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Real-Time Soft Shadow by A-Buffer

  • Dening Luo
  • Jianwei Zhang
Conference paper
Part of the Communications in Computer and Information Science book series (CCIS, volume 875)

Abstract

We present a new real-time soft shadow algorithm by A-Buffer in virtual environment. The key idea is to use A-Buffer to store the whole scene information and then to accurately compute soft shadow. In the first pass, the scenes are drawn in the center view of the complex area lights, and the target fragments of per pixel are stored into an A-Buffer. The second is to calculate the occlusion percentage according to the cone which is consisted of the shaded point and area lights from the view of the camera. The occlusion percentage is the ration of blocked area and sampled area within the cone, and it is used to calculate the shadow factor. Our algorithm could produce more realistic shadow effects in real-time and adapt to the complex scenes.

Keywords

Soft shadow Real-time A-Buffer The whole scene information Area lights 

References

  1. 1.
    Crow, F.C.: Shadow algorithms for computer graphics. In: ACM, vol. 11, no. 2, pp. 242–248 (1977)Google Scholar
  2. 2.
    Williams, L.: Casting curved shadows on curved surfaces. ACM, vol. 12, no. 3, pp. 270–274 (1978)Google Scholar
  3. 3.
    Woo, A., Poulin, P., Fournier, A.: A survey of shadow algorithms. IEEE Comput. Graph. Appl. 10(6), 13–32 (1990)CrossRefGoogle Scholar
  4. 4.
    Hasenfratz, J.M., Lapierre, M., Holzschuch, N.: A survey of real‐time soft shadows algorithms, vol. 22, no. 4, pp. 753–774. Blackwell Publishing, Hoboken (2003)Google Scholar
  5. 5.
    Scherzer, D., Wimmer, M., Purgathofer, W.: A survey of real-time hard shadow mapping methods. Comput. Graph. Forum 30(1), 169–186 (2011)CrossRefGoogle Scholar
  6. 6.
    Eisemann, E., Schwarz, M., Assarsson, U.: Real-time shadows. CRC Press, Boca Raton (2011)CrossRefGoogle Scholar
  7. 7.
    Eisemann, E., Assarsson, U., Schwarz, M.: Efficient real-time shadows. In: ACM, p. 18 (2013)Google Scholar
  8. 8.
    Heidmann, T.: Real shadows, real time. Iris Universe 18, 28–31 (1991)Google Scholar
  9. 9.
    Reeves, W.T., Salesin, D.H., Cook, R.L.: Rendering antialiased shadows with depth maps. In: ACM, vol. 21 no. 4, pp. 283–291 (1987)Google Scholar
  10. 10.
    Fernando, R.: Percentage-closer soft shadows. In: ACM, p. 35 (2005)Google Scholar
  11. 11.
    Buades, J.M., Gumbau, J., Chover, M.: Separable soft shadow mapping. Vis. Comput. 32(2), 167–178 (2016)CrossRefGoogle Scholar
  12. 12.
    Peters, C., Munstermann, C., Wetzstein, N.: Beyond hard shadows: Moment shadow maps for single scattering, soft shadows and translucent occluders. In: ACM, pp. 159–170 (2016)Google Scholar
  13. 13.
    Weiskopf, D., Ertl, T.: Shadow mapping based on dual depth layers, vol. 3, pp. 53–60 (2003)Google Scholar
  14. 14.
    Wang, Y., Molnar, S.: Second-depth shadow mapping. UNC-CS Technical report TR94-019 (1994)Google Scholar
  15. 15.
    Pagot, C.A., Comba, J.L.D., Oliveira, N.M.M.: Multiple-depth shadow maps. In: 17th Brazilian Symposium on, pp 308–315. IEEE (2004)Google Scholar
  16. 16.
    Liu, X., Hao, X., Huang, M.: Fast soft shadow by depth peeling. In: ACM, p. 126 (2010)Google Scholar
  17. 17.
    Heckbert, P.S., Herf, M.: Simulating soft shadows with graphics hardware. CARNEGIE-MELLON UNIV PITTSBURGH PA DEPT OF COMPUTER SCIENCE (1997)Google Scholar
  18. 18.
    Haeberli, P., Akeley, K.: The accumulation buffer: hardware support for high-quality rendering. ACM SIGGRAPH Comput. Graph. 24(4), 309–318 (1990)CrossRefGoogle Scholar
  19. 19.
    Heidrich, W., Brabec, S., Seidel, H.P.: Soft shadow maps for linear lights. In: Péroche, B., Rushmeier, H. (eds.) Rendering Techniques 2000. EUROGRAPH, pp. 269–280. Springer, Vienna (2000).  https://doi.org/10.1007/978-3-7091-6303-0_24CrossRefGoogle Scholar
  20. 20.
    Ying, Z., Tang, M., Dong, J.: Soft shadow maps for area light by area approximation. In: Pacific Conference on Computer Graphics and Applications, pp. 442–443 (2002)Google Scholar
  21. 21.
    Agrawala, M., Ramamoorthi, R., Heirich, A.: Efficient Image-Based Methods for Rendering Soft Shadows, pp. 375–384. ACM Press/Addison-Wesley Publishing Co. (2000)Google Scholar
  22. 22.
    Atty, L., Holzschuch, N., Lapierre, M.: Soft shadow maps: efficient sampling of light source visibility, vol. 25, no. 4, pp. 725–741 Blackwell Publishing Ltd, Hoboken (2006)Google Scholar
  23. 23.
    Guennebaud, G., Barthe, L., Paulin, M.: Real-time soft shadow mapping by backprojection, pp. 227–234 (2006)Google Scholar
  24. 24.
    Carpenter, L.: The A-buffer, an antialiased hidden surface method. ACM Siggraph Comput. Graph. 18(3), 103–108 (1984)CrossRefGoogle Scholar
  25. 25.
    Crassin, C.: Fast and accurate single-pass A-buffer using OpenGL 4.0+ (2010)Google Scholar
  26. 26.
    Xu, Z., Li, B., Cai, X.: Generate accurate soft shadows using complete occluder buffer. In: IEEE, pp. 97–104 (2015)Google Scholar
  27. 27.
    Samosky, J.T.: SectionView–a system for interactively specifying and visualizing sections through three-dimensional medical image data. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science (1993)Google Scholar

Copyright information

© Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  1. 1.College of Computer ScienceSichuan UniversityChengduChina

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