Digital landmark setting method based on road network topological structure characteristics

Abstract

The invention discloses a road network topological structure feature-based digital landmark setting method, which comprises the following steps of: firstly, loading and preprocessing a road network map of an area where an initial position of a vehicle is located, and converting the road network map into an undirected graph model; then, retrieving candidate straight chains based on an undirected graph model, searching continuous adjacent edges with course differences smaller than a preset angle threshold value, and performing de-duplication processing; calculating a road sign insertion threshold value, calculating a theoretical cumulative distance of a digital landmark insertion point and determining coordinates of the theoretical cumulative distance; and finally, matching a vehicle driving track in a digital map surveying and mapping stage according to the coordinates of the insertion points, obtaining a corresponding timestamp, and binding a local digital map data frame as reference information. According to the invention, by combining the road network topological characteristics and the positioning error model, intelligent layout of the digital landmarks is realized, redundant road sign points are effectively reduced, the positioning correction precision and the storage efficiency are improved, and the method is suitable for a vehicle-mounted navigation system in a large-range scene.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of navigation digital map construction system design, and in particular to a digital landmark setting method based on road network topological structure characteristics. BACKGROUND

[0002] The road network is a network structure formed by all roads in a certain area, including a plurality of roads of different lengths and their intersection points. The road network map data structure is simple, and compared with other forms of digital maps, it can reduce the storage space burden and meet the positioning needs in a large range of scenarios. Based on this feature, in the case of satellite signal denial, the positioning system can use the road shape and topological information of the road network to constrain the vehicle trajectory, and then introduce the global positioning information of the road network to correct the positioning error. In multi-kink and high-curvature road sections, the vehicle trajectory has a certain shape recognition degree, and matching the trajectory with the road network map can obtain good navigation error correction effect. In long straight road sections, the shape of the vehicle trajectory is similar to the shape of the road, and the road network information cannot be effectively used to correct the positioning result, so it is necessary to set reference landmarks to correct the navigation error.

[0003] Traditional road landmarks are usually in the form of wireless signal base stations or geomagnetic road induction landmarks, and a large amount of manpower and material resources need to be invested for construction and maintenance. In addition, there are problems such as limited coverage, insufficient environmental adaptability, and high deployment cost. With the development of sensor technology, using visual, laser radar and other sensors to construct digital road landmarks has gradually become a more economical and reasonable way. However, the existing road landmark setting method usually adopts equidistant layout, manual point selection and other methods. Such methods do not consider the inherent representation information of the road network topological structure characteristics, and cannot accurately distinguish the long straight road sections where the road network positioning constraint is invalid. Because there are differences in the direction of digital road landmarks such as visual and laser radar, the traditional method only uses simple geometric distance criteria for road landmark layout, which cannot be effectively applied to the new digital road landmark layout task. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a digital landmark setting method based on the road network topological structure characteristics, which models the road network topological structure path continuity and landmark direction consistency, and uses the topological features of the road network map and the road segment error accumulation trigger model to jointly determine the digital landmark setting points, thereby significantly reducing the redundant landmark points irrelevant to the trajectory in the landmark setting, and ensuring that the extracted landmark points have real matching navigation significance in the vehicle motion direction.

[0005] The present application solves the above technical problems by adopting the following technical solutions:

[0006] A digital landmark setting method based on road network topology features, comprising the following steps:

[0007] Step 1), load and preprocess the road network map of the area where the initial position of the vehicle is located;

[0008] Step 1.1), input the initial position information of the vehicle, and load the road network map of the area where the initial position of the vehicle is located from the crowd-sourced map data source;

[0009] Step 1.2), convert the road network map into an undirected graph model = , wherein the node set contains the coordinates of the road nodes in the road network map, and the road nodes include intersection center points and road segment points; the edge set contains the connecting roads between the road nodes;

[0010] Step 1.3), preprocessing the coordinates of the road nodes and converting them into coordinates in the Northeast Celestial Coordinate System;

[0011] Step 2), retrieve candidate straight chains based on the road network undirected graph model;

[0012] Step 2.1), traverse each road node in the road network undirected graph, and use a depth-first search algorithm to find all candidate straight chains, obtaining a candidate straight chain set, wherein the candidate straight chain is a continuous adjacent edge satisfying a heading difference less than a preset first angle threshold ;

[0013] Step 2.2), de-duplicate processing of the candidate straight chains in the candidate straight chain set:

[0014] Step 2.2.1), establish a registered chain set for storing registered chains, and the initial registered chain set is an empty set, and sort the candidate straight chains of the candidate straight chain set in descending order of chain length;

[0015] Step 2.2.2), sequentially screen each candidate straight chain of the candidate straight chain set:

[0016] If the forward chain or the reverse chain of the candidate straight chain is a sub-chain of any registered chain in the registered chain set, it is removed from the candidate straight chain set, otherwise it is copied as a registered chain into the registered chain set;

[0017] Step 3), calculate the landmark insertion threshold value according to the following formula :

[0018] ;

[0019] In the formula, is a preset error divergence rate threshold of the positioning system, a preset positioning accuracy threshold;

[0020] Step 4), sequentially traversing each candidate straight-chain in the candidate straight-chain set, finding the insertion points of digital landmarks, for each candidate straight-chain in the candidate straight-chain set:

[0021] Step 4.1), taking one end of the candidate straight-chain as the starting point, establishing an empty set as the insertion point set of digital landmarks;

[0022] Step 4.2), sequentially obtaining the coordinates of each road node and sequentially calculating the lengths of the road segments between adjacent road nodes;

[0023] Step 4.3), judging whether there is an intersection road node in the candidate straight-chain;

[0024] Step 4.3.1), if there is no intersection road node, calculating the theoretical cumulative distance of each digital landmark in the candidate straight-chain from the starting point of the candidate straight-chain according to the following formula:

[0025] ;

[0026] In the formula, is the theoretical cumulative distance of the th digital landmark from the starting point of the candidate straight-chain, is the positioning correction accuracy at the road node, is the positioning correction accuracy of the digital landmark;

[0027] Step 4.3.2), if there is an intersection road node, calculating the theoretical cumulative distance of each digital landmark in the candidate straight-chain from the starting point of the candidate straight-chain according to the following formula:

[0028] ;

[0029] In the formula, is the number of intersection road nodes in the candidate straight-chain;

[0030] Step 4.4), calculating the cumulative path length from the starting point of the candidate straight-chain to each road segment in the candidate straight-chain according to the following formula:

[0031] ;

[0032] In the formula, is the cumulative path length of the th road segment in the candidate straight-chain, is the length of the th road segment in the candidate straight-chain;

[0033] Step 4.5): Find the target road segment edge corresponding to the insertion point of each digital landmark. For the nth digital landmark insertion point, its corresponding target road segment edge... satisfy , , These are the candidate straight chains of the first , The cumulative path length along the edges of the road segment;

[0034] Step 4.6) Calculate the coordinates of the insertion points of each digital landmark according to the following formula, and add them to the set of insertion points of digital landmarks. middle:

[0035] ;

[0036] In the formula, Let be the coordinates of the insertion point of the nth digital landmark. , The target road segment edge corresponding to the insertion point of the nth digital landmark is respectively. Coordinates and scale parameters of road nodes on both sides ;

[0037] Step 4.7), starting from the other end of the candidate straight chain, execute steps 4.2) to 4.6), and then execute step 5).

[0038] Step 5), obtain the corresponding timestamp based on the coordinates of the insertion point of the digital landmark;

[0039] Step 5.1) Obtain the set of vehicle trajectory points from the digital map surveying stage. ;

[0040] Step 5.2), for each digital landmark insertion point and the side of the road where it is located :

[0041] Step 5.2.1), calculate the direction vector of the side of the road segment. traverse the set of trajectory points Each pair of adjacent points in Calculate the direction vector of the trajectory segment. Filter out those that meet the conditions and The candidate trajectory segments, among which, The preset second angle threshold, This is a preset distance threshold;

[0042] Step 5.2.2), calculate the road segment edges normal vector For candidate trajectory segments , by solving the equation The parameters and are obtained by solving the equation

[0043] Step 5.2.3), when

[0044] Step 5.2.3.1), calculate the foot point as the vertical nearest point;

[0045] Step 5.2.3.2), for the vertical nearest point , respectively, calculate its Euclidean distance to the trajectory endpoints and , and determine the endpoint with a closer distance as the target trajectory point ;

[0046] Step 5.2.3.3), read the timestamp of the target trajectory point , and bind the local digital map data frame corresponding to the timestamp as the reference information of the digital landmark point .

[0047] As a further optimization scheme of the digital landmark setting method based on the topological structure characteristics of the road network, the preset first angle threshold is 10°.

[0048] As a further optimization scheme of the digital landmark setting method based on the topological structure characteristics of the road network, 0.5% is taken.

[0049] Compared with the prior art, the above technical scheme has the following technical effects:

[0050] 1. The digital landmark point design scheme provided by the present application can determine the digital landmark insertion point according to the topological characteristics of the road network map and the level of vehicle positioning algorithm, thereby reducing the storage space occupation.

[0051] 2. The present application only relies on "point-line" road network map, which is very easy to obtain;

[0052] 3. The present application designs a vehicle straight road network edge discrimination method according to the topological characteristics of the road network map;

[0053] 4. The present application can determine the digital landmark insertion point existing on the road edge according to the candidate straight chain topological structure and the connection relationship;

[0054] 5. The present application determines the timestamp of the most suitable repositioning data frame to bind the digital landmark according to the nearest point discrimination method based on the vehicle trajectory point set in the surveying and mapping stage.​ Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the overall scheme for the digital landmark setting system;

[0056] Figure 2 This is a schematic diagram of the road network map structure;

[0057] Figure 3 This is a schematic diagram of a candidate straight chain;

[0058] Figure 4 This is a schematic diagram of the candidate straight chain extraction results;

[0059] Figure 5 This is a schematic diagram of vehicles merging into candidate straight-ahead chains at road intersections;

[0060] Figure 6 This is a schematic diagram of the insertion points of positive and negative digital landmarks contained in the candidate straight chain;

[0061] Figure 7 This is a schematic diagram of the target vehicle waypoint matching method;

[0062] Figure 8 This is a schematic diagram of the insertion points for the final selected digital landmarks. Detailed Implementation

[0063] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings:

[0064] This invention can be implemented in many different forms and should not be considered limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully express the scope of the invention to those skilled in the art. In the drawings, components are enlarged for clarity.

[0065] The method provided by this invention, such as Figure 1 As shown, its essence is the process of data traversal and processing, which determines the insertion point of digital road signs based on the vehicle driving trajectory and road network map obtained in the digital map surveying stage.

[0066] The following is a detailed explanation of the steps:

[0067] Step 1), load and preprocess the road network map of the area where the vehicle's initial position is located;

[0068] Step 1.1) The road network map comes from the crowdsourced map website OpenStreetMap. In the actual map matching and positioning process, the initial location information of the vehicle can be entered, and the road network map of the area where the initial location of the vehicle is located can be loaded from the crowdsourced map data source.

[0069] Step 1.2), OpenStreetMap uses a specific data structure to represent the regional road map, in which the data that best represents the topological structure of the road network is node, way and relation. Among them, node represents a geographical point with a specific position on the map, and its data structure contains the longitude and latitude where it is located; way is used to represent a certain road segment in the map, which is composed of multiple ordered nodes; relation represents the topological connection relationship between different nodes, which describes the connectivity of the road in the map. According to the "point-line" characteristics of the road network map, the road network map is converted into an undirected graph model = , wherein the node set contains the coordinates of the road nodes in the road network map, including the intersection center point and the road segment point; the edge set contains the connecting roads between the road nodes; the complex road network raw data is represented by this simple data structure, which provides convenience for subsequent road network data retrieval and structure traversal.

[0070] Step 1.3), the coordinates of the road nodes are preprocessed and converted into coordinates in the Northeastern Celestial Coordinate System; the structure of a regional road network map in the Northeastern Celestial Coordinate System is shown in Figure 2 .

[0071] Step 2), the continuous straight road segment in the road network map is defined as a candidate straight link, that is, a combination of road edges with a heading difference less than an angle threshold. Based on the road network undirected graph model, candidate straight links are retrieved;

[0072] Step 2.1), each road node in the road network undirected graph is traversed, and a depth-first search algorithm is used to find all candidate straight links, obtaining a candidate straight link set, which is a continuous adjacent edge satisfying the heading difference less than a preset first angle threshold ; as shown in Figure 3 , assuming that the road network edges , and are adjacent road network edges in the road segment that the vehicle passes through, if and are less than the threshold , the road segment edges , and can be sequentially combined to form a candidate straight link.

[0073] Step 2.2), there are a large number of repeated and overlapping parts in the preliminary extracted candidate straight link set, and the candidate straight links in the candidate straight link set need to be de-duplicated:

[0074] Step 2.2.1), a registration chain set is established for storing the registration chains, and the initial registration chain set is an empty set, and the candidate straight chains in the candidate straight chain set are sorted in descending order of chain length;

[0075] Step 2.2.2), each candidate straight chain in the candidate straight chain set is filtered in sequence:

[0076] For a candidate straight chain, it is compared with the registered candidate straight chain in forward and reverse sub-chain, and the candidate straight chain detected by the forward and reverse sub-chain can be registered. The forward and reverse sub-chain comparison criterion is that the forward and reverse chains of the current candidate straight chain cannot be the sub-chain of the registered chain. If the forward chain or the reverse chain of the candidate straight chain is the sub-chain of any registered chain in the registration chain set, it is removed from the candidate straight chain set, otherwise it is copied to the registration chain set as a registered chain; for example, the road network edge set of a candidate straight chain is , the reverse chain is , and the registered candidate straight chain set is Since the reverse chain of the candidate chain is the sub-chain of the registered candidate straight chain, the candidate straight chain is removed. All candidate straight chains that meet the conditions are registered to ensure that each edge and each candidate straight chain is added only once. The final candidate straight chain extraction effect is as follows Figure 4 , the same candidate straight chain uses the same line type, and different candidate straight chains are distinguished by end points.

[0077] Step 3), the road sign insertion threshold is calculated according to the following formula :

[0078] ;

[0079] In the formula, is a preset error divergence rate threshold of the positioning system, is a preset positioning accuracy threshold; the road sign insertion threshold of a long straight road segment is usually related to the divergence level of the vehicle-mounted positioning system. For example, if the positioning error of the inertial navigation system is 5 meters when the vehicle travels 1000 meters, the error divergence rate is considered to be 0.5%.

[0080] Step 4), each candidate straight chain in the candidate straight chain set is sequentially traversed to find the insertion point of the digital landmark. For each candidate straight chain in the candidate straight chain set:

[0081] Step 4.1), taking one end of the candidate straight chain as the starting point, an empty set is established as the insertion point set of the digital landmark;

[0082] Step 4.2) Obtain the coordinates of each road node in sequence, and calculate the length of the road segment between adjacent road nodes in sequence;

[0083] Step 4.3) Determine whether there are intersecting road nodes in the candidate straight chains;

[0084] Step 4.3.1): If there are no intersecting road nodes, calculate the theoretical cumulative distance from the insertion point of each digital landmark in the candidate straight chain to the starting point of the candidate straight chain according to the following formula:

[0085] ;

[0086] In the formula, For the first The theoretical cumulative distance from the insertion point of each digital landmark to the starting point of the candidate straight chain. To correct the positioning accuracy at road junctions, To correct the positioning accuracy of digital landmarks, when traversing candidate straight chains, the position of each landmark insertion point can be calculated by determining whether the cumulative distance condition is met. Through the above process, the prior information of long straight road segments in the road network map obtained during the mapping of vehicle navigation maps can be used to help set up digital landmarks.

[0087] Step 4.3.2), as follows Figure 5 As shown, some nodes in the candidate straight chain may become intersections with another road. If there are intersection road nodes, the theoretical cumulative distance from the insertion point of each digital landmark in the candidate straight chain to the starting point of the candidate straight chain is calculated according to the following formula:

[0088] ;

[0089] In the formula, The number of intersecting road nodes in the candidate straight chains;

[0090] Step 4.4) Calculate the cumulative path length from the starting point of the candidate straight chain to each of its segment edges using the following formula:

[0091] ;

[0092] In the formula, For the candidate straight chain, the first The cumulative path length along the edge of the road segment. For the candidate straight chain, the first The length of the side of the road segment;

[0093] Step 4.5): Find the target road segment edge corresponding to the insertion point of each digital landmark. For the nth digital landmark insertion point, its corresponding target road segment edge... satisfy , , These are the candidate straight chains of the first... , The cumulative path length along the edges of the road segment;

[0094] Step 4.6) Calculate the coordinates of the insertion points of each digital landmark according to the following formula, and add them to the set of insertion points of digital landmarks. middle:

[0095] ;

[0096] In the formula, Let be the coordinates of the insertion point of the nth digital landmark. , The target road segment edge corresponding to the insertion point of the nth digital landmark is respectively. Coordinates and scale parameters of road nodes on both sides ;

[0097] Step 4.7), starting from the other end of the candidate straight chain, execute steps 4.2) to 4.6), and then execute step 5). Figure 6 This is a schematic diagram of the insertion points of positive and negative digital landmarks contained in the candidate straight chain;

[0098] Step 5), obtain the corresponding timestamp based on the coordinates of the insertion point of the digital landmark;

[0099] Step 5.1) Obtain the set of vehicle trajectory points from the digital map surveying stage. ;

[0100] Step 5.2), for each digital landmark insertion point and the side of the road where it is located :

[0101] Step 5.2.1): For an ordered vehicle trajectory, determining whether it passes through the range of a candidate straight-ahead marker insertion point requires a comprehensive judgment combining direction and distance. For a road segment edge on the candidate straight-ahead path, the direction of the line connecting its endpoints can effectively represent its direction on the road network; therefore, the direction vector of that road segment edge is calculated. traverse the set of trajectory points Each pair of adjacent points in Calculate the direction vector of the trajectory segment. Filter out those that meet the conditions and The candidate trajectory segments, among which, The second angle threshold is preset. This is a preset distance threshold;

[0102] Step 5.2.2), for the vehicles that keep driving, intuitively, only one vertical nearest point will correspond to one single digital landmark insertion point, so the vehicle driving track point that is closer to the vertical nearest point can be regarded as the target track point. Meanwhile, according to the time stamp, the data frame that is temporally closest to the target track point when the digital landmark is mapped can be determined, and the local digital map corresponding to the data frame can be taken as the reference information of the landmark insertion point. As shown in FIG. 5.2.2, the criterion for finding the target track point is as follows: taking the position of the landmark insertion point as the foot, a vertical line perpendicular to the road network edge at the position is drawn, and the intersection of the line and the connecting line between the track point and the foot is the vertical nearest point. The normal vector of the road segment edge at the vertical nearest point is calculated, and the parameter and of the candidate track segment are solved by solving the equation Figure 7

[0103] Step 5.2.3), when

[0104] Step 5.2.3.1), the foot is calculated as the vertical nearest point;

[0105] Step 5.2.3.2), for the vertical nearest point , the Euclidean distances of the vertical nearest point to the track end points and are calculated respectively, and the end point that is closer to the vertical nearest point is determined as the target track point ;

[0106] Step 5.2.3.3), the time stamp of the target track point is read, and the local digital map data frame corresponding to the time stamp is bound as the reference information of the digital landmark point. Finally, in combination with the vehicle driving track in the process of mapping the digital landmark, the digital landmark insertion point that is consistent with the driving direction of the vehicle can be selected, as shown in FIG. 5.2.3. Figure 8

[0107] Those skilled in the art can understand that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0108] ​​​​​​​​​​​​The above detailed description of the specific embodiments of the present application has been given to understand the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for setting digital landmarks based on road network topology characteristics, characterized in that, It includes the following steps: Step 1), load and preprocess the road network map of the area where the vehicle's initial position is located; Step 1.1), input the vehicle's initial location information, and load the road network map of the area where the vehicle's initial location is located from the crowdsourced map data source; Step 1.2) Convert the road network map into an undirected graph model. = , where the node set Includes the coordinates of road nodes in the road network map, where each road node includes intersection center points and road segment points; edge set. Includes connecting roads between road nodes; Step 1.3) preprocesses the coordinates of the road nodes, converting them to coordinates in the northeast-northeast coordinate system; Step 2), retrieve candidate straight chains based on the undirected graph model of the road network; Step 2.1) Traverse each road node in the undirected graph of the road network and use a depth-first search algorithm to find all candidate straight chains, obtaining a set of candidate straight chains. The candidate straight chains are those that satisfy the condition that the heading difference is less than a preset first angle threshold. consecutive adjacent edges; Step 2.2) involves deduplicating the candidate straight chains in the candidate straight chain set: Step 2.2.1) Establish a set of registration chains for storing registration chains. The initial set of registration chains is an empty set. Sort the candidate straight chains in the candidate straight chain set in descending order of chain length. Step 2.2.2) involves sequentially filtering each candidate linear chain in the candidate linear chain set: If the forward or reverse chain of a candidate straight chain is a child chain of any registered chain in the registered chain set, remove it from the candidate straight chain set; otherwise, copy it as a registered chain into the registered chain set. Step 3), calculate the signpost insertion threshold according to the following formula. : ； In the formula, The preset error divergence rate threshold for the positioning system. This is a preset positioning accuracy threshold; Step 4): Sequentially traverse each candidate straight chain in the candidate straight chain set, finding the insertion point of the digital landmark. For each candidate straight chain in the candidate straight chain set: Step 4.1): Starting from one end of the candidate straight chain, establish an empty set. As a set of insertion points for digital landmarks; Step 4.2) Obtain the coordinates of each road node in sequence, and calculate the length of the road segment between adjacent road nodes in sequence; Step 4.3) Determine whether there are intersecting road nodes in the candidate straight chains; Step 4.3.1): If there are no intersecting road nodes, calculate the theoretical cumulative distance from the insertion point of each digital landmark in the candidate straight chain to the starting point of the candidate straight chain according to the following formula: ； In the formula, For the first The theoretical cumulative distance from the insertion point of each digital landmark to the starting point of the candidate straight chain. To correct the positioning accuracy at road junctions, To correct the positioning accuracy of digital landmarks; Step 4.3.2): If intersecting road nodes exist, calculate the theoretical cumulative distance from the insertion point of each digital landmark in the candidate straight chain to the starting point of the candidate straight chain according to the following formula: ； In the formula, The number of intersecting road nodes in the candidate straight chains; Step 4.4) Calculate the cumulative path length from the starting point of the candidate straight chain to each of its segment edges using the following formula: ； In the formula, For the candidate straight chain, the first The cumulative path length along the edge of the road segment. For the candidate straight chain, the first The length of the side of the road segment; Step 4.5): Find the target road segment edge corresponding to the insertion point of each digital landmark. For the nth digital landmark insertion point, its corresponding target road segment edge... satisfy , , These are the candidate straight chains of the first... , The cumulative path length along the edges of the road segment; Step 4.6) Calculate the coordinates of the insertion points of each digital landmark according to the following formula, and add them to the set of insertion points of digital landmarks. middle: ； In the formula, Let be the coordinates of the insertion point of the nth digital landmark. , The target road segment edge corresponding to the insertion point of the nth digital landmark is respectively. Coordinates and scale parameters of road nodes on both sides ; Step 4.7), starting from the other end of the candidate straight chain, execute steps 4.2) to 4.6), and then execute step 5). Step 5), obtain the corresponding timestamp based on the coordinates of the insertion point of the digital landmark; Step 5.1) Obtain the set of vehicle trajectory points from the digital map surveying stage. ; Step 5.2), for each digital landmark insertion point and the side of the road where it is located : Step 5.2.1), calculate the direction vector of the side of the road segment. traverse the set of trajectory points Each pair of adjacent points in Calculate the direction vector of the trajectory segment. Filter out those that meet the conditions and The candidate trajectory segments, among which, The preset second angle threshold, This is a preset distance threshold; Step 5.2.2), calculate the road segment edges normal vector For candidate trajectory segments By solving the equation Solve for the parameters and ; Step 5.2.3), when hour Step 5.2.3.1), calculate the foot of the perpendicular. As the closest vertical point; Step 5.2.3.2), for the vertical nearest point Calculate the distance to the endpoint of the trajectory respectively. and The Euclidean distance is used to determine the endpoint that is closer to the target trajectory point. ; Step 5.2.3.3), read the target trajectory points. The timestamp is then used to bind the corresponding local digital map data frame to a digital landmark. The baseline information.

2. The digital landmark setting method based on road network topology characteristics according to claim 1, characterized in that, The preset first angle threshold It is 10°.

3. The digital landmark setting method based on road network topology characteristics according to claim 1, characterized in that, Take 0.05%.

Images