Three-dimensional nuclear emergency radiation field calculation and visualization method and system

Abstract

The invention belongs to but is not limited to the technical field of three-dimensional space dose visualization, and discloses a three-dimensional nuclear emergency radiation field calculation and visualization method and system, based on a point nuclear method, a cumulative factor, mass attenuation factor and flux rate-dose rate conversion factor database is established, a mean free path solving algorithm is optimized, and a three-dimensional nuclear emergency radiation field is obtained. The geometric types of radioactive sources are expanded, and the dose calculation efficiency is improved through parallel calculation; plane dose rate drawing at a certain height is realized based on a two-dimensional texture mapping method; three-dimensional space dose rate contour surface drawing is realized based on a moving cube algorithm; and three-dimensional space dose rate volume rendering is realized based on a three-dimensional texture volume rendering technology. Radiation field dose calculation, three-dimensional radiation field dose visualization and GIS are integrated, and the system is used as a subsystem of a nuclear emergency aid decision simulation platform. The dose distribution diagram in the area can be judged more visually, and the method has a good help effect on nuclear emergency command.

Description

Technical Field

[0001] The present invention belongs to but is not limited to the technical field of three-dimensional spatial dose visualization, and in particular relates to a three-dimensional nuclear emergency radiation field calculation and visualization method and system. Background Art

[0002] The three-dimensional radiation field dose rate distribution is of great significance to the nuclear emergency decision-making support system and the dose assessment of the staff. Domestic and foreign researchers have not developed enough visualization methods for the three-dimensional radiation field dose rate. At the same time, the three-dimensional radiation field dose rate calculation and visualization are relatively separated. For example, the program developed by Kyung Hee University in South Korea can only visualize the planar dose rate, and VISIPLAN only focuses on the radiation field dose calculation. The FDS team of the University of Science and Technology of China developed the RVIS system using virtual reality technology. The system can evaluate the workload of staff in the radiation environment, optimize the maintenance path of staff, and can initially realize the visualization of the three-dimensional spatial dose rate distribution, but it does not display the geographic information system and cannot be deduced on the real terrain. With the goal of minimizing the radiation exposure of staff in the nuclear radiation environment, He Tao of the University of Science and Technology of China is mainly responsible for the design of the nuclear and radiation safety simulation system RVIS2.0 and the development of key technologies. The RVIS2.0 system was applied to the maintenance plan design and human dose assessment of the ITER poloidal field coil PF4 of the International Thermonuclear Experimental Reactor, and achieved good results, but the system does not visualize the dose.

[0003] In view of the above analysis, the technical problem that urgently needs to be solved in the prior art is: a three-dimensional nuclear emergency radiation field calculation and visualization method and system are needed. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a three-dimensional nuclear emergency radiation field calculation and visualization method and system.

[0005] The present invention is implemented as follows: a three-dimensional nuclear emergency radiation field calculation and visualization method comprises the following steps: Step 1: Establish a database of half-life and dose protection factors of commonly used radioactive materials according to the national military standard; Step 2, calculate the dose rate by point nuclear method; Step 3: Drawing the plane dose rate at a certain height based on the OGRE graphics engine and the two-dimensional texture mapping method; Step 4: Extract the isosurface of the three-dimensional regular dose rate volume data based on the OGRE graphics engine and the MarchingCube algorithm, realize the drawing of the three-dimensional radiation field dose rate isosurface and display it in the virtual scene of nuclear equipment; Step five: Based on the OGRE graphics engine and three-dimensional texture volume rendering algorithm, a dose conversion function is designed, and three-dimensional texture is created using three-dimensional regular dose volume data. On this basis, three-dimensional radiation field dose rate volume rendering is realized, and then combined with the three-dimensional model of virtual nuclear equipment, the dose distribution is displayed in the scene.

[0006] Furthermore, the three-dimensional radiation field visualization method based on the OGRE graphics engine includes: (1) creating vertex data and index data according to the dose rate volume data, and using them to form a plane mesh, an isosurface mesh or a slice mesh; (2) Create entities using mesh data, create materials based on dose rate volume data, and assign them to the entities.

[0007] Furthermore, plane visualization is a graphical display of the dose rate distribution at a certain height of the radiation field. First, the plane dose rate data of the specified height is obtained from the three-dimensional spatial dose rate volume data; secondly, a plane mesh of the specified height is created, and the texture coordinates are filled in the mesh vertex data; finally, a two-dimensional texture is created using the plane dose rate data, and a material is created based on the two-dimensional texture and assigned to the plane mesh. The plane mesh is then attached to the scene node for rendering.

[0008] Further, the three-dimensional radiation field dose rate volume isosurface rendering includes creating an isosurface mesh and solving each volume element isosurface patch; First, a voxel is constructed using 8 adjacent detection points and their dose values. Then, the state of each voxel vertex is determined according to the dose threshold given by the user (0 / 1). According to the voxel state, the intersection of each edge of the voxel with the isosurface is determined: if the states of the two vertices of the voxel edge are the same, there is no intersection; otherwise, the edge must intersect with the isosurface, and the coordinates of the intersection are solved by linear interpolation according to the dose rate value.

[0009] Where P 1 With P 2 is the endpoint coordinate of the voxel edge, D 1 With D 2 is the corresponding dose value, DTH is the given dose threshold, and P is the coordinate of the desired intersection point; After calculating the intersection points of all edges, the index coordinates are calculated according to the different states of the voxels to determine the composition of the isosurface triangles; the 14 states of the voxel isosurface can be further divided into 5 groups according to the number of vertices with a state of 0; and then the index values ​​of the isosurface patches are calculated for each of the 5 cases; In addition, in order to facilitate the recording of the isosurface connection method, the 8 vertices and 12 edges of the voxel are numbered respectively; after solving the voxel vertex coordinates and index coordinates, all voxels are traversed to solve all isosurface patches, and the index data of all isosurface patches are merged together; after traversing the entire three-dimensional space data field, the vertex data and index data of the entire isosurface mesh are obtained; then the scene manager is used to create a ManualObject object, and all the data of the isosurface mesh is input into it; at the same time, DoseConvertor is used to convert the given dose rate into color value and opacity, and add it to the vertex data of MamalObject, and finally it is attached to the scene node to render the isosurface mesh.

[0010] Furthermore, the three-dimensional radiation field dose rate volume rendering specifically includes: Step 1: Slice the radiation field volume data to obtain the sampled polygons (vertices and indices); Step 2: Use the vertex data and index data of the sliced ​​mesh to create vertex buffers and index buffers respectively. And bind it to the mesh; Step 3: Based on the 3D radiation field dose rate volume data, the dose rate conversion function is used to convert it into color values ​​and opacity, and compose a 3D texture in a certain order, and create a pixel cache at the same time; Step 4: Use 3D texture to create material, use sliced ​​mesh to create entity, bind the entity to the scene node, bind the material to the entity, and then perform volume rendering.

[0011] Further, the specific steps for solving the slice data are as follows: (1) Calculate the nearest and farthest vertices of the bounding box from the observation point; the nearest and farthest vertices can be directly calculated by the distance between the point and the plane; (2) Calculate the clipping plane; the normal vector N (A, B, C) of all clipping planes starts from the vertex closest to the observation point. A series of points (between the farthest and nearest points) are taken as a point P (x0, y0, z0) on the clipping plane at equal distances along the line of sight of the observation point. Then a series of clipping planes can be determined, as shown in the formula:

[0012] (3) Calculate the intersection points of each edge of the bounding box and the clipping plane. The coordinates of the eight vertices of the bounding box are known, so the equations of the lines of the 12 sides of the bounding box can be determined, which can be converted into the solution of the intersection points of the line and the plane. Obviously, if the edge is parallel to the clipping plane, there is no intersection point. (4) Calculate the texture coordinates of the intersection point; define the upper left front vertex P of the bounding box in the study 7The texture coordinates of (x, y, z) are (0, 0, 0), and the three-dimensional texture coordinates of the lower right back vertex of the bounding box are (1, 1, 1); then the texture coordinates of the intersection are determined according to the relative position of the intersection point p(x, , y, z), as shown in the formula: Where Width, Height, Depth are the width, height and depth of the bounding box respectively, and m, v and w are the three-dimensional texture coordinates; (5) All intersection points of the same slice are uniformly sorted clockwise or counterclockwise; (6) Calculate the slice index coordinates and determine all the triangular faces of the slice.

[0013] Furthermore, creating a vertex buffer and an index buffer specifically includes: After calculating the slice mesh data, you need to use the data to create a vertex buffer and an index buffer, and bind the vertex buffer and the index buffer to a mesh before you can use the mesh to create an entity. The specific steps are as follows: (1) Create vertex cache and index cache through the hardware manager; (2) Call the writeData function of the vertex buffer and index buffer to write the vertex data and index data of the slice grid into them respectively; (3) Use the mesh manager to create a mesh, and use the mesh to create a sub-mesh (SubMesh), and then bind the sub-mesh's vertex data (VertexData) and index data (IndexData) to the vertex cache and index cache respectively.

[0014] Further, creating a three-dimensional texture specifically includes: First, use the texture manager to create a texture, then get the pixel cache based on the texture, and then get the pixel box from the pixel cache, and fill it with the color value and opacity converted by the dose rate to form a three-dimensional texture; the dose conversion scheme is encapsulated in DoseConvertor; after creating a three-dimensional texture, you need to create a material based on it and bind it to the entity before it can be rendered; use the material manager to create a material, then call the material createTechnique to create a technique, then use the technique to create a channel, and finally call the channel's createTextureUnitState to create TextureUnitState, and call its setTextureName to bind the three-dimensional texture to the material.

[0015] Furthermore, creating entities and binding them to scene nodes specifically includes: According to the sliced ​​grid data, the createEntity method of the scene manager (SceneManager) is called to create an entity; then the createChildSceneNode of the root scene node is called to create a child scene node Node, and then the attachObject method of the Node is called to bind the entity object to the node.

[0016] Another object of the present invention is to provide a three-dimensional nuclear emergency radiation field calculation and visualization system of a three-dimensional nuclear emergency radiation field calculation and visualization method, comprising: Radiation field dose calculation module, which calculates dose rate by point kernel method; Plane visualization module, based on OGRE graphics engine and 2D texture mapping method, to draw the plane dose rate at a certain height; The isosurface visualization module extracts the isosurface of three-dimensional regular dose rate volume data based on the OGRE graphics engine and the MarchingCube algorithm, realizes the drawing of three-dimensional radiation field dose rate isosurface and displays it in the virtual scene of nuclear equipment; The volume rendering visualization module is based on the OGRE graphics engine and the 3D texture volume rendering algorithm. It designs the dose conversion function and creates 3D texture using 3D regular dose volume data. On this basis, it realizes 3D radiation field dose rate volume rendering and then displays the dose distribution in the scene in combination with the 3D model of the virtual nuclear equipment.

[0017] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows: First, the present invention provides a three-dimensional radiation dose rate distribution calculation and visualization algorithm, and develops a set of radiation field dose analysis algorithms suitable for complex shielding environments, which can quickly calculate the radiation field dose rate distribution and display the dose rate distribution in a graphical manner in the GIS scene using a scientific computing visualization algorithm. The present invention implements radiation field dose calculation based on a rasterization method, and implements radiation field dose isosurface rendering and volume rendering based on the Marching Cube algorithm and the three-dimensional texture volume rendering algorithm, respectively.

[0018] The present invention is based on the point kernel method, establishes a database of accumulation factors, mass attenuation factors and flux rate-dose rate conversion factors, optimizes the mean free path solution algorithm, expands the radiation source geometry type, uses parallel computing to improve the dose calculation efficiency, and considers more dose influencing factors.

[0019] In terms of three-dimensional radiation field dose rate visualization, the present invention adopts three different schemes: (1) Planar dose rate mapping at a certain height was achieved based on the two-dimensional texture mapping method; (2) Based on the Marching Cube algorithm, the three-dimensional dose rate isosurface rendering was realized; (3) Three-dimensional spatial dose rate volume rendering is realized based on three-dimensional texture volume rendering technology.

[0020] In the visualization scene, the present invention is combined with GIS to more intuitively judge the dose distribution map in the area, which is very helpful for nuclear emergency command.

[0021] The expected benefits and commercial value of the technical solution of the present invention after transformation are as follows: the present invention can realize the three-dimensional display of the atmospheric radiation field based on the three-dimensional GIS, and can also be extended to the three-dimensional display of the water body radiation field.

[0022] Second, the technical problems of the prior art solved by the technical solution of the present invention in industrial applications and the significant technical progress achieved are as follows: Existing technical problems solved: 1. Insufficient accuracy of dose rate calculation: In the existing technology, the calculation of radiation field dose rate mostly adopts simplified point kernel method or regular volume data model, and fails to combine national military standard and international standard data to accurately model the half-life of radioactive materials, dose protection factor, etc., thus affecting the calculation accuracy.

[0023] 2. Limited 3D dose rate visualization capabilities: Traditional dose distribution visualization is mostly limited to two-dimensional planes, and it is difficult to display three-dimensional dose field distribution in complex environments. In particular, existing technologies are difficult to meet the multi-level and multi-angle visualization needs of nuclear emergency sites.

[0024] 3. Failure to fully integrate virtual reality and graphics technology: Current nuclear radiation field analysis technology fails to effectively combine advanced three-dimensional graphics engines and virtual equipment models, lacks realistic scene display and dynamic interaction capabilities, and is unable to meet the needs of nuclear emergency drills and assessments.

[0025] 4. Lack of full-scenario simulation and analysis capabilities: Existing technologies are unable to fully cover the calculation and analysis of radiation doses for the three main dose pathways: external exposure from plumes, internal exposure from inhalation, and external exposure from ground-deposited nuclides, resulting in the inability to form a complete emergency response and assessment plan.

[0026] Significant technological advancements: 1. High-precision database based on national military standards: The present invention achieves a comprehensive calculation of external exposure doses of plumes, internal exposure doses of inhaled radioactive substances, and external exposure doses of ground-deposited nuclides by establishing a database of half-lives and dose protection factors of commonly used radioactive substances and combining it with the EPA's FGR No.12 guideline, thereby improving the scientificity and accuracy of dose rate calculations.

[0027] 2. Fusion of multiple dose calculation models: The present invention calculates the external radiation dose of plume, internal radiation dose of inhalation and external radiation dose of ground deposition respectively through formulas (1), (2) and (3), covering all major radiation pathways. It can accurately evaluate the nuclear radiation dose distribution in complex scenarios and provide comprehensive support for nuclear emergency decision-making.

[0028] 3. Innovative 3D visualization technology: The present invention combines the OGRE graphics engine, two-dimensional texture mapping, marching cube algorithm and three-dimensional texture rendering method to achieve a full range of visualization of three-dimensional radiation field dose rate, including a planar dose rate map and a three-dimensional isosurface, thereby enhancing the user's intuitive perception of dose distribution.

[0029] 4. Seamless integration with virtual equipment scenes: The present invention can combine the three-dimensional radiation field dose distribution with the three-dimensional model of virtual nuclear equipment to intuitively display the radiation dose distribution in nuclear emergency scenarios and provide immersive support for nuclear emergency drills, training and decision-making.

[0030] 5. Dynamic interaction and flexible scene adaptation: The dose conversion function designed in the present invention can dynamically adjust the dose distribution diagram according to the scene requirements, flexibly adapt to the nuclear emergency needs of different scenarios, and is suitable for rapid response and decision support at complex nuclear accident sites.

[0031] 6. Strong practicality and scalability: The technical solution of the present invention is applicable to various industrial and military scenarios such as nuclear power plants and radioactive material storage sites, and can be widely used in the fields of nuclear emergency response, nuclear accident assessment and nuclear radiation protection.

[0032] In summary, the present invention has achieved significant technical progress in the calculation and display of nuclear emergency radiation fields by integrating multiple dose calculation methods and advanced three-dimensional visualization technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a flow chart of a three-dimensional nuclear emergency radiation field calculation and visualization method provided by an embodiment of the present invention; Figure 2 It is a three-dimensional nuclear emergency radiation field calculation and visualization diagram provided by an embodiment of the present invention; Figure 3is a flow chart of a radiation field dose rate volume rendering algorithm provided by an embodiment of the present invention; Figure 4 It is a structural diagram of a three-dimensional nuclear emergency radiation field calculation and visualization system provided by an embodiment of the present invention; Figure 5 It is the atmospheric radiation field-24h-200m grid-2m height-integrated activity concentration provided by the embodiment of the present invention; Figure 6 It is the atmospheric radiation field-24h-200m grid-2m height-instantaneous activity concentration provided by the embodiment of the present invention; Figure 7 It is a public expected dose assessment sub-window provided by an embodiment of the present invention; Figure 8 This is the public expected dose assessment file format provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0035] Industrial Application Example 1: Nuclear Power Plant Accident Emergency Response and Assessment During the operation of a nuclear power plant, once a nuclear accident (such as core meltdown or radioactive material leakage) occurs, it is necessary to quickly evaluate the distribution of the radiation field and the potential harm of radiation to the environment and people. The application process of the three-dimensional nuclear emergency radiation field calculation and visualization method of the present invention in the emergency response to nuclear power plant accidents is as follows: 1. Application scenarios: Nuclear power plant accidents lead to the release of radioactive materials, and the surrounding air and ground are contaminated by radionuclides, requiring rapid assessment of external exposure doses from plumes, internal exposure from inhalation, and external exposure doses from ground deposition.

[0036] 2. Implementation steps: The method of the present invention is used to collect real-time environmental data, including nuclide types, release amounts, meteorological conditions and environmental parameters.

[0037] Based on the national military standards and EPA guidelines, the dose conversion factors of relevant nuclides are queried through the database to calculate the radiation dose of each major exposure pathway.

[0038] Combining the OGRE graphics engine and the 3D texture volume rendering method, a 3D radiation field dose distribution map around the nuclear power plant is generated.

[0039] The radiation field data is superimposed on the virtual nuclear power plant model to display the radiation dose distribution in key areas (such as the control room, cooling water pool, exhaust vents) and the surrounding environment.

[0040] 3. Application effect: Generate a clear three-dimensional radiation distribution map to intuitively display the changes in radiation intensity, allowing decision makers to quickly understand the impact range of the accident.

[0041] The marching cubes algorithm is used to extract isosurfaces, identify high-risk areas, and plan evacuation routes and emergency measures.

[0042] Provide accurate radiation assessment basis for post-accident environmental restoration and personnel protection.

[0043] Industrial application example 2: Radioactive material transportation safety monitoring During the transportation of radioactive materials, it is necessary to monitor the radioactive radiation field in real time to ensure that the radiation dose during transportation meets safety standards and avoid potential threats to the transportation personnel and the surrounding environment. The application process of the method of the present invention in this scenario is as follows: 1. Application scenarios: During the transportation of radioactive materials, the radiation field distribution along the transportation route is monitored to assess whether the radiation dose exceeds the prescribed threshold.

[0044] 2. Implementation steps: Real-time monitoring equipment is installed on transport vehicles to collect data such as radionuclide concentrations in the air and ground deposition activity.

[0045] The external radiation dose of the smoke plume and the external radiation dose of the ground deposition are calculated in real time by using the point core method and the dose calculation model of the present invention.

[0046] A 3D texture volume rendering method is used to generate real-time radiation distribution maps along the transport path, combined with a marching cubes algorithm to identify high-dose areas.

[0047] Integrate with the virtual transportation network model to dynamically adjust transportation routes to avoid high radiation areas.

[0048] 3. Application effect: Dynamic monitoring and visual display of radiation field distribution during transportation are realized to ensure the safety of the transportation process.

[0049] When abnormal radiation occurs, high-risk points can be quickly located through three-dimensional radiation maps, and transportation routes can be optimized to reduce transportation risks.

[0050] It provides technical support for the full-process safety monitoring of the transportation of radioactive materials and complies with relevant radiation safety regulations.

[0051] These two embodiments demonstrate typical application scenarios of the present invention in nuclear accident emergency response and radioactive material transportation, reflecting its significant practical value in actual industry.

[0052] like Figure 1 As shown, a three-dimensional nuclear emergency radiation field calculation and visualization method provided by an embodiment of the present invention includes the following steps: Step 1: Establish a database of half-life and dose protection factors of commonly used radioactive materials according to the national military standard; Step 2, calculate the dose rate by point nuclear method; Step 3: Drawing the plane dose rate at a certain height based on the OGRE graphics engine and the two-dimensional texture mapping method; Step 4: Extract the isosurface of the three-dimensional regular dose rate volume data based on the OGRE graphics engine and the MarchingCube algorithm, realize the drawing of the three-dimensional radiation field dose rate isosurface and display it in the virtual scene of nuclear equipment; Step five: Based on the OGRE graphics engine and three-dimensional texture volume rendering algorithm, a dose conversion function is designed, and three-dimensional texture is created using three-dimensional regular dose volume data. On this basis, three-dimensional radiation field dose rate volume rendering is realized, and then combined with the three-dimensional model of virtual nuclear equipment, the dose distribution is displayed in the scene.

[0053] The dosage calculation provided by the present invention is: According to the national standard GB / T 17982-2018, the important exposure pathways in the early stages of an accident include plume gamma external exposure, inhalation internal exposure, and ground-deposited nuclide gamma external exposure.

[0054] (1) Smoke plume External radiation dose For a certain nuclide plume External radiation dose, based on the time-integrated concentration of radionuclides in the air near the ground The formula is as follows (1) Where: - Nuclides in the air External radiation equivalent dose, in sievert (Sv) ), - Time-integrated concentration of radionuclides in the air near the ground, in becquerel-seconds per cubic meter ( ), - Dose conversion factor, i.e. the integral concentration of the nuclide per unit time External radiation dose, in , the dose conversion factors for each nuclide are taken from the FGR No.12 guideline of the U.S. Environmental Protection Agency (EPA), which is applicable to workers and adult members of the public; - Shielding factor of buildings against external exposure to smoke plumes, and for individuals Take it as 1, for the group Take it as 0.7.

[0055] (2) Exposure dose from inhaled plume For a certain nuclide inhaled plume internal exposure dose, based on the time-integrated concentration of the nuclide in the air near the ground The formula is as follows (2) Where: – The committed effective dose from inhaled plume or the committed equivalent dose to the thyroid gland, in sieverts ( ), - Time-integrated concentration of radionuclides in the air near the ground, in becquerel-seconds per cubic meter ( ), – Human respiration rate in cubic meters per second ( ), according to the national standard, the value is 2.3338*10 -4 ( ), – Inhalation dose conversion factor, i.e. committed effective dose or committed equivalent dose to thyroid gland caused by inhalation of unit activity nuclide, in units of ( .

[0056] (3) Ground sediment nuclides External radiation dose For a certain nuclide, based on the surface activity concentration of the nuclide in ground sediments The estimation formula is as follows (3) Where: – External radiation dose equivalent due to ground-based radionuclides, in sieverts ( ), - Surface activity concentration of radionuclides in ground sediments, in becquerel seconds per square meter ( ), – Dose conversion factor, the ground external radiation dose conversion factor of radionuclide i (Sv·m 2 ) / (Bq·s); The dose conversion factors for each nuclide are taken from the FGR No.12 guideline of the U.S. Environmental Protection Agency (EPA), which is applicable to workers and adult members of the public; – The time-averaged building shielding factor takes into account the indoor residence share of people. The value is 0.26.

[0057] The visualization method provided by the present invention: The design goal of the radiation field dose calculation and visualization system is to integrate radiation field dose calculation, three-dimensional radiation field dose visualization and GIS, and use the system as a subsystem of the nuclear emergency decision-making support simulation platform. At the same time, the dose calculation and three-dimensional radiation field visualization are designed as two relatively independent modules, so that the system can be used in related fields such as nuclear equipment maintenance, shielding design and radiation protection.

[0058] 1. Three-dimensional radiation field dose visualization Several implementation methods of three-dimensional spatial dose visualization are closely related to OGRE graphics. The OGRE graphics engine uses a large number of design patterns and separates the scene graph from the scene content. The scene node (SceneNode) does not contain any planted geometric content, and the specific content inherits the Renderable interface. The properties of the renderable object are contained in the entity (Entity) object, and the entity can only be rendered by attaching it to the scene node. The entity contains a series of sub-entities (SubEntity), and the sub-entity corresponds to the sub-mesh (SubMesh). The sub-mesh contains the real model data, including vertex data (VertexData) and index data (IndexData). Therefore, the three-dimensional radiation field visualization is divided into the following steps: (1) Create vertex data and index data based on dose rate volume data, and use them to form a plane mesh, an isosurface mesh or a slice mesh.

[0059] (2) Create entities using mesh data, create materials based on dose rate volume data, and assign them to entities. This includes the implementation algorithms for three-dimensional dose rate volume rendering, isosurface rendering, and plane rendering. The following will specifically describe the implementation process of the three methods of three-dimensional radiation field dose rate visualization. Plane visualization is a graphical display of the dose rate distribution at a certain height of the radiation field. The main process is as follows: first, obtain the plane dose rate data of the specified height from the three-dimensional space dose rate volume data; second, create a plane mesh of the specified height, and fill the texture coordinates in the mesh vertex data; finally, use the plane dose rate data to create a two-dimensional texture, and create a material based on the two-dimensional texture and assign the material to the plane mesh, and then attach the plane mesh to the scene node for rendering. 2. Visualization of 3D radiation field isosurface The present invention realizes three-dimensional space dose rate isosurface rendering based on marching cube algorithm. The key to realize isosurface rendering is to create isosurface mesh. The most critical part of creating isosurface mesh is to solve the isosurface triangle patch of each voxel.

[0060] The solution process of each voxel isosurface. First, the voxel is constructed using the adjacent 8 detection points and their dose values, and then the state of each voxel vertex is determined according to the dose threshold given by the user (0 / 1). According to the voxel state, the intersection of each edge of the voxel and the isosurface can be determined: if the two vertices of the voxel edge are in the same state, there is no intersection; otherwise, the edge must intersect with the isosurface, and the intersection coordinates are solved by linear interpolation according to the dose rate value.

[0061]

[0062] Where P 1 With P 2 is the endpoint coordinate of the voxel edge, D 1 With D 2 is the corresponding dose value, D TH is the given dose threshold, and P is the coordinate of the intersection point to be sought. After calculating the intersection points of all edges, it is necessary to calculate the index coordinates according to the different states of the voxels to determine the composition form of the isosurface triangles. According to the number of vertex states of 0, the 14 states of the voxel isosurface can be further divided into 5 groups. Then the index values ​​of the isosurface patches are calculated for these 5 cases respectively. In addition, in order to facilitate the recording of the isosurface connection method, the 8 vertices and 12 edges of the voxel are numbered respectively. After solving the voxel vertex coordinates and index coordinates, the connection method of the isosurface patch is uniquely determined. Therefore, it is necessary to traverse all voxels to solve all isosurface patches, and merge the index data of all isosurface patches together. After traversing the entire three-dimensional space data field, the vertex data and index data of the entire isosurface mesh are obtained. Then use the scene manager to create a ManualObject object, and input all the data of the isosurface mesh into it. At the same time, DoseConvertor is used to convert the given dose rate into color value and opacity, and then added to the vertex data of MamalObject. Finally, it is attached to the scene node to render the isosurface mesh. Figure 2 shown.

[0063] 3. 3D radiation field rendering Step 1: Slice the radiation field volume data to obtain the sampling polygons (vertices and indices). The denser the slices, the better the display effect will be, but at the same time the amount of calculation will increase.

[0064] Step 2: Use the vertex data and index data of the sliced ​​mesh to create a vertex buffer and an index buffer respectively and bind them to the mesh.

[0065] Step 3: Based on the three-dimensional radiation field dose rate volume data, the dose rate conversion function is used to convert it into color values ​​and opacity, and compose a three-dimensional texture in a certain order, and create a pixel cache at the same time.

[0066] Step 4: Use 3D texture to create material, use slice mesh to create entity, bind entity to scene node, bind material to entity, then volume rendering can be performed. The main process of volume rendering algorithm is as follows: Figure 3 shown.

[0067] The present invention provides the solution slice data: (1) Calculate the nearest and farthest vertices of the bounding box from the observation point; the nearest and farthest vertices can be directly calculated by the distance between the point and the plane.

[0068] (2) Calculate the clipping plane; the normal vector N (A, B, C) of all clipping planes is the vertex closest to the observation point as the starting point, and a series of points (between the farthest and the nearest points) are taken along the line of sight of the observation point at equal distances as a point P (x 0 ,y 0 , z 0 ) can determine a series of clipping planes, such as the formula:

[0069] (3) Calculate the intersection points of each edge of the bounding box and the clipping plane. The coordinates of the eight vertices of the bounding box are known, so the equations of the lines of the 12 sides of the bounding box can be determined, which can be converted into the solution of the intersection points of the line and the plane. Obviously, if the edge is parallel to the clipping plane, there is no intersection point. (4) Calculate the texture coordinates of the intersection point; in this study, the texture coordinates of the upper left front vertex p7 (x, y, z) of the bounding box are defined as (0, 0, 0), and the three-dimensional texture coordinates of the lower right back vertex of the bounding box are defined as (1, 1, 1); then, the texture coordinates of the intersection point are determined according to the relative position of the intersection point p (x, y, z), as shown in the formula: Where Width, Height, Depth are the width, height and depth of the bounding box respectively, and m, v and w are the three-dimensional texture coordinates; (5) All intersection points of the same slice are uniformly sorted clockwise or counterclockwise; (6) Calculate the slice index coordinates and determine all the triangular faces of the slice.

[0070] Creating vertex buffers and index buffers After calculating the slice mesh data, you need to use the data to create a vertex buffer and an index buffer, and bind the vertex buffer and index buffer to a mesh before you can use the mesh to create an entity. The specific steps are as follows: (1) Create vertex cache and index cache through the hardware manager; (2) Call the writeData function of the vertex buffer and index buffer to write the vertex data and index data of the slice grid into them respectively; (3) Use the mesh manager to create a mesh, and use the mesh to create a sub-mesh (SubMesh), and then bind the sub-mesh's vertex data (VertexData) and index data (IndexData) to the vertex cache and index cache respectively.

[0071] Creating 3D Textures First, use the texture manager to create a texture, then get the pixel cache based on the texture, then get the pixel box from the pixel cache, and fill it with the color value and opacity converted by the dose rate to form a three-dimensional texture. The dose conversion scheme is encapsulated in DoseConvertor. After creating a three-dimensional texture, you need to create a material based on it and bind it to the entity before it can be rendered. Use the material manager to create a material, then call the material createTechnique to create a technique, then use the technique to create a channel, and finally call the channel's createTextureUnitState to create TextureUnitState, and call its setTextureName to bind the three-dimensional texture to the material.

[0072] Create entities and bind them to scene nodes According to the slice mesh data, call the createEntity method of the scene manager (SceneManager) to create an entity. Then call the createChildSceneNode of the root scene node to create a child scene node Node, and then call the attachObject method of the Node to bind the entity object to the node. In this way, the slice mesh based on the 3D texture can be rendered.

[0073] like Figure 4 As shown, a three-dimensional nuclear emergency radiation field calculation and visualization system of a three-dimensional nuclear emergency radiation field calculation and visualization method provided by an embodiment of the present invention includes: Radiation field dose calculation module, which calculates dose rate by point kernel method; Plane visualization module, based on OGRE graphics engine and 2D texture mapping method, to draw the plane dose rate at a certain height; The isosurface visualization module extracts the isosurface of three-dimensional regular dose rate volume data based on the OGRE graphics engine and the MarchingCube algorithm, realizes the drawing of three-dimensional radiation field dose rate isosurface and displays it in the virtual scene of nuclear equipment; The volume rendering visualization module is based on the OGRE graphics engine and the 3D texture volume rendering algorithm. It designs the dose conversion function and creates 3D texture using 3D regular dose volume data. On this basis, it realizes 3D radiation field dose rate volume rendering and then displays the dose distribution in the scene in combination with the 3D model of the virtual nuclear equipment.

[0074] Evidence related to the technical effects obtained by the embodiments of the present invention, such as Figure 7 and Figure 8 shown.

[0075] The point kernel method and the Monte Carlo method are the main algorithms for calculating the dose rate distribution of the radiation field. The point kernel method considers the influence of scattered photons on the radiation dose by introducing a cumulative factor, and has high computational efficiency, so it is widely used in the fields of shielding design and radiation safety analysis. Based on the point kernel method, the present invention establishes a database of cumulative factors, mass attenuation factors, and flux rate-dose rate conversion factors, optimizes the mean free path solution algorithm, expands the radiation source geometry type, uses parallel computing to improve the efficiency of dose calculation, and considers more dose influencing factors.

[0076] In terms of three-dimensional radiation field dose rate visualization, the present invention adopts three different schemes: (1) Planar dose rate mapping at a certain height was achieved based on the two-dimensional texture mapping method; (2) Based on the Marching Cube algorithm, the three-dimensional dose rate isosurface rendering was realized; (3) Three-dimensional spatial dose rate volume rendering is realized based on three-dimensional texture volume rendering technology.

[0077] In the visualization scene, the present invention is combined with GIS to more intuitively judge the dose distribution map in the area, which is very helpful for nuclear emergency command.

[0078] It should be noted that the embodiments of the present invention can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated design hardware. It can be understood by a person of ordinary skill in the art that the above-mentioned devices and methods can be implemented using computer executable instructions and / or contained in a processor control code, such as a carrier medium such as a 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. Such code is provided on the carrier medium. The device and its modules of the present invention can be implemented by hardware circuits such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., can also be implemented by software executed by various types of processors, and can also be implemented by a combination of the above-mentioned hardware circuits and software, such as firmware.

[0079] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modification, equivalent substitution and improvement made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A three-dimensional nuclear emergency radiation field calculation and visualization method, characterized in that: The following steps are involved: Step 1: Establish a database of half-life and dose protection factors of commonly used radioactive materials according to the national military standard; Step 2, calculate the dose rate by point nuclear method; Step 3: Drawing the plane dose rate at a certain height based on the OGRE graphics engine and the two-dimensional texture mapping method; Step 4: Extract the isosurface of the three-dimensional regular dose rate volume data based on the OGRE graphics engine and the marching cube algorithm, realize the drawing of the three-dimensional radiation field dose rate isosurface and display it in the virtual scene of nuclear equipment; Step five: Based on the OGRE graphics engine and three-dimensional texture volume rendering algorithm, a dose conversion function is designed, and three-dimensional texture is created using three-dimensional regular dose volume data. On this basis, three-dimensional radiation field dose rate volume rendering is realized, and then combined with the three-dimensional model of virtual nuclear equipment, the dose distribution is displayed in the scene.

2. The three-dimensional nuclear emergency radiation field calculation and visualization method according to claim 1, characterized in that: The three-dimensional radiation field visualization method based on the OGRE graphics engine includes: (1) creating vertex data and index data according to the dose rate volume data, and using them to form a plane mesh, an isosurface mesh or a slice mesh; (2) Create entities using mesh data, create materials based on dose rate volume data, and assign them to the entities.

3. The three-dimensional nuclear emergency radiation field calculation and visualization method according to claim 1, characterized in that: Plane visualization is a graphical display of the dose rate distribution at a certain height of the radiation field. First, the plane dose rate data of the specified height is obtained from the three-dimensional spatial dose rate volume data; secondly, a plane mesh of the specified height is created, and texture coordinates are filled in the mesh vertex data; finally, a two-dimensional texture is created using the plane dose rate data, and a material is created based on the two-dimensional texture and assigned to the plane mesh. The plane mesh is then attached to the scene node for rendering.

4. The three-dimensional nuclear emergency radiation field calculation and visualization method according to claim 1, characterized in that: The three-dimensional radiation field dose rate volume isosurface rendering includes creating an isosurface mesh and solving each volume element isosurface patch; First, a voxel is constructed using 8 adjacent detection points and their dose values. Then, the state of each voxel vertex is determined according to the dose threshold given by the user (0 / 1). According to the voxel state, the intersection of each edge of the voxel with the isosurface is determined: if the states of the two vertices of the voxel edge are the same, there is no intersection; otherwise, the edge must intersect with the isosurface, and the coordinates of the intersection are solved by linear interpolation according to the dose rate value. Where P1 and P2 are the endpoint coordinates of the voxel edge, D1 and D2 are the corresponding dose values, DTH is the given dose threshold, and P is the coordinate of the desired intersection; After calculating the intersection points of all edges, the index coordinates are calculated according to the different states of the voxels to determine the composition of the isosurface triangles; the 14 states of the voxel isosurface are divided into 5 groups according to the number of vertices with a state of 0; Then, the index values ​​of the isosurfaces are calculated for the five cases respectively; the eight vertices and 12 edges of the voxel are numbered respectively; after solving the voxel vertex coordinates and index coordinates, all voxels are traversed to solve all isosurfaces, and the index data of all isosurfaces are merged together; After traversing the entire three-dimensional space data field, the vertex data and index data of the entire isosurface mesh are obtained; then the ManualObject object is created using the scene manager, and all the data of the isosurface mesh is input into it; At the same time, DoseConvertor is used to convert the given dose rate into color value and opacity, and added to the vertex data of MamalObject. Finally, it is attached to the scene node to render the isosurface mesh.

5. The three-dimensional nuclear emergency radiation field calculation and visualization method according to claim 1, characterized in that: 3D radiation field dose rate volume rendering specifically includes: Step 1: Slice the radiation field volume data to obtain the sampled polygons; Step 2: Use the vertex data and index data of the sliced ​​mesh to create vertex buffers and index buffers respectively. and bind it to the grid; Step 3: Based on the 3D radiation field dose rate volume data, the dose rate conversion function is used to convert it into color values ​​and opacity, and compose a 3D texture in a certain order, and create a pixel cache at the same time; Step 4: Use 3D textures to create materials, and use sliced ​​meshes to create entities. Bind the entities to scene nodes, bind materials to entities, and perform volume rendering.

6. The three-dimensional nuclear emergency radiation field calculation and visualization method according to claim 5, characterized in that: The specific steps to solve the slice data are as follows: (1) Calculate the nearest and farthest vertices of the bounding box from the observation point; the nearest and farthest vertices can be directly calculated by the distance between the point and the plane; (2) Calculate the clipping plane; the normal vector N (A, B, C) of all clipping planes starts from the vertex closest to the observation point. A series of points (between the farthest and nearest points) are taken as a point P (x0, y0, z0) on the clipping plane at equal distances along the line of sight of the observation point. Then a series of clipping planes can be determined, as shown in the formula: (3) Calculate the intersection points of each edge of the bounding box and the clipping plane. The coordinates of the eight vertices of the bounding box are known, so the equations of the lines of the 12 sides of the bounding box can be determined, which can be converted into the solution of the intersection points of the line and the plane. Obviously, if the edge is parallel to the clipping plane, there is no intersection point. (4) Calculate the texture coordinates of the intersection point; in this study, the texture coordinates of the upper left front vertex P7 (x, y, z) of the bounding box are defined as (0, 0, 0), and the three-dimensional texture coordinates of the lower right back vertex of the bounding box are defined as (1, 1, 1); then the texture coordinates of the intersection point are determined according to the relative position of the intersection point p (x, y, z), as shown in the formula: Where Width, Height, Depth are the width, height and depth of the bounding box respectively, and m, v and w are the three-dimensional texture coordinates; (5) All intersection points of the same slice are uniformly sorted clockwise or counterclockwise; (6) Calculate the slice index coordinates and determine all the triangular faces of the slice.

7. The three-dimensional nuclear emergency radiation field calculation and visualization method according to claim 5, characterized in that: Creating a vertex buffer and an index buffer specifically includes: After calculating the slice mesh data, you need to use the data to create a vertex buffer and an index buffer, and bind the vertex buffer and index buffer to a mesh before you can use the mesh to create an entity; the specific steps are as follows: (1) Create vertex cache and index cache through the hardware manager; (2) Call the writeData function of the vertex buffer and index buffer to write the vertex data and index data of the slice grid into them respectively; (3) Use the mesh manager to create a mesh, and use the mesh to create a sub-mesh, and then bind the vertex data and index data of the sub-mesh to the vertex cache and index cache respectively.

8. The three-dimensional nuclear emergency radiation field calculation and visualization method according to claim 5, characterized in that: Creating a 3D texture involves: First, use the texture manager to create a texture, then get the pixel cache based on the texture, and then get the pixel box from the pixel cache, and fill it with the color value and opacity converted by the dose rate to form a three-dimensional texture; the dose conversion scheme is encapsulated in DoseConvertor; after creating a three-dimensional texture, you need to create a material based on it and bind it to the entity before it can be rendered; use the material manager to create a material, then call the material createTechnique to create a technique, then use the technique to create a channel, and finally call the channel's createTextureUnitState to create TextureUnitState, and call its setTextureName to bind the three-dimensional texture to the material.

9. The three-dimensional nuclear emergency radiation field calculation and visualization method according to claim 5, characterized in that: Creating entities and binding them to scene nodes specifically includes: According to the sliced ​​grid data, call the createEntity method of the scene manager to create an entity; then call the createChildSceneNode of the root scene node to create a child scene node Node, and then call the attachObject method of Node to bind the entity object to the node.

10. A three-dimensional nuclear emergency radiation field calculation and visualization system according to any one of claims 1 to 9, characterized in that: include: Radiation field dose calculation module, which calculates dose rate by point kernel method; Plane visualization module, based on OGRE graphics engine and 2D texture mapping method, performs plane dose rate drawing at a certain height; The isosurface visualization module extracts the isosurface of three-dimensional regular dose rate volume data based on the OGRE graphics engine and the marching cube algorithm, realizes the drawing of three-dimensional radiation field dose rate isosurface and displays it in the virtual scene of nuclear equipment; The volume rendering visualization module is based on the OGRE graphics engine and the 3D texture volume rendering algorithm. It designs the dose conversion function and creates 3D texture using 3D regular dose volume data. On this basis, it realizes 3D radiation field dose rate volume rendering and then displays the dose distribution in the scene in combination with the 3D model of the virtual nuclear equipment.

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