Visibility Silhouettes for Semi‐Analytic Spherical Integration
Visibility Silhouettes for Semi‐Analytic Spherical Integration
复制标题
半解析球面积分的可见性轮廓
DOI：
10.1111/cgf.12257
复制
发表时间：
2014
影响因子：
2.5
通讯作者：
Wojciech Jarosz
中科院分区：
文献类型：
--
作者：
D. Nowrouzezahrai;Ilya Baran;Kenny Mitchell;Wojciech Jarosz
在每个着色点处，球形可见性函数在所有方向上对来自周围几何体的遮挡进行编码。计算这个函数是困难的和点采样的方法，如光线跟踪或硬件阴影映射，传统上被用来有效地近似它。我们提出了一个半解析的解决方案的问题，其中的球形轮廓的可见性是使用搜索的场景的4D对偶网格计算。一旦计算完成，我们就能够半解析地沿着可见性轮廓沿着积分可见性掩蔽的球面函数，而不是在整个半球上。通过这种方式，我们避免了使用点采样策略来整合可见性所产生的伪影，这是一个具有无限频率内容的函数。我们在几个应用程序上演示了我们的方法，包括来自真实照明的直接照明和预先计算的辐射传输数据的计算。此外，我们提出了一种新的频率空间方法，用于精确计算漫射表面上的所有频率阴影。我们的结果与使用重要性采样分层蒙特卡罗射线追踪计算的地面实况相匹配，在具有低到中等几何复杂度的场景中具有相当的性能。
At each shade point, the spherical visibility function encodes occlusion from surrounding geometry, in all directions. Computing this function is difficult and point‐sampling approaches, such as ray‐tracing or hardware shadow mapping, are traditionally used to efficiently approximate it. We propose a semi‐analytic solution to the problem where the spherical silhouette of the visibility is computed using a search over a 4D dual mesh of the scene. Once computed, we are able to semi‐analytically integrate visibility‐masked spherical functions along the visibility silhouette, instead of over the entire hemisphere. In this way, we avoid the artefacts that arise from using point‐sampling strategies to integrate visibility, a function with unbounded frequency content. We demonstrate our approach on several applications, including direct illumination from realistic lighting and computation of pre‐computed radiance transfer data. Additionally, we present a new frequency‐space method for exactly computing all‐frequency shadows on diffuse surfaces. Our results match ground truth computed using importance‐sampled stratified Monte Carlo ray‐tracing, with comparable performance on scenes with low‐to‐moderate geometric complexity.