Road sign arrangement method based on geometric analysis

Abstract

The invention discloses a road sign arrangement method based on geometric analysis, which comprises the following steps of: modeling through a CAD (Computer Aided Design) design drawing to generate a three-dimensional model, drawing signs, acquiring data, and simulating the shielding conditions of the signs at different road sections of an expressway; road geometric information, sign position information and vehicle information are extracted from the data, the sign distances are ranked from near to far, and the accumulated distance between each sign and the road starting point is calculated; calculating the sight distance range of a vehicle driver by combining the vehicle speed and the response time; establishing a shielding model, judging a shielding geometrical relationship by using a tetrahedron volumetric method, judging whether the sign is shielded by other objects or the sign in the vehicle driving process according to the shielding geometrical relationship, and evaluating the visibility of the sign; and based on the shielding analysis result, the layout of the sign is optimized, and the visibility and the use effect of the sign are improved. According to the method, the shielding condition of the sign under different vehicle heights, vehicle speeds and road environments can be accurately evaluated, and the visibility and driving safety of the sign are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of road sign design, and in particular to a road sign layout method based on geometric analysis. Background Art

[0002] In complex traffic environments such as highways and urban roads, the design and layout of road signs not only impacts road efficiency but also directly affects traffic safety. In recent years, the issue of obscured roadside traffic signs has attracted increasing attention from scholars both domestically and internationally. Existing technologies primarily rely on data collection through methods such as camera photography and radar sampling of existing roads in real-world environments, building simulated road networks, and using VISSIM simulations to determine occlusion probabilities. This approach is computationally complex and time-consuming.

[0003] Existing technologies, when faced with complex road traffic environments, often rely on post-process simulation and data collection methods (such as camera photography and radar measurement), using extensive field testing and calculations to assess sign occlusion. These methods suffer from cumbersome calculations, long simulation times, and high resource consumption. Furthermore, they are unable to effectively predict occlusion risks and optimize sign layouts before sign construction. Therefore, a solution is urgently needed that can plan sign layouts in advance and achieve efficient occlusion detection for complex road environments. Summary of the Invention

[0004] The purpose of the present invention is to provide a road sign layout method based on geometric analysis, which can accurately evaluate the occlusion of signs under different vehicle heights, speeds and road environments, thereby helping to optimize road sign layout in various traffic scenarios and improve sign visibility and driving safety.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A road sign layout method based on geometric analysis, the method comprising:

[0007] Step 1: Generate a 3D model using CAD design drawings, draw the signage and collect data, record the shape and position characteristics of the signage, and simulate the occlusion of the signage on different sections of the highway;

[0008] Step 2: Extract road geometry information, sign location information, and vehicle information from the collected data, sort the sign distances from near to far, and calculate the cumulative distance between each sign and the road start point;

[0009] Step 3: Calculate the driver's sight range, i.e., the range of the sign that the driver can see, by combining the vehicle speed and reaction time;

[0010] Step 4: Establish an occlusion model and use the tetrahedron volume method to determine the occlusion geometry relationship. This occlusion geometry relationship is used to determine whether the sign will be blocked by other objects or signs during vehicle movement, and to evaluate the visibility of the sign.

[0011] Step 5: Based on the occlusion analysis results of step 4, optimize the layout of the signage to improve its visibility and effectiveness.

[0012] An embodiment of the present invention further provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor is configured to run the computer program to execute the method.

[0013] An embodiment of the present invention further provides a computer storage medium, wherein the computer storage medium stores a plurality of instructions, wherein the instructions are suitable for being loaded by a processor and executing the method.

[0014] It can be seen from the technical solution provided by the above-mentioned present invention that the above-mentioned method can accurately evaluate the occlusion of signs under different vehicle heights, speeds and road environments, thereby helping to optimize the layout of road signs in various traffic scenarios and improve the visibility of signs and driving safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 A schematic flow chart of a method for laying out road signs based on geometric analysis provided by an embodiment of the present invention;

[0017] Figure 2 This is a schematic diagram of the signs according to an embodiment of the present invention being sorted by distance from near to far;

[0018] Figure 3 Schematic diagram of the calculation process of the viewing range according to an embodiment of the present invention;

[0019] Figure 4 Schematic diagram of the tetrahedron volume method according to an embodiment of the present invention;

[0020] Figure 5 Schematic diagram of the occlusion of a quadrangular pyramid according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments, and do not constitute a limitation of the present invention. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0022] like Figure 1 FIG2 is a flow chart of a method for laying out road signs based on geometric analysis according to an embodiment of the present invention. The method includes:

[0023] Step 1: Generate a 3D model using CAD design drawings, draw the signage and collect data, record the shape and position characteristics of the signage, and simulate the occlusion of the signage on different sections of the highway;

[0024] In this step, the highway is divided into two driving directions: up and down. In the occlusion analysis, only the sign occlusion in the driver's driving direction is considered, so each driving direction can be regarded as an independent scene for analysis.

[0025] When using CAD design drawings to model a scene, the road route is drawn according to the vehicle's travel direction, with the vehicle's travel direction defined as positive and the opposite direction as negative. After the route is drawn, enter the road line name and type. Road types are divided into road boundary line, road centerline, and lane centerline.

[0026] After selecting the scene and layer, the signage is drawn and data is collected to record the shape and position characteristics of the signage. The forward and reverse directions of the signage are defined based on the direction of vehicle travel, and the occlusion of the signage on different sections of the highway is simulated.

[0027] Once the lane lines and signs have been drawn, follow the subsequent steps to perform sign occlusion analysis to evaluate the visibility and occlusion effects of the signs. This process is based on the lane lines and signs, so it is necessary to ensure that the spatial position of the signs is consistent with their position in the road scene.

[0028] Step 2: Extract road geometry information, sign location information, and vehicle information from the collected data, sort the sign distances from near to far, and calculate the cumulative distance between each sign and the road start point;

[0029] In this step, road geometry information, sign location information, and vehicle information are extracted from the collected data, where:

[0030] Road geometry data represents the starting point, path, and end point of the road in coordinate form; sign location information includes the coordinates of the four vertices of each sign (latitude, longitude, and altitude); vehicle information includes the observation altitude and different speeds of the vehicle, as shown in Table 1 below:

[0031] Table 1 Observation height of different models

[0032]

[0033] Sort the signs from near to far to reduce the amount of calculation for occlusion analysis, ensure that the occlusion relationship is calculated in the order of the signs, avoid duplication and invalid analysis, and establish a logical order for subsequent analysis, such as Figure 2 FIG2 is a schematic diagram showing how signs are sorted by distance from nearest to farthest according to an embodiment of the present invention. After sorting, the occlusion of the nearest sign is calculated first. If the nearest sign is occluded, there is no need to analyze subsequent signs, thereby improving calculation efficiency.

[0034] Calculate the cumulative distance between each sign and the starting point of the road, the cumulative distance d i The actual driving distance from the starting point of the road along the road curve to the sign. The road curve consists of multiple path points, including P0, P1, P2...Pn. 0 is the starting point of the path point, n is the index of the last point in the path point sequence (counting starts from 0), and the total number of path points is n+1 (from P0 to P n ), the total number of line segments between adjacent points is n (from P0-P1 to P n-1 -P n ), a line segment is formed between each two adjacent points, and the distance d between the path points n It is calculated by Euclidean distance, the formula is as follows:

[0035]

[0036] Where (x n ,y n , z n ) is the path point P n The three-dimensional coordinates of ; j is the index of the path segment where the sign projection point is located;

[0037] By finding the projection point (x i ,y i , z i ), the cumulative distance of the sign is obtained by interpolation calculation, and the projection distance d of the sign projection point on the road proj The calculation formula is:

[0038]

[0039] Then the cumulative distance d i for:

[0040] d i =d n +d proj (3).

[0041] Step 3: Calculate the driver's sight range, i.e., the range of the sign that the driver can see, by combining the vehicle speed and reaction time;

[0042] In this step, the driver's dynamic field of view is inversely proportional to driving speed. The faster the speed, the farther the focus point is. However, the faster the focus point approaches, the narrower the field of view becomes. Human reaction time is usually between 0.2 and 0.4 seconds, and the normal reaction time of a driver is 0.3 to 1 second.

[0043] Therefore, by combining the vehicle speed and reaction time to determine the range of signs that the vehicle driver can see, we can determine which signs can block the vehicle driver from observing other signs, such as Figure 3 FIG. 1 is a schematic diagram of the process for calculating the sight range according to an embodiment of the present invention. The vehicle speed v determines the sight range d, which is calculated according to the formula:

[0044] d=t r ×v (4)

[0045] where t r is the driver's reaction time, which is used to simulate the time required for the driver to detect the sign and react; v is the vehicle speed;

[0046] In specific implementations, when performing occlusion geometry analysis, the viewpoint needs to be determined based on the height, viewing distance, and field of view. Table 2 below shows the relationship between driving speed, field of view, and viewing distance:

[0047] Table 2 Relationship between driving speed, field of view and sight distance

[0048]

[0049]

[0050] Step 4: Establish an occlusion model and use the tetrahedron volume method to determine the occlusion geometry relationship. This occlusion geometry relationship is used to determine whether the sign will be blocked by other objects or signs during vehicle movement, and to evaluate the visibility of the sign.

[0051] In this step, during actual driving, vehicle movement and sign placement are affected by factors such as visibility range, object location, and road environment. Occlusion geometry analysis uses geometric relationships to determine whether signs will be obscured by other objects or signs while the vehicle is moving. This analysis is crucial for designing a reasonable sign layout and improving traffic sign visibility. Occlusion is usually caused by multiple factors, including the following:

[0052] Sight distance and field of view limitations: Due to the driver's reaction time and vehicle speed, the driver can only see signs within a certain range. If the sign is outside the sight distance and field of view, it will not be visible.

[0053] Object occlusion: This includes large objects such as buildings, trees, and signs beside the road. These objects may block the signs from the driver's view at specific angles and distances.

[0054] Obstruction by other vehicles: If there are other vehicles in front or beside you, they may block the view of the sign.

[0055] Since signs beyond the sight range will gradually enter the sight range during the subsequent travel process, they are not considered as obstructions. Since the position and shape of other vehicles cannot dynamically obtain their accurate geometric positions in real time, this method does not consider the obstruction of other vehicles.

[0056] The core problem of occlusion geometry analysis is to determine whether an object is obscured by another object. It usually involves the spatial configuration between the viewpoint, the target object, and the obstructing object. Common geometric calculation methods include those based on ray casting, tetrahedron volume calculation, and spatial segmentation. Through occlusion geometry calculation, it is possible to clearly describe whether an object is within the line of sight and whether it is obscured by other objects.

[0057] The embodiment of the present invention uses the tetrahedron volume method to perform occlusion geometry calculation. The tetrahedron volume method is a method for determining occlusion by calculating the volume relationship between the viewpoint and the target object and the viewpoint and the occluding object. For a target object T0, if the polyhedron formed by the target object contains a point P in another object T1, then the target object T0 is considered to be occluded by the object T1 containing the point P. Through the calculation of the tetrahedron volume method, it can be detected whether the point P is inside the volume of the target object T0. Specifically:

[0058] Assume there are four points ABCD, the volume of the tetrahedron V ABCD The formula is:

[0059]

[0060] Among them, det is the mathematical symbol of determinant, which means to calculate the determinant of the matrix; x, y, z represent the coordinate components of the point in three-dimensional space; the subscript letters A, B, C, and D represent different vertices, and x A 、y A 、z A represents the coordinates of the corresponding point A, and so on;

[0061] The construction rule of the coordinate matrix is: each vertex coordinate is expanded into a four-dimensional vector (x, y, z, 1), and the four vertex coordinates are arranged in rows to form a 4×4 matrix.

[0062] like Figure 4 FIG. 1 is a schematic diagram of the tetrahedron volume method according to an embodiment of the present invention. The target object, a tetrahedron OABCD, is constructed. Point O is the viewpoint, which is located at a fixed position. If the sum of the volumes of all small tetrahedrons is equal to the volume of the tetrahedron OABCD, then:

[0063] V OABCD =V OABP +V OBCP +V OCDP +V OADP +V PABCD (6)

[0064] Then the target point P is located inside the tetrahedron OABCD, indicating that the target object is blocked;

[0065] For multiple points in the occluding object, the above process is repeated to determine whether each point occludes the target object. If all points of the occluding object are not within the volume of the target object, the target object is considered not to be occluded; otherwise, if at least one point is included in the volume of the target object, the target object is considered to be occluded, such as Figure 5 Schematic diagram of the occlusion of a quadrangular pyramid according to an embodiment of the present invention is shown, which shows full occlusion, no occlusion, and partial occlusion from left to right.

[0066] In real-world scenarios, the occlusion of a target object is often not caused by a single occluder, but may be affected by multiple occluders. Therefore, in occlusion geometry analysis, the effects of multiple occluders need to be comprehensively considered to accurately assess the visibility of the target object. When the line of sight of a target object T is blocked by multiple occluders Q1, Q2, ..., Qn, their occlusion relationships need to be comprehensively calculated. Assuming that each occluder may partially block the line of sight of the target object, the occlusion impact of multiple occluders is analyzed through the following steps:

[0067] Independent occlusion judgment: Use the tetrahedron volume method for each occluder to determine whether the target object T is occluded. The viewpoint O is located at a fixed position. The target object T will be affected by n occluders. For each occluder, construct the target object tetrahedron OABCD and determine whether each occluder Qi occludes the target object T.

[0068] Comprehensive occlusion analysis: superimpose the occlusion conditions of all occluders to determine the final occlusion state of the target object T;

[0069] In addition, multi-vehicle analysis can be performed: occlusion geometry analysis of different vehicle models at different viewing heights; multi-vehicle speed analysis: analysis of sign visibility at different speeds. Vehicle speed and reaction time jointly determine the reaction distance, and the sign sight range is optimized by analyzing the reaction distance at different speeds; multi-lane analysis: occlusion analysis of multi-lane scenes to determine the visibility of the sign in each lane; multi-viewing distance analysis: simulation of sign visibility under various viewing distance conditions to meet the requirements of different driver reaction times and complex environments; multi-occluder analysis: analysis of the impact of multiple occluders on sign visibility in complex scenes to provide support for sign layout optimization;

[0070] Taking into account the occlusion effects of different scenes, the visibility C(T) of the target object T is calculated as follows:

[0071]

[0072] Where F(T, Qi)=0 means that the target object T is blocked by the occluder Qi; F(T, Qi)=1 means that the target object T is not blocked by the occluder Qi;

[0073] Evaluate sign visibility by analyzing the combined effects of multiple obstructions. Especially in complex scenes, the accuracy of the evaluation results is ensured by comprehensively considering the overlapping effects of obstructions on the line of sight.

[0074] Furthermore, this analysis provides theoretical support for optimizing signage layout. By rationally adjusting the spatial relationship between signs and obstructions, critical signs can be prevented from being obscured, ensuring their visibility. Reducing multiple obstructions during road design and signage installation can help improve signage effectiveness and visibility, further enhancing traffic safety and user experience.

[0075] Step 5: Based on the occlusion analysis results of step 4, optimize the layout of the signage to improve its visibility and effectiveness.

[0076] For example, combined with the occlusion analysis results of step 4, the sign can be moved forward in the forward direction to reduce the occlusion effect and ensure that the sign is clearly visible in the driver's field of view. Through this adjustment, the moved sign is subjected to occlusion geometry analysis in all lanes at different vehicle speeds and different vehicle models, and the occlusion calculation is re-performed until the adjustment plan makes the sign placement optimal. This scientific sign placement adjustment plan can not only optimize the layout of the sign, but also provide a reference for subsequent road design.

[0077] It should be noted that the contents not described in detail in the embodiments of the present invention belong to the prior art known to those skilled in the art.

[0078] An embodiment of the present invention further provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor is configured to run the computer program to execute the method.

[0079] An embodiment of the present invention further provides a computer storage medium, wherein the computer storage medium stores a plurality of instructions, wherein the instructions are suitable for being loaded by a processor and executing the method.

[0080] In summary, the method described in the embodiment of the present invention uses geometric analysis to optimize the calculation process through steps such as data loading and sorting, which can significantly reduce the number of repeated calculations in complex scenes, especially by sorting obstructions and accumulating distances to avoid invalid analysis and improve the efficiency of the algorithm; the present invention uses geometric modeling and simulation to predict obstruction conditions before actual road construction and sign installation, and provide guidance for design and planning without relying on field data collection or scenes where signs have already been installed, reducing additional installation costs and maintenance costs, not only saving the cost of later reconstruction and adjustment, but also providing traffic management departments with a more scientific and reasonable decision-making basis, ensuring that drivers obtain clear and timely traffic information while driving, thereby significantly reducing the safety hazards caused by sign obstruction.

[0081] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims. The information disclosed in the background technology section of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or any form of implication that the information constitutes prior art already known to those skilled in the art.

Claims

1. A road sign layout method based on geometric analysis, characterized in that: The method comprises: Step 1: Generate a 3D model using CAD design drawings, draw the signage and collect data, record the shape and position characteristics of the signage, and simulate the occlusion of the signage on different sections of the highway; Step 2: Extract road geometry information, sign location information, and vehicle information from the collected data, sort the sign distances from near to far, and calculate the cumulative distance between each sign and the road start point; Step 3: Calculate the driver's sight range, i.e., the range of the sign that the driver can see, by combining the vehicle speed and reaction time; Step 4: Establish an occlusion model and use the tetrahedron volume method to determine the occlusion geometry relationship. This occlusion geometry relationship is used to determine whether the sign will be blocked by other objects or signs during vehicle movement, and to evaluate the visibility of the sign. Step 5: Based on the occlusion analysis results of step 4, optimize the layout of the signage to improve its visibility and effectiveness.

2. The road sign layout method based on geometric analysis according to claim 1 is characterized in that: In step 1, when using CAD design drawings to model the scene, the road route is drawn according to the vehicle's travel direction, defining the vehicle's travel direction as positive and the opposite direction as negative. After the route is drawn, enter the road line name and type, where the road type is divided into road boundary line, road centerline, and lane centerline; After selecting the scene and layer, the signage is drawn and data is collected to record the shape and position characteristics of the signage. The forward and reverse directions of the signage are defined based on the direction of vehicle travel, and the occlusion of the signage on different sections of the highway is simulated.

3. The road sign layout method based on geometric analysis according to claim 1 is characterized in that: In step 2, road geometry information, sign location information, and vehicle information are extracted from the collected data, where: Road geometry information data represents the starting point, path, and end point of the road in coordinate form; sign location information includes the coordinates of the four vertices of each sign; vehicle information includes the observation height and different speeds of the vehicle; Sort the signs from nearest to farthest to ensure that the occlusion relationship is calculated in the order of the signs. After sorting, prioritize the occlusion of the nearest sign. If the nearest sign is blocked, there is no need to analyze the subsequent signs. Calculate the cumulative distance between each sign and the starting point of the road, the cumulative distance d i is the actual driving distance from the starting point of the road along the road curve to the sign. The road curve consists of multiple path points, consisting of P0, P1, P2...Pn. 0 is the starting point of the path point, n is the index of the last point in the path point sequence, the total number of path points is n+1, the total number of line segments between adjacent points is n, and a line segment is formed between every two adjacent points. The distance d between path points n It is calculated by Euclidean distance, the formula is as follows: Where (x n ,y n , z n ) is the path point P n The three-dimensional coordinates of ; j is the index of the path segment where the sign projection point is located; By finding the projection point (x i ,y i , z i ), the cumulative distance of the sign is obtained by interpolation calculation, and the projection distance d of the sign projection point on the road proj The calculation formula is: Then the cumulative distance d i for: d i =d n +d proj (3)。 4. The road sign layout method based on geometric analysis according to claim 1 is characterized in that: In step 3, the range of signs visible to the driver is determined by combining vehicle speed and reaction time, and which signs can block the driver's view of other signs. The vehicle speed v determines the viewing distance d, which is calculated according to the formula: d=t r ×v (4) where t r is the driver's reaction time, which is used to simulate the time required for the driver to detect the sign and react; v is the vehicle speed; When performing occlusion geometry analysis, the viewpoint needs to be determined based on the height, viewing range, and field of view.

5. The road sign layout method based on geometric analysis according to claim 1 is characterized in that: In step 4, occlusion geometry analysis uses geometric relationships to determine whether the sign will be blocked by other objects or signs during vehicle driving. Specifically, the occlusion geometry calculation is performed using the tetrahedron volume method. The tetrahedron volume method is a method for determining occlusion by calculating the volume relationship between the viewpoint and the target object and between the viewpoint and the occluding object. For a target object T0, if the polyhedron formed by the target object contains a point P in another object T1, then the target object T0 is considered to be blocked by the object T1 containing the point P. Through the calculation of the tetrahedron volume method, it is possible to detect whether the point P is inside the volume of the target object T0. Specifically: Assume there are four points ABCD, the volume of the tetrahedron V ABCD The formula is: Among them, det is the mathematical symbol of determinant, which means to calculate the determinant of the matrix; x, y, z represent the coordinate components of the point in three-dimensional space; the subscript letters A, B, C, and D represent different vertices, and x A 、y A 、z A represents the coordinates of the corresponding point A, and so on; The construction rule of the coordinate matrix is: each vertex coordinate is expanded into a four-dimensional vector (x, y, z, 1), and the four vertex coordinates are arranged in rows to form a 4×4 matrix; Construct the target object tetrahedron OABCD, with point O as the viewpoint, located at a fixed position; if the sum of the volumes of all small tetrahedrons is equal to the volume of tetrahedron OABCD, then: V OABCD =V OABP +V OBCP +V OCDP +V OADP +V PABCD (6) Then the target point P is located inside the tetrahedron OABCD, indicating that the target object is blocked; For multiple points in the occluding object, the above process is repeated to determine whether each point occludes the target object. If all points of the occluding object are not within the volume of the target object, the target object is considered to be unoccluded; conversely, if at least one point is included in the volume of the target object, the target object is considered to be occluded.

6. The road sign layout method based on geometric analysis according to claim 5 is characterized in that: In step 4, when the line of sight of the target object T is blocked by multiple occluders Q1, Q2, ..., Qn, the occlusion relationship needs to be comprehensively calculated. Assuming that each occluder may partially block the line of sight of the target object, the occlusion effect of multiple occluders is analyzed through the following steps: Independent occlusion judgment: Use the tetrahedron volume method for each occluder to determine whether the target object T is occluded. The viewpoint O is located at a fixed position. The target object T will be affected by n occluders. For each occluder, construct the target object tetrahedron OABCD and determine whether each occluder Qi occludes the target object T. Comprehensive occlusion analysis: superimpose the occlusion conditions of all occluders to determine the final occlusion state of the target object T; By comprehensively considering the occlusion effects of different scene conditions, the visibility C(T) of the target object T is calculated as follows: Where F(T, Qi)=0 means that the target object T is blocked by the occluder Qi; F(T, Qi)=1 means that the target object T is not blocked by the occluder Qi; Evaluate signage visibility by analyzing the combined impact of multiple obstructions.

7. An electronic device comprising a memory and a processor, characterized in that: A computer program is stored in the memory, and the processor is configured to run the computer program to perform the method according to any one of claims 1 to 6.

8. A computer storage medium, characterized in that The computer storage medium stores a plurality of instructions, and the instructions are suitable for being loaded by a processor and executing the method according to any one of claims 1 to 6.

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