1. A computer-implemented method for rendering a 3D scene, comprising: receiving, by a rendering application executing on a processor, geometry of the scene; for each of a plurality of shade points in the scene: determining a visibility silhouette by determining contour edges and by determining visibility silhouette edges from the contour edges, wherein the visibility silhouette edges define boundaries between visible and occluded regions from a perspective of the shade point and wherein the visibility silhouette edges are determined based on changes in value of an overlap function at intersections between the contour edges and u-isolines of a parameterization, wherein the contour edges are projected onto an octahedron, wherein the parameterization is of the octahedron, wherein the overlap function indicates whether geometry is intersected by a ray originating from the shade point, and wherein the u coordinate of the octahedral parameterization is the x coordinate of the octahedron equation |x|+|y|+|z|=1, and determining a spherical visibility-masked integral, wherein spherical visibility in the integral is represented by the visibility silhouette; and accelerating a rendering of the scene using, at least in part, one or more of the spherical visibility masked integrals of the shade points.