Farmland drainage system three-dimensional visual design system based on digital twinning

Abstract

The invention discloses a three-dimensional visual design system for a farmland drainage system based on digital twinning, and relates to the field of hydraulic engineering. A point location generation module; the sequence generation module is used for screening to obtain a preparatory sampling point sequence of the farmland range; the water channel generation module forms a main drainage channel and an auxiliary drainage channel; the width setting module is used for setting the cross sectional areas of the main drainage channel and the auxiliary drainage channel; and the scheme determination module is used for calculating the construction workload of the total drainage scheme and taking the main drainage channel and the at least one auxiliary drainage channel generated by the total drainage scheme with the minimum construction workload as a final design result. By arranging the point location generation module, the sequence generation module, the canal generation module, the width setting module and the scheme determination module, the scheme capable of meeting the drainage requirement is obtained, and meanwhile the construction cost can be saved as much as possible through the scheme.

Description

Technical Field

[0001] This invention relates to the field of water conservancy engineering, specifically to a three-dimensional visualization design system for farmland drainage systems based on digital twins. Background Technology

[0002] Farmland drainage refers to the technical measures taken to remove excess surface water, soil water, and groundwater from farmland through artificial means, thereby improving soil water, fertilizer, air, and heat conditions to promote crop growth. Its core task includes eliminating waterlogging. Farmland drainage primarily needs to address the drainage needs of farmland during heavy rainfall. Many factors need to be considered when designing farmland drainage systems, including the amount of drainage and the scale of construction. However, when the drainage path changes, both the drainage volume and the construction volume change accordingly. Current technology does not adequately account for this change, making it difficult to determine the optimal design scheme. Summary of the Invention

[0003] To address the aforementioned technical problems, a three-dimensional visualization design system for farmland drainage systems based on digital twins is provided. This technical solution solves the problems mentioned in the background section.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A 3D visualization design system for farmland drainage systems based on digital twins, including: The scope division module performs three-dimensional modeling of the surface of the area where the farmland is located to obtain a three-dimensional surface model. The scope of at least one farmland block is marked in the three-dimensional surface model to obtain at least one farmland scope. The part of the three-dimensional surface model other than the farmland scope is regarded as the non-farmland scope. A point generation module, which generates drainage points within the farmland area based on the terrain. The sequence generation module uniformly sets at least one sampling point in the non-farmland area, and combines it with drainage points to form at least one sampling point sequence in the farmland area. It obtains the gradient value of the measurement point in the path generated by the sampling point sequence, and filters to obtain at least one preliminary sampling point sequence in the farmland area based on the gradient value. A water channel generation module, which combines at least one overall drainage scheme based on a pre-sampled point sequence, and forms a main drainage channel and at least one secondary drainage channel based on the overall drainage scheme; A width setting module estimates the drainage demand of the farmland area and sets the cross-sectional areas of the main drainage canal and the secondary drainage canal based on the drainage demand. The scheme determination module calculates the construction workload of the overall drainage scheme based on the width of the main drainage channel and the secondary drainage channel, and takes the main drainage channel and at least one secondary drainage channel generated by the overall drainage scheme with the minimum construction workload as the final design result.

[0005] Preferably, the process of establishing drainage points within the farmland area based on the terrain includes the following steps: At least one identification point is uniformly selected within the farmland area, and at least one reference point is uniformly selected at the edge of the farmland area; Obtain the highest water level allowed for crops planted within the farmland area, and use it as a characteristic value of the farmland area; Subtract the characteristic value of the farmland area from the height of the benchmark point to obtain the reference value of the benchmark point. Identification points with heights lower than the reference value of the benchmark point are used as the associated identification points of the benchmark point. The identification value of a benchmark is obtained by dividing the number of associated identification points by the total number of identification points. The benchmark with the smallest identification value is then used as the drainage point for the farmland area.

[0006] Preferably, the process of combining drainage points to form at least one sampling point sequence within the farmland area includes the following steps: Randomly select several of the at least one sampling point to form at least one set of sampling points; The distance from the sampling point to the drainage point is used as the evaluation value of the sampling point. The sampling points in the sampling point set are arranged in ascending order of evaluation value to obtain at least one sampling point sequence within the farmland area.

[0007] Preferably, obtaining the gradient values ​​of the measurement points in the path generated by the sampling point sequence includes the following steps: The drainage point is added to the beginning of the sampling point sequence to obtain the corrected sampling point sequence. The sampling points in the corrected sampling point sequence are connected sequentially along the surface of the farmland to obtain the sampling path. At least one measurement point is uniformly selected in the sampling path, and the height of the measurement point is used as the gradient value of the measurement point.

[0008] Preferably, the step of selecting at least one preliminary sampling point sequence for the farmland area based on gradient values ​​includes the following steps: The water flow direction in the sampling path is from the drainage point to the sampling point. According to the water flow direction in the sampling path, the measurement points are numbered from largest to smallest. If the gradient values ​​of the smaller numbered measurement points in the sampling path are all smaller than the gradient values ​​of the larger numbered measurement points, then the sampling point sequence of the generated sampling path is used as the preliminary sampling point sequence.

[0009] Preferably, the step of combining at least one overall drainage scheme based on the pre-sampled point sequence includes the following steps: Select one of the at least one preliminary sampling point sequence within the farmland area and combine them to form a preliminary drainage scheme; At least one sample point is uniformly selected in the sampling path generated by the pre-sample point sequence, the coordinates of the sample point are modeled, and the coordinates of the sample point are fitted to obtain the fitting function of the sampling path. If the fitting functions of the two sampling paths have a solution when combined, then the two sampling paths are intersecting; otherwise, the two sampling paths are not intersecting. Determine whether the sampling paths generated by the preliminary sampling point sequence in the preliminary drainage scheme are intersecting. If so, no processing is performed; otherwise, the preliminary drainage scheme is used as the overall drainage scheme.

[0010] Preferably, the process of forming a main drainage channel and at least one secondary drainage channel based on the overall drainage scheme includes the following steps: The sampling path generated from the sequence of preliminary sampling points in the overall drainage scheme is used as the secondary drainage channel; The sampling point at the end of the preliminary sampling point sequence in the overall drainage scheme is taken as the target sampling point. The target sampling points are connected in descending order of height to obtain the main drainage channel.

[0011] Preferably, estimating the drainage demand for farmland includes the following steps: Project the farmland area onto a horizontal plane to obtain the farmland projection area, identify the outline of the farmland projection area, and uniformly select at least one outline point on the outline of the farmland projection area. Coordinate modeling is performed on the contour points, and the coordinates of the contour points are fitted to obtain the contour function of the farmland projection range. The area enclosed by the contour function is integrated to obtain the projected area of ​​the farmland projection range. Based on historical rainfall data of the area where the farmland is located, the maximum rainfall velocity of the farmland is obtained, where the maximum rainfall velocity is the rainfall depth per unit time. The drainage demand of the farmland area is obtained by multiplying the projected area of ​​the farmland by the maximum rainfall rate of the corresponding farmland area.

[0012] Preferably, setting the cross-sectional area of ​​the main drainage channel and the secondary drainage channel includes the following steps: The ratio of the height difference between two sampling points to the distance difference between the projected positions of the two sampling points on the horizontal plane is taken as the tangent ratio of the two sampling points. The principal tangent ratio is obtained by taking the average of the tangent ratios of adjacent sampling points in the main drainage ditch. The principal tangent ratio is then substituted into the arctangent function to obtain the principal angle. Using the main displacement formula, the main flow velocity of the main drainage canal is calculated. The drainage demand of the farmland area is then superimposed to obtain the total drainage demand. The total drainage demand is divided by the main flow velocity to obtain the cross-sectional area of ​​the main drainage canal. The average tangent ratio of adjacent sampling points in the secondary drainage ditch is taken to obtain the secondary tangent ratio. The secondary tangent ratio is then substituted into the arctangent function to obtain the secondary angle. Using the secondary displacement formula, the secondary flow velocity of the secondary drainage canal is calculated. The drainage demand of the farmland area corresponding to the secondary drainage canal is divided by the secondary flow velocity to obtain the cross-sectional area of ​​the secondary drainage canal. The principal displacement formula is as follows: , , Where S is the length of the main drainage channel, and g is the acceleration due to gravity. From the perspective of the main channel, t is the time it takes for water to flow through the main drainage channel, and v is the mainstream velocity of the main drainage channel. The formula for the secondary displacement is as follows: , , Where L is the length of the secondary drainage ditch. Let T be the secondary angle, T be the time it takes for water to flow through the secondary drainage channel, and V be the secondary flow velocity in the secondary drainage channel.

[0013] Preferably, the calculation of the overall drainage scheme's construction workload includes the following steps: The coordinates of the sampling points in the main drainage ditch are fitted to obtain the master fitting function. The length of the main drainage ditch is then calculated based on the master fitting function. Multiply the length of the main drainage ditch by its cross-sectional area to obtain the first construction quantity; The coordinates of the sampling points in the secondary drainage ditch are fitted to obtain the secondary fitting function. The length of the secondary drainage ditch is then calculated based on the secondary fitting function. Multiply the length of the secondary drainage ditch by its cross-sectional area to obtain the second construction quantity; The total construction workload of the overall drainage scheme is obtained by superimposing the first and second construction workloads.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: By setting up modules for point generation, sequence generation, canal generation, width setting, and scheme determination, multiple farmland drainage schemes are generated. The schemes are then filtered based on the physical properties of the water flow. Simultaneously, the drainage velocity is estimated based on the slope of the scheme, thereby determining the cross-sectional area of ​​the drainage system and estimating the construction volume for each scheme. This allows for the selection of a scheme that meets drainage requirements while minimizing construction costs. The entire planning process is visualized in a three-dimensional mode for easy observation of the design process. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating the three-dimensional visualization design system for farmland drainage systems based on digital twins, as described in this invention. Figure 2 This is a schematic diagram illustrating the process of forming drainage points within a farmland area based on the terrain of the farmland area according to the present invention. Figure 3 This is a schematic diagram illustrating the process of combining drainage points to form at least one sampling point sequence within a farmland area according to the present invention. Figure 4 This is a schematic diagram illustrating the process of obtaining the gradient values ​​of measurement points in the path generated by the sampling point sequence according to the present invention. Figure 5 This is a schematic diagram of the process of forming at least one overall drainage scheme based on a sequence of pre-sampled points according to the present invention. Figure 6 This is a schematic diagram of the overall drainage scheme of the present invention, which forms a main drainage channel and at least one secondary drainage channel; Figure 7 This is a schematic diagram illustrating the process of estimating the drainage demand of farmland in accordance with the present invention. Figure 8 This is a schematic diagram illustrating the process of setting the cross-sectional areas of the main drainage channel and the secondary drainage channel according to the present invention. Figure 9 This is a flowchart illustrating the construction workload for calculating the overall drainage scheme according to the present invention. Detailed Implementation

[0016] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0017] Reference Figure 1 As shown, a 3D visualization design system for farmland drainage systems based on digital twins includes: The scope division module performs three-dimensional modeling of the surface of the area where the farmland is located to obtain a three-dimensional surface model. The scope of at least one farmland block is marked in the three-dimensional surface model to obtain at least one farmland scope. The part of the three-dimensional surface model other than the farmland scope is regarded as the non-farmland scope. A point generation module, which generates drainage points within the farmland area based on the terrain. The sequence generation module uniformly sets at least one sampling point in the non-farmland area, and combines it with drainage points to form at least one sampling point sequence in the farmland area. It obtains the gradient value of the measurement point in the path generated by the sampling point sequence, and filters to obtain at least one preliminary sampling point sequence in the farmland area based on the gradient value. A water channel generation module, which combines at least one overall drainage scheme based on a pre-sampled point sequence, and forms a main drainage channel and at least one secondary drainage channel based on the overall drainage scheme; A width setting module estimates the drainage demand of the farmland area and sets the cross-sectional areas of the main drainage canal and the secondary drainage canal based on the drainage demand. The scheme determination module calculates the construction workload of the overall drainage scheme based on the width of the main drainage channel and the secondary drainage channel, and takes the main drainage channel and at least one secondary drainage channel generated by the overall drainage scheme with the minimum construction workload as the final design result.

[0018] When designing drainage systems, it is necessary to ensure that the maximum drainage demand can be met. That is, when there is heavy rain, the water in the farmland can be drained in time and the crops in the farmland will not be drowned. Therefore, the cross-sectional area of ​​the drainage ditch needs to be designed to ensure that its drainage speed can meet the drainage demand. However, the drainage speed of the drainage ditch is related to its slope. Therefore, a series of steps are set up to analyze this in the subsequent steps.

[0019] Reference Figure 2 As shown, based on the topography of the farmland area, the process of establishing drainage points within the farmland area includes the following steps: At least one identification point is uniformly selected within the farmland area, and at least one reference point is uniformly selected at the edge of the farmland area; Obtain the highest water level allowed for crops planted within the farmland area, and use it as a characteristic value of the farmland area; Subtract the characteristic value of the farmland area from the height of the benchmark point to obtain the reference value of the benchmark point. Identification points with heights lower than the reference value of the benchmark point are used as the associated identification points of the benchmark point. The identification value of a benchmark is obtained by dividing the number of associated identification points by the total number of identification points. The benchmark with the smallest identification value is then used as the drainage point for the farmland area.

[0020] Farmland is not entirely flat; some areas are high and some are low. When draining, it is necessary to select low-lying points to ensure that the water level in the farmland is kept within a range that the crops can tolerate. Therefore, when a reference point is selected as the drainage point, the water level will be limited to the same height as the reference point. Crops at reference points higher than the reference point can tolerate this water level, while crops at reference points lower than the reference point cannot. Therefore, when selecting a reference point, it is necessary to minimize the number of reference points lower than the reference point to ensure the best possible drainage effect.

[0021] Reference Figure 3 As shown, forming a sequence of at least one sampling point within a farmland area, in conjunction with drainage points, includes the following steps: Randomly select several of the at least one sampling point to form at least one set of sampling points; The distance from the sampling point to the drainage point is used as the evaluation value of the sampling point. The sampling points in the sampling point set are arranged in ascending order of evaluation value to obtain at least one sampling point sequence within the farmland area.

[0022] Reference Figure 4 As shown, obtaining the gradient values ​​of the measurement points in the path generated by the sampling point sequence includes the following steps: The drainage point is added to the beginning of the sampling point sequence to obtain the corrected sampling point sequence. The sampling points in the corrected sampling point sequence are connected sequentially along the surface of the farmland to obtain the sampling path. At least one measurement point is uniformly selected in the sampling path, and the height of the measurement point is used as the gradient value of the measurement point.

[0023] The process of selecting at least one preliminary sampling point sequence for farmland based on gradient values ​​includes the following steps: The water flow direction in the sampling path is from the drainage point to the sampling point. According to the water flow direction in the sampling path, the measurement points are numbered from largest to smallest. If the gradient values ​​of the smaller numbered measurement points in the sampling path are all smaller than the gradient values ​​of the larger numbered measurement points, then the sampling point sequence of the generated sampling path is used as the preliminary sampling point sequence.

[0024] Once the sampling path is generated, it needs to meet the drainage requirements. Therefore, the height along the sampling path must gradually decrease; otherwise, it cannot complete the normal drainage operation. Thus, the sampling point sequence needs to be filtered to ensure that the generated sampling path can complete the normal drainage operation.

[0025] Reference Figure 5 As shown, based on the sequence of pre-sampled points, forming at least one overall drainage scheme includes the following steps: Select one of the at least one preliminary sampling point sequence within the farmland area and combine them to form a preliminary drainage scheme; At least one sample point is uniformly selected in the sampling path generated by the pre-sample point sequence, the coordinates of the sample point are modeled, and the coordinates of the sample point are fitted to obtain the fitting function of the sampling path. If the fitting functions of the two sampling paths have a solution when combined, then the two sampling paths are intersecting; otherwise, the two sampling paths are not intersecting. Determine whether the sampling paths generated by the preliminary sampling point sequence in the preliminary drainage scheme are intersecting. If so, no processing is performed; otherwise, the preliminary drainage scheme is used as the overall drainage scheme.

[0026] When generating the overall drainage scheme, it is necessary to ensure that there are no intersections between the sampling paths. Otherwise, the staggered drainage will interfere with the water flow velocity, resulting in the drainage effect not meeting the expected requirements. However, taking the staggered water flow into consideration will greatly increase the complexity. Therefore, in order to simplify the consideration process, the selected overall drainage scheme does not have staggered paths.

[0027] Reference Figure 6 As shown, based on the overall drainage scheme, forming a main drainage channel and at least one secondary drainage channel includes the following steps: The sampling path generated from the sequence of preliminary sampling points in the overall drainage scheme is used as the secondary drainage channel; The sampling point at the end of the preliminary sampling point sequence in the overall drainage scheme is taken as the target sampling point. The target sampling points are connected in descending order of height to obtain the main drainage channel.

[0028] Secondary drainage ditches drain water from farmland into the main drainage ditch. Therefore, their ends are all on the main drainage ditch, and thus, the main drainage ditch can be formed by constructing their ends.

[0029] Reference Figure 7 As shown, estimating the drainage demand for farmland includes the following steps: Project the farmland area onto a horizontal plane to obtain the farmland projection area, identify the outline of the farmland projection area, and uniformly select at least one outline point on the outline of the farmland projection area. Coordinate modeling is performed on the contour points, and the coordinates of the contour points are fitted to obtain the contour function of the farmland projection range. The area enclosed by the contour function is integrated to obtain the projected area of ​​the farmland projection range. Based on historical rainfall data of the area where the farmland is located, the maximum rainfall velocity of the farmland is obtained, where the maximum rainfall velocity is the rainfall depth per unit time. The drainage demand of the farmland area is obtained by multiplying the projected area of ​​the farmland by the maximum rainfall rate of the corresponding farmland area.

[0030] Drainage demand is the rate at which the maximum amount of rainfall increases within farmland. Since rainfall is vertical and the area of ​​farmland may be the sum of slopes, when calculating the rate of rainwater accumulation, it is necessary to calculate its projected area on the horizontal plane, and then use this to calculate the drainage demand of the farmland.

[0031] Reference Figure 8 As shown, setting the cross-sectional areas of the main drainage channel and the secondary drainage channel includes the following steps: The ratio of the height difference between two sampling points to the distance difference between the projected positions of the two sampling points on the horizontal plane is taken as the tangent ratio of the two sampling points. The principal tangent ratio is obtained by taking the average of the tangent ratios of adjacent sampling points in the main drainage ditch. The principal tangent ratio is then substituted into the arctangent function to obtain the principal angle. Using the main displacement formula, the main flow velocity of the main drainage canal is calculated. The drainage demand of the farmland area is then superimposed to obtain the total drainage demand. The total drainage demand is divided by the main flow velocity to obtain the cross-sectional area of ​​the main drainage canal. The average tangent ratio of adjacent sampling points in the secondary drainage ditch is taken to obtain the secondary tangent ratio. The secondary tangent ratio is then substituted into the arctangent function to obtain the secondary angle. Using the secondary displacement formula, the secondary flow velocity of the secondary drainage canal is calculated. The drainage demand of the farmland area corresponding to the secondary drainage canal is divided by the secondary flow velocity to obtain the cross-sectional area of ​​the secondary drainage canal. The principal displacement formula is as follows: , , Where S is the length of the main drainage channel, and g is the acceleration due to gravity. From the perspective of the main channel, t is the time it takes for water to flow through the main drainage channel, and v is the mainstream velocity of the main drainage channel. The formula for the secondary displacement is as follows: , , Where L is the length of the secondary drainage ditch. Let T be the secondary angle, T be the time it takes for water to flow through the secondary drainage channel, and V be the secondary flow velocity in the secondary drainage channel.

[0032] The calculation principles for secondary flow velocity and main flow velocity are the same. Therefore, taking secondary flow velocity as an example, flow velocity is related to acceleration, and acceleration is related to slope. According to physics, when the angle of inclination is determined, the acceleration at the inclination position can be determined. For secondary drainage channels, which consist of multiple sampling points, the angles generated by adjacent sampling points can be averaged to obtain the average acceleration of the entire path. Since the length of the path is fixed, the time taken can be determined, and the average speed of the path can be calculated. The average speed multiplied by the cross-sectional area is exactly the drainage demand of the farmland area corresponding to the secondary drainage canal. Therefore, the cross-sectional area of ​​the secondary drainage canal can be calculated. The same applies to the main drainage canal.

[0033] Reference Figure 9 As shown, calculating the overall drainage scheme's construction workload includes the following steps: The coordinates of the sampling points in the main drainage ditch are fitted to obtain the master fitting function. The length of the main drainage ditch is then calculated based on the master fitting function. Multiply the length of the main drainage ditch by its cross-sectional area to obtain the first construction quantity; The coordinates of the sampling points in the secondary drainage ditch are fitted to obtain the secondary fitting function. The length of the secondary drainage ditch is then calculated based on the secondary fitting function. Multiply the length of the secondary drainage ditch by its cross-sectional area to obtain the second construction quantity; The total construction workload of the overall drainage scheme is obtained by superimposing the first and second construction workloads.

[0034] Furthermore, this solution also proposes a storage medium on which a computer-readable program is stored. When the computer-readable program is invoked, it executes the aforementioned three-dimensional visualization design system for farmland drainage systems based on digital twins.

[0035] It is understandable that the storage medium can be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; an optical medium, such as a DVD; or a semiconductor medium, such as a solid-state drive (SSD).

[0036] In summary, the advantages of this invention are as follows: by setting up a point generation module, a sequence generation module, a canal generation module, a width setting module, and a scheme determination module, multiple farmland drainage schemes are generated. Schemes are then selected based on the physical properties of the water flow. Simultaneously, the drainage velocity is estimated based on the slope of the scheme, thereby determining the cross-sectional area of ​​the drainage system and estimating the construction volume for each scheme. This allows for selection, resulting in a scheme that meets drainage requirements while minimizing construction costs. The entire planning process is visualized in a three-dimensional mode, facilitating observation of the design process.

[0037] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A three-dimensional visualization design system for farmland drainage systems based on digital twins, characterized in that, include: The scope division module performs three-dimensional modeling of the surface of the area where the farmland is located to obtain a three-dimensional surface model. The scope of at least one farmland block is marked in the three-dimensional surface model to obtain at least one farmland scope. The part of the three-dimensional surface model other than the farmland scope is regarded as the non-farmland scope. A point generation module, which generates drainage points within the farmland area based on the terrain. The sequence generation module uniformly sets at least one sampling point in the non-farmland area, and combines it with drainage points to form at least one sampling point sequence in the farmland area. It obtains the gradient value of the measurement point in the path generated by the sampling point sequence, and filters to obtain at least one preliminary sampling point sequence in the farmland area based on the gradient value. A water channel generation module, which combines at least one overall drainage scheme based on a pre-sampled point sequence, and forms a main drainage channel and at least one secondary drainage channel based on the overall drainage scheme; A width setting module estimates the drainage demand of the farmland area and sets the cross-sectional areas of the main drainage canal and the secondary drainage canal based on the drainage demand. The scheme determination module calculates the construction workload of the overall drainage scheme based on the width of the main drainage channel and the secondary drainage channel, and takes the main drainage channel and at least one secondary drainage channel generated by the overall drainage scheme with the minimum construction workload as the final design result.

2. The three-dimensional visualization design system for farmland drainage systems based on digital twins according to claim 1, characterized in that, The process of establishing drainage points within the farmland area, based on the terrain, includes the following steps: At least one identification point is uniformly selected within the farmland area, and at least one reference point is uniformly selected at the edge of the farmland area; Obtain the highest water level allowed for crops planted within the farmland area, and use it as a characteristic value of the farmland area; Subtract the characteristic value of the farmland area from the height of the benchmark point to obtain the reference value of the benchmark point. Identification points with heights lower than the reference value of the benchmark point are used as the associated identification points of the benchmark point. The identification value of a benchmark is obtained by dividing the number of associated identification points by the total number of identification points. The benchmark with the smallest identification value is then used as the drainage point for the farmland area.

3. The three-dimensional visualization design system for farmland drainage systems based on digital twins according to claim 2, characterized in that, The process of combining drainage points to form at least one sampling point sequence within the farmland area includes the following steps: Randomly select several of the at least one sampling point to form at least one set of sampling points; The distance from the sampling point to the drainage point is used as the evaluation value of the sampling point. The sampling points in the sampling point set are arranged in ascending order of evaluation value to obtain at least one sampling point sequence within the farmland area.

4. The three-dimensional visualization design system for farmland drainage systems based on digital twins according to claim 3, characterized in that, The steps for obtaining the gradient values ​​of the measurement points in the path generated by the sampling point sequence include: The drainage point is added to the beginning of the sampling point sequence to obtain the corrected sampling point sequence. The sampling points in the corrected sampling point sequence are connected sequentially along the surface of the farmland to obtain the sampling path. At least one measurement point is uniformly selected in the sampling path, and the height of the measurement point is used as the gradient value of the measurement point.

5. The three-dimensional visualization design system for farmland drainage systems based on digital twins according to claim 4, characterized in that, The process of selecting at least one preliminary sampling point sequence for farmland based on gradient values ​​includes the following steps: The water flow direction in the sampling path is from the drainage point to the sampling point. According to the water flow direction in the sampling path, the measurement points are numbered from largest to smallest. If the gradient values ​​of the smaller numbered measurement points in the sampling path are all smaller than the gradient values ​​of the larger numbered measurement points, then the sampling point sequence of the generated sampling path is used as the preliminary sampling point sequence.

6. The three-dimensional visualization design system for farmland drainage systems based on digital twins according to claim 5, characterized in that, The process of combining at least one overall drainage scheme based on the pre-sampled point sequence includes the following steps: Select one of the at least one preliminary sampling point sequence within the farmland area and combine them to form a preliminary drainage scheme; At least one sample point is uniformly selected in the sampling path generated by the pre-sample point sequence, the coordinates of the sample point are modeled, and the coordinates of the sample point are fitted to obtain the fitting function of the sampling path. If the fitting functions of the two sampling paths have a solution when combined, then the two sampling paths are intersecting; otherwise, the two sampling paths are not intersecting. Determine whether the sampling paths generated by the preliminary sampling point sequence in the preliminary drainage scheme are intersecting. If so, no processing is performed; otherwise, the preliminary drainage scheme is used as the overall drainage scheme.

7. The three-dimensional visualization design system for farmland drainage systems based on digital twins according to claim 6, characterized in that, The process of forming a main drainage channel and at least one secondary drainage channel based on the overall drainage scheme includes the following steps: The sampling path generated from the sequence of preliminary sampling points in the overall drainage scheme is used as the secondary drainage channel; The sampling point at the end of the preliminary sampling point sequence in the overall drainage scheme is taken as the target sampling point. The target sampling points are connected in descending order of height to obtain the main drainage channel.

8. The three-dimensional visualization design system for farmland drainage systems based on digital twins according to claim 7, characterized in that, The estimation of drainage requirements for farmland includes the following steps: Project the farmland area onto a horizontal plane to obtain the farmland projection area, identify the outline of the farmland projection area, and uniformly select at least one outline point on the outline of the farmland projection area. Coordinate modeling is performed on the contour points, and the coordinates of the contour points are fitted to obtain the contour function of the farmland projection range. The area enclosed by the contour function is integrated to obtain the projected area of ​​the farmland projection range. Based on historical rainfall data of the area where the farmland is located, the maximum rainfall velocity of the farmland is obtained, where the maximum rainfall velocity is the rainfall depth per unit time. The drainage demand of the farmland area is obtained by multiplying the projected area of ​​the farmland by the maximum rainfall rate of the corresponding farmland area.

9. The three-dimensional visualization design system for farmland drainage systems based on digital twins according to claim 8, characterized in that, Setting the cross-sectional area of ​​the main drainage channel and the secondary drainage channel includes the following steps: The ratio of the height difference between two sampling points to the distance difference between the projected positions of the two sampling points on the horizontal plane is taken as the tangent ratio of the two sampling points. The principal tangent ratio is obtained by taking the average of the tangent ratios of adjacent sampling points in the main drainage ditch. The principal tangent ratio is then substituted into the arctangent function to obtain the principal angle. Using the main displacement formula, the main flow velocity of the main drainage canal is calculated. The drainage demand of the farmland area is then superimposed to obtain the total drainage demand. The total drainage demand is divided by the main flow velocity to obtain the cross-sectional area of ​​the main drainage canal. The average tangent ratio of adjacent sampling points in the secondary drainage ditch is taken to obtain the secondary tangent ratio. The secondary tangent ratio is then substituted into the arctangent function to obtain the secondary angle. Using the secondary displacement formula, the secondary flow velocity of the secondary drainage canal is calculated. The drainage demand of the farmland area corresponding to the secondary drainage canal is divided by the secondary flow velocity to obtain the cross-sectional area of ​​the secondary drainage canal. The principal displacement formula is as follows: ， ， Where S is the length of the main drainage channel, and g is the acceleration due to gravity. From the perspective of the main channel, t is the time it takes for water to flow through the main drainage channel, and v is the mainstream velocity of the main drainage channel. The formula for the secondary displacement is as follows: ， ， Where L is the length of the secondary drainage ditch. Let T be the secondary angle, T be the time it takes for water to flow through the secondary drainage channel, and V be the secondary flow velocity in the secondary drainage channel.

10. The three-dimensional visualization design system for farmland drainage systems based on digital twins according to claim 9, characterized in that, The calculation of the overall drainage scheme's construction workload includes the following steps: The coordinates of the sampling points in the main drainage ditch are fitted to obtain the master fitting function. The length of the main drainage ditch is then calculated based on the master fitting function. Multiply the length of the main drainage ditch by its cross-sectional area to obtain the first construction quantity; The coordinates of the sampling points in the secondary drainage ditch are fitted to obtain the secondary fitting function. The length of the secondary drainage ditch is then calculated based on the secondary fitting function. Multiply the length of the secondary drainage ditch by its cross-sectional area to obtain the second construction quantity; The total construction workload of the overall drainage scheme is obtained by superimposing the first and second construction workloads.

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