Method, system, device, medium and program product for extracting boundaries of closed blocks

Abstract

The present disclosure provides a method, system, device, medium and program product for extracting the boundary of a closed land parcel, the method comprising: obtaining a sequence of sampling points along a closed land parcel; each sampling point comprising geographic coordinates and instantaneous heading angle; calculating the contribution degree of each sampling point based on the geographic coordinates and the instantaneous heading angle; removing the sampling point with the lowest contribution degree from the sequence of sampling points, and recalculating the contribution degrees of the two sampling points adjacent to the removed sampling point to obtain new contribution degrees; in response to the number of sampling points being greater than a preset number threshold, jumping to the previous step; and in response to the number of sampling points being less than or equal to the number threshold, taking the sampling points in the current sequence of sampling points as the topological nodes of the boundary. The present disclosure measures the influence of the sampling points on the bending degree of the local boundary through an area contribution term, and measures the heading change rate of the sampling points through a heading change contribution term, and takes into account the removal of coordinate noise and the accurate retention of geometric corners, while ensuring shape fidelity at a high compression rate.

Description

Technical Field

[0001] This disclosure relates to the field of surveying and mapping technology, and in particular to a method, system, device, medium, and program product for extracting the boundaries of closed land parcels. Background Technology

[0002] Existing boundary extraction algorithms rely solely on spatial distance, resulting in insufficient recognition of motion features. Especially when mapping data contains random jumps (noise), existing algorithms cannot simultaneously address both "removing coordinate noise" and "accurately preserving geometric corners," and they struggle to guarantee shape fidelity under extremely high compression rates. Summary of the Invention

[0003] The technical problem to be solved by this disclosure is to address the aforementioned deficiencies in the prior art, and to provide a method, system, device, medium, and program product for extracting the boundaries of closed plots.

[0004] This disclosure solves the above-mentioned technical problems through the following technical solution:

[0005] This disclosure provides a method for extracting the boundary of a closed land parcel, the boundary extraction method comprising:

[0006] Obtain a sequence of sampling points along the closed plot; wherein each sampling point in the sampling point sequence includes geographic coordinates and instantaneous heading angle;

[0007] The contribution of each sampling point in the sampling point sequence is calculated based on the geographic coordinates and the instantaneous heading angle.

[0008] Remove the sampling point with the lowest contribution from the sampling point sequence to obtain a new sampling point sequence, and recalculate the contribution of the two sampling points adjacent to the removed sampling point to obtain the contribution of the sampling points in the new sampling point sequence;

[0009] If the number of sampling points in the sampling point sequence is greater than a preset number threshold, proceed to the previous step; if the number of sampling points in the sampling point sequence is less than or equal to the number threshold, proceed to the next step.

[0010] The sampling points in the current sampling point sequence are used as the topological nodes of the boundary.

[0011] Optionally, obtaining the sampling point sequence around the closed plot includes:

[0012] The initial sampling point sequence is obtained by moving the measuring device around the closed plot and sampling.

[0013] A tail sampling point is added to the end of the initial sampling point sequence to obtain the sampling point sequence; wherein, the geographical coordinates and the instantaneous heading angle of the tail sampling point are the same as those of the first sampling point of the initial sampling point sequence.

[0014] Optionally, the contribution degree includes an area contribution term and a heading change contribution term. The area contribution term represents the area of the triangle formed by the target sampling point and two adjacent sampling points, and the heading change contribution term represents the included angle difference of the instantaneous heading angles between the target sampling point and the two adjacent sampling points.

[0015] Calculating the contribution degree of each sampling point in the sampling point sequence based on the geographical coordinates and the instantaneous heading angle includes:

[0016] Calculating the area contribution term of each sampling point based on the geographical coordinates, and calculating the heading change contribution term of each sampling point based on the instantaneous heading angle.

[0017] For each sampling point, determining the corresponding angle weight coefficient according to the heading change contribution term.

[0018] For each sampling point, calculating the corresponding contribution degree according to a preset first proportional coefficient, a preset second proportional coefficient, the corresponding area contribution term, the corresponding heading change contribution term, and the corresponding angle weight coefficient.

[0019] Optionally, the sampling point sequence and calculating the contribution degree of each sampling point are represented by the following formula:

[0020] P = P1, P2, …, P N , P i =(x i , y i , θ i );

[0021] ;

[0022] When 1 < i < N:

[0023] ;

[0024] Δθ i = atan2(sin(θ i+1 - θ i-1 ), cos(θ i+1 - θ i-1 ));

[0025] When i = 1:

[0026] ;

[0027] Δθ1 = atan2(sin(θ2-θ)) N ),cos ( θ2-θ N ));

[0028] When i=N:

[0029] ;

[0030] Δθ N = atan2(sin ( θ1-θ N-1 ),cos ( θ1-θ N-1 ));

[0031] Where P represents the sampling point sequence, and N represents the number of sampling points in the current sampling point sequence. i x represents the sampling point with index i in the sampling point sequence. i The x-coordinate of the sampling point i in the geographic coordinate system is represented by y. i θ represents the ordinate of the geographic coordinates of the sampling point i. i This represents the instantaneous heading angle of the sampling point with index i.

[0032] S i K represents the contribution of the sampling point with index i. β K represents the first proportionality coefficient. α A represents the second proportionality coefficient. i Δθ represents the area contribution term of the sampling point at index i. i W represents the heading change contribution term of the sampling point with index i. i The angle weighting coefficient of the sampling point with index i is indicated.

[0033] x i-1 The x-coordinate of the geographic coordinates of the sampling point with index (i-1) is represented by x. i+1 The x-coordinate of the geographic coordinates of the sampling point with index (i+1) is represented by y. i-1 The y-coordinate in the geographic coordinates of the sampling point with index (i-1) is represented by the ordinate. i+1 The vertical coordinate of the sampling point with index (i+1) in the geographic coordinates;

[0034] atan2 represents the arctangent function in four quadrants, sin represents the sine function, cos represents the cosine function, and θ... i-1 θ represents the instantaneous heading angle of the sampling point with index (i-1). i+1 The instantaneous heading angle of the sampling point with index (i+1) is represented.

[0035] Optionally, determining the corresponding angle weighting coefficient for each sampling point based on the heading change contribution term includes:

[0036] For each sampling point, in response to the absolute value of the corresponding heading change contribution item being greater than a preset heading angle threshold, the corresponding angle weight coefficient is set to a preset first weight value; in response to the absolute value of the corresponding heading change contribution item being less than or equal to the heading angle threshold, the corresponding angle weight coefficient is set to a preset second weight value.

[0037] The first weight value is several times larger than the second weight value.

[0038] Alternatively, the angle weighting coefficient can be determined using the following formula:

[0039] ;

[0040] Among them, W i Δθ represents the angle weighting coefficient of the sampling point with index i in the sampling point sequence. i θ represents the heading change contribution of the sampling point with index i. th This represents the heading angle threshold.

[0041] This disclosure also provides a boundary extraction system for closed land parcels, the boundary extraction system comprising: an acquisition module and an extraction module;

[0042] The acquisition module is used to acquire a sequence of sampling points around the closed plot; wherein, each sampling point in the sampling point sequence includes geographic coordinates and instantaneous heading angle;

[0043] The extraction module is used to calculate the contribution of each sampling point in the sampling point sequence based on the geographic coordinates and the instantaneous heading angle;

[0044] The extraction module is further configured to remove the sampling point with the lowest contribution from the sampling point sequence to obtain a new sampling point sequence, and recalculate the contribution of the two sampling points adjacent to the removed sampling point to obtain the contribution of the sampling points in the new sampling point sequence;

[0045] The extraction module is further configured to, in response to the number of sampling points in the sampling point sequence being greater than a preset number threshold, jump to the previous step; and in response to the number of sampling points in the sampling point sequence being less than or equal to the number threshold, proceed to the next step.

[0046] The extraction module is also used to use the sampling points in the current sampling point sequence as the topological nodes of the boundary.

[0047] Optionally, the obtaining module is further configured to obtain an initial sampling point sequence obtained by sampling when the measuring device moves around the closed plot;

[0048] The obtaining module is further configured to add a tail sampling point at the end of the initial sampling point sequence to obtain the sampling point sequence; wherein, the geographical coordinates and instantaneous heading angle of the tail sampling point are the same as those of the first sampling point of the initial sampling point sequence.

[0049] Optionally, the contribution degree includes an area contribution term and a heading change contribution term, the area contribution term represents the area of the triangle formed by the target sampling point and two adjacent sampling points, and the heading change contribution term represents the included angle difference of the instantaneous heading angles between the target sampling point and the two adjacent sampling points;

[0050] The extraction module is further configured to calculate the area contribution term of each sampling point based on the geographical coordinates, and calculate the heading change contribution term of each sampling point based on the instantaneous heading angle;

[0051] The extraction module is further configured to determine a corresponding angle weight coefficient for each sampling point according to the heading change contribution term;

[0052] The extraction module is further configured to calculate the corresponding contribution degree for each sampling point according to a preset first proportional coefficient, a preset second proportional coefficient, the corresponding area contribution term, the corresponding heading change contribution term, and the corresponding angle weight coefficient.

[0053] Optionally, the sampling point sequence and the contribution degree of each sampling point are represented by the following formula:

[0054] P = P1, P2, …, P N , P i =(x i , y i , θ i );

[0055] ;

[0056] When 1 < i < N:

[0057] ;

[0058] Δθ i = atan2(sin(θ i+1 - θ i-1 ), cos(θ i+1 - θ i-1 ));

[0059] When i=1:

[0060] ;

[0061] Δθ1 = atan2(sin(θ2-θ)) N ),cos ( θ2-θ N ));

[0062] When i=N:

[0063] ;

[0064] Δθ N = atan2(sin ( θ1-θ N-1 ),cos ( θ1-θ N-1 ));

[0065] Where P represents the sampling point sequence, and N represents the number of sampling points in the current sampling point sequence. i x represents the sampling point with index i in the sampling point sequence. i The x-coordinate of the sampling point i in the geographic coordinate system is represented by y. i θ represents the ordinate of the geographic coordinates of the sampling point i. i This represents the instantaneous heading angle of the sampling point with index i.

[0066] S i K represents the contribution of the sampling point with index i. β K represents the first proportionality coefficient. α A represents the second proportionality coefficient. i Δθ represents the area contribution term of the sampling point at index i. i W represents the heading change contribution term of the sampling point with index i. i The angle weighting coefficient of the sampling point with index i is indicated.

[0067] x i-1 The x-coordinate of the geographic coordinates of the sampling point with index (i-1) is represented by x. i+1 The x-coordinate of the geographic coordinates of the sampling point with index (i+1) is represented by y. i-1 The y-coordinate in the geographic coordinates of the sampling point with index (i-1) is represented by the ordinate. i+1 The vertical coordinate of the sampling point with index (i+1) in the geographic coordinates;

[0068] atan2 represents the arctangent function in four quadrants, sin represents the sine function, cos represents the cosine function, and θ... i-1 θ represents the instantaneous heading angle of the sampling point with index (i-1).i+1 The instantaneous heading angle of the sampling point with index (i+1) is represented.

[0069] Optionally, the extraction module is further configured to, for each sampling point, in response to the absolute value of the corresponding heading change contribution item being greater than a preset heading angle threshold, set the corresponding angle weight coefficient to a preset first weight value; and in response to the absolute value of the corresponding heading change contribution item being less than or equal to the heading angle threshold, set the corresponding angle weight coefficient to a preset second weight value.

[0070] The first weight value is several times larger than the second weight value.

[0071] Alternatively, the angle weighting coefficient can be determined using the following formula:

[0072] ;

[0073] Among them, W i Δθ represents the angle weighting coefficient of the sampling point with index i in the sampling point sequence. i θ represents the heading change contribution of the sampling point with index i. th This represents the heading angle threshold.

[0074] This disclosure also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and for running on the processor, wherein the processor executes the computer program to implement the aforementioned method for extracting the boundaries of closed plots.

[0075] This disclosure also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the aforementioned method for extracting the boundaries of closed plots.

[0076] This disclosure also provides a computer program product, including a computer program that, when executed by a processor, implements the aforementioned method for extracting the boundaries of closed plots.

[0077] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of this disclosure.

[0078] The positive and progressive effects of this disclosure are as follows: the contribution of each sampling point in the sampling point sequence is calculated based on geographic coordinates and instantaneous heading angle. Only one sampling point with the lowest contribution is removed from the sampling point sequence at a time, and the contribution of the two affected adjacent sampling points is recalculated to obtain the contribution of the sampling points in the new sampling point sequence. This process continues until the number of sampling points is greater than a preset threshold, thereby continuously increasing the compression to a certain limit. The sampling points in the current sampling point sequence are used as the topological nodes of the boundary. The contribution includes an area contribution and a heading change contribution. The area contribution measures the influence of the sampling point on the bending degree of the local boundary, and the heading change contribution measures the heading change rate of the sampling point. By continuously increasing the compression, it can balance "removing coordinate noise" and "accurately preserving geometric corners". At the same time, it can also preserve the instantaneous heading angle by sampling points with high contribution to ensure shape fidelity under extremely high compression. Attached Figure Description

[0079] Figure 1 A flowchart illustrating a method for extracting the boundary of a closed land parcel, as provided in Embodiment 1 of this disclosure;

[0080] Figure 2 A flowchart illustrating a specific implementation of step S11 of a method for extracting the boundary of a closed plot provided in Embodiment 1 of this disclosure;

[0081] Figure 3 A flowchart illustrating a specific implementation of step S12 of a method for extracting the boundary of a closed plot provided in Embodiment 1 of this disclosure;

[0082] Figure 4 This is a schematic diagram of a boundary extraction system for a closed land parcel provided in Embodiment 2 of this disclosure;

[0083] Figure 5 This is a schematic diagram of the structure of an electronic device provided in Embodiment 3 of this disclosure. Detailed Implementation

[0084] The present disclosure is further illustrated below by way of embodiments, but the present disclosure is not limited to the scope of the embodiments described herein.

[0085] The prefixes such as "first" and "second" used in this disclosure are merely for distinguishing different descriptive objects and do not limit the position, order, priority, quantity, or content of the described objects. The use of ordinal numbers and other prefixes used to distinguish descriptive objects in this disclosure does not constitute a limitation on the described objects. The description of the described objects is given in the claims or the context of the embodiments, and should not be construed as an unnecessary limitation. Furthermore, in the description of this embodiment, unless otherwise stated, "multiple" means two or more.

[0086] Example 1

[0087] Figure 1 A flowchart illustrating a method for extracting the boundary of a closed land parcel, provided as an exemplary embodiment of this disclosure, is included. The boundary extraction method comprises:

[0088] S11. Obtain the sampling point sequence along a closed plot. Each sampling point in the sampling point sequence includes geographic coordinates and instantaneous heading angle.

[0089] S12. Calculate the contribution of each sampling point in the sampling point sequence based on geographic coordinates and instantaneous heading angle.

[0090] S13. Remove the sampling point with the lowest contribution from the sampling point sequence to obtain a new sampling point sequence. Recalculate the contribution of the two sampling points adjacent to the removed sampling point to obtain the contribution of the sampling points in the new sampling point sequence.

[0091] S14. If the number of sampling points in the sampling point sequence is greater than the preset number threshold, jump to the previous step; if the number of sampling points in the sampling point sequence is less than or equal to the number threshold, proceed to the next step.

[0092] S15. Use the sampling points in the current sampling point sequence as the boundary topology nodes.

[0093] In this sampling point sequence, the sampling points are obtained by sampling along a closed plot. Due to the sampling time interval, the tail sampling point (termination point) is close to or coincides with the first sampling point (starting point) in geographic coordinates, which can link the first and tail sampling points (i.e., the starting point and the termination point) to ensure the topological closure of the plot.

[0094] The existing technology has the following specific defects:

[0095] (1) Limitations of single-dimensional judgment: Traditional algorithms (such as Douglas-Peucker) only utilize geometric positions. When there is a noise jitter of 5cm at the sampling point, if the threshold is set to a small value, such as 3cm, the algorithm will mistakenly retain a large number of noise points, resulting in a jagged boundary of the plot; if the threshold is set to a large value, the real corner information will be lost.

[0096] (2) Loss of semantic information: The existing point set simplification ignores the heading angle vector during sampling. In actual operation, even if the coordinate offset is small, the drastic change in heading angle often represents a critical boundary turning point. Traditional algorithms will straighten it, causing serious contour distortion.

[0097] (3) The contradiction between compression and accuracy: In order to filter out noise, traditional algorithms must increase the distance threshold, which will cause small concave and convex features (such as the grooves on the side of a rectangle) to be completely erased.

[0098] In this embodiment, the contribution rate can comprehensively reflect the influence of the sampling point on the bending degree of the local boundary and the rate of change of the sampling point's heading. Specifically, the contribution rate can include an area contribution term and a heading change contribution term. The area contribution term measures the influence of the sampling point on the bending degree of the local boundary, and the heading change contribution term measures the rate of change of the sampling point's heading.

[0099] The contribution is calculated for the entire sequence, which means traversing the scoring sequence.

[0100] After calculating the contribution of the entire sequence, only one sampling point with the lowest contribution is removed at a time, and the contributions of the two affected adjacent sampling points are recalculated. This is done in real-time iteration, recalculating the contributions of the affected neighboring sampling points. Since the contributions of adjacent sampling points change after removing the sampling point with the lowest contribution, the contributions of the two adjacent sampling points affected by the removed sampling point are updated, while the contributions of other sampling points remain unchanged.

[0101] The process iterates repeatedly until the number of sampling points exceeds a preset threshold, achieving a sufficiently high compression ratio, even an extremely high compression ratio for a significant proportion of land parcel sampling point data. During compression, key boundary transitions are preserved, enabling dynamic greedy iterative elimination. A typical implementation can reduce 500 sampling points to 8-10 skeletal feature points, with a maximum compression rate exceeding 95%, providing users with boundary points that fully preserve land parcel features. The number threshold can be set according to specific needs.

[0102] Based on the hard constraint of the heading angle, the algorithm is naturally immune to noise that causes erratic coordinate jumps but a stable heading. It can automatically filter out measurement deviations, restore smooth physical edges, and achieve intelligent noise reduction with a sense of direction.

[0103] The identification is extremely accurate by using small features with small geographical coordinate offsets but large changes in heading angle (such as local concavity of the edge of a rectangle), avoiding the phenomenon of corners being forcibly straightened, and achieving high-fidelity restoration of tiny concave and convex features.

[0104] Based on the closed-loop design, the final output set of sampling points (i.e. feature points) can be directly used for area calculation, boundary cruise and automatic navigation tasks without additional post-processing, achieving native topological closure consistency.

[0105] In this embodiment, the contribution of each sampling point in the sampling point sequence is calculated based on geographic coordinates and instantaneous heading angle. Only one sampling point with the lowest contribution is removed from the sampling point sequence at a time, and the contribution of the two affected adjacent sampling points is recalculated to obtain the contribution of the sampling points in the new sampling point sequence. This process continues until the number of sampling points is greater than a preset threshold, that is, the compression is continuously increased to a certain limit. The sampling points in the current sampling point sequence are used as the topological nodes of the boundary. The contribution includes area contribution and heading change contribution. The area contribution measures the influence of the sampling point on the bending degree of the local boundary, and the heading change contribution measures the heading change rate of the sampling point. By continuously increasing the compression, it can take into account both "removing coordinate noise" and "accurately preserving geometric corners". At the same time, it can also preserve the instantaneous heading angle by sampling points with high contribution to ensure shape fidelity under extremely high compression.

[0106] In an optional embodiment, refer to Figure 2 Step S11 includes:

[0107] S111. Obtain the initial sampling point sequence obtained by moving the measuring device around the closed plot to collect samples.

[0108] S112. Add a tail sampling point to the end of the initial sampling point sequence to obtain a sampling point sequence. The geographical coordinates and instantaneous heading angle of the tail sampling point are the same as those of the first sampling point in the initial sampling point sequence.

[0109] The measuring device can be either a drone or a vehicle.

[0110] In this embodiment, a tail sampling point P is added at the end of the initial sampling point sequence. N P N =P1, which makes the data in the sequence automatically close. Whether or not a tail sampling point is added does not affect the contribution calculation and number compression of the sampling points. Adding a tail sampling point that is the same as the first sampling point will automatically close the first and last points to facilitate program checking and verification.

[0111] In an optional embodiment, the contribution includes an area contribution term and a heading change contribution term. The area contribution term represents the area of ​​the triangle formed by the target sampling point and two adjacent sampling points, and the heading change contribution term represents the angle difference between the instantaneous heading angles of the target sampling point and two adjacent sampling points.

[0112] Reference Figure 3 Step S12 includes:

[0113] S121. Calculate the area contribution of each sampling point based on geographic coordinates, and calculate the heading change contribution of each sampling point based on instantaneous heading angle.

[0114] S122. For each sampling point, determine the corresponding angle weighting coefficient based on the heading change contribution term.

[0115] S123. For each sampling point, calculate the corresponding contribution based on the preset first proportional coefficient, the preset second proportional coefficient, the corresponding area contribution item, the corresponding heading change contribution item, and the corresponding angle weighting coefficient.

[0116] The first and second proportional coefficients are used to balance the area contribution (geometric component) and the heading change contribution. The first and second proportional coefficients can be set according to the actual situation.

[0117] With sampling points (P) i The sampling point with index i in the sampling point sequence is taken as the current target sampling point, and the area contribution term (A) is calculated. i ) is used to measure sampling points (P) i The contribution (influence) of the degree of bending of the local boundary, the area contribution term (A) i ) is the current target sampling point (P) i ) and its two adjacent sampling points (P) i-1 and P i+1 The area of ​​the directed triangle formed by these three points (default unit: square meters) is larger. The larger the absolute value of the area, the larger the sampling point (P) is. i The further it deviates from the line connecting the front and back.

[0118] The contribution of heading change (Δθ) i ) is used to measure sampling points (P) i A large rate of change in heading is more important for extracting boundary topology. A larger angle weighting coefficient makes it less likely for points to be removed; the angle weighting coefficient is used to ensure that important sampling points are not removed. The angle weighting coefficient can be set according to the actual situation.

[0119] In this embodiment, the area contribution term is used to measure the contribution (influence) of the sampling point on the bending degree of the local boundary. The area contribution term is the area of ​​the directed triangle formed by the three points. The larger the absolute value of the area, the more the sampling point deviates from the front and back lines. The heading change contribution term is used to measure the heading change rate of the sampling point. The larger the heading change rate, the more important it is for extracting the boundary topology. The larger the angle weight coefficient, the less likely it is to be removed. The angle weight coefficient is used to ensure that important sampling points are not removed.

[0120] In an optional embodiment, the following formula is used to represent the sampling point sequence and to calculate the contribution of each sampling point:

[0121] P = P1, P2, ..., P N , P i =(x i ,y i ,θi )。

[0122] 。

[0123] When 1 < i < N:

[0124] 。

[0125] Δθ i = atan2(sin ( θ i+1 -θ i-1 ),cos ( θ i+1 -θ i-1 ))。

[0126] When i = 1:

[0127] 。

[0128] Δθ1 = atan2(sin ( θ2 - θ N ),cos ( θ2 - θ N ))。

[0129] When i = N:

[0130] 。

[0131] Δθ N = atan2(sin ( θ1 - θ N-1 ),cos ( θ1 - θ N-1 ))。

[0132] Where P represents the sampling point sequence, N represents the number of sampling points in the current sampling point sequence, P i represents the sampling point with sequence number i in the sampling point sequence, x i represents the abscissa in the geographical coordinates of the sampling point with sequence number i, y i represents the ordinate in the geographical coordinates of the sampling point with sequence number i, θ i represents the instantaneous heading angle of the sampling point with sequence number i.

[0133] S i represents the contribution degree of the sampling point with sequence number i, K β represents the first proportionality coefficient, K α represents the second proportionality coefficient, A i represents the area contribution term of the sampling point with sequence number i, Δθ i represents the heading change contribution term of the sampling point with sequence number i, W i represents the angular weight coefficient of the sampling point with sequence number i.

[0134] x i-1The x-coordinate of the geographic coordinates of the sampling point with index (i-1) is represented by x. i+1 The x-coordinate of the geographic coordinates of the sampling point with index (i+1) is represented by y. i-1 The y-coordinate of the geographic coordinates of the sampling point with index (i-1) is represented by the ordinate. i+1 The vertical coordinate of the sampling point with index (i+1) in the geographic coordinates.

[0135] atan2 represents the arctangent function in four quadrants, sin represents the sine function, cos represents the cosine function, and θ... i-1 θ represents the instantaneous heading angle of the sampling point with index (i-1). i+1 The instantaneous heading angle of the sampling point with index (i+1) is represented.

[0136] The heading change contribution term uses the atan2 formula to avoid jumps across 0 / 360 degrees. The contribution calculation for the first and last sampling points is similar to that for sampling points between sequences. One of the first and last sampling points may be removed, but neither will be removed.

[0137] This embodiment provides a specific implementation method for calculating contribution.

[0138] In an optional embodiment, step S122 includes:

[0139] For each sampling point, in response to the absolute value of the corresponding heading change contribution being greater than a preset heading angle threshold, the corresponding angle weight coefficient is set to a preset first weight value; in response to the absolute value of the corresponding heading change contribution being less than or equal to the heading angle threshold, the corresponding angle weight coefficient is set to a preset second weight value.

[0140] The first weight value is several times larger than the second weight value.

[0141] Among them, the heading angle threshold (e.g., 30 degrees), the first weight value, and the second weight value can be set according to the actual situation.

[0142] In this embodiment, nonlinear feature gain is achieved through a first weight value and a second weight value. By setting the corresponding angle weight coefficient to the first weight value, it is ensured that sampling points whose absolute value of the heading change contribution (the change in heading angle of adjacent points) is greater than the heading angle threshold are not removed, that is, it is ensured that sampling points that reflect the boundary topological transition are not accidentally deleted.

[0143] In an optional embodiment, the angle weighting coefficient is determined using the following formula:

[0144] .

[0145] Among them, W iΔθ represents the angle weighting coefficient of sampling point i in the sampling point sequence. i θ represents the heading change contribution of sampling point i. th This indicates the heading angle threshold.

[0146] In this embodiment, the first weight value is several times larger than the second weight value. The first weight value can be an order of magnitude higher than the second weight value. For example, the first weight value is set to 10 and the second weight value is set to 1.

[0147] Example 2

[0148] Corresponding to the aforementioned embodiments of the method for extracting the boundaries of closed plots, this disclosure also provides embodiments of a system for extracting the boundaries of closed plots.

[0149] Figure 4 This is a schematic diagram of a boundary extraction system for a closed plot of land, provided as an exemplary embodiment of the present disclosure. The system includes: an acquisition module 1 and an extraction module 2.

[0150] Acquisition module 1 is used to acquire a sequence of sampling points along a closed plot. Each sampling point in the sequence includes geographic coordinates and instantaneous heading angle.

[0151] Extraction module 2 is used to calculate the contribution of each sampling point in the sampling point sequence based on geographic coordinates and instantaneous heading angle.

[0152] Extraction module 2 is also used to remove the sampling point with the lowest contribution from the sampling point sequence to obtain a new sampling point sequence, and recalculate the contribution of the two sampling points adjacent to the removed sampling point to obtain the contribution of the sampling points in the new sampling point sequence.

[0153] Extraction module 2 is also used to jump to the previous step in response to the number of sampling points in the sampling point sequence being greater than a preset number threshold; and to proceed to the next step in response to the number of sampling points in the sampling point sequence being less than or equal to the number threshold.

[0154] Extraction module 2 is also used to define topological nodes with the sampling points in the current sampling point sequence as boundaries.

[0155] In this embodiment, the contribution of each sampling point in the sampling point sequence is calculated based on geographic coordinates and instantaneous heading angle. Only one sampling point with the lowest contribution is removed from the sampling point sequence at a time, and the contribution of the two affected adjacent sampling points is recalculated to obtain the contribution of the sampling points in the new sampling point sequence. This process continues until the number of sampling points is greater than a preset threshold, that is, the compression is continuously increased to a certain limit. The sampling points in the current sampling point sequence are used as the topological nodes of the boundary. The contribution includes area contribution and heading change contribution. The area contribution measures the influence of the sampling point on the bending degree of the local boundary, and the heading change contribution measures the heading change rate of the sampling point. By continuously increasing the compression, it can take into account both "removing coordinate noise" and "accurately preserving geometric corners". At the same time, it can also preserve the instantaneous heading angle by sampling points with high contribution to ensure shape fidelity under extremely high compression.

[0156] In an optional embodiment, the acquisition module 1 is further configured to acquire the initial sampling point sequence obtained by the measuring device moving around the closed plot to collect samples.

[0157] The acquisition module 1 is also used to add a tail sampling point at the end of the initial sampling point sequence to obtain a sampling point sequence. The geographical coordinates and instantaneous heading angle of the tail sampling point are the same as those of the first sampling point in the initial sampling point sequence.

[0158] In an optional embodiment, the contribution includes an area contribution term and a heading change contribution term. The area contribution term represents the area of ​​the triangle formed by the target sampling point and two adjacent sampling points, and the heading change contribution term represents the angle difference between the instantaneous heading angles of the target sampling point and two adjacent sampling points.

[0159] Extraction module 2 is also used to calculate the area contribution of each sampling point based on geographic coordinates and the heading change contribution of each sampling point based on instantaneous heading angle.

[0160] Extraction module 2 is also used to determine the corresponding angle weighting coefficient for each sampling point based on the contribution of heading change.

[0161] Extraction module 2 is also used to calculate the corresponding contribution for each sampling point based on the preset first proportional coefficient, the preset second proportional coefficient, the corresponding area contribution item, the corresponding heading change contribution item, and the corresponding angle weighting coefficient.

[0162] In an optional embodiment, the following formula is used to represent the sampling point sequence and to calculate the contribution of each sampling point:

[0163] P = P1, P2, ..., P N , P i =(x i ,y i ,θi )

[0164] .

[0165] When 1 < i < N:

[0166] .

[0167] Δθ i = atan2(sin(θ i+1 - θ i-1 ), cos(θ i+1 - θ i-1 ))

[0168] When i = 1:

[0169] .

[0170] Δθ1 = atan2(sin(θ2 - θ N ), cos(θ2 - θ N ))

[0171] When i = N:

[0172] .

[0173] Δθ N = atan2(sin(θ1 - θ N-1 ), cos(θ1 - θ N-1 ))

[0174] Where P represents the sampling point sequence, N represents the number of sampling points in the current sampling point sequence, P i represents the sampling point with serial number i in the sampling point sequence, x i represents the abscissa in the geographical coordinates of the sampling point with serial number i, y i represents the ordinate in the geographical coordinates of the sampling point with serial number i, θ i represents the instantaneous heading angle of the sampling point with serial number i

[0175] S i represents the contribution degree of the sampling point with serial number i, K β represents the first proportionality coefficient, K α represents the second proportionality coefficient, A i represents the area contribution term of the sampling point with serial number i, Δθ i represents the heading change contribution term of the sampling point with serial number i, W i represents the angular weight coefficient of the sampling point with serial number i

[0176] x i-1The x-coordinate of the geographic coordinates of the sampling point with index (i-1) is represented by x. i+1 The x-coordinate of the geographic coordinates of the sampling point with index (i+1) is represented by y. i-1 The y-coordinate of the geographic coordinates of the sampling point with index (i-1) is represented by the ordinate. i+1 The vertical coordinate of the sampling point with index (i+1) in the geographic coordinates.

[0177] atan2 represents the arctangent function in four quadrants, sin represents the sine function, cos represents the cosine function, and θ... i-1 θ represents the instantaneous heading angle of the sampling point with index (i-1). i+1 The instantaneous heading angle of the sampling point with index (i+1) is represented.

[0178] In an optional embodiment, the extraction module 2 is further configured to, for each sampling point, in response to the absolute value of the corresponding heading change contribution item being greater than a preset heading angle threshold, set the corresponding angle weight coefficient to a preset first weight value; and in response to the absolute value of the corresponding heading change contribution item being less than or equal to the heading angle threshold, set the corresponding angle weight coefficient to a preset second weight value.

[0179] The first weight value is several times larger than the second weight value.

[0180] In an optional embodiment, the angle weighting coefficient is determined using the following formula:

[0181] .

[0182] Among them, W i Δθ represents the angle weighting coefficient of sampling point i in the sampling point sequence. i θ represents the heading change contribution of sampling point i. th This indicates the heading angle threshold.

[0183] For the system embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to in the description of the method embodiments. The system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this disclosure according to actual needs.

[0184] Example 3

[0185] Figure 5This is a schematic diagram of the structure of an electronic device according to an example embodiment of the present disclosure. The electronic device includes a memory, a processor, and a computer program stored in the memory and used to run on the processor. When the processor executes the computer program, it implements the boundary extraction method for closed plots described in any of the above embodiments. Figure 5 The electronic device 90 shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments disclosed herein.

[0186] like Figure 5 As shown, the electronic device 90 can be manifested as a general-purpose computing device, such as a server device. The components of the electronic device 90 may include, but are not limited to: at least one processor 91, at least one memory 92, and a bus 93 connecting different system components (including memory 92 and processor 91).

[0187] Bus 93 includes a data bus, an address bus, and a control bus.

[0188] The memory 92 may include volatile memory, such as random access memory (RAM) 921 and / or cache memory 922, and may further include read-only memory (ROM) 923.

[0189] The memory 92 may also include a program tool 925 (or utility) having a set (at least one) program module 924, such program module 924 including but not limited to: an operating system, one or more application programs, other program modules, and program data, each or some combination of these examples may include an implementation of a network environment.

[0190] The processor 91 executes various functional applications and data processing by running computer programs stored in the memory 92, such as the boundary extraction method for closed plots provided in any of the above embodiments.

[0191] Electronic device 90 can also communicate with one or more external devices 94 (e.g., keyboard, pointing device, etc.). This communication can be performed through input / output (I / O) interface 95. Furthermore, electronic device 90 can also communicate with one or more networks (e.g., local area network (LAN), wide area network (WAN), and / or public network, such as the Internet) via network adapter 96. As shown, network adapter 96 communicates with other modules of electronic device 90 via bus 93. It should be understood that, although not shown in the figure, other hardware and / or software modules can be used in conjunction with electronic device 90, including but not limited to: microcode, device drivers, redundant processors, external disk drive arrays, RAID (disk array) systems, tape drives, and data backup storage systems.

[0192] It should be noted that although several units / modules or sub-units / modules of the electronic device have been mentioned in the detailed description above, this division is merely exemplary and not mandatory. In fact, according to embodiments of this disclosure, the features and functions of two or more units / modules described above can be embodied in one unit / module. Conversely, the features and functions of one unit / module described above can be further divided and embodied by multiple units / modules.

[0193] Example 4

[0194] This disclosure also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the boundary extraction method for closed plots provided in any of the above embodiments.

[0195] The readable storage medium may be more specifically adopted, including but not limited to: portable disk, hard disk, random access memory, read-only memory, erasable programmable read-only memory, optical storage device, magnetic storage device, or any suitable combination thereof.

[0196] Example 5

[0197] This disclosure also provides a computer program product, including a computer program that, when executed by a processor, implements the boundary extraction method for closed plots as described in any of the preceding embodiments.

[0198] The program code for executing the computer program product of this disclosure can be written in any combination of one or more programming languages, and the program code can be executed entirely on a user device, partially on a user device, as a stand-alone software package, partially on a user device and partially on a remote device, or entirely on a remote device.

[0199] While specific embodiments of this disclosure have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of this disclosure is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of this disclosure, but all such changes and modifications fall within the scope of protection of this disclosure.

Claims

1. A method for extracting the boundary of a closed land parcel, characterized in that, The boundary extraction method includes: Obtaining a sequence of sampling points along one circle of the closed plot; wherein, each sampling point in the sequence of sampling points includes a geographic coordinate and an instantaneous heading angle; Calculating the contribution degree of each sampling point in the sequence of sampling points based on the geographic coordinate and the instantaneous heading angle; Removing the sampling point with the lowest contribution degree from the sequence of sampling points to obtain a new sequence of sampling points, and recalculating the contribution degrees of the two sampling points adjacent to the removed sampling point to obtain the contribution degrees of the sampling points in the new sequence of sampling points; In response to the number of sampling points in the sequence of sampling points being greater than a preset number threshold, jumping to the previous step; in response to the number of sampling points in the sequence of sampling points being less than or equal to the number threshold, proceeding to the next step; Using the sampling points in the current sequence of sampling points as the topological nodes of the boundary.

2. The method for extracting the boundary of a closed plot as described in claim 1, characterized in that, The obtaining of the sequence of sampling points along one circle of the closed plot includes: Obtaining an initial sequence of sampling points obtained by a measuring device sampling along one circle of the closed plot; Adding a tail sampling point at the end of the initial sequence of sampling points to obtain the sequence of sampling points; wherein, the geographic coordinate and the instantaneous heading angle of the tail sampling point are the same as those of the head sampling point of the initial sequence of sampling points.

3. The method for extracting the boundary of a closed plot as described in claim 1, characterized in that, The contribution degree includes an area contribution term and a heading change contribution term. The area contribution term represents the area of the triangle formed by the target sampling point and two adjacent sampling points, and the heading change contribution term represents the included angle difference of the instantaneous heading angles between the target sampling point and the two adjacent sampling points; The calculating of the contribution degree of each sampling point in the sequence of sampling points based on the geographic coordinate and the instantaneous heading angle includes: Calculating the area contribution term of each sampling point based on the geographic coordinate, and calculating the heading change contribution term of each sampling point based on the instantaneous heading angle; For each sampling point, determining a corresponding angle weight coefficient according to the heading change contribution term; For each sampling point, calculating the corresponding contribution degree according to a preset first proportional coefficient, a preset second proportional coefficient, the corresponding area contribution term, the corresponding heading change contribution term, and the corresponding angle weight coefficient.

4. The method for extracting the boundary of a closed plot as described in claim 3, characterized in that, The following formula is used to represent the sequence of sampling points and calculate the contribution degree of each sampling point: P=P1,P2,… ,P N , P i =(x i ,y i ,θ i ); ； When 1 < i < N: ； Dth i = atan2(sin ( θ i+1 -θ i-1 ),cos (θ i+1 -θ i-1 )); When i = 1: ； Δθ1= atan2(sin ( θ2-θ N ),cos (θ2-θ N )); When i = N: ； Dth N = atan2(sin ( θ1-θ N-1 ),cos ( θ1-θ N-1 )); Where P represents the sampling point sequence, and N represents the number of sampling points in the current sampling point sequence. i x represents the sampling point with index i in the sampling point sequence. i The x-coordinate of the sampling point i in the geographic coordinate system is represented by y. i θ represents the ordinate of the geographic coordinates of the sampling point i. i This represents the instantaneous heading angle of the sampling point with index i. S i K represents the contribution of the sampling point with index i. β K represents the first proportionality coefficient. α A represents the second proportionality coefficient. i Δθ represents the area contribution term of the sampling point at index i. i W represents the heading change contribution term of the sampling point with index i. i The angle weighting coefficient of the sampling point with index i is indicated. x i-1 The x-coordinate of the geographic coordinates of the sampling point with index (i-1) is represented by x. i+1 The x-coordinate of the geographic coordinates of the sampling point with index (i+1) is represented by y. i-1 The y-coordinate in the geographic coordinates of the sampling point with index (i-1) is represented by the ordinate. i+1 The vertical coordinate of the sampling point with index (i+1) in the geographic coordinates; atan2 represents the arctangent function in four quadrants, sin represents the sine function, cos represents the cosine function, and θ... i-1 θ represents the instantaneous heading angle of the sampling point with index (i-1). i+1 The instantaneous heading angle of the sampling point with index (i+1) is represented.

5. The method for extracting the boundary of a closed plot as described in claim 3, characterized in that, The determining of the corresponding angle weight coefficient for each sampling point according to the heading change contribution term includes: For each sampling point, in response to the absolute value of the corresponding heading change contribution term being greater than a preset heading angle threshold, setting the corresponding angle weight coefficient to a preset first weight value; in response to the absolute value of the corresponding heading change contribution term being less than or equal to the heading angle threshold, setting the corresponding angle weight coefficient to a preset second weight value; Wherein, the first weight value is several times larger than the second weight value.

6. The method for extracting the boundary of a closed plot as described in claim 5, characterized in that, The following formula is used to determine the angle weight coefficient: ； Among them, W i Δθ represents the angle weighting coefficient of the sampling point with index i in the sampling point sequence. i θ represents the heading change contribution of the sampling point with index i. th This represents the heading angle threshold.

7. A boundary extraction system for closed land parcels, characterized in that, The boundary extraction system includes: an acquisition module, an extraction module; The acquisition module is used to acquire a sequence of sampling points around the closed plot; wherein, each sampling point in the sampling point sequence includes geographic coordinates and instantaneous heading angle; The extraction module is used to calculate the contribution of each sampling point in the sampling point sequence based on the geographic coordinates and the instantaneous heading angle; The extraction module is further configured to remove the sampling point with the lowest contribution from the sampling point sequence to obtain a new sampling point sequence, and recalculate the contribution of the two sampling points adjacent to the removed sampling point to obtain the contribution of the sampling points in the new sampling point sequence; The extraction module is further configured to, in response to the number of sampling points in the sampling point sequence being greater than a preset number threshold, jump to the previous step; and in response to the number of sampling points in the sampling point sequence being less than or equal to the number threshold, proceed to the next step. The extraction module is also used to use the sampling points in the current sampling point sequence as the topological nodes of the boundary.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and for running on the processor, characterized in that, When the processor executes the computer program, it implements the boundary extraction method for closed plots as described in any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the boundary extraction method for closed plots as described in any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the boundary extraction method for closed plots as described in any one of claims 1-6.

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