Penumbras and hotspots

The goal in this recipe will be to achieve a nice resolution shadow with a convincing shadow Falloff. As we've seen, not all of the available lighting solutions support penumbras. If you are not sure what a penumbra is, place the tip of your finger on the table and look at the shadow your hand casts. Around the tip of the finger the shadow will look darker and sharper than it looks as the distance between the table and your hand increases. Hotspots, the bright part of a spotlight, also have a penumbra caused by distance from the light to the surface. What causes the penumbra? Since the source of light is not an absolute point but in fact a surface, the angle of light isn't really coming from one place. Not all of the light is blocked equally around an object's edges, which leads to soft gradients in the shadow.

Before we begin, it is strongly suggested that the initial step when delving into shadow casting in UDK would be to look over the documentation provided by Epic...