Monitoring precision control method of coastal zone shore-based digital image monitoring system

Abstract

The invention relates to a monitoring precision control method for a coastal zone shore-based digital image monitoring system, and the method comprises the steps: calculating the spatial distribution of the spatial resolution of the coastal zone shore-based digital image monitoring system through a monitoring precision estimation method; selecting a monitoring equipment erection position according to a monitoring precision requirement; adjusting the installation angle of the monitoring equipment to enable the image collected by the monitoring equipment to meet the requirement; monitoring precision verification points are arranged, monitoring system precision verification is carried out, and if the precision requirement is not met, imaging model parameter optimization is carried out by using a multi-parameter optimization algorithm; pixel coordinates of the monitoring indexes are extracted through a high-precision image recognition algorithm, the projection resolution of geographic correction is set according to the monitoring precision requirement, and high-precision geographic positioning of the monitoring indexes is achieved; permanent monitoring precision control points are arranged, actual geographic coordinates are recorded, imaging model parameters are calibrated regularly, and the monitoring precision of the monitoring system is maintained in long-term operation. According to the invention, the full-period monitoring precision control of the shore-based digital image monitoring system covering the coastal zone from design, construction to long-term operation is realized, and the requirements of refined monitoring evaluation and digital management and protection of coastal zone evolution are met.

Description

Technical Field

[0001] The invention relates to a monitoring accuracy control method for a coastal zone shore-based digital image monitoring system, belonging to the technical field of coastal zone monitoring. Background Art

[0002] The coastal zone is an active area where land and sea interact. It is also an area with intensive human activities and an important spatial resource on which high-quality economic and social development depends. Under the dual influence of natural factors such as climate change and human activities such as engineering construction, coastal areas are changing more and more dramatically. Efficient and accurate monitoring of the dynamic changes of the coastal zone is a hot topic in coastal protection, restoration, disaster prevention and mitigation, and integrated management.

[0003] Traditional coastal monitoring is mainly based on scattered artificial beach surveys, which have limitations such as limited monitoring range, low data density, inability to measure in bad weather, insufficient time continuity, single monitoring object, and high risk of personnel safety. It is difficult to meet the needs of the current development trend of refined monitoring and evaluation of coastal evolution and digital management and protection. Therefore, the shore-based digital image monitoring system of the coastal zone has become a new method in the field of coastal monitoring. This method comprehensively adopts digital image monitoring technology and image interpretation technology, combined with advanced theories of coastal dynamics, sediment, and landform evolution, to achieve synchronous monitoring of multiple coastal dynamics and terrain elements. It has the characteristics of all-weather, long-term, continuous, real-time, large-scale, unmanned, etc., and is suitable for coastal monitoring under various application scenarios and goals.

[0004] For example, patent CN110213536B provides a monitoring method for a shore-based digital image monitoring system in a coastal zone, which discloses a specific method for realizing long-term real-time coastal topography and dynamic observation based on a shore-based digital image monitoring system in a coastal zone, but does not disclose any technology or method for monitoring accuracy control. In fact, the monitoring accuracy of the shore-based digital image monitoring system in a coastal zone is affected by multiple factors such as optical sensor parameters, lens parameters, equipment height, monitoring distance, beach slope, image processing algorithm, etc. It is difficult to estimate its monitoring accuracy, which causes difficulties in system design and construction. In the process of building a shore-based digital image monitoring system in a coastal zone, technicians usually use a two-step calibration method to determine the imaging model parameters. This method is based on the least squares method to solve the model parameters, has large errors and is easy to fall into a local optimal solution, resulting in low system monitoring accuracy. In the long-term operation of the monitoring system, due to environmental factors such as strong winds and equipment aging, lens parameters, equipment angles, etc. may change, resulting in reduced system monitoring accuracy. How to effectively control these influencing factors in the complex and diverse coastal field environment, ensure the monitoring accuracy of the shore-based digital image monitoring system in the coastal zone, and realize long-term accurate monitoring of the coastal zone area is an important problem that troubles relevant technicians.

[0005] Therefore, it is necessary to provide a monitoring accuracy control method for the coastal shore-based digital image monitoring system to ensure the monitoring accuracy of long-term coastal monitoring. Summary of the invention

[0006] The present invention provides a monitoring accuracy control method for a shore-based digital image monitoring system in a coastal zone, which realizes full-cycle monitoring accuracy control of the shore-based digital image monitoring system in a coastal zone from design, construction to long-term operation, and meets the needs of refined monitoring and evaluation of coastal zone evolution and digital management and maintenance.

[0007] The technical solution adopted by the present invention to solve its technical problem is:

[0008] A monitoring accuracy control method for a coastal zone shore-based digital image monitoring system specifically comprises the following steps:

[0009] Step S1, establishing a monitoring accuracy estimation formula according to the equipment parameters designed for the shore-based digital image monitoring system for the coastal zone and the terrain characteristics of the target monitoring area, and calculating the spatial distribution of the spatial resolution of the shore-based digital image monitoring system for the coastal zone;

[0010] Step S2, based on the spatial distribution result calculated in step S1 and according to the monitoring accuracy requirement, obtain the location where the monitoring equipment is installed;

[0011] Step S3, adjusting the installation angle of the monitoring device so that the skyline in the image collected by the device remains horizontal and the target monitoring area is located in the middle of the image, so that the actual monitoring accuracy of the coastal zone shore-based digital image monitoring system meets the estimation;

[0012] Step S4, arranging accuracy verification points, collecting pixel coordinates of the accuracy verification points through the coastal zone shore-based digital image monitoring system, converting the pixel coordinates of the accuracy verification points into projected geographic coordinates based on the imaging model parameters obtained by the traditional system calibration method, and comparing them with the actual geographic coordinates of the accuracy verification points to verify the monitoring accuracy of the coastal zone shore-based digital image monitoring system;

[0013] If the monitoring accuracy requirement is met, proceed directly to step S5;

[0014] If the monitoring accuracy requirement is not met, the parameters are optimized until the monitoring accuracy requirement is met and then step S5 is performed;

[0015] Step S5, based on the shore-based digital image monitoring system of the coastal zone that meets the monitoring accuracy requirements determined in step S4, a high-precision image recognition algorithm is used to extract the pixel coordinates of the target monitoring indicators, and the projection resolution of the geo-correction is set according to the monitoring accuracy requirements to achieve high-precision geographic positioning of the target monitoring indicators; wherein the extracted target monitoring indicators include the waterside line, wave-breaking point coastal dynamic geomorphic features;

[0016] Step S6, deploying permanent monitoring precision control points and recording actual geographic coordinates, regularly calibrating the parameters of the imaging model, and maintaining the monitoring accuracy of the coastal zone shore-based digital imaging monitoring system in long-term operation;

[0017] Furthermore, in step S1, the monitoring accuracy estimation formula established is:

[0018]

[0019] In formula (1), Ac represents the monitoring accuracy of the shore-based digital image monitoring system in the coastal zone, k is the accuracy coefficient of the target monitoring index identification, P is the pixel size, H is the height of the monitoring equipment, f is the focal length of the lens, a is the depression angle of the monitoring equipment, and β is the terrain slope;

[0020] Furthermore, in step S1, the monitoring accuracy of the monitoring accuracy estimation formula (1) is further derived as a function with the distance between the monitoring equipment and the target monitoring beach as the independent variable, that is, the spatial distribution of the spatial resolution of the coastal shore-based digital image monitoring system, which is:

[0021]

[0022] In formula (2), F(r) is the spatial resolution at a distance r from the shore-based digital image monitoring system in the coastal zone;

[0023] Furthermore, in step S2, the location where the monitoring equipment is installed is determined by limiting the spatial resolution in formula (2), that is, if the spatial resolution at r is set ≤ the monitoring accuracy requirement, then the location where the monitoring equipment is installed satisfies:

[0024]

[0025] In formula (3), Δ is the monitoring accuracy requirement;

[0026] Furthermore, in step S4, the specific steps of verifying the monitoring accuracy of the coastal zone shore-based digital image monitoring system are as follows:

[0027] Step S41, collecting pixel coordinates (u, v) and actual geographic coordinates (x, y, z) of N accuracy verification points;

[0028] Step S42: According to the imaging model parameters, the pixel coordinates (u, v) of the accuracy verification point are converted into the plane projection geographic coordinates (x t ,y t ), the conversion method is:

[0029]

[0030] Among them, (un ,v n ) and the pixel coordinates (u, v) of the accuracy verification point satisfy the following equation, which is solved by iteration:

[0031]

[0032] In formula (4)-formula (7), (X c ,Y c ,Z c ) is the geographic coordinate of the monitoring device, T1-T8, m1-m9, w are all parameters used in the conversion process and have no special meaning; u0, v0, f x 、f y , θ, τ, d1, d2, d3, d4, and d5 are all imaging model parameters, which are obtained through system calibration during the construction phase of the shore-based digital imaging monitoring system in the coastal zone;

[0033] Step S43, calculate the projected geographic coordinates (x t ,y t ,z) and the actual geographic coordinates (x, y, z) to obtain the actual monitoring accuracy of the coastal shore-based digital image monitoring system, and then determine whether it meets the monitoring accuracy requirements:

[0034]

[0035] In formula (8), σ g The root mean square error between the projected geographic coordinates and the actual geographic coordinates of the accuracy verification point;

[0036] Step S44, using the imaging model parameters as variables, the pixel coordinates (u, v) of the accuracy verification point and the actual geographic coordinates (x, y, z) as parameters, and formula (8) as an analytical expression, construct the objective function:

[0037]

[0038] Step S45, using unconstrained nonlinear multivariate optimization, find the global optimal solution that minimizes the constructed objective function, that is:

[0039]

[0040] Further, in step S43, based on different actual working conditions, the actual monitoring accuracy of the coastal zone shore-based digital image monitoring system can also be expressed by the root mean square error of the projected pixel coordinates of the accuracy verification point:

[0041]

[0042] In formula (11), (ut ,v t ) is the projection pixel coordinate, which can also be obtained according to step S42, then the objective function constructed in step S44 is

[0043]

[0044] Furthermore, in step S5, the high-precision image recognition algorithm is an edge detection algorithm with sub-pixel accuracy, and the projection resolution of the geographic correction should satisfy Δ D ≤Δ,Δ D is the projection resolution of geographic correction, and Δ is the monitoring accuracy requirement.

[0045] Through the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0046] 1. The monitoring accuracy control method of the shore-based digital image monitoring system of the coastal zone provided by the present invention can estimate the spatial distribution of the spatial resolution of the system in the design stage of the shore-based digital image monitoring system of the coastal zone, reasonably select the installation location of the monitoring system, and provide a basis for the construction of such a system;

[0047] 2. The monitoring accuracy control method of the coastal zone shore-based digital image monitoring system provided by the present invention overcomes the problem of large error and easy to fall into the local optimal solution of the two-step calibration method through accuracy verification and imaging model parameter optimization, and can significantly improve the monitoring accuracy of such systems;

[0048] 3. The monitoring accuracy control method of the coastal shore-based digital image monitoring system provided by the present invention can overcome the problem of accuracy loss caused by lens aging and viewing angle deviation through permanent accuracy control points and regular parameter calibration, thereby ensuring the long-term monitoring accuracy of such systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0050] Figure 1 It is a flow chart of the monitoring accuracy control method of the coastal zone shore-based digital image monitoring system provided by the present invention;

[0051] Figure 2 It is a principle diagram of the monitoring accuracy estimation method of the coastal zone shore-based digital image monitoring system provided by the present invention;

[0052] Figure 3 It is a spatial distribution diagram of the spatial resolution of the shore-based digital image monitoring system for the coastal zone provided by the preferred embodiment of the present invention;

[0053] Figure 4 It is a schematic diagram of the accuracy verification result of the shore-based digital image monitoring system for the coastal zone according to the preferred embodiment provided by the present invention;

[0054] Figure 5 It is a schematic diagram of the imaging model parameter optimization process and results of the preferred embodiment provided by the present invention. DETAILED DESCRIPTION

[0055] The present invention will now be described in further detail with reference to the accompanying drawings. In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "left side", "right side", "upper part", "lower part", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and "first", "second", etc. do not indicate the importance of the components, and therefore cannot be understood as a limitation on the present invention. The specific parameters and dimensions used in this embodiment are only for illustrating the technical solution, and do not limit the scope of protection of the present invention.

[0056] As described in the background technology, the shore-based digital image monitoring system for the coastal zone is a new method in the field of coastal zone monitoring. The existing technology does not fully consider the influence of multiple factors such as optical sensor parameters, lens parameters, equipment height, monitoring distance, beach slope, image processing algorithm, etc. on its monitoring accuracy, resulting in problems such as difficult to estimate, guarantee, and maintain the monitoring accuracy. Therefore, in response to the above problems, this application provides a monitoring accuracy control method for a shore-based digital image monitoring system for the coastal zone, which can achieve full-cycle monitoring accuracy control covering system design, construction to long-term operation, and ensure the monitoring accuracy of long-term coastal monitoring.

[0057] Figure 1 As shown, the specific steps include:

[0058] Step S1, establishing a monitoring accuracy estimation formula according to the equipment parameters designed for the shore-based digital image monitoring system for the coastal zone and the terrain characteristics of the target monitoring area, and calculating the spatial distribution of the spatial resolution of the shore-based digital image monitoring system for the coastal zone;

[0059] The monitoring accuracy estimation formula established here is:

[0060]

[0061] In formula (1), Ac represents the monitoring accuracy of the shore-based digital image monitoring system in the coastal zone, k is the accuracy coefficient of the target monitoring index identification, P is the pixel size, H is the height of the monitoring equipment, f is the focal length of the lens, α is the depression angle of the monitoring equipment, and β is the terrain slope.

[0062] Through geometric transformation, Ac in formula (1) is further derived as a function with the distance between the monitoring equipment and the target monitoring beach as the independent variable, which is the spatial distribution of the spatial resolution of the coastal shore-based digital image monitoring system. The formula is:

[0063]

[0064] In formula (2), F(r) is the spatial resolution at a distance r from the shore-based digital image monitoring system in the coastal zone.

[0065] Step S2, based on the spatial distribution result calculated in step S1 and according to the monitoring accuracy requirement, obtain the location where the monitoring equipment is installed;

[0066] The specific solution is to determine the location of the monitoring equipment by limiting the spatial resolution in formula (2). The restriction condition is to set the spatial resolution at r ≤ the monitoring accuracy requirement, then the location of the monitoring equipment satisfies:

[0067]

[0068] In formula (3), Δ is the monitoring accuracy requirement.

[0069] Step S3, adjusting the installation angle of the monitoring equipment so that the skyline in the image it collects remains horizontal and the target monitoring area is located in the middle of the image, so that the actual monitoring accuracy of the coastal zone shore-based digital image monitoring system meets the estimate.

[0070] Step S4, a series of marking points, namely, accuracy verification points, are arranged in the target area of ​​coastal zone monitoring, pixel coordinates of the accuracy verification points are collected by the coastal zone shore-based digital image monitoring system, and the pixel coordinates of the accuracy verification points are converted into projected geographic coordinates based on the imaging model parameters obtained by the traditional system calibration method, and the projected geographic coordinates are compared with the actual geographic coordinates of the accuracy verification points to verify the monitoring accuracy of the coastal zone shore-based digital image monitoring system; the specific steps of verification are:

[0071] Step S41, collecting pixel coordinates (u, v) and actual geographic coordinates (x, y, z) of N accuracy verification points;

[0072] Step S42: According to the imaging model parameters, the pixel coordinates (u, v) of the accuracy verification point are converted into the plane projection geographic coordinates (x t ,y t ), the conversion method is:

[0073]

[0074]

[0075] Among them, (u n ,v n ) and the pixel coordinates (u, v) of the accuracy verification point satisfy the following equation, which is solved by iteration:

[0076]

[0077] In formula (4)-formula (7), (X c ,Y c ,Z c ) is the geographic coordinate of the monitoring device, T1-T8, m1-m9, w are all parameters used in the conversion process and have no special meaning; u0, v0, f x 、f y , θ, τ, d1, d2, d3, d4, and d5 are all parameters of the imaging model, which are obtained through system calibration during the construction phase of the shore-based digital imaging monitoring system in the coastal zone;

[0078] Step S43, calculate the projected geographic coordinates (x t ,y t ,z) and the actual geographic coordinates (x, y, z) to obtain the actual monitoring accuracy of the coastal shore-based digital image monitoring system, and then determine whether it meets the monitoring accuracy requirements. The projected geographic coordinates are the measured values ​​of the geographic coordinates of the accuracy verification point obtained by the coastal shore-based digital image monitoring system. By comparing it with the true value (x, y) of the geographic coordinates of the accuracy verification point, the error of the monitoring system is obtained, that is:

[0079]

[0080] In formula (8), σ g The root mean square error between the projected geographic coordinates and the actual geographic coordinates of the accuracy verification point;

[0081] If the monitoring accuracy requirement is met, then directly proceed to step S5; if the monitoring accuracy requirement is not met, then use a multi-parameter optimization algorithm to optimize the imaging model parameters, and continue to step S44 until the monitoring accuracy meets the requirement and then proceed to step S5;

[0082] Step S44, using the imaging model parameters as variables, the pixel coordinates (u, v) and actual geographic coordinates (x, y, z) of the accuracy verification point as parameters, and the projected geographic coordinates (x t ,y t ,z) and the actual geographic coordinates (x, y, z) g As an analytical expression, construct the objective function:

[0083] f(X)=σ g (X) (9)

[0084]

[0085] Step S45, using unconstrained nonlinear multivariate optimization, find the global optimal solution that minimizes the constructed objective function, that is:

[0086]

[0087] It should be noted that in step S43, based on different actual working conditions, the actual monitoring accuracy of the coastal shore-based digital image monitoring system can also be expressed by the root mean square error of the projected pixel coordinates of the accuracy verification point:

[0088]

[0089] In formula (11), (u t ,v t ) is the projection pixel coordinate, which can also be obtained according to step S42, that is, u, v, x in formula (4)-formula (7) are replaced by t ,y t Replace with u respectively t ,v t ,x,y, then the objective function constructed in step S44 is

[0090]

[0091] After the accuracy verification and imaging model parameter optimization have reached the monitoring accuracy requirement of the coastal shore-based digital imaging monitoring system, since the system needs to operate stably for a long time, steps S5 and S6 are provided next to maintain the monitoring accuracy of the monitoring system during long-term operation.

[0092] Step S5, based on the shore-based digital image monitoring system of the coastal zone that meets the monitoring accuracy requirements determined in step S4, a high-precision image recognition algorithm is used to extract the pixel coordinates of the target monitoring indicators, and the projection resolution of the geo-correction is set according to the monitoring accuracy requirements to achieve high-precision geographic positioning of the target monitoring indicators; wherein the extracted target monitoring indicators include coastal dynamic geomorphic features such as waterside lines and wave-breaking points;

[0093] In this step, the high-precision image recognition algorithm is an edge detection algorithm with sub-pixel accuracy. In order to ensure the monitoring accuracy of the coastal shore-based digital image monitoring system, the projection resolution of the geographic correction is limited to meet Δ D ≤Δ,Δ D is the projection resolution of geographic correction, Δ is the monitoring accuracy requirement, and such a limitation can prevent the projection from causing loss of monitoring accuracy.

[0094] Step S6, deploy permanent monitoring precision control points and record actual geographic coordinates, regularly calibrate the parameters of the imaging model, and maintain the monitoring accuracy of the coastal zone shore-based digital imaging monitoring system in long-term operation.

[0095] Example:

[0096] In order to further demonstrate the superiority of the monitoring accuracy control method of the coastal zone shore-based digital image monitoring system provided by the present application, the present application provides a specific embodiment:

[0097] A shore-based digital image monitoring system in a coastal zone is designed. The resolution of the image acquisition device used is 3840×2160 pixels, the size of the optical sensor is 1 / 1.8 inches, the lens focal length is 8mm, the height of the monitoring device is 30m, the beach slope is 1:20, and the monitoring accuracy requirement is 0.10m. This embodiment is implemented by Figure 1 The steps shown achieve control over the monitoring accuracy of the system.

[0098] Step S1, according to the equipment parameters designed for the coastal zone shore-based digital image monitoring system and the terrain characteristics of the target monitoring area, using Figure 2 The monitoring accuracy estimation method shown is used to calculate the spatial distribution of the spatial resolution of the coastal shore-based digital image monitoring system:

[0099]

[0100] Step S2, based on the spatial distribution result calculated in step S1 and the monitoring accuracy requirement, obtain the location of the monitoring equipment:

[0101]

[0102] Figure 3 As shown, in the embodiment, the location where the monitoring equipment is set up should be no more than 259.19 meters away from the target monitoring beach.

[0103] During the system construction phase, the actual monitoring accuracy of the monitoring system is evaluated and improved through steps S3 and S4. Specifically, in step S3, the installation angle of the monitoring device is adjusted so that the skyline in the image collected by the monitoring device remains horizontal and the target monitoring beach area appears in the middle of the image.

[0104] Step S4, deploying accuracy verification points, verifying the monitoring accuracy of the coastal zone shore-based digital image monitoring system, and optimizing the imaging model parameters using a multi-parameter optimization algorithm. The specific implementation steps are as follows:

[0105] Step S41, arrange and collect the coordinates of 6 accuracy verification points, as shown in Table 1:

[0106] Table 1 Coordinates of accuracy verification points in the embodiment

[0107] Serial number Pixel coordinates Actual geographic coordinates 1 (940.27,2040.08) (30.979,70.458,2.433) 2 (2012.48,1756.18) (50.317,83.537,1.573) 3 (2795.36,1779.04) (58.192,78.647,1.347) 4 (3080.96,2106.36) (47.105,58.822,2.404) 5 (3625.48,2106.18) (51.229,55.677,2.434) 6 (3787.30,1790.12) (67.130,70.503,1.517)

[0108] Step S42: According to the system calibration result, the imaging model parameters in the embodiment are u0=1920, v0=1080, f x =8210,f y =7590, d1=-0.02, d2=0.02, d3=0.01, d4=-0.06, d5=0.04, θ=1.483,τ=

[0109] 0.011, the projected geographic coordinates (x t ,y t ), the result is as follows Figure 4 shown.

[0110] Step S43, calculate the root mean square error of the projected geographic coordinates of the accuracy verification point to represent the monitoring accuracy of the monitoring system:

[0111]

[0112] Step S44, construct an objective function with imaging model parameters as variables, pixel coordinates and actual geographic coordinates of the accuracy verification points as parameters, and root mean square error of the accuracy verification points as an analytical expression. Preferably, this embodiment uses the root mean square error of the projected geographic coordinates of the accuracy verification points as the objective function:

[0113] f(X)=σ g (X)

[0114]

[0115] Step S45, using unconstrained nonlinear multivariate optimization, to find the global optimal solution that minimizes the objective function.

[0116]

[0117] Specifically, a genetic algorithm is used to solve the global optimal solution, with the system calibration result as the initial solution, the population size is 300, and convergence is achieved after 5086 generations of evolution. The convergence process is shown in Figure 5 5a in . The optimal solution of the imaging model parameters is [1931.137, 1622.335, 8399.666, 8328.628, -0.427, -1.000, -1.000, -0.064, -0.005, 0.532, 1.406, 0.012], as shown in Figure 5 After optimization, the root mean square error of the projected geographic coordinates of the accuracy verification point is 0.075m, as shown in Figure 5b. Figure 5 As shown in 5c, the monitoring accuracy requirement is met and the next step can be performed.

[0118] Continue to maintain the monitoring accuracy of the long-term monitoring system. In step S5, use an edge detection algorithm with sub-pixel accuracy to extract monitoring indicators such as coastline, wave height, and wave-breaking zone range. The geo-correction projection resolution Δ D =0.10m, to avoid loss of monitoring accuracy.

[0119] Step S6, deploy permanent monitoring precision control points and record actual geographic coordinates, regularly calibrate the parameters of the imaging model, and maintain the monitoring accuracy of the coastal zone shore-based digital imaging monitoring system in long-term operation.

[0120] In summary, this application aims at the problems that the monitoring accuracy of the shore-based digital image monitoring system in the coastal zone is difficult to predict, the imaging model has low accuracy, and the accuracy loss in long-term operation. It provides a monitoring accuracy control method for the shore-based digital image monitoring system in the coastal zone. The spatial distribution of the spatial resolution of the shore-based digital image monitoring system in the coastal zone is calculated by using the monitoring accuracy estimation method; the location of the monitoring equipment is selected according to the monitoring accuracy requirements; the installation angle of the monitoring equipment is adjusted so that the skyline in the image collected by the monitoring equipment remains horizontal, and the target monitoring area is presented in the middle of the image; monitoring accuracy verification points are arranged to verify the accuracy of the monitoring system. If the accuracy requirements are not met, the imaging model parameters are optimized using a multi-parameter optimization algorithm; the pixel coordinates of the monitoring indicators are extracted using a high-precision image recognition algorithm, and the projection resolution of the geographic correction is set according to the monitoring accuracy requirements to achieve high-precision geographic positioning of the monitoring indicators; permanent monitoring accuracy control points are arranged and the actual geographic coordinates are recorded, and the imaging model parameters are calibrated regularly to maintain the monitoring accuracy of the monitoring system in long-term operation. The present invention can realize the full-cycle monitoring accuracy control of the shore-based digital image monitoring system covering the coastal zone from design, construction to long-term operation, and meet the needs of refined monitoring and evaluation of coastal evolution and digital management and protection.

[0121] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0122] The meaning of "and / or" described in this application means that the situations where each exists alone or both exist at the same time are included.

[0123] The term “connection” as used in this application may mean a direct connection between components or an indirect connection between components via other components.

[0124] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A monitoring accuracy control method for a coastal zone shore-based digital image monitoring system, characterized in that: The specific steps include: Step S1, establishing a monitoring accuracy estimation formula according to the equipment parameters designed for the shore-based digital image monitoring system for the coastal zone and the terrain characteristics of the target monitoring area, and calculating the spatial distribution of the spatial resolution of the shore-based digital image monitoring system for the coastal zone; Step S2, based on the spatial distribution result calculated in step S1 and according to the monitoring accuracy requirement, obtain the location where the monitoring equipment is installed; Step S3, adjusting the installation angle of the monitoring device so that the skyline in the image collected by the device remains horizontal and the target monitoring area is located in the middle of the image, so that the actual monitoring accuracy of the coastal zone shore-based digital image monitoring system meets the estimation; Step S4, arranging accuracy verification points, collecting pixel coordinates of the accuracy verification points through the coastal zone shore-based digital image monitoring system, converting the pixel coordinates of the accuracy verification points into projected geographic coordinates based on the imaging model parameters obtained by the traditional system calibration method, and comparing them with the actual geographic coordinates of the accuracy verification points to verify the monitoring accuracy of the coastal zone shore-based digital image monitoring system; If the monitoring accuracy requirement is met, proceed directly to step S5; If the monitoring accuracy requirement is not met, the parameters are optimized until the monitoring accuracy requirement is met and then step S5 is performed; Step S5, based on the shore-based digital image monitoring system of the coastal zone that meets the monitoring accuracy requirements determined in step S4, a high-precision image recognition algorithm is used to extract the pixel coordinates of the target monitoring indicators, and the projection resolution of the geo-correction is set according to the monitoring accuracy requirements to achieve high-precision geographic positioning of the target monitoring indicators; wherein the extracted target monitoring indicators include the waterside line, wave-breaking point coastal dynamic geomorphic features; Step S6, deploy permanent monitoring precision control points and record actual geographic coordinates, regularly calibrate the parameters of the imaging model, and maintain the monitoring accuracy of the coastal zone shore-based digital imaging monitoring system in long-term operation.

2. The monitoring accuracy control method of the coastal zone shore-based digital image monitoring system according to claim 1 is characterized by: In step S1, the monitoring accuracy estimation formula established is: In formula (1), Ac represents the monitoring accuracy of the shore-based digital image monitoring system in the coastal zone, k is the accuracy coefficient of the target monitoring index identification, P is the pixel size, H is the height of the monitoring equipment, f is the focal length of the lens, α is the depression angle of the monitoring equipment, and β is the terrain slope.

3. The monitoring accuracy control method of the coastal zone shore-based digital image monitoring system according to claim 2 is characterized by: In step S1, the monitoring accuracy of the monitoring accuracy estimation formula (1) is further derived as a function with the distance between the monitoring equipment and the target monitoring beach as the independent variable, that is, the spatial distribution of the spatial resolution of the coastal shore-based digital image monitoring system, which is: In formula (2), F(r) is the spatial resolution at a distance r from the shore-based digital image monitoring system in the coastal zone.

4. The monitoring accuracy control method of the coastal zone shore-based digital image monitoring system according to claim 3 is characterized by: In step S2, the location where the monitoring equipment is installed is determined by limiting the spatial resolution in formula (2), that is, if the spatial resolution at r is set ≤ the monitoring accuracy requirement, then the location where the monitoring equipment is installed satisfies: In formula (3), Δ is the monitoring accuracy requirement.

5. The monitoring accuracy control method of the coastal zone shore-based digital image monitoring system according to claim 1 is characterized by: In step S4, the specific steps of verifying the monitoring accuracy of the coastal zone shore-based digital image monitoring system are as follows: Step S41, collecting pixel coordinates (u, v) and actual geographic coordinates (x, y, z) of N accuracy verification points; Step S42: According to the imaging model parameters, the pixel coordinates (u, v) of the accuracy verification point are converted into the plane projection geographic coordinates (x t ,y t ), the conversion method is: Among them, (u n ,v n ) and the pixel coordinates (u, v) of the accuracy verification point satisfy the following equation, which is solved by iteration: In formula (4)-formula (7), (X c ,Y c ,Z c ) is the geographic coordinate of the monitoring device, T1-T8, m1-m9, w are all parameters used in the conversion process and have no special meaning; u0, v0, f x 、f y , θ, τ, d1, d2, d3, d4, and d5 are all imaging model parameters, which are obtained through system calibration during the construction phase of the shore-based digital imaging monitoring system in the coastal zone; Step S43, calculate the projected geographic coordinates (x t ,y t ,z) and the actual geographic coordinates (x, y, z) to obtain the actual monitoring accuracy of the coastal shore-based digital image monitoring system, and then determine whether it meets the monitoring accuracy requirements: In formula (8), σ g The root mean square error between the projected geographic coordinates and the actual geographic coordinates of the accuracy verification point; Step S44, using the imaging model parameters as variables, the pixel coordinates (u, v) of the accuracy verification point and the actual geographic coordinates (x, y, z) as parameters, and formula (8) as an analytical expression, construct the objective function: Step S45, using unconstrained nonlinear multivariate optimization, find the global optimal solution that minimizes the constructed objective function, that is:

6. The monitoring accuracy control method of the coastal zone shore-based digital image monitoring system according to claim 5 is characterized by: In step S43, based on different actual working conditions, the actual monitoring accuracy of the coastal shore-based digital image monitoring system can also be expressed by the root mean square error of the projected pixel coordinates of the accuracy verification point: In formula (11), (u t ,v t ) is the projection pixel coordinate, which can also be obtained according to step S42, then the objective function constructed in step S44 is 7. The monitoring accuracy control method of the coastal zone shore-based digital image monitoring system according to claim 1 is characterized by: In step S5, the high-precision image recognition algorithm is an edge detection algorithm with sub-pixel accuracy, and the projection resolution of the geographic correction should meet Δ D ≤Δ,Δ D is the projection resolution of geographic correction, and Δ is the monitoring accuracy requirement.

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