Automatic river curve contradiction detection method

Abstract

The embodiment of the invention provides an automatic river curve contradiction detection method, and relates to the technical field of geographic information data processing, and the method comprises the following steps: generating river element data and contour line element data through vector map data, traversing the river element data and the contour line element data, and calculating a river curve contradiction; the intersection points and the elevation values corresponding to the intersection points are stored in the river element data; elevation values of all points corresponding to each river element in the river element data are obtained, and all the points of the river elements are sorted according to the descending order of the elevation values; traversing the intersection point coordinate list, calculating to obtain a first direction angle corresponding to the first vector line segment, and calculating to obtain a second direction angle corresponding to the second vector line segment; and judging whether the river element curve has contradiction or not through the angle of the first direction angle, the angle of the second direction angle and the sensitivity value. According to the scheme, through automatic detection, the river curve contradiction detection efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of geographic information data processing, and in particular to a method for automatically detecting river bend contradictions. Background Art

[0002] In the construction of basic surveying and mapping geography, the problem of river bend contradictions not only affects the reading and use of maps, but also has a negative impact on the production and update of basic geographic spatial data. Therefore, river bend contradiction detection is an important part of map quality detection, and it plays an important role in improving the accuracy and application value of map data. With the continuous advancement of technology, automated and intelligent data detection methods are becoming more perfect and popular, thus providing stronger support for the quality control of basic surveying and mapping geographic data.

[0003] The current automatic detection of river bend contradictions mainly considers that river elements cross the same contour line multiple times in a small area. For the contradiction problem that river elements do not follow the valley direction, the method of manual visual detection is basically adopted. This method is slow and inefficient. When performing batch detection operations, it requires a lot of manpower and material resources, and the operation cycle is long. In addition, the effect of manual visual detection is better when the deviation of the valley of the river element not passing through the contour line is large, but when the deviation is small, it basically relies on personal experience and judgment, it is difficult to grasp the standard, and it is easy to miss the inspection.

[0004] In summary, the existing river bend contradiction detection methods have low automation, incomplete detection, low efficiency, and are difficult to cope with batch detection tasks. In the face of increasing vector map data, there is an urgent need for a river bend contradiction detection method that is fast, low cost, accurate and reliable, comprehensive and highly automated. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides a method for automatically detecting river bend contradictions to solve the technical problems of difficulty in judging river bend contradictions and low degree of automation in the prior art. The method comprises:

[0006] Generate river element data and contour element data through vector map data, traverse the river element data and contour element data, obtain the intersection point of each river element and the contour line, generate a list of intersection point coordinates, and save the intersection point and the elevation value corresponding to the intersection point into the river element data;

[0007] Obtain the elevation values ​​of all points corresponding to each river element in the river element data, take the river element as a unit, sort all the points of the river element in descending order of elevation value, and generate sorted river element data;

[0008] Traverse the intersection point coordinate list, take the intersection point as the center point, determine the first vector line segment along the direction of the contour line through the contour line feature data, calculate and obtain the first direction angle corresponding to the first vector line segment, traverse the intersection point coordinate list, take the intersection point as the starting point, determine the second vector line segment along the direction of the river element flow through the sorted river element data, and calculate and obtain the second direction angle corresponding to the second vector line segment;

[0009] Set the sensitivity value, and determine whether there is a contradiction in the river bend based on the angle of the first direction angle, the angle of the second direction angle, and the sensitivity value.

[0010] Compared with the prior art, the at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0011] By inserting intersection points into river feature data without elevation values ​​and calculating the elevation value of each component point of the river feature, adjusting the component points of the river feature data so that the elevation values ​​are sorted from large to small, checking and filtering the river feature data after the intersection points are inserted, calculating the directions of the vector line segments on both sides of the intersection points on the contour lines, and calculating the angle between each contour line vector and the river feature vector, the river bend contradiction in the vector map data can be detected. This detection method has strong accuracy and high reliability, can effectively improve the detection speed of river bend contradictions, and avoid the problems of missed detection and high-frequency false detection in manual detection and traditional methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 It is a flow chart of a method for automatically detecting river bend contradictions provided by an embodiment of the present invention;

[0014] Figure 2 is a flow chart of a method for automatically detecting river bend contradictions provided by an embodiment of the present invention;

[0015] Figure 3 It is a schematic diagram of the azimuth angle calculation principle provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0017] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0018] The embodiment of the present invention proposes an automatic detection method for river bend contradictions, aiming to solve the shortcomings of current detection technology and improve the accuracy and efficiency of detection. The specific steps are as follows:

[0019] First, calculate all the intersections of rivers and contour lines, and assign elevation values ​​to the corresponding contour lines. Secondly, sort the river intersections in descending order according to their elevation values, and obtain the linear river elements after inserting the intersections. Calculate the azimuths of the vector segments on both sides of the intersections on the contour lines from near to far, as well as the azimuths of the vector segments from the intersection point to the current intersection point of the river element and then to the next intersection point. Finally, calculate the angle between the azimuth of the vector segment on each contour line element and the azimuth of the vector segment on the river element, and count the ratio of all angles less than 90 degrees. If the ratio is less than the preset sensitivity value (the default value is 0.75), it is judged that there is a river bend contradiction; otherwise, it is judged that there is no river bend contradiction.

[0020] In an embodiment of the present invention, a method for automatically detecting river meander contradictions is provided, such as Figure 1 and Figure 2 As shown, the method includes:

[0021] Step S101: Generate river element data and contour element data through vector map data, traverse the river element data and contour element data, obtain the intersection point of each river element and the contour line, generate a list of intersection point coordinates, and save the intersection point and the elevation value corresponding to the intersection point into the river element data;

[0022] Step S102: obtaining the elevation values ​​of all points corresponding to each river element in the river element data, taking the river element as a unit, and sorting all the points of the river element in descending order of elevation values, to generate sorted river element data;

[0023] Step S103: traverse the intersection point coordinate list, take the intersection point as the center point, determine the first vector line segment along the direction of the contour line through the contour line element data, calculate and obtain the first direction angle corresponding to the first vector line segment, traverse the intersection point coordinate list, take the intersection point as the starting point, determine the second vector line segment along the direction of the river element flow through the sorted river element data, and calculate and obtain the second direction angle corresponding to the second vector line segment;

[0024] Step S104: setting a sensitivity value, and judging whether there is a contradiction in the river bend by the angle of the first direction angle, the angle of the second direction angle and the sensitivity value.

[0025] In the specific implementation, in order to calculate the intersection point of the current river element and the contour line and the contour line element data containing the intersection line, filter out the river elements that have no intersection relationship with the contour line, and leave the river elements that have an intersection relationship with the contour line. The following steps are used to traverse the river element data and the contour line element data, obtain the intersection point of each river element and the contour line, generate a list of intersection point coordinates, and insert the intersection point into the corresponding contour line element data:

[0026] Traverse the river feature data and perform the following operations until all river features in the river feature data are processed: traverse the contour line feature data to obtain the intersection point between the current river feature and the contour line. If there is an intersection point, save the intersection point to the intersection point coordinate list; obtain the elevation value of the corresponding intersection point based on the elevation value of the contour line; traverse the intersection point coordinate list and insert the intersection point and the corresponding elevation value of the intersection point into the corresponding contour line feature data.

[0027] Specifically, the contour feature data and river feature data are filtered out from the vector map data according to the type of landforms, and the elevation value is obtained from the attribute record corresponding to the current contour line. The elevation value is assigned to the current contour line data and the Z coordinate is established, so that the contour line X, Y coordinates become X, Y, Z coordinates.

[0028] In the specific implementation, in order to unify all river feature data into single-line river feature data, the following steps are performed to convert the double-line river feature data into single-line river feature data:

[0029] The river element type of each river element in the river element data is determined, and the double-line river element data in the river element data is converted into single-line river element data according to the river element type, and then saved in the river element data.

[0030] Specifically, determine whether the river element is a single-line river element or a double-line river element. If it is a double-line river element, calculate the center line of the spatial geometry of the double-line river element, and convert the double-line river element into a single-line river element through the center line of the spatial geometry, so as to simplify the river element data.

[0031] Specifically, the linear river elements are traversed, and then the contour line elements are traversed, and then the intersection points of the current linear river elements and the contour line elements are found to generate a list of river-contour line element intersection point coordinates that have an intersection relationship with both the river and the contour line.

[0032] In the specific implementation, in order to sort the river feature data according to the elevation value (that is, the rivers (river features) are sorted according to the physical characteristics of flowing from high to low), the elevation value is first calculated, and the elevation values ​​of all points of each river feature in the river feature data are obtained through the following steps:

[0033] Get the coordinate dimension of each river feature in the river feature data; if the coordinate dimension is two-dimensional, calculate the elevation values ​​of all points in each river feature through the intersection point coordinate list; if the coordinate dimension is three-dimensional, get the elevation values ​​of all points in each river feature.

[0034] In specific implementation, the following steps are used to calculate the elevation values ​​of all points in each river element through the intersection point coordinate list:

[0035] Traverse the intersection point coordinate list and insert the intersection point into the corresponding river feature data; calculate the distance between the intersection point and other points in the river feature, and calculate the elevation values ​​of all points in each river feature through the distance and the elevation value of the intersection point.

[0036] Specifically, determine the coordinate dimension of the river element. If it is two-dimensional, insert the traversed intersection points into the corresponding river element point list, and calculate the elevation values ​​of the remaining points according to the ratio of the contour distance between the two points and the length of the river element between the contour lines of the two points.

[0037] In the specific implementation, in order to delete abnormal river element data from the river element data (abnormal means that the elevation value of the river element rises with the flow direction of the river element, that is, the river flows from low to high), the following steps are performed to directly obtain the elevation value and delete the abnormal data if the coordinate dimension of the river element is three-dimensional:

[0038] If the coordinate dimension of the river element is three-dimensional, before obtaining the elevation value of the river element, determine whether the elevation value corresponding to each river element in the river element data satisfies the condition from high to low; if the condition is not met, save the data of the river element to the abnormal river element data and delete it from the river element data.

[0039] Specifically, the first two points of the river element are used to determine whether the elevation values ​​of the current river component points are from high to low or from low to high. If it is from low to high, the order of the current river elements is reversed to form an order from high to low.

[0040] Specifically, if the coordinate dimension of the river element is three-dimensional, it is determined whether the elevation values ​​of all points in the current river element data satisfy the condition that the elevation value of the previous point is greater than the elevation value of the next point. If not, it is recorded in the abnormal river spatial geometry list; otherwise, it is recorded in the normal linear river element list.

[0041] In specific implementation, in order to calculate the direction of the first vector line segment on both sides of the intersection point on the contour line, the following steps are used to traverse the intersection point coordinate list, take the intersection point as the center point, determine the first vector line segment along the direction of the contour line through the contour line feature data, and calculate the angle of the first direction angle corresponding to the first vector line segment:

[0042] Traverse the intersection point coordinate list and perform the following operations until all intersection points are processed: traverse the contour line feature data, take the intersection point as the center point, use the distance difference method, and determine multiple first vector line segments along the two directions of the contour line; take the angle between each first vector line segment and the positive direction of the X-axis of the coordinate system where the intersection point coordinate list is located as the first direction angle, and obtain multiple first direction angles.

[0043] In a specific implementation, in order to facilitate the calculation of the first direction angle, the following steps are performed to convert the first direction angle into an angle within a set angle range if the first direction angle exceeds 360 degrees:

[0044] After obtaining the first direction angle, obtain the angle of the first direction angle; determine whether the angle of each first direction angle is within a set angle range, where the set angle range is 0 to 360 degrees; if the angle of the first direction angle is not within the set angle range, convert the angle of each first direction angle to within the set angle range.

[0045] like Figure 3 As shown, the list of intersection points of contour lines and rivers (the list of intersection point coordinates) is traversed, and after obtaining the intersection point, the coordinate points on the contour line are traversed again to find the current intersection point on the contour line using the distance difference method, and then the two nearest vector line segments c1, c2, c3, and c4 on both sides of the intersection point on the contour line are calculated, and the azimuth of these four vector line segments from the near intersection point to the far intersection point is calculated. If the calculated azimuth is not within the range of 0 to 360 degrees, the azimuth of the c1, c2, c3, and c4 vectors is added or subtracted by an appropriate multiple of 360 degrees, and the azimuth of the c1, c2, c3, and c4 vectors is converted to the range of 0 to 360 degrees.

[0046] The distance difference method is to calculate the distance between two points less than a certain minimum value (for example, 10 -8 ). Taking the two closest vector segments on both sides of the intersection point on the same contour line can increase the reliability of the judgment.

[0047] The method for determining the second direction angle is the same as the first direction angle (traverse the intersection point coordinate list and perform the following operations until all intersection points are processed: traverse the river feature data, take the intersection point as the starting point, and determine the second vector line segment along the flow direction of the river feature through the sorted river feature data). Use the same method as that for determining the first direction angle to find the intersection point on the river feature (the intersection point of the river feature and the contour line), and calculate the second azimuth angle of the vector line segment r1 from the intersection point to the next point of the intersection point (the angle between the second vector line segment and the positive direction of the X-axis, Figure 3 In the embodiment of the invention, the calculated angle is 1, and the angle of the second azimuth of the r1 vector is converted to the range of 0 to 360 degrees by the same method as in the previous step. The direction of flow of the river element is from high to low according to the elevation value of the river element point.

[0048] In specific implementation, the following steps are used to determine whether a river bend is contradictory based on the angle of the first direction angle, the angle of the second direction angle, and the sensitivity value:

[0049] Determine the number of angles less than 90 degrees among the angles of the first direction angle and the angles of the second direction angle, take the number as the judgment basis number, and take the sum of the number of the first direction angle and the number of the second direction angle as the total number; calculate the ratio of the judgment basis number to the total number, and take the ratio as the actual sensitivity value; compare the actual sensitivity value with the sensitivity value, if the actual sensitivity value is less than the sensitivity value, then the river bend has a contradiction, if the actual sensitivity value is greater than or equal to the sensitivity value, then the river bend has no contradiction.

[0050] Specifically, the ratio of the number of angles less than 90 degrees to the total number of angles (first direction angle and second direction angle) between the c1, c2, c3 and c4 vector segments (four first vector segments) on the contour lines and the r1 vector segment (one second vector segment) on the linear river elements is calculated through the above recorded results. By comparing the ratio with the input sensitivity value, it is determined whether there is a river bend contradiction. If the ratio is less than the input sensitivity value (the default is 0.75), there is a river bend contradiction, otherwise there is no river bend contradiction.

[0051] The automatic detection method for river bend contradictions of the embodiment of the present invention improves the accuracy and efficiency of river bend contradiction detection, and can also effectively reduce the workload of manual inspection, thereby ensuring the quality and consistency of vector map data. Through automated analysis, river bend contradictions can be quickly and reliably identified and processed, thereby optimizing the production process of vector map data.

[0052] The embodiments of the present invention achieve the following technical effects:

[0053] The automatic detection method for river bend contradictions in the embodiment of the present invention can quickly check for logical errors in the direction of river elements that are inconsistent with common sense from the entire vector map data containing dense contour lines and complex river elements; through automated detection, the accuracy and efficiency of river bend contradiction detection can be greatly improved, human errors can be reduced, and at the same time, the dependence on manual detection can be reduced, reducing labor costs and resource consumption; by accurately calculating the spatial relationship between river elements and contour lines, and combining geographical common sense to make reasonable judgments, the efficiency of river bend contradiction detection is significantly improved, and it is suitable for large-scale, high-precision vector map data quality detection, which not only optimizes the detection process of vector map data, but also provides a solid foundation for the application of geographic spatial data.

[0054] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the embodiments of the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for automatically detecting river meander contradictions, characterized in that: include: Generate river element data and contour element data through vector map data, traverse the river element data and contour element data, obtain the intersection point of each river element and the contour line, generate a list of intersection point coordinates, and save the intersection point and the elevation value corresponding to the intersection point into the river element data; Obtaining the elevation values ​​of all points corresponding to each river element in the river element data, taking the river element as a unit, and sorting all the points of the river element in descending order of the elevation values, to generate sorted river element data; Traversing the intersection point coordinate list, taking the intersection point as the center point, determining a first vector line segment along the direction of the contour line through the contour line element data, and calculating a first direction angle corresponding to the first vector line segment; traversing the intersection point coordinate list, taking the intersection point as the starting point, determining a second vector line segment along the direction of flow of the river element through the sorted river element data, and calculating a second direction angle corresponding to the second vector line segment; A sensitivity value is set, and whether there is a contradiction in the river bend is determined according to the angle of the first direction angle, the angle of the second direction angle, and the sensitivity value.

2. The automatic detection method for river bend contradictions according to claim 1, characterized in that: Traversing the intersection point coordinate list, taking the intersection point as the center point, determining a first vector line segment along the direction of the contour line through the contour line element data, and calculating a first direction angle corresponding to the first vector line segment, including: Traverse the intersection point coordinate list and perform the following operations until all the intersection points are processed; Traversing the contour line element data, taking the intersection point as the center point, using the distance difference method, and determining a plurality of first vector line segments along two directions of the contour line; The angle between each of the first vector line segments and the positive direction of the X-axis of the coordinate system where the intersection point coordinate list is located is taken as a first direction angle to obtain a plurality of the first direction angles.

3. The automatic detection method for river bend contradictions as claimed in claim 2, characterized in that: Also includes: After obtaining the first direction angle, obtaining the angle of the first direction angle; Determine whether each of the first direction angles is within a set angle range, wherein the set angle range is 0 to 360 degrees; If the angle of the first direction angle is not within the set angle range, the angle of each of the first direction angles is converted to within the set angle range.

4. The automatic detection method for river bend contradictions according to claim 1, characterized in that: Judging whether there is a contradiction in the river bend by using the angle of the first direction angle, the angle of the second direction angle and the sensitivity value includes: Determine the number of angles less than 90 degrees among the first direction angle and the second direction angle, use the number as the determination basis quantity, and use the sum of the number of the first direction angle and the number of the second direction angle as the total quantity; Calculating the ratio of the number of judgment bases to the total number, and taking the ratio as the actual sensitivity value; Whether there is a contradiction in the river bend is determined based on the actual sensitivity value and the sensitivity value.

5. The automatic detection method for river bend contradictions according to claim 4 is characterized in that: Judging whether there is a contradiction between the meander according to the actual sensitivity value and the sensitivity value includes: Comparing the actual sensitivity value with the sensitivity value, if the actual sensitivity value is smaller than the sensitivity value, then there is a contradiction in the meander; If the actual sensitivity value is greater than or equal to the sensitivity value, there is no contradiction in the meander.

6. The automatic detection method for river bend contradictions according to claim 1, characterized in that: Traversing the river element data and the contour line element data, obtaining the intersection points of each river element and the contour line, generating a list of intersection point coordinates, and saving the intersection points and the elevation values ​​corresponding to the intersection points to the river element data, including: Traversing the river element data, performing the following operations until all river elements in the river element data are processed; Traversing the contour line element data, obtaining the intersection point between the current river element and the contour line, and if the intersection point exists, saving the intersection point into the intersection point coordinate list; According to the elevation value of the contour line, obtain the elevation value of the corresponding intersection point; The intersection point coordinate list is traversed, and the intersection points and the elevation values ​​corresponding to the intersection points are inserted into the corresponding contour line element data.

7. The automatic detection method for river bend contradictions according to claim 1, characterized in that: Obtaining the elevation values ​​of all points corresponding to each river element in the river element data, including: Obtaining the coordinate dimension of each river element in the river element data; If the coordinate dimension is two-dimensional, the elevation values ​​of all points in each river element are calculated through the intersection point coordinate list; If the coordinate dimension is three-dimensional, obtain the elevation values ​​of all points in each river element.

8. The automatic detection method for river bend contradictions according to claim 7, characterized in that: The elevation values ​​of all points in each river element are calculated through the intersection point coordinate list, including: Traversing the intersection point coordinate list, and inserting the intersection point into the corresponding river element data; The distance between the intersection point and other points in the river element is calculated, and the elevation values ​​of all points in each river element are calculated through the distance and the elevation value of the intersection point.

9. The method for automatically detecting river meander contradictions according to any one of claims 1 to 8, characterized in that: Also includes: The river element type of each river element in the river element data is determined, and after converting the double-line river element data in the river element data into single-line river element data according to the river element type, the data is saved in the river element data.

10. The method for automatically detecting river meander contradictions according to any one of claims 1 to 8, characterized in that: Also includes: If the coordinate dimension of the river element is three-dimensional, before obtaining the elevation value of the river element, determine whether the elevation value corresponding to each river element in the river element data satisfies the order from high to low; If the condition is not met, the data of the river element is saved to the abnormal river element data and deleted from the river element data.

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