CN112330812B - A gas diffusion visualization method and system - Google Patents

Abstract

The invention discloses a gas diffusion visualization method and system. The method includes: S1, obtaining the gas diffusion parameters and the height of the gas diffusion surface to be observed, using the Gaussian diffusion model to obtain multiple diffusion points distributed at equal intervals on the gas diffusion surface to be observed and the gas concentration value of each diffusion point, according to the diffusion point Construct the diffusion point data array based on the positional relationship; S2, obtain the vertex indices of all triangle patches in the diffusion point data array; S3, draw the triangle patch according to the vertex index of the triangle patch, and match the color array; S4, convert the vertex data of all triangle patches The color array matched with each triangular facet is input to the OSG platform for rendering and display. The accuracy of visualization details is determined by the distance between diffusion points. The smaller the distance between point data, the higher the visualization accuracy; it can quickly and easily obtain the vertex index of the triangle patch, avoiding the cumbersome calculation of the vertex index array, and the visualization in OSG is more realistic. simulation.

Description

A gas diffusion visualization method and system

technical field

The invention relates to the technical field of environmental safety, in particular to a gas diffusion visualization method and system.

Background technique

In life, it is often necessary to visualize the diffusion of gases (such as poisonous gas, smoke, etc.), and intuitively understand the range of gas diffusion, so as to conduct pollution assessment and guide personnel evacuation.

In the prior art, the combination of Gaussian smoke diffusion model and GIS has been widely studied, and the visualization of Gaussian smoke diffusion on the ArcGIS platform has been well known to the public; OSG (Open Scene Graph), as an open source graphics rendering library, performs Gaussian smoke diffusion Visualization of gas diffusion has not been studied. When rendering data on the OSG platform, it is generally discrete data. It is necessary to use interpolation to interpolate the data to become regular grid data before rendering, and it is also necessary to calculate the patch vertex index array to perform OSG rendering. Interpolation The process of processing and calculating the vertex index array is complex, computationally intensive and time-consuming.

Contents of the invention

The present invention aims at at least solving the technical problems existing in the prior art, and particularly innovatively proposes a gas diffusion visualization method and system.

In order to achieve the above object of the present invention, according to the first aspect of the present invention, the present invention provides a gas diffusion visualization method, comprising: step S1, obtaining gas diffusion parameters and the height of the gas diffusion surface to be observed, using a Gaussian diffusion model Obtain multiple diffusion points distributed at equal intervals in the gas diffusion surface to be observed and the gas concentration value of each diffusion point, convert the Gaussian coordinate system coordinates of the diffusion points into world coordinate system coordinates, and construct the diffusion point data array according to the positional relationship of the diffusion points , each element in the diffusion point data array includes the world coordinate system coordinates and the gas concentration value of the same diffusion point; step S2, obtain all triangle patch vertex indices of the diffusion point data array; step S3, according to the triangle surface The vertex index draws a triangle patch, and a group of triangle patch vertex indexes draws a triangle patch, based on the concentration values of the three vertices of the triangle patch to match the color array; step S4, the vertex data of all triangle patches and each triangle patch The color array matched by the patch is input to the OSG platform for rendering and display.

The above technical solution: This method produces multiple diffusion points at equal intervals on the gas diffusion surface to be observed, and the accuracy of the visualization details is determined by the distance between the diffusion points. The smaller the distance between the point data, the higher the visualization accuracy; based on the diffusion point data The equidistant positional relationship can quickly and easily obtain the vertex index of the triangular patch, saving the cumbersome calculation of the vertex index array; the OSG platform is a 3D digital earth engine library developed based on the 3D engine OSG, which can realize a 3D virtual earth and can Realistically render the topography of the smoke diffusion environment, perform color rendering through the vertex data of the triangular patch and the matching color array of each triangular patch to generate isosurface primitives, and complete the visualization of point data in OSG, which can be more intuitive It can accurately display the pollution range of flue gas, realize more realistic simulation, and facilitate the evaluation of pollution.

In a preferred embodiment of the present invention, in step S2, the process of obtaining the triangular patch vertex index of the diffusion point data array is as follows: for any adjacent four diffusion points in the diffusion point data array, set four diffusion points The points are the diffusion point P _i,j with the number of rows i and the number of columns j, the diffusion point P i,j+1 with the number of rows i and the number of columns j+1, and the diffusion point P _i,j+1 with the number of rows i+1 and the number of columns j Diffusion point P _i+1,j , diffusion point P i+1,j+1 with row number i+1 and column number j ₊₁ , two sets of triangular patch vertex indices are defined in the four diffusion points, one set The triangle patch vertex index is composed of the number of rows and columns of the diffusion points P _i,j , P _i,j+1 , P _i+1,j , and the other set of triangle patch vertex indexes is composed of the diffusion points P _i,j+1 , P _i+1,j and P _i+1,j+1 are composed of rows and columns, and both i and j are positive integers.

The above technical solution: based on the equidistant positional relationship of the diffusion point data, instead of calculating the vertex index array, the positional relationship characteristics of the diffusion point are used to directly define the vertex index of the triangle patch as the number of rows and columns of the three vertices. While improving the fineness of the mesh, the process is simplified and the tedious calculation of calculating the vertex index array is saved.

其中，C(x,y,z,H)表示位置点(x,y,z,H)的气体浓度；Q表示气体排放速度；σ_y表示侧向扩散系数，为气体在高斯坐标系y轴方向分布的标准偏差，

γ₁表示第一比例系数，

表示第一指数系数；σ_z表示竖向扩散系数，为气体在高斯坐标系z轴方向分布的标准偏差，

γ₂表示第二比例系数，

表示第二指数系数；U^p表示气体源排放口处的平均风速；H表示气体源有效高度；x表示下风向上扩散点距离气体源排放点的距离；y表示在高斯坐标系xoy平面上到x轴的垂直距离；z表示气体扩散面高度。In a preferred embodiment of the present invention, the gas diffusion parameters include all or part of the position of the gas source, the average wind speed at the outlet, the gas discharge velocity, and the effective height of the gas source. In a preferred embodiment of the present invention, in the step S1, the Gaussian diffusion model is:

Among them, C(x, y, z, H) represents the gas concentration at the position point (x, y, z, H); Q represents the gas emission velocity; σ _y represents the lateral diffusion coefficient, which is the gas on the y-axis of the Gaussian coordinate system standard deviation of the orientation distribution,

γ ₁ represents the first scaling factor,

Indicates the first index coefficient; σ _z indicates the vertical diffusion coefficient, which is the standard deviation of gas distribution in the z-axis direction of the Gaussian coordinate system,

γ ₂ represents the second scaling factor,

Indicates the second index coefficient; U ^p indicates the average wind speed at the outlet of the gas source; H indicates the effective height of the gas source; x indicates the distance between the downwind diffusion point and the gas source discharge point; The vertical distance of the axis; z represents the height of the gas diffusion surface.

The above technical solution: using the diffusion points produced by the Gaussian diffusion model, the pollution range of the flue gas can be intuitively displayed, and the visualization of the Gaussian diffusion model is realized.

In a preferred embodiment of the present invention, the process of transforming the Gaussian coordinate system coordinates of the diffusion point into the world coordinate system coordinates is: if the Gaussian coordinate system coordinates of the diffusion point are (x, y, C), then the diffusion point The world coordinate system coordinates of the point are (LON', LAT', C); the specific solution process includes: Step A, the longitude LON calculation formula is:

纬度LAT计算公式为：

其中，C表示扩散点(x,y)的气体浓度值；B_f表示底点纬度，通过高斯x轴坐标求取；y表示高斯y轴坐标；e表示地球椭圆第一偏心率；e^∫表示地球椭圆第二偏心率；a表示地球椭圆长半轴；所述B_f的获取过程为：步骤一，设i为迭代次数，变量m₀＝a(1-e²)，变量

变量

变量

变量

变量

变量

变量

变量

设B_f的初始迭代值为B_f ¹＝x/a₀，ε为差值阈值，0＜|ε|＜0.000001；步骤二，计算

判断B_f ⁱ⁺¹-B_f ⁱ＜ε是否成立，若B_f ⁱ⁺¹-B_f ⁱ＜ε成立，令B_f＝B_f ⁱ⁺¹，获取B_f的过程结束，进入步骤B，若B_f ⁱ⁺¹-B_f ⁱ＜ε不成立，令i＝i+1，返回步骤一；步骤B，通过LON计算公式和纬度LAT计算公式获得数据原点(0，0)的经纬度坐标(LAT₀,LON₀)；将所述扩散点的高斯坐标系坐标(x,y)代入经度LON计算公式和纬度LAT计算公式获得(LAT_i,LON_i)；设世界坐标系模拟场景中的事故点为(LAT_s,LON_s)，则所述扩散点的世界坐标系坐标为：LAT'＝LAT_i-LAT₀+LAT_s，LON'＝LON_i-LON₀+LON_s。

Latitude LAT calculation formula is:

Among them, C represents the gas concentration value of the diffusion point (x, y); B _f represents the latitude of the bottom point, obtained through the Gaussian x-axis coordinate; y represents the Gaussian y-axis coordinate; e represents the first eccentricity of the earth ellipse; e ^∫ represents The second eccentricity of the earth ellipse; a represents the semi-major axis of the earth ellipse; the acquisition process of the B _f is: Step 1, set i as the number of iterations, variable m ₀ =a(1-e ² ), variable

variable

variable

variable

variable

variable

variable

variable

Let the initial iteration value of B _f be B _f ¹ =x/a ₀ , ε is the difference threshold, 0<|ε|<0.000001; step 2, calculate

Determine whether B _f ⁱ⁺¹ -B _f ⁱ <ε is true, if B _f ⁱ⁺¹ -B _f ⁱ <ε is true, set B _f =B _f ⁱ⁺¹ , the process of obtaining B _f is over, and enter step B, If B _f ⁱ⁺¹ -B _f ⁱ <ε is not established, let i=i+1, return to step one; step B, obtain the latitude and longitude coordinates (LAT) of the data origin (0, 0) through the calculation formula of LON and the calculation formula of latitude ₀ , LON ₀ ); Substituting the Gaussian coordinate system coordinates (x, y) of the diffusion point into the longitude LON calculation formula and the latitude LAT calculation formula to obtain (LAT _i , LON _i ); set the world coordinate system to simulate the accident point in the scene is (LAT _s , LON _s ), then the world coordinate system coordinates of the diffusion point are: LAT'=LAT _i -LAT ₀ +LAT _s , LON'=LON _i -LON ₀ +LON _s .

The above technical solution: the world coordinate system coordinates of the diffusion point can be quickly and accurately converted.

In a preferred embodiment of the present invention, the process of matching the color array based on the concentration values of the three vertices of the triangular surface in step S3 includes: establishing multiple color arrays and multiple gas concentration ranges, and the color array and gas concentration Ranges correspond one-to-one, and the color array is expressed as [R, G, B, A], wherein R, G, B represent the three primary color components of the color, and A represents the transparency of the color; The color array corresponding to the gas concentration range of the value or the gas concentration range of the average value of the three vertex concentration values is used as the color array matched by the triangular patch.

The above technical solution: generating isosurface primitives is beneficial to gas diffusion evaluation.

In order to achieve the above object of the present invention, according to a second aspect of the present invention, the present invention provides a gas diffusion visualization system, including a gas diffusion parameter acquisition module, a processor and an OSG platform, and the processor is respectively connected with the gas diffusion parameter The acquisition module is connected to the OSG platform; the processor executes the gas diffusion visualization method of the present invention, and inputs the vertex data of all triangular faces and the corresponding color array of each triangular face into the OSG platform, and the OSG platform performs rendering processing And display the rendering processing result.

The above technical solution: produce multiple diffusion points at equal intervals on the gas diffusion surface to be observed, and the accuracy of the visualization details is determined by the distance between the diffusion points. The smaller the distance between the point data, the higher the visualization accuracy; The positional relationship of the triangular surface can quickly and easily obtain the vertex index of the triangle surface, saving the tedious calculation of calculating the vertex index array; the OSG platform is a 3D digital earth engine library developed based on the 3D engine osg, which can realize a 3D virtual earth and can be real Render the topography of the smoke diffusion environment, perform color rendering through the vertex data of the triangular patch and the color array matched by each triangular patch to generate isosurface primitives, and complete the visualization of point data in OSG, which can be displayed more intuitively The pollution range of the flue gas can achieve a more realistic simulation, which is conducive to the evaluation of pollution.

Description of drawings

Fig. 1 is a schematic flow chart of a gas diffusion visualization method in a specific embodiment of the present invention;

Fig. 2 is a schematic diagram of a gas source in a specific embodiment of the present invention.

detailed description

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

In describing the present invention, it should be understood that the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", The orientation or positional relationship indicated by "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than Nothing indicating or implying that a referenced device or element must have a particular orientation, be constructed, and operate in a particular orientation should therefore not be construed as limiting the invention.

In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be mechanical connection or electrical connection, or two The internal communication of each element may be directly connected or indirectly connected through an intermediary. Those skilled in the art can understand the specific meanings of the above terms according to specific situations.

The present invention discloses a gas diffusion visualization method. In a preferred embodiment, the flow diagram of the method is shown in Figure 1, which specifically includes:

Step S1, obtain the gas diffusion parameters and the height of the gas diffusion surface to be observed, use the Gaussian diffusion model to obtain multiple diffusion points distributed at equal intervals on the gas diffusion surface to be observed and the gas concentration value of each diffusion point, and convert the Gaussian coordinates of the diffusion points to System coordinates are converted into world coordinate system coordinates, and the diffusion point data array is constructed according to the positional relationship of the diffusion points, and each element in the diffusion point data array includes the world coordinate system coordinates and gas concentration values of the same diffusion point;

Step S2, obtaining all triangle patch vertex indexes of the diffusion point data array;

Step S3, draw a triangle patch according to the vertex index of the triangle patch, draw a triangle patch with a group of triangle patch vertex indexes, and match the color array based on the concentration values of the three vertices of the triangle patch;

Step S4, input the vertex data of all triangle faces and the matching color array of each triangle face into the OSG platform for rendering and displaying. Through the OSGEarth loading mechanism, the isosurface rendering under the geodetic coordinate system is loaded to the corresponding longitude and latitude position of the earth model to realize visualization.

In this embodiment, the height of the gas diffusion surface to be observed may be the height of the observed gas diffusion surface from the sea level, that is, the altitude. This method outputs the gas diffusion schematic diagram of the gas diffusion surface to be observed after inputting the height of the gas diffusion surface to be observed. The gas is preferably, but not limited to, various fire smoke, polluted gas and toxic gas discharged from flue gas of chemical plants.

In this embodiment, the diffusion points in the gas diffusion surface to be observed are equally spaced in the x-axis and y-axis directions of the Gaussian coordinate system, forming a series of array points, so the diffusion point data array is constructed according to the positional relationship of the diffusion points In , the physical distance between rows is equal to the physical distance between columns.

In this embodiment, the position coordinates of the diffusion point obtained by using the Gaussian diffusion model are based on the Gaussian coordinate system. Preferably, the Gaussian coordinate system needs to be converted into a latitude-longitude coordinate system first, and the diffusion point data (longitude, latitude, concentration) is saved to TXT In the file, the diffusion point data is converted from the latitude and longitude coordinate system to the world coordinate system of OSG Digital Earth through the OSG platform, so that it can be rendered and visualized on the OSG platform. It is preferred but not limited to programming the Gaussian diffusion model and other steps of the method by Python.

In a preferred embodiment, in step S2, the process of obtaining the triangular patch vertex index of the diffusion point data array is as follows: for any adjacent four diffusion points in the diffusion point data array, the four diffusion points are respectively Diffusion point P _i,j with row number i and column number j, diffusion point P _i,j+1 with row number i and column number j+1, diffusion point P with row number i+1 column number j _i+1,j , the diffusion point P _i+1,j+1 with the number of rows i+1 and the number of columns j+1, defines two sets of triangular patch vertex indices in the four diffusing points, and a set of triangular patch The vertex index is composed of the number of rows and columns of the diffusion points P _i,j , P _i,j+1 , P _i+1,j , and the other group of triangular patch vertex indexes is composed of the diffusion points P _i,j+1 , P _{i+1 , j} , P _{i+1, j+1} rows and columns, i and j are both positive integers.

In this embodiment, the triangle patch vertex index is set by the number of rows and columns of the diffusion point data array. The triangle patch vertex index is the order of the points when the triangle patch is drawn, and the triangle surface is drawn in sequence from three points, which can be pre-set Set the OSG vertex index array, and store the obtained triangle patch vertex index into the OSG vertex index array. The triangular patch vertex index acquisition process is as follows: the first and second diffusion points of the first row of data and the number of rows and columns of the first diffusion point of the second row form a set of triangular patch vertex indices, and then the second row and column number of the first row of data The number of rows and columns of the first and second diffusion points in the second row forms another set of triangular patch vertex indices; the four point data in the point data array form 2 sets of triangular patch vertex indices, according to the diffusion point array rows The sequence numbers are cycled sequentially to obtain the vertex indexes (that is, the row and column positions) of all the data.

In a preferred embodiment, the gas diffusion parameters include all or part of the position of the gas source, the average wind speed at the outlet, the gas discharge speed, and the effective height of the gas source.

In a preferred embodiment, as shown in the schematic diagram of the gas source structure in Figure 2, in step S1, the Gaussian diffusion model is:

γ₁表示第一比例系数，

表示第一指数系数；σ_z表示竖向扩散系数，为气体在高斯坐标系z轴方向分布的标准偏差，

γ₂表示第二比例系数，

表示第二指数系数；U^p表示气体源排放口处的平均风速；H表示气体源有效高度；x表示下风向上扩散点距离气体源排放点的距离；y表示在高斯坐标系xoy平面上到x轴的垂直距离；z表示气体扩散面高度。Among them, C(x, y, z, H) represents the gas concentration at the position point (x, y, z, H); Q represents the gas emission velocity; σ _y represents the lateral diffusion coefficient, which is the gas on the y-axis of the Gaussian coordinate system standard deviation of the orientation distribution,

γ ₁ represents the first scaling factor,

Indicates the first index coefficient; σ _z indicates the vertical diffusion coefficient, which is the standard deviation of gas distribution in the z-axis direction of the Gaussian coordinate system,

γ ₂ represents the second scaling factor,

Indicates the second index coefficient; U ^p indicates the average wind speed at the outlet of the gas source; H indicates the effective height of the gas source; x indicates the distance between the downwind diffusion point and the gas source discharge point; The vertical distance of the axis; z represents the height of the gas diffusion surface.

均可在GB3840－91《制定地方大气污染物排放标准的技术方法》中表D1根据模拟情况选取；第二比例系数γ₂、第二指数系数

均可在GB3840－91《制定地方大气污染物排放标准的技术方法》中表D2根据模拟情况选取。In this embodiment, preferably, the first proportional coefficient γ ₁ , the first exponential coefficient

All can be selected according to the simulation situation in Table D1 of GB3840-91 "Technical Methods for Establishing Local Air Pollutant Emission Standards"; the second proportional coefficient γ ₂ and the second index coefficient

All can be selected according to the simulation situation in Table D2 of GB3840-91 "Technical Methods for Establishing Local Air Pollutant Emission Standards".

In a preferred embodiment, the process of transforming the Gaussian coordinate system coordinates of the diffusion point into the world coordinate system coordinates is as follows:

Assuming that the Gaussian coordinate system coordinates of the diffusion point are (x, y, C), then the world coordinate system coordinates of the diffusion point are (LON', LAT', C); the specific solution process includes:

Step A, the longitude LON calculation formula is:

Latitude LAT calculation formula is:

Among them, C represents the gas concentration value of the diffusion point (x, y); B _f represents the latitude of the bottom point, obtained through the Gaussian x-axis coordinate; y represents the Gaussian y-axis coordinate; e represents the first eccentricity of the earth ellipse; e ^∫ represents The second eccentricity of the earth ellipse; a represents the semi-major axis of the earth ellipse;

The acquisition process of _Bf is:

变量

变量

变量

变量

变量

变量

变量

设B_f的初始迭代值为B_f ¹＝x/a₀，ε为差值阈值，0＜|ε|＜0.000001；Step 1, set i as the number of iterations, variable m ₀ =a(1-e ² ), variable

variable

variable

variable

variable

variable

variable

variable

Let the initial iteration value of B _f be B _f ¹ =x/a ₀ , ε is the difference threshold, 0<|ε|<0.000001;

判断B_f ⁱ⁺¹-B_f ⁱ＜ε是否成立，若B_f ⁱ⁺¹-B_f ⁱ＜ε成立，令B_f＝B_f ⁱ⁺¹，获取B_f的过程结束，进入步骤B，若B_f ⁱ⁺¹-B_f ⁱ＜ε不成立，令i＝i+1，返回步骤一；Step two, calculate

Determine whether B _f ⁱ⁺¹ -B _f ⁱ <ε is true, if B _f ⁱ⁺¹ -B _f ⁱ <ε is true, set B _f =B _f ⁱ⁺¹ , the process of obtaining B _f is over, and enter step B, If B _f ⁱ⁺¹ -B _f ⁱ <ε is not established, set i=i+1 and return to step 1;

Step B, obtain the latitude and longitude coordinates (LAT ₀ , LON ₀ ) of the data origin (0, 0) through the LON calculation formula and the latitude LAT calculation formula; Substitute the Gaussian coordinate system coordinates (x, y) of the diffusion point into the longitude LON calculation The formula and the latitude LAT calculation formula are obtained (LAT _i , LON _i ); if the accident point in the world coordinate system simulation scene is (LAT _s , LON _s ), then the world coordinate system coordinates of the diffusion point are: LAT'=LAT _i −LAT ₀ +LAT _s , LON′=LON _i −LON ₀ +LON _s .

In a preferred embodiment, the process of matching the color array based on the concentration values of the three vertices of the triangular surface in step S3 includes: establishing multiple color arrays and multiple gas concentration ranges, the color arrays correspond to the gas concentration ranges one by one, The color array is expressed as [R, G, B, A], where R, G, and B represent the three primary color components of the color, and A represents the transparency of the color; the gas concentration range of the three vertex concentration values of the triangular surface or the three vertices The color array corresponding to the gas concentration range where the average concentration value is located is used as the color array matched by the triangular patch.

The invention also discloses a gas diffusion visualization system. In a preferred embodiment, the system includes a gas diffusion parameter acquisition module, a processor and an OSG platform, and the processor is respectively connected to the gas diffusion parameter acquisition module and the OSG platform; The device implements the above gas diffusion visualization method, and inputs the vertex data of all triangular faces and the color array corresponding to each triangular face into the OSG platform, and the OSG platform performs rendering processing and displays the rendering processing results.

In this embodiment, the gas diffusion parameter acquisition module can be used to acquire the gas diffusion parameters and the height of the gas diffusion surface to be observed. The gas diffusion parameter acquisition module is preferably but not limited to a keyboard light input device.

In the description of this specification, descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific examples", or "some examples" mean that specific features described in connection with the embodiment or example , structure, material or feature is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the invention is defined by the claims and their equivalents.

Claims (5)

1. A gas diffusion visualization method, characterized in that, comprising: Step S1, obtain the gas diffusion parameters and the height of the gas diffusion surface to be observed, use the Gaussian diffusion model to obtain multiple diffusion points distributed at equal intervals on the gas diffusion surface to be observed and the gas concentration value of each diffusion point, and convert the Gaussian coordinates of the diffusion points to The system coordinates are converted into world coordinate system coordinates, and the diffusion point data array is constructed according to the positional relationship of the diffusion points, and each element in the diffusion point data array includes the world coordinate system coordinates and the gas concentration value of the same diffusion point; Step S2, obtaining all triangle patch vertex indexes of the diffusion point data array; Step S3, draw a triangle patch according to the vertex index of the triangle patch, draw a triangle patch with a group of triangle patch vertex indexes, and match the color array based on the concentration values of the three vertices of the triangle patch; Step S4, input the vertex data of all triangular faces and the matching color array of each triangular face into the OSG platform for rendering and displaying; In the step S1, the Gaussian diffusion model is:

Among them, C(x, y, z, H) represents the gas concentration at the position point (x, y, z, H); Q represents the gas emission velocity; σ _y represents the lateral diffusion coefficient, which is the gas on the y-axis of the Gaussian coordinate system standard deviation of the orientation distribution,

γ ₁ represents the first scaling factor,

Indicates the first index coefficient; σ _z indicates the vertical diffusion coefficient, which is the standard deviation of gas distribution in the z-axis direction of the Gaussian coordinate system,

γ ₂ represents the second scaling factor,

Indicates the second index coefficient; U ^p indicates the average wind speed at the outlet of the gas source; H indicates the effective height of the gas source; x indicates the distance between the downwind diffusion point and the gas source discharge point; The vertical distance of the axis; z represents the height of the gas diffusion surface; The process of transforming the Gaussian coordinate system coordinates of the diffusion point into the world coordinate system coordinates is: Assuming that the Gaussian coordinate system coordinates of the diffusion point are (x, y, C), then the world coordinate system coordinates of the diffusion point are (LON', LAT', C), and the specific solution process includes: Step A, the longitude LON calculation formula is:

The formula for calculating latitude LAT is:

Among them, C represents the gas concentration value of the diffusion point (x, y); B _f represents the latitude of the bottom point, obtained through the Gaussian x-axis coordinate; y represents the Gaussian y-axis coordinate; e represents the first eccentricity of the earth ellipse; e ^∫ represents The second eccentricity of the earth ellipse; a represents the semi-major axis of the earth ellipse; The acquisition process of _Bf is: Step 1, set i as the number of iterations, variable m ₀ =a(1-e ² ), variable

variable

variable

variable

variable

variable

variable

variable

Let the initial iteration value of B _f be B _f ¹ =x/a ₀ , ε is the difference threshold, 0<|ε|<0.000001; Step two, calculate

Determine whether B _f ⁱ⁺¹ -B _f ⁱ <ε is true, if B _f ⁱ⁺¹ -B _f ⁱ <ε is true, set B _f =B _f ⁱ⁺¹ , the process of obtaining B _f is over, and enter step B, If B _f ⁱ⁺¹ -B _f ⁱ <ε is not established, set i=i+1 and return to step 1; Step B, obtain the latitude and longitude coordinates (LAT ₀ , LON ₀ ) of the data origin (0,0) through the LON calculation formula and the latitude LAT calculation formula; Substitute the Gaussian coordinate system coordinates (x, y) of the diffusion point into the longitude LON calculation The formula and the latitude LAT calculation formula are obtained (LAT _i , LON _i ); if the accident point in the world coordinate system simulation scene is (LAT _s , LON _s ), then the world coordinate system coordinates of the diffusion point are: LAT'=LAT _i −LAT ₀ +LAT _s , LON′=LON _i −LON ₀ +LON _s . 2. gas diffusion visualization method as claimed in claim 1, is characterized in that, in step S2, the process of obtaining the triangular patch vertex index of diffusion point data array is: For any four adjacent diffusion points in the diffusion point data array, let the four diffusion points be the diffusion point P i,j with the row number i and the column number j, and the diffusion point P _i,j with the row number i and the column number j+1 Point P _i,j+1 , diffusion point P _i+1,j with row number i+1 and column number j, diffusion point P _i+1,j+ with row number i+1 and column number j+1 _1. Define two sets of triangular patch vertex indices in the four diffusion points. A set of triangular patch vertex indices consists of the number of rows and columns of diffusion points P _i,j , P _i,j+1 , and P _i+1,j . Another set of triangular patch vertex indices consists of the number of rows and columns of diffusion points P _i,j+1 , P _i+1,j , and P _i+1,j+1 , where i and j are both positive integers. 3. The gas diffusion visualization method according to claim 1, wherein the gas diffusion parameters include all or part of the gas source position, the average wind speed at the discharge port, the gas discharge velocity, and the effective height of the gas source. 4. The gas diffusion visualization method according to claim 1, wherein the process of matching the color array based on the concentration values of the 3 vertices of the triangle surface in the step S3 comprises: Establish multiple color arrays and multiple gas concentration ranges. The color arrays correspond to the gas concentration ranges one by one. The color arrays are expressed as [R, G, B, A], where R, G, and B represent the three primary color components of the color , A represents the transparency of the color; The color array corresponding to the gas concentration range of the three vertex concentration values of the triangular surface or the gas concentration range of the average value of the three vertex concentration values is used as the matching color array of the triangular surface. 5. A gas diffusion visualization system, characterized in that, comprises a gas diffusion parameter acquisition module, a processor and an OSG platform, and the processor is connected with the gas diffusion parameter acquisition module and the OSG platform respectively; The processor executes the gas diffusion visualization method described in any one of claims 1-4, inputs the vertex data of all triangular faces and the color array corresponding to each triangular face into the OSG platform, performs rendering processing by the OSG platform and The result of the rendering process is displayed.

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