Rendering Multiply Scattered Light Beam Shafts Using Narrow Beam Approximation

抄録

Lighting phenomena in participating media play important roles in many scenes. For its realistic rendering, it is necessary to simulate multiple light scattering in the media. This paper proposes an efficient and reasonably accurate method simulating multiply scattered light emitted from spot or beam light sources. This method utilizes the narrow beam theory, which analytically approximates multiple scattering phenomena for concentrated beam light sources. Although its naive straight-forward application does not allow satisfactory image synthesis, we successfully adopted the theory into a ray-marching scheme and obtained much improved results. Further, we discussed sampling issues to reduce aliasing artifacts and proposed an adaptive sampling scheme and an analytic filtering method. The method was successfully applied to shaft-of-light rendering.