A method for modeling a target reflection region of a millimeter wave radar, an electronic device, a storage medium, a program product and a vehicle

Abstract

Embodiments of the present application provide a modeling method of a millimeter wave radar target reflection area, an electronic device, a storage medium, a program product and a vehicle. The method comprises: in a millimeter wave radar simulation based on ray tracing, for any ray tube emitted from a radar emission source, determining candidate patches covered by the ray tube on a target surface to obtain a candidate patch set; in the case where the candidate patch set includes multiple candidate patches, determining multiple patches in the candidate patch set that satisfy a preset merging condition as belonging to the same smooth surface; performing merging processing on the multiple patches determined as belonging to the same smooth surface to generate an equivalent normal vector; and calculating a return wave contribution of the ray tube to a radar receiving end after reflection on the target surface according to the equivalent normal vector and area information of the multiple patches belonging to the same smooth surface. While ensuring real-time, the calculation accuracy is improved.

Description

Technical Field

[0001] This application relates to the field of millimeter-wave radar technology, and more specifically, to a method for modeling the reflection region of a millimeter-wave radar target, an electronic device, a storage medium, a program product, and a vehicle. Background Technology

[0002] Millimeter-wave radar is one of the key sensors in the environmental perception system of autonomous vehicles. It typically operates in the 76GHz–81GHz frequency band and can provide information such as target distance, speed, angle, and reflection intensity in scenarios with poor visibility, such as rain, fog, and nighttime. During the development and verification of autonomous driving algorithms, to reduce the cost of real-vehicle testing and improve coverage of hazardous and boundary scenarios, it is usually necessary to build a virtual radar model in the HiL / SIL simulation environment that can output radar point clouds, detect targets, or display raw radar signals.

[0003] In physical-level radar simulations, the interaction between radar waves and targets such as vehicles, roads, guardrails, road signs, and pedestrians typically needs to consider factors such as geometric propagation, reflection, scattering, multipath propagation, obstruction, material properties, Doppler effects caused by relative motion, and receiver signal processing. Physical sensor models in existing autonomous driving simulation platforms are generally considered to have high realism, but they also involve significant computational demands. For vehicle-mounted radar, models such as the IPG CarMaker Radar RSI Model, ANSYS HFSS SBR+, dSPACE AURELION, Remcom WaveFarer, ALTair Feko+WinProp, CST's Asymptotic Solver, Siemens Simcenter Prescan Physics-Based Radar, RadarSimPy, and NVIDIA Sionna RT exist. These models simulate electromagnetic wave propagation using ray tracing and consider the effects of multipath / repeating propagation, relative Doppler, road clutter, and target missed / false detections. Such models require modeling the properties of the target material, such as the relative permittivity and scattering characteristics, because these parameters significantly affect the reflection direction and the intensity of the reflected wave field.

[0004] From the perspective of high-frequency electromagnetic approximation methods, common methods include geometrical optics (GO), physical optics (PO), Shooting and Bouncing Rays (SBR), SBR+, Physical Diffraction Theory (PTD), and Uniform Diffraction Theory (UTD). SBR (Shooting and Bouncing Rays Method) / SBR+ (Shooting and Bouncing Rays Method+) methods typically discretize the emitted wave into a large number of rays or ray tubes. These rays undergo one or more reflections at the target surface, and the scattered field is then calculated using the PO approximation. The ANSYS HFSSSBR+ official documentation describes SBR+ as a hybrid high-frequency approximation method combining GO and PO. It emits a large number of rays from the radiation source towards the visible scattering geometry. These rays are weighted by antenna patterns or current distributions and can be represented as divergent volumetric ray tubes.

[0005] However, in real-time simulations of autonomous driving, targets such as vehicles, guardrails, road edges, curved body surfaces, tires, rearview mirrors, and road sign edges are typically composed of numerous surfaces. When a beam of light with a finite angular width or finite solid angle illuminates the target surface, its actual coverage area may not fall on the single surface hit by the central ray, but may span multiple adjacent or non-adjacent surfaces, and may be partially obstructed by closer surfaces. If the simulation model calculates the echo using only the single surface hit by the central ray as the reflecting surface, it will produce deviations in the judgment of reflection area, normal direction, and visibility at target edges, curved transition areas, and partially obstructed areas, leading to distortions in radar point cloud intensity, position, continuity, and stability. While performing physical optical integration on each surface covered by the ray can preserve surface details, it introduces a huge computational burden when a large number of rays cover multiple surfaces in vehicle simulations, making it difficult to meet the real-time requirements of HiL / SiL simulations. Summary of the Invention

[0006] The purpose of this application is to provide a modeling method, electronic device, storage medium, program product, and vehicle for millimeter-wave radar target reflection areas, so as to achieve the technical effect of improving modeling accuracy and echo calculation accuracy while meeting the real-time requirements of vehicle simulation.

[0007] The first aspect of this application provides a method for modeling the reflection region of a millimeter-wave radar target, the method comprising: In millimeter-wave radar simulation based on ray tracing, for any ray tube emitted from the radar source, the candidate patches covered by the ray tube on the target surface are determined, and a set of candidate patches is obtained. When the candidate patch set includes multiple candidate patches, multiple patches in the candidate patch set that meet the preset merging conditions are determined to belong to the same smooth surface; the preset merging conditions include that the angle between the normal vectors of adjacent patches is less than a preset normal angle threshold, and that the cumulative deviation of the normal vectors of each patch relative to the reference normal vector is less than a preset cumulative deviation threshold. Multiple facets that are determined to belong to the same smooth surface are merged to generate an equivalent normal vector; the equivalent normal vector is used to characterize the comprehensive normal direction of each facet belonging to the same smooth surface after weighted average of the effective visible projected area; Based on the equivalent normal vector and the area information of multiple facets belonging to the same smooth surface, the echo contribution of the ray tube to the radar receiver after reflection from the target surface is calculated.

[0008] In the above implementation process, all candidate patches covered by the ray tube on the target surface are identified and it is determined whether they belong to the same smooth surface, replacing the processing method of hitting a single patch by the central ray in related technologies. Based on the determination that they belong to the same smooth surface, an equivalent normal vector is generated with the effective visible projected area of ​​each patch as the weight, and the echo contribution is calculated by combining the area information of each patch. Thus, while maintaining the real-time simulation framework at the ray tube level, it avoids the huge computational pressure brought by patch-by-pattern integration, meets the real-time requirements of vehicle simulation, and avoids the deviation in the judgment of reflection area, normal direction, and visibility caused by ignoring multiple patches covered by the ray tube or using only a single normal vector in the transition area of ​​the surface in related technologies, thereby improving the simulation accuracy of radar echo intensity, target position, and point cloud continuity.

[0009] Furthermore, the method also includes: If the candidate patch set includes a candidate patch, the normal vector of the candidate patch is taken as the equivalent normal vector, and the projected area of ​​the candidate patch in the incident direction of the ray tube is taken as the area information.

[0010] In the above implementation process, for the case where the candidate patch set contains only one patch, the normal vector is directly simplified to the normal vector of the single patch itself, and the area information is simplified to its projected area in the incident direction. This avoids performing redundant weighted average calculations in scenarios where there is no need for merging and judgment, and ensures the accurate acquisition of the key geometric parameters (i.e., normal and effective projected area) required for the calculation of induced current in physical optics.

[0011] Further, the reference normal vector is the normal vector of the surface hit by the center ray of the ray tube; the step of determining multiple surfaces in the candidate surface set that meet the preset merging conditions as belonging to the same smooth surface includes: Multiple facets that meet the following conditions are determined to belong to the same smooth surface: the angle between the normal vectors of any adjacent facets is less than the preset normal angle threshold, and the angle between the normal vector of any facet in the candidate facet set and the reference normal vector is less than the preset cumulative deviation threshold; the preset cumulative deviation threshold is the product of the preset normal angle threshold and the preset constant coefficient.

[0012] In the above implementation process, it is ensured that the multiple merged patches truly form a continuous and smooth surface geometrically, thus ensuring the continuity and physical reality of the reflection normal in radar simulation.

[0013] Further, the equivalent normal vector is generated through the following steps: Obtain the effective visible projected area and normal vector of each facet belonging to the same smooth surface; For each patch, calculate the proportion of the effective visible projected area of ​​the patch to the total effective visible projected area of ​​all patches belonging to the same smooth surface; Using the aforementioned proportion as the weight, the normal vectors of each facet are weighted and summed, and the result of the weighted sum is taken as the equivalent normal vector.

[0014] In the above implementation process, the normal vector information of multiple facets is compressed into a single equivalent normal vector by using an area-weighted normal vector averaging method, thus achieving effective dimensionality reduction of the geometric features of the target surface. The weighting method fully considers the effective area proportion of each facet actually participating in reflection, making the equivalent normal vector closer to physical reality and providing accurate geometric parameters for subsequent echo contribution calculation.

[0015] Further, the area information includes the effective visible projected area of ​​each facet; the calculation of the echo contribution of the ray tube to the radar receiver after reflection from the target surface, based on the equivalent normal vector and the area information of multiple facets belonging to the same smooth surface, includes: The equivalent normal vector is used as the basis for the common incident direction vector of each patch belonging to the same smooth surface; Obtain the incident angles of each facet belonging to the same smooth surface; Determine the Fresnel reflection coefficient for each surface piece for each incident angle; Based on the normal vector of each facet and the incident direction vector of the ray tube, calculate the reflection direction vector corresponding to each facet. Using the effective visible projected area of ​​each patch, the Fresnel reflection coefficient, and the reflection direction vector, the physical optical current contribution of each patch to the radar receiver is calculated. The echo contribution is obtained by superimposing the physical optical current contributions of each facet.

[0016] In the above implementation, the normal vector is equivalently processed (i.e., all facets share the same incident direction vector), but the area information and Fresnel reflection coefficient retain the individual differences of each facet. While improving computational efficiency (eliminating the need to calculate the incident direction separately), it maintains high accuracy in material reflection characteristics and local geometric details.

[0017] Further, the area information includes the equivalent reflection area, which characterizes the equivalent visible projected area of ​​multiple facets belonging to the same smooth surface in the incident direction of the ray tube; the step of calculating the echo contribution of the ray tube to the radar receiver after reflection from the target surface based on the equivalent normal vector and the area information of multiple facets belonging to the same smooth surface includes: The equivalent normal vector is used to replace the individual normal vectors of each patch belonging to the same smooth surface; The equivalent reflective area is used to replace the projected area of ​​each patch belonging to the same smooth curved surface; Based on physical optics algorithms, the echo contribution is calculated according to the replaced equivalent normal vector and the replaced equivalent reflection area.

[0018] In the above implementation process, both the normal vector and the area are equivalent, and multiple patches are completely merged into an equivalent plane for calculation. This greatly improves the calculation efficiency and is suitable for flat or nearly flat regions with small curvature and small differences in the normal vectors of each patch (such as large flat areas such as car doors and hoods).

[0019] Furthermore, the equivalent reflective area is generated through the following steps: The sum of the effective visible projected areas of all patches belonging to the same smooth surface is obtained as the total effective visible projected area; Obtain the incident direction vector of the ray tube; The equivalent reflection area is obtained based on the equivalent normal vector and the incident direction vector.

[0020] In the above implementation process, by compressing the dispersed effective visible projection area of ​​each patch into a single equivalent reflective area parameter, a unified representation of the area information of multiple patches belonging to the same smooth surface is achieved. This provides a directly usable equivalent area parameter for subsequent echo contribution calculation based on physical optics algorithms, thereby avoiding the repetitive calculation caused by processing each patch separately.

[0021] Further, obtaining the sum of the effective visible projected areas of all patches belonging to the same smooth surface includes: Each facet belonging to the same smooth curved surface is projected onto the cross-sectional plane of the ray tube to obtain the two-dimensional projection area of ​​each facet on the cross-sectional plane; The visibility of the two-dimensional projection area is determined, and the area blocked by other facets along the ray tube direction is removed to obtain the effective visible projection area of ​​each facet. Based on the effective visible projection area of ​​each patch, determine the sum of the effective visible projection areas of all patches belonging to the same smooth surface.

[0022] In the above implementation process, the effective area of ​​each surface that actually participates in reflection was accurately calculated, and the boundary constraints of the ray tube section and the mutual occlusion relationship between the surfaces were taken into account, providing accurate area data for the calculation of the equivalent reflection area.

[0023] Further, the visibility determination of the two-dimensional projection area, eliminating areas obscured by other facets along the ray tube direction, to obtain the effective visible projection area of ​​each facet includes: For any two-dimensional coordinate point on the cross-sectional plane of the X-ray tube, if the two-dimensional coordinate point falls within the two-dimensional projection area of ​​multiple facets, the distance values ​​of each facet at the two-dimensional coordinate point along the X-ray tube direction are compared, and the projection area of ​​the facet with the smallest distance value at the two-dimensional coordinate point is retained as the effective visible projection area.

[0024] In the above implementation process, by comparing the distance values ​​of each patch at the same two-dimensional coordinate point, only the nearest unobstructed patch is retained, eliminating the false reflection contribution of the obstructed area and ensuring the authenticity of the radar echo simulation.

[0025] A second aspect of this application provides an electronic device, the electronic device comprising: processor; Memory used to store processor-executable instructions; Wherein, when the processor invokes the executable instructions, it implements any of the methods described in the first aspect.

[0026] A third aspect of this application provides a computer-readable storage medium having computer instructions stored thereon, which, when executed by a processor, implement any of the methods described in the first aspect.

[0027] A fourth aspect of this application provides a computer program product, the computer program product including a computer program, which, when executed by a processor, implements any of the methods described in the first aspect.

[0028] A fifth aspect of this application provides a vehicle that performs radar echo calculation using any of the methods described in the first aspect. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 A flowchart illustrating a method for modeling the reflection region of a millimeter-wave radar target, provided in an embodiment of this application; Figure 2 This is a structural block diagram of an electronic device provided in an embodiment of this application. Detailed Implementation

[0031] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0032] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0033] In related technologies, it is possible to simulate radar wave propagation, multipath propagation, material reflection, and a certain degree of scattering, and real-time requirements can be met through GPU (graphics card) acceleration. The idea of ​​representing emitted rays as emission and scattering ray tubes with vector field weights has been disclosed in these technologies. However, these technologies do not provide a specific modeling method for the problem of a single ray tube's limited coverage area spanning multiple surfaces and exhibiting local occlusion. For vehicle simulation, a large number of rays will cover multiple surfaces, thus the solutions in these technologies would create enormous computational pressure, making it almost impossible to meet real-time requirements.

[0034] Overall, the related technologies either involve excessive computation, making it difficult to meet the real-time requirements of HiL / SiL, or they are overly simplified, easily ignoring the geometric details of objects.

[0035] This application addresses the modeling problem between the limited coverage area of ​​the ray beam and discrete surface targets. To this end, it proposes to move beyond simply equating a single ray beam to a single surface hit by the central ray. Instead, it identifies multiple candidate surfaces covered by the ray beam based on the actual coverage area of ​​the target surface. Combining the surface position, normal, material, and occlusion relationships, it determines the effective visible area truly involved in radar reflection. An equivalent reflecting surface is then generated from this effective visible area for subsequent calculations of echo intensity, reflection direction, and point cloud output. This approach, while ensuring real-time performance, considers more of the target's geometry and occlusion relationships, improving modeling and echo calculation accuracy. Specifically, the improved modeling accuracy is achieved by identifying all candidate surfaces covered by the ray beam and performing smooth surface merging, overcoming the biases in reflection area, normal direction, and visibility judgment caused by ignoring multiple surfaces covered by the ray beam in related technologies. The improved echo calculation accuracy, based on the improved modeling accuracy, is achieved by calculating the echo contribution using equivalent normal vectors and area information, overcoming the distortions in radar point cloud intensity, position, continuity, and stability in related technologies.

[0036] Based on this, embodiments of this application provide a method for modeling the reflection region of a millimeter-wave radar target, referring to... Figure 1 , Figure 1 This is a flowchart illustrating a method for modeling the reflection region of a millimeter-wave radar target, as provided in an embodiment of this application.

[0037] In this embodiment, the method includes: Step S10: In the millimeter-wave radar simulation based on ray tracing, for any ray tube emitted from the radar source, determine the candidate patches that the ray tube covers on the target surface, and obtain the candidate patch set. It should be noted that, in the SBR / SBR+ method, the rays emitted from the radiation source towards the visible scattering geometry are not geometrically infinite straight lines, but rather bundles with finite angular widths or finite solid angles. The ANSYS HFSS SBR+ official documentation describes rays as divergent, volumetric ray tubes with antenna pattern or current distribution weighting.

[0038] Regarding candidate patches, targets in autonomous driving simulations (such as vehicles, guardrails, road edges, curved vehicle bodies, tires, rearview mirrors, road sign edges, etc.) are generally represented by a mesh composed of a large number of patches. These patches can be triangular, quadrilateral, or other polygonal patches; in this embodiment, a triangular patch is used as an example. The ray tube has a finite cross-sectional area, and its actual coverage area when irradiating the target surface may span multiple adjacent or non-adjacent patches.

[0039] This embodiment differs from related technologies in that it only considers a single surface hit by the central ray as the reflecting surface. Instead, it actively identifies all surfaces actually covered by the ray tube, providing a candidate set for subsequent smooth surface merging determination.

[0040] In practical implementation, for each ray tube emitted from the radar source, the cross-sectional area of ​​the ray tube at its location on the target surface is first obtained. The specific calculation method for the ray tube cross-sectional area can be adjusted according to different ray tracing sampling algorithms. As an exemplary approximate calculation method, it can be based on the solid angle of the ray tube. and the propagation distance from the starting point of the ray tube to the target surface. Calculate the cross-sectional area of ​​the ray tube at the target surface location according to the following formula: Formula 1; In Equation 1, Let X be the cross-sectional area of ​​the X-ray tube at the target surface. The distance from the starting point of the ray tracing to the intersection point on the target surface. The solid angle of the X-ray tube.

[0041] In obtaining the cross-sectional area Then, the cross-sectional area of ​​the ray tube on the target surface is spatially intersected with the target mesh, and all patches that intersect with the cross-sectional area are extracted as candidate patches, forming a set of candidate patches.

[0042] The cross-sectional area of ​​the ray tube can be approximated by any geometric shape, such as a circle, ellipse, or polygon, and its specific shape does not affect the recognition result of the candidate facet.

[0043] Step S20: If the candidate patch set includes multiple candidate patches, determine that multiple patches in the candidate patch set that meet the preset merging conditions belong to the same smooth surface; the preset merging conditions include that the angle between the normal vectors of adjacent patches is less than a preset normal angle threshold, and that the cumulative deviation of the normal vectors of each patch relative to the reference normal vector is less than a preset cumulative deviation threshold. It should be noted that this embodiment aims to determine whether multiple patches in the candidate set can be approximated as the same smooth surface, so as to facilitate subsequent merging processing.

[0044] The physical meaning of a smooth surface: In electromagnetic scattering calculations, smoothness means that the surface has no geometric discontinuities (such as edges, creases, cracks, etc.) that would cause non-mirror reflection of electromagnetic waves within the region of ray irradiation. When the normal vectors of multiple surfaces change continuously, their scattering characteristics for incident electromagnetic waves are approximately equivalent to a continuous surface.

[0045] In some embodiments, the preset merging conditions include facets sharing edges or vertices, facets having the same material properties, the angle between the normal vectors of adjacent facets being less than a preset normal angle threshold, and the cumulative deviation of each facet's normal vector relative to the reference normal vector being less than a preset cumulative deviation threshold.

[0046] In some embodiments, the preset merging condition is an optional combination condition, that is, one or more of the following can be used as the determination condition: edge connectivity, adjacent normal vector angle threshold, and cumulative normal vector deviation threshold. For example, multiple patches that satisfy one of the following conditions can be determined to belong to the same smooth surface: the angle between the normal vectors of any adjacent patches is less than the preset normal vector angle threshold, and the cumulative deviation of the normal vectors of each patch relative to the reference normal vector is less than the preset cumulative deviation threshold; or, any adjacent patches have edge connectivity, and the angle between the normal vectors of adjacent patches is less than the preset normal vector angle threshold; or, any adjacent patches have edge connectivity, and the angle between the normal vectors of each patch and the reference normal vector is less than the preset cumulative deviation threshold.

[0047] Sharing edges or vertices requires that the patches be topologically connected to ensure that the merged region is connected and to avoid erroneously merging spatially separated patches.

[0048] Material properties include electrical conductivity, magnetic permeability, refractive index, reflection coefficient, and refractive index. These properties can be determined based on the specific modeling requirements. Electromagnetic waves experience abrupt changes in reflection / transmission coefficients at the interface between different materials; if the material properties are different, they cannot be combined.

[0049] The preset normal angle threshold can be adjusted according to the actual accuracy requirements. This threshold controls the maximum normal change rate between adjacent patches.

[0050] The cumulative normal deviation being less than the preset cumulative deviation threshold controls the overall normal variation range of the entire merged region from a global perspective.

[0051] In the specific implementation, the criteria for determining whether multiple patches belong to the same smooth surface are as follows: Edge connectivity: Two faces should share at least one edge; Same material: The two facets are made of the same material and have the same roughness, and the same type of transmission / refraction. The included angle between adjacent normals cannot be too large: for two adjacent surfaces Calculate the dihedral angle ,like Then the condition is met; where: : noodle The normal vector, The threshold for the angle between the normal vectors of adjacent facets can be adjusted according to actual accuracy requirements. The cumulative normal vector deviation should not be too large: if the normal vector of the surface hit by the center of the ray tube is... Then the angle between the normal vector of any facet and the normal vector of the central facet should be less than 1. . These are constant coefficients and can be adjusted according to accuracy requirements; Constraints for determining whether they are the same smooth surface and It can be a fixed constant, or it can be set as a parameter that varies with distance, depending on the distance / angle between the target and the sensor.

[0052] Step S30: Merge multiple facets that are determined to belong to the same smooth surface to generate an equivalent normal vector; the equivalent normal vector is used to characterize the comprehensive normal direction of each facet belonging to the same smooth surface after weighted average of the effective visible projected area; It should be noted that the essence of the merging process is not to change the original mesh data, but to treat these patches as a unified scattering unit at the computational level, thereby avoiding the need to perform full-link calculations for each patch separately.

[0053] The physical meaning of the equivalent normal vector: When multiple patches are determined to belong to the same smooth surface, a single normal vector is used to replace the normal vectors of the multiple patches for subsequent calculations. This normal vector is not a simple arithmetic mean of the normal vectors of each patch, but a weighted average with the effective visible projected area of ​​each patch as the weight. The larger the area of ​​the patch, the greater its influence on the equivalent normal vector, and the larger the area of ​​the region, the greater its contribution to the echo.

[0054] Step S40: Calculate the echo contribution of the ray tube to the radar receiver after reflection from the target surface based on the equivalent normal vector and the area information of multiple facets belonging to the same smooth surface.

[0055] It should be noted that in PO (physical optics), the induced current distribution on the target surface is related to the incident field, the surface normal vector, and the area. Using the equivalent normal vector and area information, the field strength contribution of the reflected wave at the radar receiver can be calculated, thereby generating the position, intensity, and phase information of the radar point cloud.

[0056] In this embodiment, all candidate patches covered by the ray tube on the target surface are identified and it is determined whether they belong to the same smooth surface, replacing the processing method of hitting a single patch by the central ray in related technologies. Based on the determination that they belong to the same smooth surface, an equivalent normal vector is generated with the effective visible projected area of ​​each patch as the weight, and the echo contribution is calculated by combining the area information of each patch. Thus, while maintaining the real-time simulation framework at the ray tube level, it avoids the huge computational pressure brought by patch-by-pattern integration, meets the real-time requirements of vehicle simulation, and avoids the deviations in the judgment of reflection area, normal direction, and visibility caused by ignoring multiple patches covered by the ray tube or using only a single normal vector in the transition area of ​​the surface in related technologies, thereby improving the simulation accuracy of radar echo intensity, target position, and point cloud continuity.

[0057] Based on any of the above embodiments, the method further includes: If the candidate patch set includes a candidate patch, the normal vector of the candidate patch is taken as the equivalent normal vector, and the projected area of ​​the candidate patch in the incident direction of the ray tube is taken as the area information.

[0058] It should be noted that the cross-sectional area of ​​the ray tube may contain exactly one patch within the target surface coverage area. This situation is also common in actual simulations, especially in close-range or low-resolution scene meshes or high ray sampling density scenes. When there is only one patch, there is no need for weighted averaging; the equivalent normal vector is equivalent to the normal vector of that single patch.

[0059] Projected area in the incident direction of the ray tube: In physical optics (PO), the induced current is proportional to the projected area of ​​the incident wave on the surface. Projecting the actual area of ​​the patch onto a plane perpendicular to the incident direction yields an equivalent area for effectively receiving radar wave energy.

[0060] In this embodiment, for the case where the candidate patch set contains only one patch, the normal vector is directly simplified to the normal vector of the single patch itself, and the area information is simplified to its projected area in the incident direction. This avoids performing redundant weighted average calculations in scenarios where there is no need for merging and judgment, and ensures the accurate acquisition of the key geometric parameters (i.e., normal and effective projected area) required for the calculation of induced current in physical optics.

[0061] Based on any of the above embodiments, the reference normal vector is the normal vector of the surface hit by the central ray of the ray tube; the step of determining multiple surfaces in the candidate surface set that meet the preset merging conditions as belonging to the same smooth surface includes: Multiple facets that meet the following conditions are determined to belong to the same smooth surface: the angle between the normal vectors of any adjacent facets is less than the preset normal angle threshold, and the angle between the normal vector of any facet in the candidate facet set and the reference normal vector is less than the preset cumulative deviation threshold; the preset cumulative deviation threshold is the product of the preset normal angle threshold and the preset constant coefficient.

[0062] It should be noted that the reference normal vector is the normal vector of the area hit by the central ray of the X-ray tube: In the SBR / SBR+ method, each X-ray tube is typically represented by a central ray that marks its propagation path. The area where the central ray intersects the target surface first serves as the reference. The normal vector of this area is used as the reference for determining the cumulative deviation, thus providing a clear physical benchmark for the determination criteria.

[0063] The constraint that the angle between the normal vectors of any two adjacent faces is less than a preset threshold is a local continuity constraint. This condition, based on local geometric topology, ensures that the change in normal vector between any two adjacent faces in the merged region is gradual, preventing non-smooth features with abrupt changes in normal vectors (such as body lines, creases, etc.) from being incorrectly merged.

[0064] The constraint that the angle between the normal vector of any facet and the reference normal vector is less than a preset cumulative deviation threshold is a global consistency constraint. This condition, based on the overall geometry, ensures that the normal deviation of the entire merged region relative to the central facet does not exceed a preset range, thus preventing the erroneous merging of regions that are locally continuous but have excessive overall curvature (such as large-curvature arc surfaces) into approximately smooth surfaces.

[0065] Specifically, These are preset constant coefficients that can be adjusted according to accuracy requirements. k>1 allows the cumulative deviation of the entire region to be greater than the local deviation of adjacent patches—the overall curvature of a continuous surface can be greater than the local curvature at each step.

[0066] Optionally, determining that multiple facets in the candidate facet set that meet preset merging conditions belong to the same smooth surface includes: determining that multiple facets that meet one of the following conditions belong to the same smooth surface: The angle between the normal vectors of any two adjacent facets is less than the preset normal angle threshold, and the angle between the normal vector of any facet in the candidate facet set and the reference normal vector is less than the preset cumulative deviation threshold; the preset cumulative deviation threshold is the product of the preset normal angle threshold and a preset constant coefficient. Any adjacent facets are edge-connected, and the angle between the normal vectors of adjacent facets is less than the preset normal angle threshold. Any adjacent facets are edge-connected, and the angle between the normal vector of each facet and the reference normal vector is less than the preset cumulative deviation threshold.

[0067] It should be understood that the condition that any adjacent facets are edge-connected and the angle between the normal vectors of adjacent facets is less than the preset normal angle threshold is determined from the perspective of local smoothness and is applicable to scenarios that only focus on the smoothness of local surfaces.

[0068] Edge connectivity means that any two faces must share an edge (or vertex) topologically to ensure that the merged region is spatially connected, thus preventing the incorrect merging of spatially separated faces.

[0069] The adjacent normal vector angle constraint means that for any pair of adjacent facets, the angle (i.e., dihedral angle) between their normal vectors must be less than a preset normal angle threshold. This threshold controls the maximum allowable rate of change of the normal vector between adjacent facets.

[0070] When both of the above conditions are met, it indicates that the region is a geometrically continuous and locally smooth surface. Even if the normal vector may have a large cumulative deflection (e.g., a curved surface with a large curvature) in the global scope of the entire region, it can still be determined as the same smooth surface.

[0071] The condition that adjacent faces are edge-connected and the angle between the normal vector of each face and the reference normal vector is less than the preset cumulative deviation threshold is determined from the perspective of global directional consistency. This condition includes a cumulative normal vector deviation constraint. The angle between the normal vector of each face within the region and the reference normal vector (e.g., the normal vector of the face hit by the center ray of the ray tube) must be less than the preset cumulative deviation threshold. This condition is suitable for scenarios that require control of global normal consistency. It does not directly constrain the rate of change of normal vectors between adjacent faces, but rather constrains the directional deviation of each face relative to a common reference. This means that as long as the normal vectors of all faces are within an allowable deviation range around the reference normal vector, even if the angle between the normal vectors of some adjacent faces is large (e.g., due to the meshing method), they can still be determined as the same smooth surface.

[0072] In this embodiment, it is ensured that the multiple merged patches truly form a continuous and smooth surface geometrically, thus ensuring the continuity and physical reality of the reflection normal in radar simulation.

[0073] Based on any of the above embodiments, the equivalent normal vector is generated through the following steps: Obtain the effective visible projected area and normal vector of each facet belonging to the same smooth surface; For each patch, calculate the proportion of the effective visible projected area of ​​the patch to the total effective visible projected area of ​​all patches belonging to the same smooth surface; Using the aforementioned proportion as the weight, the normal vectors of each facet are weighted and summed, and the result of the weighted sum is taken as the equivalent normal vector.

[0074] It should be noted that the effective visible projected area refers to the projected area on the cross-section of the ray tube of the area of ​​a panel that is actually illuminated by the ray tube and is not obscured by other panels. When a part of a panel is obscured by other, closer panels, the obscured part is not included in the reflection calculation and is not counted in the effective visible projected area.

[0075] Normal vectors of each facet: The geometric normal vectors of a facet are calculated from the coordinates of its three vertices and are directed outwards perpendicular to the facet plane.

[0076] In this embodiment, the effective visible projected area of ​​each facet is used as the weight to perform a weighted summation of the normal vectors of each facet, thereby obtaining an equivalent normal vector that can characterize the summation normal direction of the entire smooth surface.

[0077] For example, assuming there are m patches belonging to the same smooth surface, the equivalent normal vector is calculated using the following equation 2: Formula 2; In Equation 2, Let be the visible projected area of ​​the m-th facet.

[0078] Larger surfaces contribute more to the overall echo, and therefore should be given a higher weight when calculating the equivalent normal vector. This is more in line with physical reality than a simple arithmetic mean—the electromagnetic wave energy reflected from a large curved surface is much stronger than that from a small curved surface.

[0079] In addition, based on the above-mentioned weighted generalization idea with the effective visible projected area as the weight, those skilled in the art can use other equivalent calculation methods besides Equation 2 above to generate the equivalent normal vector, such as using different normalization methods, iterative accumulation methods, or other weighted average variants.

[0080] In this embodiment, the normal vector information of multiple facets is compressed into a single equivalent normal vector by using an area-weighted normal vector averaging method, achieving effective dimensionality reduction of the target surface geometric features. The weighting method fully considers the effective area proportion of each facet actually participating in reflection, making the equivalent normal vector closer to physical reality and providing accurate geometric parameters for subsequent echo contribution calculation.

[0081] Based on any of the above embodiments, the area information includes the effective visible projected area of ​​each surface patch; the calculation of the echo contribution of the ray tube to the radar receiver after reflection from the target surface, based on the equivalent normal vector and the area information of multiple surface patches belonging to the same smooth surface, includes: The equivalent normal vector is used as the basis for the common incident direction vector of each patch belonging to the same smooth surface; Obtain the incident angles of each facet belonging to the same smooth surface; Determine the Fresnel reflection coefficient for each surface piece for each incident angle; Based on the normal vector of each facet and the incident direction vector of the ray tube, calculate the reflection direction vector corresponding to each facet. Using the effective visible projected area of ​​each patch, the Fresnel reflection coefficient, and the reflection direction vector, the physical optical current contribution of each patch to the radar receiver is calculated. The echo contribution is obtained by superimposing the physical optical current contributions of each facet.

[0082] It should be noted that since multiple patches have been determined to belong to the same smooth surface, their directions relative to the incident wave are not significantly different, and they can be calculated using the same incident direction vector. Specifically, the average orientation of the smooth surface is determined based on the equivalent normal vector, and then the incident angle of the wave relative to the surface is determined. Using the same incident direction vector for each patch saves computational effort compared to calculating the incident direction of each patch separately.

[0083] Specifically, based on each facet's own normal vector and the shared incident direction vector, the incident angle for each facet is calculated. The incident angle is the angle between the incident direction and the facet's normal vector. This preserves the individual differences of each facet—although the incident direction is the same, the incident angles of each facet are not exactly the same because their normal vectors are slightly different.

[0084] The Fresnel reflection coefficient is the ratio of the electric field strength of the reflected wave to the electric field strength of the incident wave when an electromagnetic wave is reflected at a medium interface. It depends on the incident angle, polarization, and the complex permittivity of the medium. The reflection coefficients of radar waves vary significantly on different material surfaces such as metal car bodies, plastic bumpers, and glass windows. This embodiment uses tables or calculates the corresponding Fresnel reflection coefficient for each surface at its own incident angle, preserving the individual differences in material reflection characteristics.

[0085] According to the law of specular reflection—the angle of reflection equals the angle of incidence, and the reflection direction, incident direction, and normal vector are coplanar—calculate the reflection direction vector for each surface. Since the normal vectors of each surface are different, the reflection directions are also different.

[0086] The core idea of ​​Physical Optics (PO) is that in the irradiated area of ​​the target surface, the induced current is approximately equal to the tangential component of the incident magnetic field on the surface multiplied by 2, and then multiplied by the Fresnel reflection coefficient. The PO current contribution of each patch is related to the following factors: the intensity of the incident magnetic field—determined by the electromagnetic field energy carried by the ray tube; the Fresnel reflection coefficient—determined by the material and the angle of incidence; the effective visible projected area—determining the size of the area actually involved in scattering; and the reflection direction—determining the direction of energy distribution in space.

[0087] The PO current contributions of all patches belonging to the same smooth surface are vector-superimposed to obtain the total echo contribution of the ray tube at the radar receiver after reflection in this region.

[0088] In this embodiment, the normal vector is equivalently processed (i.e., all facets share the same incident direction vector), but the area information and Fresnel reflection coefficient retain the individual differences of each facet. While improving computational efficiency (eliminating the need to calculate the incident direction separately), it maintains high accuracy in material reflection characteristics and local geometric details.

[0089] Based on any of the above embodiments, the area information includes the equivalent reflection area, which is used to characterize the equivalent visible projection area of ​​multiple facets belonging to the same smooth surface in the incident direction of the ray tube; the step of calculating the echo contribution of the ray tube to the radar receiver after reflection from the target surface based on the equivalent normal vector and the area information of multiple facets belonging to the same smooth surface includes: The equivalent normal vector is used to replace the individual normal vectors of each patch belonging to the same smooth surface; The equivalent reflective area is used to replace the projected area of ​​each patch belonging to the same smooth curved surface; Based on physical optics algorithms, the echo contribution is calculated according to the replaced equivalent normal vector and the replaced equivalent reflection area.

[0090] It should be noted that in this embodiment, the different normal vectors of multiple facets are uniformly replaced by a single equivalent normal vector. This means that in subsequent calculations, the entire smooth surface is regarded as an equivalent plane with a single orientation.

[0091] The equivalent reflective area is the sum of the visible projected areas of multiple facets. This area is used to characterize the equivalent visible projected area of ​​this set of facets in the incident direction.

[0092] Physical Optics (PO) is a high-frequency electromagnetic field approximation method used to calculate the induced current generated when radar waves strike a target surface, thereby determining the target's contribution to the radar echo. The basic assumption of PO is that when electromagnetic waves strike a target surface, they induce a current. This algorithm ignores electromagnetic coupling between surfaces (i.e., it ignores secondary illumination from a current on one surface to other surfaces), approximating that the induced current at each point on the target surface is determined solely by the incident wave. Specifically, the induced current at a point is proportional to the incident magnetic field strength, the Fresnel reflection coefficient, and the geometric relationship between the surface normal and the incident direction.

[0093] By substituting the equivalent normal vector and equivalent reflective area into the physical optics formula, the overall echo contribution of the region is calculated as an equivalent plane. This calculation only needs to be performed once, rather than calculating and superimposing for each surface individually.

[0094] In this embodiment, both the normal vector and the area are equivalent, and multiple facets are completely merged into an equivalent plane for calculation. This greatly improves the calculation efficiency and is suitable for flat or nearly flat areas with small curvature and small differences in the normal vectors of each facet (such as large flat areas such as car doors and hoods).

[0095] Based on any of the above embodiments, the equivalent reflective area is generated through the following steps: The sum of the effective visible projected areas of all patches belonging to the same smooth surface is obtained as the total effective visible projected area; Obtain the incident direction vector of the ray tube; The equivalent reflection area is obtained based on the equivalent normal vector and the incident direction vector.

[0096] It should be noted that the total effective visible projected area represents the sum of the effective visible projected areas of all patches belonging to the same smooth surface on the cross-sectional plane of the ray tube. It quantifies the total interception capability of the smooth surface for incident wave energy along the propagation direction of the ray tube. The incident direction vector of the ray tube points from the radar source to the target surface and serves as the spatial reference for subsequent calculation of the projected area and determination of the reflection direction.

[0097] Equivalent reflective area: The sum of the effective visible projected areas of each surface piece measured on the cross-sectional plane of the ray tube is converted by direction cosine and projected back onto an equivalent plane perpendicular to the incident direction, thus obtaining the equivalent visible area of ​​the smooth surface in the direction of incident wave propagation. This equivalent reflective area is used to uniformly calculate the echo contribution of the smooth surface to the radar receiver.

[0098] In some embodiments, the equivalent reflective area is generated through the following steps: The sum of the effective visible projected areas of all patches belonging to the same smooth surface is obtained as the total effective visible projected area; Obtain the incident direction vector of the ray tube; Calculate the dot product of the equivalent normal vector and the incident direction vector; When the dot product is greater than a preset threshold, the equivalent reflective area is obtained based on the ratio of the total effective visible projected area to the dot product. When the dot product is less than or equal to the preset threshold, the equivalent reflective area is set to zero, or the ray tube is discarded.

[0099] In the specific implementation, the equivalent reflection area is generated through the following steps: The sum of the effective visible projected areas of all patches belonging to the same smooth surface is taken as the total effective visible projected area A. p,tot ; Obtain the incident direction vector of the ray tube. ; Calculate the equivalent normal vector With the incident direction vector dot product ; Determine whether the dot product is greater than a preset threshold ε (ε>0). The preset threshold ε is a positive number close to zero, and its value can be preset according to the simulation accuracy requirements and numerical stability requirements, for example, ε=10. 6 Or ε=10 8 This is used to avoid numerical calculation overflow or calculation results that have no physical meaning due to an excessively small dot product; When the dot product is greater than the preset threshold, the equivalent reflective area is calculated according to the ratio of the total effective visible projected area to the dot product, using the following formula 3: Formula 3; In Equation 3, This represents the total visible projected area.

[0100] When the dot product is less than or equal to the preset threshold, it indicates that the equivalent normal vector is nearly perpendicular to the incident direction vector (i.e., the incident wave irradiates the smooth surface at a grazing incidence angle, where grazing incidence means that the incident wave irradiates in a direction almost parallel to the surface, i.e., the incidence angle is close to 90 degrees) or is incident in the opposite direction. At this time, the effective reflection area of ​​the surface approaches zero, and the equivalent reflection area is determined to be zero, or the ray tube is discarded and not included in the subsequent echo contribution calculation.

[0101] In some embodiments, the method for calculating the equivalent reflection area based on the equivalent normal vector and the incident direction vector is not limited to Equation 3 above. Optionally, the ray tube can be projected onto the plane containing the patch hit by its central ray, the projected area of ​​the ray tube on the plane can be calculated, and the equivalent reflection area can be obtained based on the geometric relationship between the equivalent normal vector and the plane normal vector.

[0102] That is, the equivalent reflection area is calculated based on the equivalent normal vector and the incident direction vector, including: dividing the total effective visible projection area by the dot product of the equivalent normal vector and the incident direction vector to obtain the equivalent reflection area; or, projecting the ray tube onto the plane where the surface hit by its central ray is located, calculating the projection area on the plane, and converting it into the equivalent reflection area based on the relationship between the equivalent normal vector and the plane normal vector.

[0103] In this embodiment, by compressing the dispersed effective visible projection area of ​​each patch into a single equivalent reflective area parameter, a unified representation of the area information of multiple patches belonging to the same smooth surface is achieved. This provides a directly usable equivalent area parameter for subsequent echo contribution calculation based on physical optics algorithms, thereby avoiding redundant calculations caused by processing each patch separately.

[0104] Based on any of the above embodiments, obtaining the sum of the effective visible projected areas of all patches belonging to the same smooth surface includes: Each facet belonging to the same smooth curved surface is projected onto the cross-sectional plane of the ray tube to obtain the two-dimensional projection area of ​​each facet on the cross-sectional plane; The visibility of the two-dimensional projection area is determined, and the area blocked by other facets along the ray tube direction is removed to obtain the effective visible projection area of ​​each facet. Based on the effective visible projection area of ​​each patch, determine the sum of the effective visible projection areas of all patches belonging to the same smooth surface.

[0105] It should be noted that the cross-sectional plane of the X-ray tube is a two-dimensional plane perpendicular to the direction of X-ray tube propagation. The cross-sectional area of ​​the X-ray tube on this plane can be approximated by a circle, ellipse, or polygon. This plane serves as the reference coordinate system for calculating the projection and occlusion relationships of the surface.

[0106] Two-dimensional projection area: The two-dimensional area obtained by projecting a facet in three-dimensional space onto the cross-sectional plane along the direction of the ray tube. This two-dimensional area represents the spatial range occupied by the facet on the cross-section.

[0107] When the two-dimensional projection areas of multiple patches covered by the same ray tube overlap on the cross-sectional plane, only the closest patch can be irradiated along the propagation direction of the ray tube. The blocked patch area does not receive incident wave energy and cannot generate reflected echoes.

[0108] In some embodiments, visibility determination is achieved by constructing a depth function. That is, for each two-dimensional coordinate point on the cross-sectional plane, if it falls into multiple patch projection areas simultaneously, the distance values ​​of each patch at that point along the propagation direction are compared, and only the projection of the patch with the smallest distance at that point is valid.

[0109] Each candidate patch must first undergo ray tube cross-section trimming (i.e., areas outside the cross-section do not receive ray tube energy), then undergo visibility determination (areas blocked by closer patches do not participate in reflection), and finally the retained area is determined as the effective visible projection area.

[0110] The total effective visible projected area is obtained by summing the effective visible projected areas of each facet. After visibility determination, the same two-dimensional coordinate point will not be counted repeatedly in the area of ​​multiple facets. Therefore, the total effective visible projected area is essentially the total area of ​​all effective visible regions within the cross-section of the ray tube.

[0111] Optionally, obtaining the sum of the effective visible projected areas of all facets belonging to the same smooth surface includes: projecting each facet belonging to the same smooth surface onto the cross-sectional plane of the ray tube to obtain a two-dimensional projection area of ​​each facet on the cross-sectional plane, and performing a visibility determination on the two-dimensional projection area to determine the sum of the effective visible projected areas of all facets; or, projecting the ray tube onto the plane where the facets belonging to the same smooth surface are hit by the central ray to obtain a two-dimensional projection area of ​​the ray tube on the plane, and determining the sum of the effective visible projected areas of all facets based on the two-dimensional projection area.

[0112] In this context, projecting the ray tube onto the plane of the patch means projecting the three-dimensional spatial region of the ray tube onto the two-dimensional plane of the patch hit by the central ray along the propagation direction of the ray tube, obtaining the coverage area of ​​the ray tube on the plane, and then determining the actual range of the patch irradiated by the ray tube, and calculating the sum of the effective visible projection areas accordingly.

[0113] In this embodiment, the effective area of ​​each surface that actually participates in reflection is accurately calculated, and the boundary constraints of the ray tube section and the mutual occlusion relationship between the surfaces are taken into account, providing accurate area data for the calculation of the equivalent reflection area.

[0114] Based on any of the above embodiments, the step of determining the visibility of the two-dimensional projection area and removing areas blocked by other facets along the ray tube direction to obtain the effective visible projection area of ​​each facet includes: For any two-dimensional coordinate point on the cross-sectional plane of the X-ray tube, if the two-dimensional coordinate point falls within the two-dimensional projection area of ​​multiple facets, the distance values ​​of each facet at the two-dimensional coordinate point along the X-ray tube direction are compared, and the projection area of ​​the facet with the smallest distance value at the two-dimensional coordinate point is retained as the effective visible projection area.

[0115] It should be noted that the distance value along the ray tube direction is as follows: For each two-dimensional coordinate point on the cross-sectional plane, back to three-dimensional space, that point corresponds to a straight line parallel to the ray tube direction (i.e., the depth line along the propagation direction). This line intersects with each patch to obtain a three-dimensional intersection point, and the distance between this intersection point and the radar source is the distance value of that patch at that two-dimensional coordinate point.

[0116] The smallest distance value = the nearest facet = the unobstructed facet. Along the direction of the ray tube propagation, the first facet encountered blocks all the faces behind it. The facet in front receives and reflects the incident wave, while the facets behind cannot be illuminated.

[0117] For each two-dimensional coordinate point, only the projection area of ​​the nearest facet at that point is included in the effective visible projection area, while the projection areas of all distant faces at that point are discarded.

[0118] In practical implementation, the modeling method for the millimeter-wave radar target reflection region, after determining that multiple patches belong to the same smooth surface, has two calculation modes: The first method calculates the equivalent current and its echo contribution to Rx for each patch separately: Since multiple patches are determined to belong to the same smooth surface, the same incident direction vector can be used to approximate all patches. This eliminates the need for separate calculations, thus improving calculation speed.

[0119] First, calculate the angle of incidence for each of these surfaces; then, look up the Fresnel coefficient for each surface: calculate the corresponding value for each angle of incidence. The Fresnel reflection coefficient is then calculated; the reflection direction is then calculated; the projected area of ​​each patch is then calculated; and finally, the PO current and its contribution to the sensor echo are calculated.

[0120] Taking a triangular facet as an example, the second method of calculating the equivalent normal vector and projected area only calculates the overall echo contribution. Note that this method can approximate and correct the phase when calculating the echo of a larger plane.

[0121] 1. Calculate the effective visible projection area of ​​the m-th facet on the cross-sectional plane of the ray tube: a. definition: The portion obscured by the closer triangular facet; among which, : noodle The two-dimensional triangle projected onto the cross-sectional plane of the ray tube. The two-dimensional cross-sectional area of ​​the X-ray tube at point A can be a circle, a quadrilateral, or a polygon, depending on the shape used to simulate the X-ray tube cross-section. The two-dimensional region that can actually receive the energy from this ray tube; b. Establish the cross-sectional plane of the X-ray tube: The cross-sectional area of ​​the X-ray tube is denoted as: The cross-sectional area can be approximated by a circle, an ellipse, or a polygon; c. Project the patch onto the cross-sectional plane to obtain the projected two-dimensional triangle. ; d. First, cut the cross-section of the ray tube: First, calculate: ; where ∩ represents the intersection operation of geometric regions, and the above intersection result Q m area |Q m | Make a judgment: If This indicates that although the patch is in the candidate set, it is not covered by the current ray tube projection and can be discarded if |Q m If |>0, then the cropped region Q will be retained. m Used for subsequent visibility determination.

[0122] e. Visibility rule: For the same two-dimensional point If it falls on multiple This indicates that the projections of these patches along the ray tube direction overlap. In this case, only the patch first hit by the ray tube can be retained. This determination can be achieved by constructing a depth function.

[0123] 2. Superimpose the results of all the patches and calculate the total visible projected area; 3. Calculate the equivalent normal vector using Equation 2 above; 4. Calculate the equivalent area using Equation 3 above.

[0124] In this embodiment, by comparing the distance values ​​of each patch at the same two-dimensional coordinate point, only the nearest unobstructed patch is retained, eliminating the false reflection contribution of the obstructed area and ensuring the authenticity of the radar echo simulation.

[0125] Based on the methods described in any of the above embodiments, this application also provides, as follows: Figure 2 The diagram shows the structure of an electronic device. Figure 2 At the hardware level, the electronic device includes a processor, an internal bus, a network interface, memory, and non-volatile memory, and may also include other hardware required for business operations. The processor reads the corresponding computer program from the non-volatile memory into memory and then runs it to implement the methods described in any of the above embodiments.

[0126] Based on the methods described in any of the above embodiments, this application also provides a computer storage medium storing a computer program, which, when executed by a processor, can be used to perform the methods described in any of the above embodiments.

[0127] Based on the methods described in any of the above embodiments, this application also provides a computer program product, which includes one or more computer programs or instructions. The computer program or instructions may be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. When executed by a processor, the computer program implements the methods described in any of the above embodiments.

[0128] Based on the methods described in any of the above embodiments, this application also provides a vehicle that uses the methods described in any of the above embodiments to perform radar echo calculation.

[0129] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can also be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0130] In addition, the functional modules in the various embodiments of this application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0131] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0132] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0133] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0134] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A method for modeling the reflection region of a millimeter-wave radar target, characterized in that, The method includes: In millimeter-wave radar simulation based on ray tracing, for any ray tube emitted from the radar source, the candidate patches covered by the ray tube on the target surface are determined, and a set of candidate patches is obtained. When the candidate patch set includes multiple candidate patches, multiple patches in the candidate patch set that meet the preset merging conditions are determined to belong to the same smooth surface; the preset merging conditions include that the angle between the normal vectors of adjacent patches is less than a preset normal angle threshold, and that the cumulative deviation of the normal vectors of each patch relative to the reference normal vector is less than a preset cumulative deviation threshold. Multiple facets that are determined to belong to the same smooth surface are merged to generate an equivalent normal vector; the equivalent normal vector is used to characterize the comprehensive normal direction of each facet belonging to the same smooth surface after weighted average of the effective visible projected area; Based on the equivalent normal vector and the area information of multiple facets belonging to the same smooth surface, the echo contribution of the ray tube to the radar receiver after reflection from the target surface is calculated.

2. The method according to claim 1, characterized in that, The method further includes: If the candidate patch set includes a candidate patch, the normal vector of the candidate patch is taken as the equivalent normal vector, and the projected area of ​​the candidate patch in the incident direction of the ray tube is taken as the area information.

3. The method according to claim 1, characterized in that, The reference normal vector is the normal vector of the surface hit by the central ray of the ray tube; the step of determining multiple surfaces in the candidate surface set that meet the preset merging conditions as belonging to the same smooth surface includes: Multiple facets that meet the following conditions are determined to belong to the same smooth surface: the angle between the normal vectors of any adjacent facets is less than the preset normal angle threshold, and the angle between the normal vector of any facet in the candidate facet set and the reference normal vector is less than the preset cumulative deviation threshold; the preset cumulative deviation threshold is the product of the preset normal angle threshold and the preset constant coefficient.

4. The method according to claim 1, characterized in that, The equivalent normal vector is generated through the following steps: Obtain the effective visible projected area and normal vector of each facet belonging to the same smooth surface; For each patch, calculate the proportion of the effective visible projected area of ​​the patch to the total effective visible projected area of ​​all patches belonging to the same smooth surface; Using the aforementioned proportion as the weight, the normal vectors of each facet are weighted and summed, and the result of the weighted sum is taken as the equivalent normal vector.

5. The method according to claim 1, characterized in that, The area information includes the effective visible projected area of ​​each facet; the calculation of the echo contribution of the ray tube to the radar receiver after reflection from the target surface, based on the equivalent normal vector and the area information of multiple facets belonging to the same smooth surface, includes: The equivalent normal vector is used as the basis for the common incident direction vector of each patch belonging to the same smooth surface; Obtain the incident angles of each facet belonging to the same smooth surface; Determine the Fresnel reflection coefficient for each surface piece for each incident angle; Based on the normal vector of each facet and the incident direction vector of the ray tube, calculate the reflection direction vector corresponding to each facet. Using the effective visible projected area of ​​each patch, the Fresnel reflection coefficient, and the reflection direction vector, the physical optical current contribution of each patch to the radar receiver is calculated. The echo contribution is obtained by superimposing the physical optical current contributions of each facet.

6. The method according to claim 1, characterized in that, The area information includes the equivalent reflection area, which is the area obtained based on the total effective visible projected area and the incident direction vector of the ray tube. The total effective visible projected area is the sum of the effective visible projected areas of all facets belonging to the same smooth surface. The calculation of the echo contribution of the ray tube to the radar receiver after reflection from the target surface, based on the equivalent normal vector and the area information of multiple facets belonging to the same smooth surface, includes: The equivalent normal vector is used to replace the individual normal vectors of each patch belonging to the same smooth surface; The equivalent reflective area is used to replace the projected area of ​​each patch belonging to the same smooth curved surface; Based on physical optics algorithms, the echo contribution is calculated according to the replaced equivalent normal vector and the replaced equivalent reflection area.

7. The method according to claim 6, characterized in that, The equivalent reflective area is generated through the following steps: The sum of the effective visible projected areas of all patches belonging to the same smooth surface is obtained as the total effective visible projected area; Obtain the incident direction vector of the ray tube; The equivalent reflection area is obtained based on the equivalent normal vector and the incident direction vector.

8. The method according to claim 7, characterized in that, The step of obtaining the sum of the effective visible projected areas of all patches belonging to the same smooth surface includes: Each facet belonging to the same smooth curved surface is projected onto the cross-sectional plane of the ray tube to obtain the two-dimensional projection area of ​​each facet on the cross-sectional plane; The visibility of the two-dimensional projection area is determined, and the area blocked by other facets along the ray tube direction is removed to obtain the effective visible projection area of ​​each facet. Based on the effective visible projection area of ​​each patch, determine the sum of the effective visible projection areas of all patches belonging to the same smooth surface.

9. The method according to claim 8, characterized in that, The visibility determination of the two-dimensional projection area, removing areas obscured by other facets along the ray tube direction, yields the effective visible projection area of ​​each facet, including: For any two-dimensional coordinate point on the cross-sectional plane of the X-ray tube, if the two-dimensional coordinate point falls within the two-dimensional projection area of ​​multiple facets, the distance values ​​of each facet at the two-dimensional coordinate point along the X-ray tube direction are compared, and the projection area of ​​the facet with the smallest distance value at the two-dimensional coordinate point is retained as the effective visible projection area.

10. An electronic device, characterized in that, The electronic device includes: processor; Memory used to store processor-executable instructions; Wherein, when the processor invokes the executable instructions, it implements the method according to any one of claims 1-9.

11. A computer-readable storage medium, characterized in that, It stores computer instructions that, when executed by a processor, implement the method described in any one of claims 1-9.

12. A computer program product, characterized in that, The computer program product includes a computer program that, when executed by a processor, implements the method of any one of claims 1-9.

13. A vehicle, characterized in that, The vehicle uses the method described in any one of claims 1-9 to perform radar echo calculation.

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