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Geometry Image-based Shadow Volume Algorithm for Subdivision Surfaces

This paper presents an enhanced algorithm for real-time shadow volume generation on subdivision surface models. By utilizing dual geometry images, we significantly improve the efficiency and accuracy of silhouette detection and shadow volume creation. Our approach includes a robust silhouette detection mechanism paired with a directed visibility interpolation method. Additionally, we evaluate performance under dynamic lighting conditions, providing a comparison against existing methods. The results demonstrate improved rendering efficiency and silhouette accuracy. The findings are vital for applications in realistic graphics rendering.

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Geometry Image-based Shadow Volume Algorithm for Subdivision Surfaces

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  1. Geometry Image-based Shadow Volume Algorithm for Subdivision Surfaces Min Tang, Jin-Xiang Dong College of Computer Science, Zhejiang University {tang_m, djx}@zju.edu.cn

  2. Contents • Related Works • Main Contributions • Algorithm Pipeline • Evaluation • Silhouette Detection • Implementation and Results • Demo • Conclusion & Future Works

  3. Related Works • Subdivision Surface Evaluation on GPU • GPU based shadow volume algorithm • Geometry Image The work here is a extension of our previous work at CGI06: Real-time Shadow Volume Algorithm for Subdivision Surface Based Models by Min Tang, et al.

  4. Main Contributions Improved efficiency: By using two geometry images to pack all the patches’ information, the efficiencies of silhouette detection and shadow volume generation are greatly improved (2 render-to-texture ops per model under dynamic lighting). Improved accuracy: An enhanced silhouette detection method is designed to improve accuracy and ensure robustness

  5. Algorithm Pipeline

  6. Evaluation

  7. Silhouette Detection Directed visibility interpolation for silhouette extraction (+ for visible, - for invisible)

  8. Silhouette Detection (b) Silhouette detection using the directed visibility interpolation method (a) Silhouette detection using normal vector of adjacent facets in [17]

  9. Silhouette Detection Cracks caused by numeric instability [17] Smooth linked silhouettes

  10. Silhouette Detection Cracks caused by numeric instability [17] Smooth linked silhouettes

  11. Silhouette Detection Our result with the same light source Shadow leaks caused by the cracks [17]

  12. Silhouette Rendring

  13. Shadow Volume Generation

  14. Comparison with [17]

  15. Implementation and Results

  16. Demo&Source Code http://www.cs.wichita.edu/~tang/SubShadow/subShadow.htm.

  17. Conclusion & future works Extension to geometry images Speed is limited by the RTVA efficiency

  18. Thanks！ Q&A

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