring the omnidirectional speckle image inside the cavity, the acquired omnidirectional speckle image inside the cavity is expanded, and the expanded omnidirectional speckle image is further matched.

[0082] In a preferred embodiment of the present invention, since the above processing is all performed on a virtual plane, it is preferable to apply a cavity imaging model based on monocular speckle structured light when the speckle distance, speckle size, and distribution in the omnidirectional speckle image within the cavity are consistent across different depth reflection surfaces and are only offset along the baseline direction within the projection space.

[0083] Then, a semi-global stereo matching algorithm (SGM algorithm) is used to match the unfolded omnidirectional speckle image. The matching result, i.e., the column coordinates of the camera and the camera's virtual principal point, is represented as follows: .

[0084] Next, the final disparity for each pixel is calculated. It's worth noting that the Winner Takes All (WTA) principle is used to calculate the final disparity for each pixel. Specifically,

[0085] The final disparity of each pixel satisfies: (1);

[0086] In equation (1), For depth information, For parallax, The length of the baseline between the projector and the camera. The focal length of the camera; For the column coordinates of the camera; The column coordinates of the camera's virtual principal point.

[0087] Then, by converting the disparity map into a depth map, a 3D point cloud of the well casing cavity to be measured is reconstructed. The reconstructed 3D point cloud of the well casing cavity satisfies the following:

[0088] (2);

[0089] (3);

[0090] in, , , These are the coordinate components in the camera coordinate system; It is the depth information corresponding to the i-th pixel; , It is the pixel coordinate of the i-th pixel in the image plane; These are the row coordinates of the camera's virtual principal point; The coordinates of the cylindrical coordinate system of the three-dimensional point cloud of the well casing cavity to be measured are given. Using the radius of the reference cylinder, the unfolded image resolution is... .

[0091] Thus, this invention provides a three-dimensional measurement method for well casing cavities based on omnidirectional speckle structured light. It constructs a cavity imaging model based on monocular speckle structured light and determines the calibration workpiece. Based on this calibration workpiece, the cavity imaging model based on monocular speckle structured light is calibrated in three dimensions. Finally, a semi-global stereo matching algorithm (SGM algorithm) is used to match the acquired omnidirectional speckle images within the cavity. After cost aggregation, the WTA (Winner Takes All) principle is adopted to obtain the final disparity of each pixel, ultimately obtaining the three-dimensional point cloud of the well casing cavity to be measured, realizing the image processing and cavity point cloud reconstruction process.

[0092] This invention provides a method for three-dimensional measurement of well casing cavities based on omnidirectional speckle structured light. The method includes the following steps: Step S1: Constructing a cavity imaging model based on monocular speckle structured light; Step S2: Determining the calibration workpiece; Step S3: Performing three-dimensional calibration of the cavity imaging model based on monocular speckle structured light based on the calibration workpiece; Step S4: Preparing a speckle image using a local position random speckle algorithm; omnidirectionally projecting the prepared speckle image onto the well casing cavity to be measured, acquiring the omnidirectional speckle image within the cavity; Step S5: Unfolding the acquired omnidirectional speckle image within the cavity; Matching the unfolded omnidirectional speckle image using the cavity imaging model based on monocular speckle structured light; Calculating the final disparity of each pixel to complete the three-dimensional point cloud reconstruction of the well casing cavity to be measured.

[0093] The three-dimensional measurement method for well casing cavity based on omnidirectional speckle structured light, which has the above-mentioned step characteristics, has at least the following technical advantages compared with the existing technology:

[0094] 1) The present invention provides a three-dimensional measurement method for well casing cavity based on omnidirectional speckle structured light. Based on the monocular speckle structured light measurement principle, it utilizes a virtual optical center and image unfolding algorithm to convert the complex well casing cavity measurement scenario into a planar measurement mode, thereby realizing efficient three-dimensional reconstruction of a single cavity image and avoiding multiple measurements and complex registration operations.

[0095] 2) The present invention provides a three-dimensional measurement method for well casing cavity based on omnidirectional speckle structured light, which has many advantages such as high precision, full field of view, high efficiency and reliable detection results. It provides an efficient and feasible solution for well casing morphology measurement, simplifies the existing cavity measurement process, and is applicable to the detection process of various complex cavities such as well casing.

[0096] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for three-dimensional measurement of well casing cavity based on omnidirectional speckle structured light, characterized in that, The steps include the following: Step S1: Construct a cavity imaging model based on monocular speckle structured light; Step S2: Determine the calibration workpiece; Step S3: Based on the calibrated workpiece, perform three-dimensional calibration of the cavity imaging model based on monocular speckle structured light; Step S4: Use the local location random speckle algorithm to prepare a speckle image; The prepared speckle image is omnidirectionally projected into the well casing cavity to be measured, and the omnidirectional speckle image inside the cavity is acquired. Step S5: Expand the acquired omnidirectional speckle image inside the cavity; A cavity imaging model based on monocular speckle structured light is applied to match the unfolded omnidirectional speckle image; Calculate the final disparity of each pixel to complete the 3D point cloud reconstruction of the well casing cavity to be measured; The process of constructing a cavity imaging model based on monocular speckle structured light in step S1 is specifically described as follows: Establish a spatial coordinate system; set the virtual projection optical center and the virtual imaging optical center, and determine the virtual image plane of the monocular speckle structured light based on the virtual projection optical center and the virtual imaging optical center; Unfold the virtual image plane of monocular speckle structured light to obtain a cavity imaging model based on monocular speckle structured light; Step S5, which calculates the final disparity of each pixel to complete the 3D point cloud reconstruction of the well casing cavity to be measured, is specifically described as follows: The final disparity of each pixel satisfies: （1）； In equation (4), For depth information, For parallax, The length of the baseline between the projector and the camera. The focal length of the camera; For the column coordinates of the camera; The column coordinates of the camera's virtual principal point; The reconstructed three-dimensional point cloud of the well casing cavity to be measured satisfies: （2）； （3）； in, , , These are the coordinate components in the camera coordinate system; It is the depth information corresponding to the i-th pixel; , It is the pixel coordinate of the i-th pixel in the image plane; These are the row coordinates of the camera's virtual principal point; The coordinates of the cylindrical coordinate system of the three-dimensional point cloud of the well casing cavity to be measured are given. Using the radius of the reference cylinder, the unfolded image resolution is... .

2. The method for three-dimensional measurement of well casing cavity based on omnidirectional speckle structured light according to claim 1, characterized in that, The process of performing three-dimensional calibration of the cavity imaging model based on monocular speckle structured light based on the calibrated workpiece in step S3 is specifically described as follows: Based on the calibrated workpiece, the camera parameters are calibrated to obtain the camera parameters; The speckle pattern based on a cavity imaging model using monocular speckle structured light is omnidirectionally projected into a standard cylinder to obtain a reference speckle surface; an image of the reference speckle surface is acquired using a camera, and this image is unfolded into a virtual reference speckle image; The speckle pattern of the cavity imaging model based on monocular speckle structured light is omnidirectionally projected onto the calibration workpiece by a projector. The calibration image with speckle features is acquired by a camera, the corner points of the ring imaging area are extracted, and they are converted into virtual plane coordinates. The DIC algorithm based on ZNCC is used to calculate the displacement of the corner points of the annular imaging region relative to the virtual reference speckle image; the virtual optical center coordinates of the projector and the equation of the reference plane are solved to complete the calibration of the projector and the reference plane.

3. The method for three-dimensional measurement of well casing cavity based on omnidirectional speckle structured light according to claim 1, characterized in that, The process of matching the unfolded omnidirectional speckle image using a cavity imaging model based on monocular speckle structured light in step S5 is specifically described as follows: Within the projection space, the distance between speckles, speckle size, and distribution in the omnidirectional speckle image within the cavity are made consistent on different depth reflecting surfaces, and are offset only along the baseline direction. A cavity imaging model based on monocular speckle structured light is then applied. A semi-global stereo matching algorithm is used to match the unfolded omnidirectional speckle image.

Images