Normalized diffusion profile for subsurface scattering rendering

A subsurface scattering rendering shader using a normalized diffusion profile for realistic skin/translucent material rendering (Burleys Principled BSDF work).

The disclosure provides an approach for rendering images which include subsurface scattering effects. In one aspect, a shader computes subsurface scattering effects via a ray-tracing or point-based technique using a normalized diffusion profile. The shader may use the inverse of a cumulative density function associated with the normalized diffusion profile todetermine, for each ray intersecting the surface, points on the surface at which to evaluate the normalized diffusion profile. To determine the lit surface of a pixel due to subsurface scattering, the shader may multiply the result of the integral of the normalized diffusion profile for each of the R, G, and B color components by corresponding components ofa diffuse color constant. Further, the shader may scale the integral of the normalized diffusion profile based on a scaling function which accounts for a forward-scattering natureof a medium and compensates for out-of-plane scattering.

BRIEF DESCRIPTION OF THE DRAWINGS(1) So that the manner inwhich the above recited aspects are attained and can be understood in detail, a more particular description of aspects of the disclosure, briefly summarized above, may be had by reference to the appended drawings.(2) It is to be noted, however, that the appended drawings illustrate only typical aspects of this disclosure and are therefore not to be considered limiting of its scope.(3) FIG. 1 illustrates an approach for determining subsurface scattering effects.(4) FIG. 2 illustrates a method for rendering an image which includes subsurface scattering effects using a normalized diffusion profile.(5) FIG. 3 illustrates an alternative method for rendering an image which includes subsurface scattering effects using a normalized diffusion profile.(6) FIG. 4 is a block diagram of a system configured to implement one or more aspects of the disclosure.DETAILED DESCRIPTION(7) FIG. 1 illustrates an approach for determining subsurface scattering effects. As shown in panel A, a light ray 102 which is incident on the surface of a media 100 enters the volume 100 and scatters within the volume 100 before exiting in part as light ray 104, which a viewer 105 (e.g., a camera) sees. Although only one scattering path 103 is depicted, multiple subsurface scattering events may occur along different paths in the volume 100, with light from such scattering events transported through the volume 100 and outgoing at multiple points and in multi