Methods for rendering a 3D object includes determining incident illumination for object surface points, determining surface colors associated with these points, determining diffuse illumination values associated with these points, associating a 3D grid having vertices the object, determining input scattering values for the vertices from the incident illumination and the surface colors associated with these points, low pass filtering the input scattering values to determine modified scattering values for the vertices, determining output scattering values for these points from the modified scattering values for the vertices, and determining reflected illumination values for these points from the output scattering values, surface material colors, and incident illumination for these points