Achieving interactivity for applications with physically-accurate caustics is proven to be a challenging task. We present a hybrid method utilizing ray tracing and rasterization which enables water caustic coverage to vast view distance in real-time. Inspired by photon mapping, we optimize the generation of photons using cascaded caustic maps to avoid tracing the first bounce of a ray from a light, replacing that step with rasterization. We introduce cascades as a set of caustic maps with varying resolution based on the distance from the viewer. In addition, since we adopt a splatting approach where each photon is rasterized into the image based on the extent of its contribution, we trace photon differentials in order to determine the size, shape and intensity of the splats so as to achieve adaptive anisotropic flux density estimation. Finally, to mitigate undersampled regions where lack of photons leads to noise, we propose the use of a cross-bilateral filter with an adaptive kernel radius. The radius is based on the perceived radiant energy of a photon relative to the scene’s luminance, and drastically improves performance. We demonstrate how the use of our method is able to perform interactive rendering of large-scale dynamic water caustics.

事实证明，为具有物理精确焦散的应用程序实现交互性被证明是一项具有挑战性的任务。我们提出了一种利用光线追踪和光栅化的混合方法，该方法可以实时将水焦散覆盖到广阔的视距。受光子贴图的启发，我们使用级联焦散贴图优化光子的生成，以避免追踪光线的第一次反弹，并用光栅化代替该步骤。我们将级联作为一组焦散贴图引入，这些焦散贴图根据与观察者的距离具有不同的分辨率。此外，由于我们采用了 splatting 方法，其中每个光子根据其贡献的程度被光栅化到图像中，我们跟踪光子差异以确定 splats 的大小、形状和强度，从而实现自适应各向异性通量密度估计。最后，为了减轻缺乏光子导致噪声的欠采样区域，我们建议使用具有自适应内核半径的交叉双边滤波器。半径基于光子相对于场景亮度的感知辐射能量，并显着提高性能。我们演示了如何使用我们的方法能够执行大规模动态水焦散的交互式渲染。