Subdivision Next-Event Estimation for Path-Traced Subsurface Scattering

We present an unbiased Monte Carlo technique for sampling high frequency illumination through a geometrically complex refractive interface enclosing a scattering medium. This situation is difficult to handle efficiently and is a common source of image noise. Based on the incoming light at a chosen surface point, we place an intermediate path vertex within the medium to form a two-bounce connection to the light that satisfies the law of refraction.