Path Tracing RBF Particle Volumes

Particle volume data are common in scientific computing applications such as cosmology and molecular dynamics, and increasingly in smoke and fluid animations. Path tracing particle data directly has historically proven challenging; most existing approaches rely on conversion to structured volumes, proxy geometry such as slicing or splatting, or special techniques optimized for ray casting but not path tracing. However, it remains desirable to render particles without simplification and with full control over the volume reconstruction filter, in a manner consistent with increasingly ubiquitous ray tracing APIs. In this chapter, we detail a method for quickly traversing, sampling, and path tracing particle volumes using a radial basis function (RBF) model, implemented using the Intel Open Volume Kernel Library (VKL) and OSPRay rendering framework but suited for general ray tracing hardware and software APIs.