volume | PIER Journals

2009-02-05

Analysis of Shadowing Processing Technique Based on Modeling Using NURBS

Yun-Xue Xu,

Dr. Yun-Xue Xu

National Key Laboratory of Antennas and Microwave Technology

Xidian University

China

Homepage

Ying Guan,

Dr. Ying Guan

National Laboratory of Antennas and Microwave Technology

Xidian University

China

Homepage

Feng-Tao Zha,

Dr. Feng-Tao Zha

Xidian University

China

Homepage

Wen Jiang,

Prof. Wen Jiang

Xidian University

China

Homepage

Shu-Xi Gong

Prof. Shu-Xi Gong

Xidian University

China

Homepage

Progress In Electromagnetics Research, Vol. 89, 325-338, 2009

doi:10.2528/PIER08123002 | Google Scholar

Abstract

The shadowing relationship between facet elements can be determined rapidly through analytical expressions. On the basis of modeling using curved surfaces, an effective shadowing processing algorithm is proposed which is in combination with that used in the shadowing judgement of facet elements. Firstly several sampling points are taken on the ergodic curved surface element to construct a group of facet elements, which can replace the curved surface element. Then the shadowing processing between the stationary phase point and the ergodic curved surface element is converted to that between the stationary phase point and several facet elements, thus avoiding utilizing optimization method and can increase the computation speed. Similarly, the shadowing processing between the stationary phase segment and the ergodic curved surface element is converted to that between the stationary phase segment and several facet elements. And the trimming algorithm is used to accurately find the visible part of the stationary phase segment, which gets rid of the rough shadowing processing technique that determines the visibility of the whole stationary phase segment through the visibility of the center of the stationary phase segment. Therefore, the computation precision is greatly improved. When there exists a huge number of curved surfaces, maximum-minimum preprocessing is utilized to increase the computation speed. Examples show that this novel algorithm is superior to the traditional one in both computation speed and precision.

Download Full Article (314) View Full Article volume

Citation

Copy Export

Yun-Xue Xu, Ying Guan, Feng-Tao Zha, Wen Jiang, and Shu-Xi Gong, "Analysis of Shadowing Processing Technique Based on Modeling Using NURBS," Progress In Electromagnetics Research, Vol. 89, 325-338, 2009.
doi:10.2528/PIER08123002

References

1. Shi, F.-Z., Computer-aided Geometric Design and NURBS, Beihang University, 1994.

2. Chen, M., X.-W. Zhao, Y. Zhang, and C.-H. Liang, "Analysis of antenna around NURBS surface with iterative MoM-PO technique," Journal of Electromagnetic Waves and Applications, Vol. 20, No. 12, 1667-1680, 2006.
doi:10.1163/156939306779292372 Google Scholar

3. Wang, N., Y. Zhang, and C. H. Liang, "Creeping ray-tracing algorithm of UTD method based on NURBS models with the source on surface," Journal of Electromagnetic Waves and Applications, Vol. 20, No. 14, 1981-1990, 2006.
doi:10.1163/156939306779322602 Google Scholar

4. Chen, X. J. and X. W. Shi, "Backscattering of electrically large perfect conducting targets modeled by NURBS surfaces halfspace ," Progress In Electromagnetics Research, PIER 77, 215-224, 2007. Google Scholar

5. Zhao, Y., X.-W. Shi, and L. Xu, "Modeling with NURBS surfaces used for the calculation of RCS," Progress In Electromagnetics Research, PIER 78, 49-59, 2008. Google Scholar

6. Gordon, W. B., "Far-field approximation to the Kirchhoff-Helmholtz representation of scattered field," IEEE Trans. AP, Vol. 23, No. 7, 590-592, 1975. Google Scholar

7. Perez, J. and M. F. Catedra, "Application of physical optics to the RCS computation of bodies modeled with NURBS surface," IEEE Trans. AP, Vol. 42, No. 10, 1404-1411, 1994. Google Scholar

8. Greiner, G. and K. Hormann, "Efficient clipping of arbitrary polygons," ACM Transactions on Graphics, Vol. 17, No. 2, 71-83, 1998.
doi:10.1145/274363.274364 Google Scholar

9. Domingo, M., F. Rivas, J. Perez, and M. F. Catedra, "Computation of the RCS of complex bodies modeled using NURBS surface," IEEE Trans. AP, Vol. 37, No. 6, 36-46, 1995. Google Scholar

10. Sefi, S., "Ray tracing tools for high frequency electromagnetics simulations," Royal Institute of Technology, Sweden, 2003. Google Scholar

11. Chen, M., Y. Zhang, N. Wang, and N. Wang, "Study of the shadowing technique in the NURBS-PO method," Journal of Xidian University, Vol. 33, No. 3, Jun.2006. Google Scholar

12. Wang, N. and C. Liang, "Study on the occlusions between rays and NURBS surfaces in optical methods," Progress In Electromagnetics Research, PIER 71, 243-249, 2007. Google Scholar

13. Liu, Y.-K., Y. Gao, and Y.-Q. Huang, "An efficient algorithm for polygon clipping," Chinese Journal of Software, Vol. 14, No. 4, 845-856, 2003. Google Scholar