Soft Shadows

The soft shadow effect is obtained by using non-point light sources and by shooting multiple shadow rays from intersection points. Planar light sources are used, and the shadow rays are shot across the surface of the light in a jittered grid pattern. The percent of the rays that hit the light determine how much of the light is visible from the intersection point and so how much of the colour at the intersection point is visible.

Basic point light source with hard shadows.

Planar light source with shadow grid size of 1.

Planar light source with shadow grid size of 2.

Planar light source with shadow grid size of 3.

Planar light source with shadow grid size of 4.

Planar light source with shadow grid size of 5.

Planar light source with shadow grid size of 4 and anti-aliasing.