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图学学报

图学学报 ›› 2022, Vol. 43 ›› Issue (4): 707-714.DOI: 10.11996/JG.j.2095-302X.2022040707

• 计算机图形学与虚拟现实 • 上一篇    下一篇

基于虚拟光源的实时半透明材质渲染

  

  1. 四川大学计算机学院，四川 成都 610065
  • 出版日期:2022-08-31 发布日期:2022-08-15
  • 通讯作者: 张严辞(1975)，男，教授，博士。主要研究方向为计算机图形学与虚拟现实等
  • 基金资助:
    国家重大项目(GJXM92579)

Virtual light-based translucent material rendering in real-time

  1. Computer Science Department, Sichuan University, Chengdu Sichuan 610065, China
  • Online:2022-08-31 Published:2022-08-15
  • Contact: ZHANG Yan-ci (1975), professor, Ph.D. His main research interests cover computer graphics, virtual reality, etc
  • Supported by:
    National Major Project of China (GJXM92579)

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摘要：

半透明材质渲染是实时渲染领域的重要研究部分。针对透射渲染依赖于准确的透射厚度计算，往往受限于场景模型和光照的复杂度问题，提出一种基于虚拟光源来计算半透明材质渲染中的透射厚度的方法。即在场景中增加一个虚拟光源，并在虚拟光源处使用排序算法来计算场景的深度信息。在计算从真实光源到着色点处的透射厚度时，提出在两者世界空间连线的直线段上进行采样，统计在物体内部的采样点占总采样点数目的比例，乘以直线段的长度得到估计结果。并且，当场景中存在多个真实光源时，基于采样的方法能够
复用虚拟光源中存储的场景深度信息。该算法能够有效地提升透射厚度计算的准确率，也能减轻场景中光源数量增多带来的显存开销问题。实验证明该方法能在效率、效果和显存开销之间取得较好的平衡。

关键词: 半透明材质渲染, 透射厚度, 虚拟光源, 排序算法, 多光源

Abstract:

Translucent material rendering is an essential part of the field of real-time rendering. Transmission rendering relies on the accurate calculation of transmission thickness and is often limited by the complexity of scene models and lighting. This paper proposed a virtual light-based method to calculate the transmission thickness in translucent material rendering. A virtual light was added to the scene, and the sorting algorithm was employed at the virtual light for the depth information of the scene. In calculating the transmission thickness from the real light source to the shading point, it was proposed to take samples on a straight line segment of the world space connecting the two points, calculate the proportion of sampled points inside the object to the total number, which was multiplied by the length of the straight line segment, thus obtaining the estimation. Moreover, in the case of multiple real light sources
in the scene, the sampling-based method could reuse the scene depth information stored in the virtual light. The proposed method could effectively enhance the accuracy of transmission thickness calculation, and reduce the memory overhead caused by the increasing number of light sources. Experiments show that the proposed method can strike a good balance between efficiency, effectiveness, and memory overhead.

Key words: translucent material rendering, transmission thickness, virtual light, sorting algorithm, multiple lights

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