论文标题
将线性转化的余弦带到各向异性GGX
Bringing Linearly Transformed Cosines to Anisotropic GGX
论文作者
论文摘要
线性转化的余弦（LTC）是一个分布家族，由于其分析集成属性，用于实时区域遮盖。现代游戏引擎使用无处不在的GGX模型的LTC近似，但是当前仅存在各向同性GGX的近似值，因此不支持各向异性GGX。尽管较高的维度本身提出了挑战，但我们表明，在各向异性案例中安装，后处理，存储和插值LTC时会出现其他一些问题。这些操作中的每一个都必须仔细进行，以避免渲染工件。我们通过引入和利用LTC的不变性特性来找到每个操作的强大解决方案。结果，我们获得了一个小$ 8^4 $查找桌，该表为各向异性GGX提供了合理且无伪影LTC的近似值，并将其带入实时区域浅色阴影。
Linearly Transformed Cosines (LTCs) are a family of distributions that are used for real-time area-light shading thanks to their analytic integration properties. Modern game engines use an LTC approximation of the ubiquitous GGX model, but currently this approximation only exists for isotropic GGX and thus anisotropic GGX is not supported. While the higher dimensionality presents a challenge in itself, we show that several additional problems arise when fitting, post-processing, storing, and interpolating LTCs in the anisotropic case. Each of these operations must be done carefully to avoid rendering artifacts. We find robust solutions for each operation by introducing and exploiting invariance properties of LTCs. As a result, we obtain a small $8^4$ look-up table that provides a plausible and artifact-free LTC approximation to anisotropic GGX and brings it to real-time area-light shading.
