Ray tracing method and system based on NURBS curved surface

Abstract

The invention discloses a ray tracing method and system based on NURBS, and mainly solves the problems of low speed and low precision of an existing ray tracing method. The scheme is as follows: the method comprises the following steps of 1, representing a curved surface as a plurality of curved surface elements according to the curved surface node distance information; 2, excluding part of curvedsurface elements without an intersection by utilizing axis arrangement bounding boxes of the curved surface elements; 3, further excluding the curved surface elements without the intersection by utilizing a triangular surface element control network; 4, taking the intersections of the ray and the residual curved surface elements by utilizing an extreme value search iteration method; and 5, tracking the ray by utilizing a geometrical relationship and a Fresnel law to form recursion in order to trace a ray trajectory. According to the method and the system, more curved surface elements withoutthe intersection are excluded by the axis arrangement bounding boxes and the triangular surface element control network, so that the ray tracing time is shortened; the ray-curved surface intersectionis solved through the extreme value search iteration, so that the precision of the intersection is improved; and the method and the system can be used for rapidly and accurately computing the radar scattering cross section area of a surface curved target.

Description

technical field [0001] The invention belongs to the technical field of radar, and in particular relates to a ray tracing method, which can be used to accurately calculate the RCS of a curved surface object. Background technique [0002] When calculating the radar cross section of a target, the scattered field of the target includes not only the field produced by one scattering, but also the field produced by multiple scattering. The calculation of the scattered field generated by electromagnetic waves after multiple reflections on the target surface requires the application of the bouncing ray method SBR, and ray tracing is the essence of the algorithm. For the case where the target surface is curved, a large number of small-sized triangular planar elements are generally used to approximate the target surface, which will distort the model of the target itself, and the influence of curvature is ignored in the ray tracing process, so that the calculation results Artifacts app...

AI Technical Summary

Problems solved by technology

There are a lot of defects in the Newton iteration method: First, because it is necessary to ensure that there is at most one intersection point in the iteration area, the preparatory work takes a lot of time

Secondly, because the Newton iterative method has strict requirements on the initial value, if the initial value is not selected properly, it may iterate out wrong intersection points or fail to converge, resulting in missing or wrong intersection points, which will make some effective ray tracing invalid, and then make RCS The calculation accuracy is not high; it may also happen that the result crosses the boundary of the iteration area during the iteration process, which requires re-selecting the initial iteration value and re-iterating, thus increasing the time consumption of ray tracing and making the overall calculation of the target RCS become complicated

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