Method, device and application of outdoor fast ray tracing model

Abstract

The application belongs to the technical field of radio wave propagation prediction modeling and optimization, and discloses a construction method, system, device and terminal of an outdoor fast ray tracing model, 3D digital geometric information of an outdoor environment of a ray tracing model is imported, and initial input parameters of the ray tracing model are fixed; the input parameters are initialized, including a transmitting antenna operating frequency, a transmitting power, a transmitting and receiving antenna position and environmental electrical parameters; the ray tracing model is run, and field strength, power and multipath information of a prediction point are calculated. The application imports a column model into an outdoor ray tracing algorithm, and the column model has much fewer surface elements than a triangular surface element model, so that the calculation efficiency of the ray tracing algorithm is greatly improved. In a specific outdoor environment, compared with a ray tracing algorithm model based on a triangular surface element model, the ray tracing algorithm efficiency of the transformed column surface element model provided by the application is higher, and the modeling model of common software can be directly used.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of radio wave propagation prediction modeling and optimization, and particularly relates to a method, system, device and terminal for constructing an outdoor fast ray tracing model. BACKGROUND

[0002] Currently, the ray tracing wireless channel prediction model is the application of computer graphics, geometric optics and other technologies in the field of electromagnetic calculation. Compared with the traditional empirical wireless channel prediction model, the ray tracing model is a deterministic calculation model that can accurately predict the received power and multipath information of a complex outdoor scene. The model needs to input actual environment model data, transmit antenna power, transmit electromagnetic wave frequency, the location of the transmitting and receiving point in the environment and other information, and then calculate the received power and multipath information of the receiving point through simulated ray tracing, so as to simulate the real radio wave propagation process. However, the existing ray tracing wireless channel prediction model has low computational efficiency. The present application simplifies the environment model data based on physical laws to improve the computational efficiency.

[0003] In the application of actual outdoor scenes, the electromagnetic wave signal is regarded as an idealized light ray through the ray tracing algorithm, so that the propagation of the electromagnetic wave signal in the indoor medium can be calculated in the form of tracing the ray. Starting from a certain initial source point, the electromagnetic wave in the form of a ray experiences direct reflection, transmission, diffraction and reaches a certain prediction point. The size of the electromagnetic wave signal at the prediction point is determined by the size of the source point transmitting electromagnetic wave signal and the attenuation generated in the propagation process. The outdoor scene area is large, and the number of traditional triangular facet elements is large, which makes the computational efficiency low. The method of converting the triangular facet element model into a cylinder model can effectively improve the efficiency of the ray tracing algorithm.

[0004] Common digital geometric models are mostly triangular facet element described geometric models, such as.stl files,.obj files, etc. which are commonly described by triangular facet elements and corresponding normal vectors. Such models have a large number of facet elements, resulting in low computational efficiency. In outdoor environments, especially in urban environments, most buildings are polygonal cylinders or can be approximated as cylinders, but the output models of most modeling software are in triangular facet element format.

[0005] Limited by the input model information, if the input triangular facet element model building is small, the converted model building is also small. For particularly complex buildings such as courtyards and quadrangles, internal information will be lost. For buildings with non-cylindrical shapes, the model will have a large distortion.

[0006] Through the above analysis, the problems and defects of the prior art are:

[0007] (1)The existing ray tracing model calculation efficiency is affected by the number of environment facets, the more the number of facets, the longer the calculation time, and the model output by the common modeling software is a triangular facet model with more number of facets.

[0008] (2)Limited by the input model information, if the input triangular facet model building is less, the building of the converted model is also less, for special complex buildings such as courtyards, the internal information will be lost, and for buildings with non-cylinder shape, the model will have large distortion. SUMMARY

[0009] In view of the problems in the prior art, the present application provides a method, system, device and terminal for constructing an outdoor fast ray tracing model.

[0010] The present application is implemented as follows: a method for constructing an outdoor fast ray tracing model, the method comprising: importing 3D digital geometric information and corresponding material electromagnetic information of an outdoor environment of a ray tracing model; in a second step, optimizing the scene model into a corresponding cylinder model; then fixing the initial input parameters of the ray tracing model, including the operating frequency of the transmitting antenna, the transmitting power, the position of the transmitting and receiving antennas and the environmental electrical parameters; finally, running the ray tracing model based on the new scene information model, and calculating the field strength, power and multipath information of the prediction point.

[0011] Further, the method for constructing an outdoor fast ray tracing model comprises the following steps:

[0012] Step one: importing a triangular facet representation of a geometric digital model file in.stl and.obj formats to obtain triangular facet geometry representing the geometric model of the outdoor simulation environment; this step is to obtain specific scene information for calculation and is the basis for establishing a deterministic model.

[0013] Step two: projecting the triangular facets to a two-dimensional plane to obtain a line segment set, calculating the collision intersection of the line segments after deduplication of the line segment set, and establishing a directed graph of points on the plane; this step is the basic step for converting to a cylinder model.

[0014] Step three: finding a loop in the directed graph by using a breadth-first algorithm or a depth-first algorithm, the loop being a two-dimensional projection contour of a building; this step is the key step for converting to a cylinder model.

[0015] Step four: obtaining corresponding height information to convert the triangular facet model into a cylinder model; importing the cylinder model into a ray tracing algorithm and calculating the received signal power; this step is based on the cylinder model to develop electromagnetic calculation.

[0016] Further, in the step one, the initial input file is in the format of points or patches, including three-dimensional information of points and normal vector of patches.

[0017] Further, in the step two, the obtained projection line segment needs to be processed, specifically including: removing repeated line segments; and splicing adjacent line segments on the same straight line.

[0018] Further, in the step three, the obtained two-dimensional projection contour of the building needs to be processed, specifically including: merging and deleting the two-dimensional projection contour with inclusion relationship.

[0019] Further, in the step four, the initial input parameters include the operating frequency of the transmitting antenna, the transmitting power, the position of the transmitting and receiving antennas and the environmental electrical parameters.

[0020] Another object of the present application is to provide an outdoor fast ray tracing model construction system applying the outdoor fast ray tracing model construction method, which comprises:

[0021] A triangular patch geometry data acquisition module is used to import the triangular patch representation of the geometry digital model file of.stl and.obj, and obtain the triangular patch geometry representing the outdoor simulation environment geometry model;

[0022] A point directed graph establishment module is used to project the triangular patch to a two-dimensional plane to obtain a line segment set, calculate the collision intersection of the line segments after deduplication of the line segment set, and establish a point directed graph on the plane;

[0023] A directed graph ring finding module is used to find the ring in the directed graph through the breadth-first algorithm or the depth-first algorithm, and the ring is the two-dimensional projection contour of the building;

[0024] A received signal power calculation module is used to obtain corresponding height information, convert the triangular patch model into a column model, import the column model into the ray tracing algorithm, and calculate the received signal power.

[0025] Another object of the present application is to provide a computer device, which comprises a memory and a processor, the memory stores a computer program, and the computer program is executed by the processor to make the processor execute the steps of the outdoor fast ray tracing model construction method.

[0026] Another object of the present application is to provide a computer readable storage medium, which stores a computer program, and the computer program is executed by the processor to make the processor execute the steps of the outdoor fast ray tracing model construction method.

[0027] Another object of the present application is to provide an information data processing terminal for implementing the construction system of the outdoor fast ray tracing model.

[0028] In combination with the above technical solutions and the technical problems solved, the technical solutions of the present application have the following advantages and positive effects:

[0029] First, in view of the technical problems existing in the prior art and the difficulty in solving the problems, the present application is closely combined with the technical solutions to be protected and the results and data in the research and development process, and the technical problems solved by the technical solutions of the present application are analyzed in detail and profoundly, and some creative technical effects brought about after the problems are solved are described as follows:

[0030] The method for constructing an outdoor fast ray tracing model provided by the present application projects a common geometric digital model represented by a triangular facet element to a two-dimensional plane to obtain a line segment set, calculates the collision intersection of the line segments after deduplication of the line segment set, establishes a directed graph of points on the plane based on the information, and calculates the loops in the directed graph, removes the contained loops, and thus obtains the two-dimensional projection contour of the model; the corresponding height information is obtained, and the triangular facet element model can be converted into a simpler cylinder model; the cylinder model is imported into the outdoor ray tracing algorithm, and since the number of facets of the cylinder model is much smaller than that of the triangular facet element model, the calculation efficiency of the ray tracing algorithm is greatly improved.

[0031] Second, from the perspective of the product as a whole, the technical solutions to be protected by the present application have the following technical effects and advantages:

[0032] In a specific outdoor environment, for example, in a city environment with many buildings, compared with the ray tracing algorithm model based on the triangular facet element model, the ray tracing algorithm of the converted cylinder facet element model provided by the present application has higher efficiency without affecting the calculation accuracy, and can directly use the modeling model of common software.

[0033] Third, as the auxiliary evidence for the creativity of the claims of the present application, the following important aspects are also embodied:

[0034] The technical solutions of the present application solve the technical problems that people have long been eager to solve but have failed to successfully solve: the present application solves the problem of calculation efficiency of the wireless channel prediction model based on the ray tracing algorithm, improves the calculation speed of electromagnetic propagation in an outdoor environment (especially in a city environment with many buildings), and further provides services for base station location deployment, network planning decision, etc. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0036] Figure 1 is a flow chart of the method for constructing the outdoor fast ray tracing model provided by the embodiments of the present application;

[0037] Figure 2 is a schematic diagram of a common.stl digital three-dimensional environment model provided by the embodiments of the present application;

[0038] Figure 3 is a grid diagram of a common.stl digital three-dimensional environment model provided by the embodiments of the present application;

[0039] Figure 4 is a two-dimensional projection contour diagram of an outdoor scene building provided by the embodiments of the present application;

[0040] Figure 5 is a building column model diagram of an outdoor scene provided by the embodiments of the present application;

[0041] Figure 6 is a ray tracing multipath information diagram provided by the embodiments of the present application;

[0042] Figure 7 is a received signal power coverage diagram provided by the embodiments of the present application. DETAILED DESCRIPTION

[0043] In order to make the objects, technical solutions and advantages of the present application more clear, the following will further describe the present application in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0044] In view of the problems in the prior art, the present application provides a method, system, device and terminal for constructing an outdoor fast ray tracing model, which will be described in detail below in combination with the drawings.

[0045] I. Explanation of the embodiments. In order to enable those skilled in the art to fully understand how the present application is specifically implemented, this part is an explanation of the embodiments of the technical solutions of the claims.

[0046] As shown in Figure 1 the method for constructing the outdoor fast ray tracing model provided by the embodiments of the present application includes the following steps:

[0047] S101, importing 3D digital geometric information of an outdoor environment of a ray tracing model;

[0048] S102, initial input parameters of the ray tracing model are fixed and initialized;

[0049] S103, the ray tracing model is run, and the field strength, power and multipath information of the predicted point are calculated.

[0050] As a preferred embodiment, the method for constructing the outdoor fast ray tracing model provided by the embodiment of the application comprises the following steps:

[0051] Step 1, a common.stl,.obj or other triangular facet representation geometric digital model file is imported to obtain triangular facet geometry representing the geometric model of the outdoor simulation environment. This step mainly provides environmental information for the simulation of the ray tracing model, and is an input parameter for obtaining the column facet model.

[0052] Step 2, the triangular facets are projected onto a two-dimensional plane to obtain a line segment set, and the collision intersection of the line segments is calculated after the line segment set is de-duplicated to establish a directed graph of points on the plane. This step is to obtain the projection point information of the building.

[0053] Step 3, loops in the directed graph are found by using a breadth-first algorithm or a depth-first algorithm; these loops are the two-dimensional projection contours of the building. This step is to obtain the two-dimensional projection contours of the building.

[0054] Step 4, the corresponding height information is obtained, and the triangular facet model can be converted into a column model. The column model is imported into the ray tracing algorithm, and the received signal power is calculated. This step inputs other information required by the ray tracing and calculates the multipath information and the received signal power.

[0055] In step 1 provided by the embodiment of the application, the initial input file is in the format of points or facets, including three-dimensional information of points and normal vectors of facets.

[0056] In step 2 provided by the embodiment of the application, the obtained projection line segments need to be processed, specifically including: removing duplicate line segments; and splicing adjacent line segments on the same straight line.

[0057] In step 3 provided by the embodiment of the application, the obtained two-dimensional projection contours of the building need to be processed, specifically including: merging and deleting two-dimensional projection contours having a containing relationship.

[0058] In step 4 provided by the embodiment of the application, the initial input parameters include the operating frequency of the transmitting antenna, the transmitting power, the positions of the transmitting and receiving antennas and environmental electrical parameters.

[0059] The construction system of the outdoor fast ray tracing model provided by the embodiment of the application comprises:

[0060] A triangular facet geometry data acquisition module is configured to import a triangular facet representation geometry digital model file in.stl or.obj format to obtain triangular facet geometry representing an outdoor simulation environment geometry model;

[0061] A point directed graph establishment module is configured to project the triangular facet to a two-dimensional plane to obtain a line segment set, calculate collision intersection of the line segments after deduplication of the line segment set, and establish a point directed graph on the plane;

[0062] A directed graph loop searching module is configured to search for a loop in the directed graph by using a breadth-first algorithm or a depth-first algorithm, and the loop is a two-dimensional projection contour of the building;

[0063] A received signal power calculation module is configured to obtain corresponding height information, convert the triangular facet model into a cylinder model, import the cylinder model into a ray tracing algorithm, and calculate the received signal power.

[0064] II. Application Examples. In order to prove the creativity and technical value of the technical solutions of the present application, this part is an application example of the technical solutions of the claims on a specific product or related technology.

[0065] How to better deploy base stations in a 5G urban environment is one of the problems currently faced by the industry. Since the electromagnetic wave frequency used by 5G is high, the energy loss of electromagnetic wave propagation is large, and the coverage range of a base station with the same power is greatly reduced compared with a 4G base station. Since the traditional statistical-based algorithm is not accurate many times, the deterministic algorithm has the advantage of high precision at this time. The present application improves the calculation efficiency of the deterministic algorithm, and meets the needs of not affecting the calculation result precision and improving the calculation efficiency.

[0066] III. Evidence of the effects of the embodiments. The embodiments of the present application have achieved some positive effects during research and development or use, and indeed have great advantages compared with the prior art. The following content is described in combination with data, graphs and the like during the test process.

[0067] As shown in Figure 2 and Figure 3 , the input geometry file used by the embodiments of the present application is an.stl file. This file contains vertex information and normal information of the triangular facet of the building. The.stl file can only be used to represent a closed surface or body. There are two types of.stl files: one is ASCII plain code format, and the other is binary format.

[0068] After reading the.stl file, the edge information of the geometric object is obtained, and the z coordinate of the edge is removed to obtain a set of line segments on a two-dimensional plane. The repeated line segments are removed, and adjacent line segments on the same straight line are spliced. The collision intersection of the line segments is calculated, and a directed graph of points on the plane is established based on this information. The loops in the directed graph are found by using a depth-first algorithm, and these loops are the two-dimensional projection contours of the building, as shown in FIG. 1. Figure 4

[0069] According to the z coordinate information of the triangular surface corresponding to the line segment, the height of the building can be obtained, and the two-dimensional projection contour can be used to obtain a cylinder model, as shown in FIG. 2. Figure 5

[0070] The cylinder model is imported into a corresponding ray tracing algorithm, and the position of the transmitting antenna (50, 50, 3), the position of the receiving antenna (150, 80, 3), the operating frequency of the transmitting antenna (26 GHz), the transmitting power of the transmitting antenna (1 w), and the environmental electrical parameters (see Table 1) are set. The multipath information and the received signal power of electromagnetic propagation can be calculated, as shown in FIGS. 3 and 4, respectively. Figure 6 Figure 7

[0071] Table 1 Material properties used in simulation calculation (26 GHz)

[0072] Material Material No. Relative dielectric constant Electrical conductivity (S / m) Air 0 1 0 Concrete 2 5.31 0.4557

[0073] It should be noted that the embodiments of the present application can be realized by hardware, software or a combination of software and hardware. The hardware part can be realized by using special logic; the software part can be stored in a memory and executed by a suitable instruction execution system, such as a microprocessor or a specially designed hardware. Those skilled in the art can understand that the above-mentioned devices and methods can be realized by using computer executable instructions and / or included in processor control code, such as provided on a carrier medium, such as a magnetic disk, CD or DVD-ROM, a programmable memory, such as a read-only memory (firmware), or a data carrier, such as an optical or electronic signal carrier. The devices of the present application and their modules can be realized by a hardware circuit, such as a very large scale integrated circuit or a gate array, a semiconductor, such as a logic chip, a transistor, or a programmable hardware device, such as a field programmable gate array, a programmable logic device, etc. They can also be realized by software executed by various types of processors, or by a combination of the above-mentioned hardware circuit and software, such as firmware.

[0074] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any modification, equivalent replacement and improvement made by those skilled in the art within the technical range disclosed by the present application, as long as it is within the spirit and principle of the present application, should be covered within the protection scope of the present application.​​​​

Claims

1. A method for constructing an outdoor fast ray tracing model, characterized in that, The method for constructing the outdoor fast ray tracing model includes: importing the 3D digital geometric information of the outdoor environment of the ray tracing model, while fixing the initial input parameters of the ray tracing model; initializing the input parameters, running the ray tracing model, and calculating the field strength, power, and multipath information of the prediction point; wherein, the initial input parameters include the operating frequency of the transmitting antenna, the transmitting power, the position of the transmitting and receiving antennas, and the environmental electrical parameters; The method for constructing the outdoor fast ray tracing model includes the following steps: Step 1: Import the .stl and .obj triangular facet geometric model files to obtain the triangular facet geometric data representing the geometric model of the outdoor simulation environment. Step 2: Project the triangular facets onto a two-dimensional plane to obtain a set of line segments. After deduplicating the line segments, calculate the collision and intersection of the line segments and establish a directed graph of the points on the plane. Step 3: Find the cycle in the directed graph using either a breadth-first search algorithm or a depth-first search algorithm. The cycle is the two-dimensional projected outline of the building. Step 4: Obtain the corresponding height information and convert the triangular facet model into a cylindrical model; import the cylindrical model into the ray tracing algorithm and calculate the received signal power.

2. The method for constructing an outdoor fast ray tracing model as described in claim 1, characterized in that, In step one, the initial input file is in the format of points or polygons, including the three-dimensional information of the points and the normal vectors of the polygons.

3. The method for constructing an outdoor fast ray tracing model as described in claim 1, characterized in that, In step two, the obtained projected line segments need to be processed, specifically including: removing duplicate line segments; and splicing adjacent line segments that are on the same straight line.

4. The method for constructing an outdoor fast ray tracing model as described in claim 1, characterized in that, In step three, the obtained two-dimensional projection outline of the building needs to be processed, specifically including merging and deleting two-dimensional projection outlines that have an inclusion relationship.

5. A system for constructing an outdoor fast ray tracing model using the method for constructing an outdoor fast ray tracing model as described in any one of claims 1 to 4, characterized in that, The system for building the outdoor fast ray tracing model includes: The triangular element geometric data acquisition module is used to import geometric digital model files representing triangular elements in .stl and .obj formats to obtain triangular element geometric data representing the geometric model of the outdoor simulation environment. The directed graph building module is used to project triangular elements onto a two-dimensional plane to obtain a set of line segments. After deduplication of the line segment set, the collision and intersection of the line segments are calculated, and a directed graph of points on the plane is built. The directed graph loop finding module is used to find loops in a directed graph using a breadth-first search algorithm or a depth-first search algorithm. The loop is the two-dimensional projected outline of a building. The received signal power calculation module is used to obtain the corresponding height information, convert the triangular facet model into a cylinder model, import the cylinder model into the ray tracing algorithm, and calculate the received signal power.

6. A computer device, characterized in that, The computer device includes a memory and a processor. The memory stores a computer program that, when executed by the processor, causes the processor to perform the steps of the method for constructing an outdoor fast ray tracing model as described in any one of claims 1 to 4.

7. A computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the method for constructing an outdoor fast ray tracing model as described in any one of claims 1 to 4.

8. An information data processing terminal, characterized in that, The information data processing terminal is used to implement the outdoor rapid ray tracing model construction system as described in claim 5.

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