The Shadow Map shader creates a .tiff image of the shadow to be projected as the shadow map. You can manipulate this .tiff in the Texture settings.
The two Texture Type settings that can be used with the Shadow Map shader are Shadow Map and Light Map
The Light Area field contains settings that let you create soft shadows in your scene.
Enter a value in the Sample Count field to create a more precise map of the lighted area. The more light area sampled, the longer the generating time, and the better the resolution.
The default Sample Count is 3.
The Radius determines the light radius distribution (in centimeters) for all the light in a scene. A larger radius results in a larger penumbra, which is the space between perfect shadow and full light.
You must use Generate Map to view the results of Radius and Sample Count. Generate Preview Map does not show changes.