Stray radiation ray tracing method and device based on radiation transmission model

Abstract

The present invention provides a stray radiation ray tracing method and device based on a radiation transfer model, including: using a traditional ray tracing method within the component range of a uniform temperature field; using a radiation transfer tracing method within a non-uniform temperature field, and using a radiation transfer model to calculate the energy beam transmission process of a microelement surface; wherein the traditional ray tracing and radiation transmission tracing processes are independent, the tracing process of each ray is independent, and the energy beam transmission process of each microelement surface is independent. The present invention combines the traditional non-sequential ray tracing method, combines the thermal radiation transmission process with the stray light analysis process, uses the traditional ray tracing method within the component range of a uniform temperature field, introduces a radiation transfer factor within a non-uniform temperature field, and uses a radiation transfer model to calculate the energy beam transmission process of a microelement surface. The integrated analysis simulation results of thermal radiation stray light are real-time and intuitive, and are suitable for simulation applications of non-uniform temperature fields and temperature gradient systems.

Description

Technical Field

[0001] The present invention relates to the field of computer simulation, and in particular to a method and device for tracing stray radiation rays based on a radiation transmission model. Background Art

[0002] With the increasing demand for optical system indicators, simulation and analysis of external stray light in optical systems are also widely used in various optical systems with high image quality and high stray light suppression ratio. The simulation and analysis of external stray light in optical systems mainly use non-sequential ray tracing technology to convert stray light into light with direction and energy, trace all external stray light rays, and perform statistics at the image plane to finally obtain the path and results of the stray light.

[0003] At present, traditional non-sequential ray tracing technology is mostly aimed at ray tracing technology for the purpose of graphics rendering, using geometric optics as the calculation model, and the existing non-sequential ray tracing directly traverses all rays to complete the calculation from the light source to the receiver. The technology with rendering equation as the core focuses on visual effects and realism, and is not suitable for high-precision and efficient analysis of stray light in optical systems. The speed and analysis ability of traditional non-sequential ray traversal tracing methods are affected by the traversal method. Each ray must be traced before the next ray can be traced. Therefore, there are problems such as the tracing process cannot be interrupted, the source of the tracing results is not easy to analyze, and the tracing speed is greatly affected by the number of rays and the energy threshold. Summary of the invention

[0004] The embodiments of the present invention provide a method and device for tracing stray radiation rays based on a radiation transfer model, so as to at least solve the technical problems of low ray tracing speed and low result accuracy in the existing methods.

[0005] According to an embodiment of the present invention, a stray radiation ray tracing method based on a radiation transfer model is provided, comprising the following steps:

[0006] Traditional ray tracing methods are used across the component with a uniform temperature field;

[0007] The radiation transfer tracing method is used in the non-uniform temperature field, and the radiation transfer model is used to calculate the energy beam transfer process of the micro-element surface;

[0008] The traditional ray tracing and radiation transmission tracing processes are independent, the tracing process of each ray is independent, and the energy beam transmission process of each microelement surface is independent.

[0009] Further, conventional ray tracing methods are used within the component range of the uniform temperature field including:

[0010] The simulations were performed using the stray light ray tracing Monte Carlo method over the component with a uniform temperature field.

[0011] Further, simulation using stray light ray tracing Monte Carlo method within the component range of uniform temperature field includes:

[0012] Get the initial information of the light: the starting coordinates (x0, y0, z0) of the light emitted from the light source, the direction vector (l0, m0, n0), the energy E0 carried by the light, and the wavelength λ;

[0013] Determine the intersection of the light: find the first surface that intersects with the light. If there is no intersection, stop tracing this light. If there is an intersection, determine the intersection coordinates (x1, y1, z1), the normal direction vector (l n1 ,m n1 ,n n1 ), and obtain the optical properties of the surface;

[0014] Direction of emitted light: The spatial distribution of the direction of light transmission includes specular reflection, refraction, and scattering. If the optical surface is specular reflection or refraction, the emission direction and energy of the light are calculated by the reflection or refraction formula. If the optical surface is specular scattering, the emission direction and energy are distributed by the bidirectional reflectance distribution function BRDF.

[0015] Through the above process, a ray tracing of a surface is completed, and the newly generated ray intersection point (x1, y1, z1), direction vector (l1, m1, n1), and ray energy E1 are the starting conditions for the next tracing. In the ray tracing process, each ray is composed of the above calculation process.

[0016] Further, the simulation using the stray light ray tracing Monte Carlo method within the component range of the uniform temperature field also includes:

[0017] Ray cutoff: The termination condition of ray tracing is that the ray reaches the preset image plane; the ray energy is less than the threshold.

[0018] Furthermore, the radiation transmission tracing method in the non-uniform temperature field includes:

[0019] In the infrared self-radiation simulation process of the optical system with non-uniform temperature, the non-uniform temperature distribution surface is first determined, and the Monte Carlo method of thermal radiation transmission is used to simulate the non-uniform temperature distribution surface.

[0020] Furthermore, the Monte Carlo method for heat radiation transfer on a surface with non-uniform temperature distribution is used for simulation including:

[0021] Meshing: Meshing each element of the optical system into micro-surface elements and micro-voxels;

[0022] Calculation of the radiant illumination of a micro-surface element: Take the temperature T in the micro-surface element iand the emissivity ε of the element, and the radiant illumination of the element microelement surface in its use band is calculated according to Planck's radiation law;

[0023] Energy beam launch point model: The coordinates of the energy beam launch point (x i ,y i ,z i );

[0024] Energy beam emission direction model: Use the Monte Carlo method to determine the pitch angle θ of the energy beam emission direction i and azimuth

[0025] Radiative transfer energy calculation: Use energy conduction theory to calculate the luminous flux dφ from the emitting microelement surface to the receiving microelement surface c ;

[0026] Through the above process, the radiation calculation from one microelement surface to another microelement surface is completed, and the radiation transfer factor B of the microelement surface is calculated successively. ij , energy beam emission point intersection (x i ,y i ,z i ), energy beam emission direction Finally, the radiation transfer factor B from each microelement surface to the detector microelement surface is obtained by calculation. ij Then the irradiance of the temperature gradient element is calculated.

[0027] Furthermore, in the process of meshing the elements of the optical system into micro-surface elements and micro-volume elements, the temperature, heat flux, and heat flux are uniform within the unit micro-element.

[0028] Furthermore, a heterogeneous parallel GPU acceleration processing method is adopted in the process of calculating the energy beam transmission of the micro-element surface using the radiation transfer model.

[0029] Furthermore, the calculation process of the heterogeneous parallel GPU acceleration processing method includes:

[0030] The algorithm is optimized by GPU acceleration method, and the CUDA parallel computing architecture is used to enable GPU to realize parallel general computing;

[0031] The ray tracing under uniform temperature field and the thermal radiation calculation tasks under non-uniform temperature field are decomposed, the calculation units are independently allocated, and an instruction set suitable for GPU parallel processing is constructed.

[0032] Another embodiment of the present invention provides a stray radiation ray tracing device based on a radiation transfer model, comprising:

[0033] A conventional ray tracing unit for applying a conventional ray tracing method within a component range of a uniform temperature field;

[0034] A radiation transfer tracing unit is used to calculate the energy beam transmission process of a microelement surface using a radiation transfer tracing method in a non-uniform temperature field and a radiation transfer model;

[0035] The traditional ray tracing and radiation transmission tracing processes are independent, the tracing process of each ray is independent, and the energy beam transmission process of each microelement surface is independent.

[0036] A storage medium stores a program file capable of implementing any of the above-mentioned stray radiation ray tracing methods based on a radiation transfer model.

[0037] A processor is used to run a program, wherein when the program is run, any one of the above-mentioned stray radiation ray tracing methods based on a radiation transfer model is executed.

[0038] The stray radiation ray tracing method and device based on the radiation transfer model in the embodiment of the present invention combines the traditional non-sequential ray tracing method, combines the thermal radiation transmission process with the stray light analysis process, adopts the traditional ray tracing method within the component range of the uniform temperature field, introduces the radiation transfer factor in the non-uniform temperature field, and adopts the radiation transfer model to calculate the energy beam transmission process of the micro-element surface. Compared with the traditional stray light analysis method, the integrated analysis simulation results of thermal radiation stray light are real-time and intuitive, and are suitable for simulation applications of non-uniform temperature fields and temperature gradient systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0040] Figure 1 It is a flow chart of the stray radiation ray tracing method based on the radiation transfer model of the present invention;

[0041] Figure 2 The overall flow chart of the stray radiation ray tracing method based on the radiation transmission model of the present invention;

[0042] Figure 3 It is a description diagram of the bidirectional reflectance distribution function BSDF in the present invention;

[0043] Figure 4 It is a diagram of the energy conduction process in the present invention;

[0044] Figure 5 It is a module diagram of the stray radiation ray tracing device based on the radiation transmission model of the present invention. DETAILED DESCRIPTION

[0045] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0046] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0047] Example 1

[0048] According to an embodiment of the present invention, a stray radiation ray tracing method based on a radiation transfer model is provided. Figure 1 , including the following steps:

[0049] S101: Using traditional ray tracing method within the component range of uniform temperature field;

[0050] S102: using a radiation transfer tracing method in a non-uniform temperature field and using a radiation transfer model to calculate the energy beam transmission process of the micro-element surface;

[0051] The traditional ray tracing and radiation transmission tracing processes are independent, the tracing process of each ray is independent, and the energy beam transmission process of each microelement surface is independent.

[0052] The stray radiation ray tracing method based on the radiation transfer model in the embodiment of the present invention is combined with the traditional non-sequential ray tracing method, the thermal radiation transmission process and the stray light analysis process are combined, the traditional ray tracing method is used within the component range of the uniform temperature field, the radiation transfer factor is introduced into the non-uniform temperature field, and the radiation transfer model is used to calculate the energy beam transmission process of the micro-element surface. Compared with the traditional stray light analysis method, the thermal radiation stray light integrated analysis simulation results are real-time and intuitive, and are suitable for simulation applications of non-uniform temperature fields and temperature gradient systems.

[0053] Among them, the traditional ray tracing method used within the component range of uniform temperature field includes:

[0054] The simulations were performed using the stray light ray tracing Monte Carlo method over the component with a uniform temperature field.

[0055] Among them, the simulation using the stray light ray tracing Monte Carlo method within the component range of a uniform temperature field includes:

[0056] Get the initial information of the light: the starting coordinates (x0, y0, z0) of the light emitted from the light source, the direction vector (l0, m0, n0), the energy E0 carried by the light, and the wavelength λ;

[0057] Determine the intersection of the light: find the first surface that intersects with the light. If there is no intersection, stop tracing this light. If there is an intersection, determine the intersection coordinates (x1, y1, z1), the normal direction vector (l n1 ,m n1 ,n n1 ), and obtain the optical properties of the surface;

[0058] Direction of emitted light: The spatial distribution of the direction of light transmission includes specular reflection, refraction, and scattering. If the optical surface is specular reflection or refraction, the emission direction and energy of the light are calculated by the reflection or refraction formula. If the optical surface is specular scattering, the emission direction and energy are distributed by the bidirectional reflectance distribution function BRDF.

[0059] Through the above process, a ray tracing of a surface is completed, and the newly generated ray intersection point (x1, y1, z1), direction vector (l1, m1, n1), and ray energy E1 are the starting conditions for the next tracing. In the ray tracing process, each ray is composed of the above calculation process.

[0060] Among them, the simulation using the stray light ray tracing Monte Carlo method within the component range of the uniform temperature field also includes:

[0061] Ray cutoff: The termination condition of ray tracing is that the ray reaches the preset image plane; the ray energy is less than the threshold.

[0062] Among them, the radiation transmission tracing method used in the non-uniform temperature field includes:

[0063] In the infrared self-radiation simulation process of the optical system with non-uniform temperature, the non-uniform temperature distribution surface is first determined, and the Monte Carlo method of thermal radiation transmission is used to simulate the non-uniform temperature distribution surface.

[0064] Among them, the Monte Carlo method of heat radiation transfer on the surface of non-uniform temperature distribution is used for simulation, including:

[0065] Meshing: Meshing each element of the optical system into micro-surface elements and micro-voxels;

[0066] Calculation of the radiant illumination of a micro-surface element: Take the temperature T in the micro-surface element i and the emissivity ε of the element, and the radiant illumination of the element microelement surface in its use band is calculated according to Planck's radiation law;

[0067] Energy beam launch point model: The coordinates of the energy beam launch point (x i ,y i ,z i );

[0068] Energy beam emission direction model: Use the Monte Carlo method to determine the pitch angle θ of the energy beam emission direction i and azimuth

[0069] Radiative transfer energy calculation: Use energy conduction theory to calculate the luminous flux dφ from the emitting microelement surface to the receiving microelement surface c ;

[0070] Through the above process, the radiation calculation from one microelement surface to another microelement surface is completed, and the radiation transfer factor B of the microelement surface is calculated successively. ij , energy beam emission point intersection (x i ,y i ,z i ), energy beam emission direction Finally, the radiation transfer factor B from each microelement surface to the detector microelement surface is obtained by calculation. ij Then the irradiance of the temperature gradient element is calculated.

[0071] Among them, when the elements of the optical system are meshed and divided into micro-surface elements and micro-volume elements, their temperature, heat flux and heat flux are uniform within the unit micro-element.

[0072] Among them, a heterogeneous parallel GPU acceleration processing method is adopted in the process of calculating the energy beam transmission of the micro-element surface using the radiation transfer model.

[0073] The calculation process of the heterogeneous parallel GPU acceleration processing method includes:

[0074] The algorithm is optimized by GPU acceleration method, and the CUDA parallel computing architecture is used to enable GPU to realize parallel general computing;

[0075] The ray tracing under uniform temperature field and the thermal radiation calculation tasks under non-uniform temperature field are decomposed, the calculation units are independently allocated, and an instruction set suitable for GPU parallel processing is constructed.

[0076] The following is a detailed description of the stray radiation ray tracing method based on the radiation transmission model of the present invention with reference to a specific embodiment:

[0077] Based on the currently used interactive stray radiation analysis technology, the surface traced each time is a whole, and the temperature non-uniformity in actual applications and the heat transfer effect in system applications are not considered, thus affecting the accuracy of the simulation. The present invention proposes a stray radiation ray tracing method based on a radiation transfer model, combined with the traditional non-sequential ray tracing method, combining the thermal radiation transmission process with the stray light analysis process, using the traditional ray tracing method within the component range of the uniform temperature field, introducing the radiation transfer factor in the non-uniform temperature field, and using the radiation transmission model to calculate the energy beam transmission process of the micro-element surface. Compared with the traditional stray light analysis method, the integrated analysis simulation results of thermal radiation stray light are real-time and intuitive, and are suitable for simulation applications of non-uniform temperature fields and temperature gradient systems.

[0078] In the present invention, the traditional ray tracing and radiation transmission tracing processes are independent, the tracing process of each ray is independent, and the energy beam transmission process of each microelement surface is independent, which is suitable for heterogeneous parallel acceleration algorithms. Combined with the GPU's node task allocation, the speed of ray tracing and the accuracy of the results will be greatly improved.

[0079] This embodiment discloses a stray radiation ray tracing method based on a radiation transmission model, and its overall process is as follows: Figure 2 As shown in the figure. In the simulation of infrared self-radiation of optical systems with non-uniform temperature, the non-uniform temperature distribution surface is first determined, and the Monte Carlo method of thermal radiation transmission is used on the non-uniform temperature distribution surface, and the stray light ray tracing Monte Carlo method is used on the other surfaces. During the simulation process, the two methods are used together and independently of each other, and the heterogeneous parallel GPU processing method is used in the calculation process to improve the simulation efficiency.

[0080] (1) Stray light ray tracing Monte Carlo method

[0081] Get the initial information of the light: the starting coordinates (x0, y0, z0) of the light emitted from the light source, the direction vector (l0, m0, n0), the energy E0 carried by the light, and the wavelength λ.

[0082] Determine the intersection of light rays: Use the gridding method to evenly divide the optical system structure model into spaces, and use the spatial bounding box method to perform recursion until the maximum recursion depth is reached to complete the Boolean operation of intersection. By continuously reducing the subspace, find the first surface that intersects with the light ray. If there is no intersection, stop tracing this ray. If there is an intersection, determine the intersection coordinates (x1, y1, z1), the normal direction vector (l n1 ,m n1 ,n n1 ) and obtain the optical properties of the surface.

[0083] Direction of emitted light: The spatial distribution of the direction of light transmission includes specular reflection, refraction, and scattering. If the optical surface is specular reflection or refraction, the emission direction and energy of the light are calculated by the reflection or refraction formula. If the optical surface has scattering properties, the emission direction and energy are distributed by the bidirectional reflectance distribution function BRDF. If the optical surface is specular reflection or refraction, the emission direction of the light is calculated by the reflection or refraction formula. The reflection formula and refraction formula are as follows:

[0084] θ r =θ i

[0085]

[0086] The incident angle of the incident light is θ i , the angle of the outgoing light is θ r , n1 and n2 are the transmittances on both sides of the medium respectively.

[0087] The energy distribution on a smooth surface follows the law of conservation of energy, that is, the sum of the reflectivity R, transmittance T and the medium surface absorptivity A is 1.

[0088] R+T+A=1

[0089] The reflected and refracted light energies are:

[0090]

[0091]

[0092] If the optical surface has scattering properties, the anisotropic reflectance characteristics of the surface are described by the bidirectional reflectance distribution function BRDF, such as Figure 3 As shown, the function expression of BRDF is as follows:

[0093]

[0094] When the light reaches the scattering surface, the Monte Carlo method is used to randomly generate the direction vector of the light, and the corresponding light energy value is assigned according to the BRDF and the total cumulative scattering TIS. For example, in Lambertian scattering, the BRDF is as follows:

[0095]

[0096] Through the above process, a ray trace of a surface can be completed. The newly generated ray intersection point (x1, y1, z1), direction vector (l1, m1, n1), and ray energy E1 are the starting conditions for the next tracing. In the ray tracing process, each ray is composed of the above calculation process.

[0097] Ray Cutoff: The termination conditions for ray tracing are as follows:

[0098] The light reaches the preset image plane;

[0099] When the light energy is less than a certain threshold, the ray tracing is terminated.

[0100] (2) Monte Carlo method based on radiation transfer model

[0101] Meshing: The elements of the optical system are meshed into micro-surface elements and micro-volume elements, and the temperature, heat flux or heat flux is considered to be uniform within the unit micro-element.

[0102] Calculation of the radiant illumination of a micro-surface element: Take the temperature T in the micro-surface element i And the emissivity ε of the component, according to Planck's radiation law, the radiant illumination of the micro-element surface of the component in its use band is calculated. According to Planck's radiation law, the formula for calculating the radiant illumination of the micro-element surface of the component in its use band is as follows:

[0103]

[0104] Energy beam emission point model: The energy beam emission point is determined by using the Monte Carlo method. Taking a three-dimensional rectangle in a rectangular coordinate system as an example, the coordinates of the energy beam emission point can be generated using the uniform point projection method. Let [x min ,x max ]、[y min ,y max ]、[z min ,z max ] are the value ranges of the energy beam in the x direction, y direction, and z direction, respectively, R x , R y is a random number uniformly distributed in the interval [[0, 1], then the coordinates of the emission point (x i ,y i ,z i ). They are:

[0105] x i =R x (x max -x min )+x min

[0106] y i =R y (y max -y min )+y min

[0107] z i =f(x i ,y i )

[0108] Energy beam emission direction model: The energy beam emission direction is determined using the Monte Carlo method. For anisotropic emission surface elements, the pitch angle θ and azimuth angle of the energy beam emission direction in the emission coordinate system are They are:

[0109]

[0110] For isotropic emitting volume elements, the zenith angle and circumferential angle of the energy beam emission direction are:

[0111]

[0112] Where R θ , are the elevation angle θ and the azimuth angle A uniformly distributed random number.

[0113] Radiative transfer energy calculation: Use energy conduction theory to calculate the luminous flux dφ from the emitting microelement surface to the receiving microelement surface c .

[0114] The radiation transmission process in the optomechanical system conforms to the energy conduction theory. The propagation of radiation between two microelement surfaces in the same medium is as follows: Figure 4 As shown, the formula is as follows:

[0115]

[0116] Where, dφ c is the light flux received by the microelement surface, L S is the illuminance of the emitting microelement surface, dA s is the area of ​​the emitting microelement surface, dA c is the area of ​​the receiving microelement surface, θ c and θ s is the angle between the line connecting the receiving micro-element surface and the transmitting micro-element surface and their respective normals, and R is the length of the line connecting the centers of the receiving micro-element surface and the transmitting micro-element surface.

[0117] Due to L S =BRDF·E S ,but:

[0118]

[0119] Through the above process, the radiation calculation from one microelement surface to another microelement surface can be completed, and the radiation transfer factor B of the microelement surface can be calculated successively. ij , energy beam emission point intersection (x i ,y i ,z i ), energy beam emission direction Finally, the radiation transfer factor B from each microelement surface to the detector microelement surface is obtained by calculation. ij Then the irradiance of the temperature gradient element is calculated, and the calculation formula is as follows:

[0120]

[0121] (3) The heterogeneous parallel GPU accelerated computing process is as follows:

[0122] Since the face metadata and light data are independent of each other during calculation, there is no need for data interaction between different data processing processes, and they do not interfere with each other. The coupling degree is extremely low, which matches the parallel data processing capability of the GPU platform. Therefore, the tracing process can be calculated in parallel. This type of calculation belongs to intensive instruction calculation. Therefore, the GPU acceleration method is used to optimize the algorithm, and the CUDA parallel computing architecture is used to enable the GPU to achieve parallel general computing. The ray tracing under uniform temperature field and the thermal radiation calculation task under non-uniform temperature field are decomposed, and the computing units are independently allocated to construct an instruction set suitable for GPU parallel processing.

[0123] Compared with the prior art, the advantages of the present invention are at least:

[0124] (1) High simulation accuracy

[0125] Compared with the traditional stray radiation simulation method, the present invention distinguishes between uniform temperature elements and non-uniform temperature elements in the optical system. The uniform temperature elements use the ray tracing simulation method, while the non-uniform temperature elements use the thermal radiation analysis method. Compared with the traditional simulation method, the setting and simulation of temperature gradient elements can be realized, the calculation results are closer to the actual situation, and the simulation accuracy is improved in principle.

[0126] (2) Fast calculation speed

[0127] The present invention discretizes the simulation process and divides it into sub-processes of facet calculation and ray calculation. Each unit calculation process is relatively independent and has extremely low coupling, which matches the parallel data processing capability of the GPU platform. The GPU acceleration method is used to optimize the algorithm, and the CUDA parallel computing architecture is used to enable the GPU to realize parallel general computing. Compared with the traditional stray radiation simulation method, the computing efficiency is greatly improved.

[0128] The product of the present invention has been verified by simulation, and has good effect. The simulation results of integrated analysis of thermal radiation stray light are real-time and intuitive, and are suitable for simulation applications of non-uniform temperature fields and temperature gradient systems.

[0129] Example 2

[0130] According to another embodiment of the present invention, a stray radiation ray tracing device based on a radiation transfer model is provided. Figure 5,include:

[0131] A conventional ray tracing unit 201, for using a conventional ray tracing method within a component range of a uniform temperature field;

[0132] The radiation transmission tracing unit 202 is used to calculate the energy beam transmission process of the micro-element surface by using the radiation transmission tracing method in the non-uniform temperature field and the radiation transmission model;

[0133] The traditional ray tracing and radiation transmission tracing processes are independent, the tracing process of each ray is independent, and the energy beam transmission process of each microelement surface is independent.

[0134] The stray radiation ray tracing device based on the radiation transfer model in the embodiment of the present invention combines the traditional non-sequential ray tracing method, combines the thermal radiation transmission process with the stray light analysis process, adopts the traditional ray tracing method within the component range of the uniform temperature field, introduces the radiation transfer factor in the non-uniform temperature field, and adopts the radiation transfer model to calculate the energy beam transmission process of the micro-element surface. Compared with the traditional stray light analysis method, the integrated analysis simulation results of thermal radiation stray light are real-time and intuitive, and are suitable for simulation applications of non-uniform temperature fields and temperature gradient systems.

[0135] The following is a detailed description of the stray radiation ray tracing device based on the radiation transmission model of the present invention with reference to a specific embodiment:

[0136] Based on the currently used interactive stray radiation analysis technology, the surface traced each time is a whole, and the temperature non-uniformity in actual applications and the heat transfer effect in system applications are not considered, thus affecting the accuracy of the simulation. The present invention proposes a stray radiation ray tracing device based on a radiation transfer model, which combines the traditional non-sequential ray tracing method, combines the thermal radiation transmission process with the stray light analysis process, uses the traditional ray tracing method within the component range of the uniform temperature field, introduces the radiation transfer factor in the non-uniform temperature field, and uses the radiation transmission model to calculate the energy beam transmission process of the micro-element surface. Compared with the traditional stray light analysis method, the integrated analysis simulation results of thermal radiation stray light are real-time and intuitive, and are suitable for simulation applications of non-uniform temperature fields and temperature gradient systems.

[0137] In the present invention, the traditional ray tracing and radiation transmission tracing processes are independent, the tracing process of each ray is independent, and the energy beam transmission process of each microelement surface is independent, which is suitable for heterogeneous parallel acceleration algorithms. Combined with the GPU's allocation of node tasks, the speed of ray tracing and the accuracy of the results will be greatly improved.

[0138] This embodiment discloses a stray radiation ray tracing device based on a radiation transmission model, and its overall process is as follows: Figure 2As shown in the figure. In the simulation of infrared self-radiation of optical systems with non-uniform temperature, the non-uniform temperature distribution surface is first determined, and the Monte Carlo method of thermal radiation transmission is used on the non-uniform temperature distribution surface, and the stray light ray tracing Monte Carlo method is used on the other surfaces. During the simulation process, the two methods are used together and independently of each other, and the heterogeneous parallel GPU processing method is used in the calculation process to improve the simulation efficiency.

[0139] (1) Stray light ray tracing Monte Carlo method

[0140] Get the initial information of the light: the starting coordinates (x0, y0, z0) of the light emitted from the light source, the direction vector (l0, m0, n0), the energy E0 carried by the light, and the wavelength λ.

[0141] Determine the intersection of light rays: Use the gridding method to evenly divide the optical system structure model into spaces, and use the spatial bounding box method to perform recursion until the maximum recursion depth is reached to complete the Boolean operation of intersection. By continuously reducing the subspace, find the first surface that intersects with the light ray. If there is no intersection, stop tracing this ray. If there is an intersection, determine the intersection coordinates (x1, y1, z1), the normal direction vector (l n1 ,m n1 ,n n1 ) and obtain the optical properties of the surface.

[0142] Direction of emitted light: The spatial distribution of the direction of light transmission includes specular reflection, refraction, and scattering. If the optical surface is specular reflection or refraction, the emission direction and energy of the light are calculated by the reflection or refraction formula. If the optical surface has scattering properties, the emission direction and energy are distributed by the bidirectional reflectance distribution function BRDF. If the optical surface is specular reflection or refraction, the emission direction of the light is calculated by the reflection or refraction formula. The reflection formula and refraction formula are as follows:

[0143] θ r =θ i

[0144]

[0145] The incident angle of the incident light is θ i , the angle of the outgoing light is θ r , n1 and n2 are the transmittances on both sides of the medium respectively.

[0146] The energy distribution on a smooth surface follows the law of conservation of energy, that is, the sum of the reflectivity R, transmittance T and the medium surface absorptivity A is 1.

[0147] R+T+A=1

[0148] The reflected and refracted light energies are:

[0149]

[0150]

[0151] If the optical surface has scattering properties, the anisotropic reflectance characteristics of the surface are described by the bidirectional reflectance distribution function BRDF, such as Figure 3 As shown, the function expression of BRDF is as follows:

[0152]

[0153] When the light reaches the scattering surface, the Monte Carlo method is used to randomly generate the direction vector of the light, and the corresponding light energy value is assigned according to the BRDF and the total cumulative scattering TIS. For example, in Lambertian scattering, the BRDF is as follows:

[0154]

[0155] Through the above process, a ray trace of a surface can be completed. The newly generated ray intersection point (x1, y1, z1), direction vector (l1, m1, n1), and ray energy E1 are the starting conditions for the next tracing. In the ray tracing process, each ray is composed of the above calculation process.

[0156] Ray Cutoff: The termination conditions for ray tracing are as follows:

[0157] The light reaches the preset image plane;

[0158] When the light energy is less than a certain threshold, the ray tracing is terminated.

[0159] (2) Monte Carlo method based on radiation transfer model

[0160] Meshing: The elements of the optical system are meshed into micro-surface elements and micro-volume elements, and the temperature, heat flux or heat flux is considered to be uniform within the unit micro-element.

[0161] Calculation of the radiant illumination of a micro-surface element: Take the temperature T in the micro-surface element i And the emissivity ε of the component, according to Planck's radiation law, the radiant illumination of the micro-element surface of the component in its use band is calculated. According to Planck's radiation law, the formula for calculating the radiant illumination of the micro-element surface of the component in its use band is as follows:

[0162]

[0163] Energy beam emission point model: The energy beam emission point is determined by using the Monte Carlo method. Taking a three-dimensional rectangle in a rectangular coordinate system as an example, the coordinates of the energy beam emission point can be generated using the uniform point projection method. Let [x min ,x max]、[y min ,y max ]、[z min ,z max ] are the value ranges of the energy beam in the x direction, y direction, and z direction, respectively, R x , R y is a random number uniformly distributed in the interval [[0, 1], then the coordinates of the emission point (x i ,y i ,z i ). They are:

[0164] x i =R x (x max -x min )+x min

[0165] y i =R y (y max -y min )+y min

[0166] z i =f(x i ,y i )

[0167] Energy beam emission direction model: The energy beam emission direction is determined using the Monte Carlo method. For anisotropic emission surface elements, the pitch angle θ and azimuth angle of the energy beam emission direction in the emission coordinate system are They are:

[0168]

[0169] For isotropic emitting volume elements, the zenith angle and circumferential angle of the energy beam emission direction are:

[0170]

[0171] Where R θ , are the elevation angle θ and the azimuth angle A uniformly distributed random number.

[0172] Radiative transfer energy calculation: Use energy conduction theory to calculate the luminous flux dφ from the emitting microelement surface to the receiving microelement surface c .

[0173] The radiation transmission process in the optomechanical system conforms to the energy conduction theory. The propagation of radiation between two microelement surfaces in the same medium is as follows: Figure 4 As shown, the formula is as follows:

[0174]

[0175] Where, dφ c is the light flux received by the microelement surface, L S is the illuminance of the emitting microelement surface, dA s is the area of ​​the emitting microelement surface, dA c is the area of ​​the receiving microelement surface, θ c and θ s is the angle between the line connecting the receiving micro-element surface and the transmitting micro-element surface and their respective normals, and R is the length of the line connecting the centers of the receiving micro-element surface and the transmitting micro-element surface.

[0176] Due to L S =BRDF·E S ,but:

[0177]

[0178] Through the above process, the radiation calculation from one microelement surface to another microelement surface can be completed, and the radiation transfer factor B of the microelement surface can be calculated successively. ij , energy beam emission point intersection (x i ,y i ,z i ), energy beam emission direction Finally, the radiation transfer factor B from each microelement surface to the detector microelement surface is obtained by calculation. ij Then the irradiance of the temperature gradient element is calculated, and the calculation formula is as follows:

[0179]

[0180] (3) The heterogeneous parallel GPU accelerated computing process is as follows:

[0181] Since the face metadata and light data are independent of each other during calculation, there is no need for data interaction between different data processing processes, and they do not interfere with each other. The coupling degree is extremely low, which matches the parallel data processing capability of the GPU platform. Therefore, the tracing process can be calculated in parallel. This type of calculation belongs to intensive instruction calculation. Therefore, the GPU acceleration method is used to optimize the algorithm, and the CUDA parallel computing architecture is used to enable the GPU to achieve parallel general computing. The ray tracing under uniform temperature field and the thermal radiation calculation task under non-uniform temperature field are decomposed, and the computing units are independently allocated to construct an instruction set suitable for GPU parallel processing.

[0182] Compared with the prior art, the advantages of the present invention are at least:

[0183] (1) High simulation accuracy

[0184] Compared with the traditional stray radiation simulation method, the present invention distinguishes between uniform temperature elements and non-uniform temperature elements in the optical system. The uniform temperature elements use the ray tracing simulation method, while the non-uniform temperature elements use the thermal radiation analysis method. Compared with the traditional simulation method, the setting and simulation of temperature gradient elements can be realized, the calculation results are closer to the actual situation, and the simulation accuracy is improved in principle.

[0185] (2) Fast calculation speed

[0186] The present invention discretizes the simulation process and divides it into sub-processes of facet calculation and ray calculation. Each unit calculation process is relatively independent and has extremely low coupling, which matches the parallel data processing capability of the GPU platform. The GPU acceleration method is used to optimize the algorithm, and the CUDA parallel computing architecture is used to enable the GPU to realize parallel general computing. Compared with the traditional stray radiation simulation method, the computing efficiency is greatly improved.

[0187] The product of the present invention has been verified by simulation, and has good effect. The simulation results of integrated analysis of thermal radiation stray light are real-time and intuitive, and are suitable for simulation applications of non-uniform temperature fields and temperature gradient systems.

[0188] Example 3

[0189] A storage medium stores a program file capable of implementing any of the above-mentioned stray radiation ray tracing methods based on a radiation transfer model.

[0190] Example 4

[0191] A processor is used to run a program, wherein when the program is run, any one of the above-mentioned stray radiation ray tracing methods based on a radiation transfer model is executed.

[0192] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0193] In the above embodiments of the present invention, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0194] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the system embodiments described above are only schematic. For example, the division of units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0195] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed over multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0196] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0197] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk and other media that can store program codes.

[0198] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A stray radiation ray tracing method based on a radiation transfer model, characterized in that: The following steps are involved: Traditional ray tracing methods are used across the component with a uniform temperature field; The radiation transfer tracing method is used in the non-uniform temperature field, and the radiation transfer model is used to calculate the energy beam transfer process of the micro-element surface; The traditional ray tracing and radiation transmission tracing processes are independent, the tracing process of each ray is independent, and the energy beam transmission process of each microelement surface is independent; The conventional ray tracing method within the component range of the uniform temperature field includes: Simulations were performed using the stray light ray tracing Monte Carlo method within the component range with a uniform temperature field; The simulation using the stray light ray tracing Monte Carlo method within the component range of the uniform temperature field includes: Get the initial information of the light: the starting coordinates (x0, y0, z0) of the light emitted from the light source, the direction vector (l0, m0, n0), the energy E0 carried by the light, and the wavelength λ; Determine the intersection of the light: find the first surface that intersects with the light. If there is no intersection, stop tracing this light. If there is an intersection, determine the intersection coordinates (x1, y1, z1), the normal direction vector (l n1 ,m n1 ,n n1 ), and obtain the optical properties of the surface; Direction of emitted light: The spatial distribution of the direction of light transmission includes specular reflection, refraction, and scattering. If the optical surface is specular reflection or refraction, the emission direction and energy of the light are calculated by the reflection or refraction formula. If the optical surface is specular scattering, the emission direction and energy are distributed by the bidirectional reflectance distribution function BRDF. Through the above process, a ray tracing of a surface is completed. The newly generated ray intersection point (x1, y1, z1), direction vector (l1, m1, n1), and ray energy E1 are the starting conditions for the next tracing. In the ray tracing process, each ray is obtained by the above calculation process. Ray cutoff: The termination condition of ray tracing is that the ray reaches the preset image plane; the ray energy is less than the threshold.

2. The stray radiation ray tracing method based on the radiation transfer model according to claim 1, characterized in that: The radiation transmission tracing method in the non-uniform temperature field includes: In the infrared self-radiation simulation process of the optical system with non-uniform temperature, the non-uniform temperature distribution surface is first determined, and the Monte Carlo method of thermal radiation transmission is used to simulate the non-uniform temperature distribution surface.

3. The stray radiation ray tracing method based on the radiation transfer model according to claim 2, characterized in that: The Monte Carlo method for simulating heat radiation transmission on a surface with non-uniform temperature distribution includes: Meshing: Meshing each element of the optical system into micro-surface elements and micro-voxels; Calculation of the radiant illumination of a micro-surface element: Take the temperature T in the micro-surface element i and the emissivity ε of the element, and the radiant illumination of the element microelement surface in its use band is calculated according to Planck's radiation law; Energy beam launch point model: The coordinates of the energy beam launch point (x i ,y i ,z i ); Energy beam emission direction model: Use the Monte Carlo method to determine the pitch angle θ of the energy beam emission direction i and azimuth Radiative transfer energy calculation: Use energy conduction theory to calculate the luminous flux dφ from the emitting microelement surface to the receiving microelement surface c ; Through the above process, the radiation calculation from one microelement surface to another microelement surface is completed, and the radiation transfer factor B of the microelement surface is calculated successively. ij , energy beam emission point intersection (x i ,y i ,z i ), energy beam emission direction Finally, the radiation transfer factor B from each microelement surface to the detector microelement surface is obtained by calculation. ij Then the irradiance of the temperature gradient element is calculated.

4. The stray radiation ray tracing method based on the radiation transfer model according to claim 3 is characterized in that: In the process of meshing the components of the optical system into micro-surface elements and micro-volume elements, the temperature, heat flux, and heat flux are uniform within the unit micro-element.

5. The stray radiation ray tracing method based on the radiation transfer model according to claim 1, characterized in that: Heterogeneous parallel GPU acceleration processing method is used in the process of calculating energy beam transmission on micro-element surfaces using the radiation transfer model.

6. The stray radiation ray tracing method based on the radiation transfer model according to claim 5, characterized in that: The calculation process of the heterogeneous parallel GPU acceleration processing method includes: The algorithm is optimized by GPU acceleration method, and the CUDA parallel computing architecture is used to enable GPU to realize parallel general computing; The ray tracing under uniform temperature field and the thermal radiation calculation tasks under non-uniform temperature field are decomposed, the calculation units are independently allocated, and an instruction set suitable for GPU parallel processing is constructed.

7. A stray radiation ray tracing device based on a radiation transfer model using the stray radiation ray tracing method based on a radiation transfer model according to claim 1, characterized in that: include: A conventional ray tracing unit for applying a conventional ray tracing method within a component range of a uniform temperature field; A radiation transfer tracing unit is used to calculate the energy beam transmission process of a microelement surface by using a radiation transfer tracing method in a non-uniform temperature field and a radiation transfer model; The traditional ray tracing and radiation transmission tracing processes are independent, the tracing process of each ray is independent, and the energy beam transmission process of each microelement surface is independent.

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