A method based on structured digital base maps and line mileage mapping

Abstract

The application discloses a kind of methods based on structured digital bottom map and line mileage mapping, method includes the following steps: function relationship between line segment curve and city coordinate system is established, line segment curve includes straight line segment, circular curve segment and easement curve segment;According to function relationship, line mileage is converted into plane coordinate under city coordinate system;Mapping relationship between SVG pixel point and line mileage is established;According to mapping relationship, SVG pixel point is converted into line mileage, or according to line mileage, the position of corresponding SVG pixel point is determined;Based on function relationship and mapping relationship, the bidirectional conversion between SVG pixel point, line mileage and plane coordinate is realized.The advantages of the present application are: the plane coordinate-line mileage-SVG pixel point automatic bidirectional conversion method based on rail transit line mileage is realized, which provides a basis for the precise positioning and viewport calling of rail transit digital objects in GIS scenario.

Description

Technical Field

[0001] This invention relates to the technical field of rail transit, and in particular to a method based on mapping structured digital base maps to line mileage. Background Technology

[0002] Rail transit is a multi-disciplinary, long-lifespan, and multi-level transportation system involving elevated, ground-level, and underground structures. The track area is the main functional area for maintaining its transportation function. Throughout the entire lifecycle of rail transit planning, design, construction, operation, and maintenance, the route plan, longitudinal profile, and plan and longitudinal profile drawings are the fundamental drawings and data for collaborative work among various disciplines. They contain precise geometric information about the route, information on the distribution of equipment along the route, and the spatial relationships between various disciplines.

[0003] Currently, rail transit line design deliverables are primarily in CAD format, including tables of horizontal curve elements, coordinate tables of each stake, and information on longitudinal profile slope change points. These documents offer high accuracy and complete information, playing a crucial role in the construction phases such as line design and construction layout. However, as urban rail transit gradually transitions from a large-scale construction phase to an operation and maintenance phase, the traditional design deliverable format, represented by CAD, is showing increasingly obvious limitations in the digital application of the operation and maintenance phase.

[0004] The main problems with existing technologies are as follows: (1) CAD design results are difficult to apply directly in the Internet and digital scenarios: Rail transit line alignment and longitudinal profile maps are curve combinations that map one-to-one with GIS coordinates, characterized by their singular mileage and accurate representation of length and direction. However, existing design deliverables are all in CAD format, with their underlying data structures and storage methods designed for printing and professional design software, making them unsuitable for direct display and interactive operation on lightweight terminals such as web and mobile devices. In operation and maintenance management scenarios such as equipment inspection, fault location, and emergency repair, the need for readily available, on-demand access to basic data is extremely urgent, but CAD files are large, rely on specialized software, and have low levels of data structuring, making it difficult to support these application scenarios.

[0005] (2) The underground space lacks the support of a satellite positioning system, resulting in inaccurate matching of ground and underground locations: Most urban rail transit lines are located underground, and the areas where train operations and maintenance personnel work lack signal coverage from satellite positioning systems such as GPS and BeiDou. The correspondence between ground coordinates and underground locations cannot be directly obtained through satellite positioning. As a result, during routine maintenance and emergency repairs, ground command personnel have difficulty accurately knowing the precise location of underground workers, making it difficult to coordinate location information between different specialties and easily leading to location mismatches.

[0006] (3) There is a gap in the way the route plan is expressed compared to the operation and maintenance management requirements: Rail transit construction has a long cycle, with a planning and design lifespan of up to 100 years. During this period, there is both original data from the construction phase and updated data generated from major renovations during the operation phase. The data delivered during the design and construction phases contain a large number of professional terms and engineering symbols. Furthermore, due to the different versions of specifications required during the construction phase, there are differences in the way drawings are expressed and annotation habits. During the operation and maintenance phase, there is a lack of visual and intuitive ways of expressing these data, making it difficult for front-line operation and maintenance personnel to understand and apply them, and easily leading to misuse of the data.

[0007] (4) Lack of location-based basic data organization and retrieval methods: The basic data for rail transit is diverse and abundant, including dozens of professional drawings and documents such as line alignment and longitudinal profiles, equipment layout diagrams along the line, communication and signaling system diagrams, power supply system diagrams, and track structure diagrams. Currently, this data is mostly stored and managed in discrete file formats, lacking an organizational method based on spatial location as the core index. When maintenance personnel need to access relevant data for a specific location on-site, they cannot retrieve it through the intuitive "click location → get data" method; they must first manually search through a large number of files, which is inefficient and prone to omissions.

[0008] (5) There is a contradiction between the expressive precision of the SVG format and the requirements of circuit engineering: SVG is an object-oriented image representation for the internet, with advantages such as small file size, support for interactive operations, and the ability to bind data to elements, making it suitable for display on the web. However, it uses pixels as the basic drawing unit and does not have a length dimension. When an SVG graphic is enlarged or reduced, the correspondence between pixels and physical length changes, making it unsuitable for direct use in precise length measurement and position calculation in rail transit line engineering.

[0009] To address some of the aforementioned issues, several technical solutions have been explored. These include improving the rendering methods for SVG tile maps and map road annotations in general mapping applications, and optimizing the management and reuse efficiency of SVG icons. However, these solutions do not address the specific application scenario of rail transit line profile maps, nor do they solve the problem of accurate mapping between line mileage, urban coordinate systems, and SVG pixels. Furthermore, they do not address underground space positioning based on line mileage or the structured organization of basic data.

[0010] Therefore, the rail transit industry urgently needs a structured base map generation method that can migrate CAD design results to the Internet, and realize accurate two-way conversion between line mileage, urban coordinate system and SVG pixels, so as to provide basic support for the digital management of the entire life cycle of rail transit lines. Summary of the Invention

[0011] The purpose of this invention is to address the shortcomings of the prior art by providing a method based on the mapping of structured digital base maps and railway line mileage. This method establishes a functional relationship between the segmented curves of each railway line and the urban coordinate system based on the curve element table of the rail transit line plane, providing a basis for subsequent pixel-mileage-coordinate conversion calculations.

[0012] The objective of this invention is achieved through the following technical solutions: A method based on mapping structured digital base maps to route mileage, the method comprising the following steps: S1: Establish the functional relationship between the segmented curves of the route and the urban coordinate system. The segmented curves of the route include straight line segments, circular curve segments, and transition curve segments. S2: Based on the aforementioned functional relationship, convert the route mileage into planar coordinates in the urban coordinate system; S3: Establish the mapping relationship between SVG pixels and line mileage; S4: Based on the mapping relationship, convert the SVG pixels into line mileage, or determine the position of the corresponding SVG pixels based on the line mileage; S5: Based on the functional relationship and the mapping relationship, realize the bidirectional conversion between SVG pixels, line mileage, and planar coordinates.

[0013] Step S1 specifically includes: Obtain the city coordinates of each segment node of the route, wherein the segment nodes include the endpoints of straight line segments, circular curve segments, and transition curve segments; Establish coordinate functions for straight line segments, circular curve segments, and transition curve segments respectively; Connect the coordinate functions of each segmented curve according to the route to form a segmented function table for the entire route.

[0014] In step S1, the coordinate function of the line segment is calculated as follows: When the mileage point k Located in the i When within the segmented straight line segment, the mileage point k The corresponding city coordinates are: ; ; in,( , )and( , ) are respectively the first i The starting and ending coordinates of the segmented straight line segment. For the first j The length of the piecewise curve, For the first i The length of the segmented straight line.

[0015] In step S1, the coordinate function of the circular curve segment is calculated as follows: Get the i The radius of the piecewise circular curve segment r i and the coordinates of the center of the circle ( , ); Determining the direction of rotation of a circular curve segment using the two-dimensional cross product of the circular arc: ; in,( , )and( , ) are respectively the first i The starting and ending coordinates of the segmented circular curve segment; when A > 0 is counterclockwise, when A When < 0, the direction is clockwise; Calculate the central angle at the starting point of the circular curve segment. Central angle with the endpoint : ; ; Calculate the mileage point based on the direction of rotation. k corresponding central angle : , A > 0; , A < 0; in, For the first j The length of the piecewise curve, For the first i The length of the segmented circular curve; Calculate mileage k Corresponding city coordinates: ; .

[0016] In step S1, the coordinate function of the transition curve segment is obtained by fitting the curve with straight lines. The transition curve segment is divided into several differential segments according to the preset segment length, and the coordinate function of the straight line segment of each differential segment is used for fitting calculation.

[0017] In step S3, a uniform scaling method is used to establish the mapping relationship between SVG pixels and line mileage: Set the conversion ratio between SVG base image pixels and line length. B Combined with screen scaling factor s Mouse click on a pixel on the screen The corresponding route mileage is: ; in, This represents the starting pixel position of the line on the SVG base map.

[0018] In step S3, the mapping relationship between SVG pixels and line mileage is established using a segmented scaling method: The lines are divided into different proportions according to application requirements. m The lengths of each segment are as follows: l 1. l 2... l m The conversion ratios for each segment are as follows: B 1. B 2... B m The pixel values ​​of each segment boundary point are p 1. p 2... p m The mileage corresponding to each dividing point is k 1. k 2... k m ; Combined with screen scaling factor s Mouse click on a pixel on the screen p x The corresponding route mileage is: ; First, the boundary pixels are located. p x The section in question, with its starting point being... The endpoint is p i The corresponding mileage is k i-1 , k i The corresponding conversion ratio is .

[0019] The method further includes step S6, which is as follows: The basic equipment data of rail transit lines are linked to the SVG base map according to mileage information; Based on the mileage information corresponding to the device, the pixel position of the device on the SVG base map and the planar coordinates in the city coordinate system are determined through the bidirectional conversion in step S5.

[0020] The advantages of this invention are: it realizes an automated bidirectional conversion method of "planar coordinates - line mileage - SVG pixels" based on rail transit line mileage, providing a foundation for the accurate positioning and viewport access of rail transit digital objects in GIS scenarios; it realizes the alignment of underground and above-ground data between different disciplines; and it can form an underground space positioning system covering the entire network by connecting local positioning systems such as Bluetooth and 5G. Attached Figure Description

[0021] Figure 1 This is a schematic diagram illustrating the steps of the method based on the mapping of structured digital base maps and line mileage in this invention; Figure 2 This is a diagram showing the relationship between the unified rail transit line mileage and SVG pixels and GIS coordinates in this invention. Figure 3 This is a schematic diagram illustrating the calculation principle of the mileage calculation plane coordinates in this invention; Figure 4 This is a schematic diagram illustrating the calculation principle of SVG pixel mileage in this invention. Detailed Implementation

[0022] The features and other related features of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, so as to facilitate understanding by those skilled in the art: Example: Figures 1-2 As shown, this embodiment relates to a method based on mapping structured digital base maps to route mileage. The method mainly includes the following steps: S1: Establish the functional relationship between the segmented curves of the route and the urban coordinate system. The segmented curves of the route include straight sections, circular curve sections and transition curve sections.

[0023] In this embodiment, as Figure 3 As shown, the city coordinates of each segment node of the route are obtained. Segment nodes include endpoints of straight sections, circular curve sections, and transition curve sections. Coordinate functions for straight sections, circular curve sections, and transition curve sections are established respectively. The coordinate functions of each segment curve are connected end-to-end according to the route direction to form a segment function table for the entire route. The total number of segment curves for the route is... n The coordinates of the segment nodes of the line are ( x 0, y0), ( x 1, y 1)...( x n , y n The lengths of the piecewise curves are respectivelyl 1. l 2... ln .

[0024] The method for calculating the coordinate function of a line segment is as follows: When the mileage point k Located in the i When within the segmented straight line segment, the mileage point k The corresponding city coordinates are: ; ; in,( , )and( , ) are respectively the first i The starting and ending coordinates of the segmented straight line segment. For the first j The length of the piecewise curve, For the first i The length of the segmented straight line. (in the following way) , For example, it is a kilometer point on a straight line segment. k a The corresponding planar coordinates.

[0025] The method for calculating the coordinate function of a circular curve segment is as follows: Get the i The radius of the piecewise circular curve segment r i and the coordinates of the center of the circle ( , ); Determining the direction of rotation of a circular curve segment using the two-dimensional cross product of the circular arc: ; in,( , )and( , ) are respectively the first i The starting and ending coordinates of the segmented circular curve segment; when A > 0 is counterclockwise, when A When < 0, the direction is clockwise; when A =0 represents a straight line, which can be degenerated into the formula for calculating a straight line segment; Calculate the central angle at the starting point of the circular curve segment. Central angle with the endpoint : ; ; Calculate the mileage point based on the direction of rotation. k corresponding central angle : , A > 0; , A < 0; in, For the first j The length of the piecewise curve, For the first i The length of the segmented circular curve; Calculate mileage k Corresponding city coordinates: ; .

[0026] by( , For example, it refers to the kilometer points on the circular curve segment. k b The corresponding planar coordinates.

[0027] The coordinate function of the transition curve segment is obtained by fitting a straight line to the curve. The transition curve segment is divided into several differential segments according to a preset segment length, and the coordinate function of the straight line segment of each differential segment is used for fitting calculation. In actual line design, the shape of the transition curve segment is generally fitted according to a segmented circular arc curve or a segmented straight line segment. When the segment size is controlled to 1m, the coordinate deviation is at the millimeter level, which meets the upper limit of the schedule requirements for positioning of the engineering and maintenance information system.

[0028] S2: Based on the functional relationship, convert the route mileage into planar coordinates in the urban coordinate system.

[0029] S3: Establish the mapping relationship between SVG (Scalable Vector Graphics) pixels and route mileage.

[0030] In this embodiment, a uniform ratio method or a segmented ratio method can be used to establish the mapping relationship between SVG pixels and line mileage.

[0031] A uniform scaling method is used to establish the mapping relationship between SVG pixels and line mileage: Set the conversion ratio between pixels and line length in the SVG base map (i.e., structured digital base map). B Combined with screen scaling factor s Mouse click on a pixel on the screen The corresponding route mileage is: ; in, This represents the starting pixel position of the line on the SVG base map.

[0032] like Figure 4 As shown, the mapping relationship between SVG pixels and line mileage is established using a segmented scaling method: The lines are divided into different proportions according to application requirements. m The lengths of each segment are as follows: l 1. l 2... l m The conversion ratios for each segment are as follows: B 1. B 2... B m The pixel values ​​of each segment boundary point are p 1. p 2... p m The mileage corresponding to each dividing point is k 1. k 2... k m ; Combined with screen scaling factor s Mouse click on a pixel on the screen p x The corresponding route mileage is: ; First, the boundary pixels are located. p x The section in question, with its starting point being... The endpoint is p i The corresponding mileage is k i-1 , k i The corresponding conversion ratio is .

[0033] S4: Based on the mapping relationship, convert SVG pixels into line mileage, or determine the position of the corresponding SVG pixel based on the line mileage.

[0034] S5: Based on functional and mapping relationships, it enables bidirectional conversion between SVG pixels, line mileage, and planar coordinates.

[0035] S6: Connect the basic equipment data of the rail transit line to the SVG base map according to the mileage information; based on the mileage information corresponding to the equipment, determine the pixel position of the equipment on the SVG base map and the planar coordinates under the city coordinate system through the bidirectional conversion in step S5.

[0036] Taking a subway mainline (upbound) as an example, the coordinate transformation of each mileage point is achieved through the route map, the conversion between pixel points and GIS coordinates is achieved through SVG, and the SVG format enables the rapid, structured access to the integrated equipment map. Specifically, the following steps are included: (1) Based on the composition of the subway main line up line, each straight section, transition curve section and circular curve section is decomposed into a straight section by substituting the curve with a straight line for each transition curve section according to the method of 1m.

[0037] (2) Based on the starting point mileage and coordinates of each straight line segment, form the mileage coordinate transformation algorithm for each straight line segment according to the corresponding formula.

[0038] (3) Each circular curve segment is converted into a mileage coordinate conversion algorithm according to the corresponding formula, and a segmented function table for mileage coordinate conversion of the entire line is formed.

[0039] (4) Using the station center alignment method, with the station center as the node, the segmentation ratio of each section is determined, and the conversion function between SVG pixels and mileage is formed to realize the conversion between SVG and coordinates.

[0040] (5) Input the mileage list of the managed objects according to the survey data, realize the attachment of each device object on the SVG map, and realize the coordinate transformation of each device object.

[0041] The beneficial technical effects of this embodiment are as follows: it realizes an automated bidirectional conversion method of "planar coordinates - line mileage - SVG pixels" based on the mileage of rail transit lines, providing a foundation for the accurate positioning and viewport calling of digital objects of rail transit in GIS scenarios; it realizes the alignment of underground and above-ground data between different disciplines; and it can form an underground space positioning system covering the entire network by connecting local positioning systems such as Bluetooth and 5G.

Claims

1. A method based on mapping structured digital base maps to route mileage, characterized in that... The method includes the following steps: S1: Establish the functional relationship between the segmented curves of the route and the urban coordinate system. The segmented curves of the route include straight line segments, circular curve segments, and transition curve segments. S2: Based on the aforementioned functional relationship, convert the route mileage into planar coordinates in the urban coordinate system; S3: Establish the mapping relationship between SVG pixels and line mileage; S4: Based on the mapping relationship, convert the SVG pixels into line mileage, or determine the position of the corresponding SVG pixels based on the line mileage; S5: Based on the functional relationship and the mapping relationship, realize the bidirectional conversion between SVG pixels, line mileage, and planar coordinates.

2. The method for mapping structured digital base maps to route mileage as described in claim 1, characterized in that... Step S1 specifically includes: Obtain the city coordinates of each segment node of the route, wherein the segment nodes include the endpoints of straight line segments, circular curve segments, and transition curve segments; Establish coordinate functions for straight line segments, circular curve segments, and transition curve segments respectively; Connect the coordinate functions of each segmented curve according to the route to form a segmented function table for the entire route.

3. The method for mapping structured digital base maps to route mileage as described in claim 2, characterized in that... In step S1, the coordinate function of the line segment is calculated as follows: When the mileage point k Located in the i When within the segmented straight line segment, the mileage point k The corresponding city coordinates are: ； ； in,( , )and( , ) are respectively the first i The starting and ending coordinates of the segmented straight line segment. For the first j The length of the piecewise curve, For the first i The length of the segmented straight line.

4. The method for mapping structured digital base maps to route mileage as described in claim 2, characterized in that... In step S1, the coordinate function of the circular curve segment is calculated as follows: Get the i The radius of the piecewise circular curve segment r i and the coordinates of the center of the circle ( , ); Determining the direction of rotation of a circular curve segment using the two-dimensional cross product of the circular arc: ； in,( , )and( , ) are respectively the first i The starting and ending coordinates of the segmented circular curve segment; when A > 0 is counterclockwise, when A When < 0, the direction is clockwise; Calculate the central angle at the starting point of the circular curve segment. Central angle with the endpoint : ； ； Calculate the mileage point based on the direction of rotation. k corresponding central angle : ， A > 0； ， A < 0； in, For the first j The length of the piecewise curve, For the first i The length of the segmented circular curve; Calculate mileage k Corresponding city coordinates: ； 。 5. The method for mapping structured digital base maps to route mileage as described in claim 2, characterized in that... In step S1, the coordinate function of the transition curve segment is obtained by fitting the curve with straight lines. The transition curve segment is divided into several differential segments according to the preset segment length, and the coordinate function of the straight line segment of each differential segment is used for fitting calculation.

6. The method for mapping structured digital base maps to route mileage as described in claim 1, characterized in that... In step S3, a uniform scaling method is used to establish the mapping relationship between SVG pixels and line mileage: Set the conversion ratio between SVG base image pixels and line length. B Combined with screen scaling factor s Click the screen pixel with the mouse The corresponding route mileage is: ； in, This represents the starting pixel position of the line on the SVG base map.

7. The method for mapping structured digital base maps to route mileage as described in claim 1, characterized in that... In step S3, the mapping relationship between SVG pixels and line mileage is established using a segmented scaling method: The lines are divided into different proportions according to application requirements. m The segments are of various lengths. l 1. l 2... l m The conversion ratios for each segment are as follows: B 1. B 2... B m The pixel values ​​of the segment boundary points are: p 1. p 2... p m The mileage corresponding to each dividing point is k 1. k 2... k m ; Combined with screen scaling factor s Click the screen pixel with the mouse p x The corresponding route mileage is: ； First, the boundary pixels are located. p x The section in question, with its starting point being... The endpoint is p i The corresponding mileage is k i-1 , k i The corresponding conversion ratio is .

8. The method for mapping structured digital base maps to route mileage as described in claim 1, characterized in that... The method further includes step S6, which is as follows: The basic equipment data of rail transit lines are linked to the SVG base map according to mileage information; Based on the mileage information corresponding to the device, the pixel position of the device on the SVG base map and the planar coordinates in the city coordinate system are determined through the bidirectional conversion in step S5.

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