Hi I would like to add shadow maps to my out-door scene. The problem is that since the visible area is large, the result is very grainy. What can I do to improve the visual quality of the shadows?

Cascaded shadow Maps, also known as Parallel-Split Shadow Maps (a google search on Cascaded Shadow Maps yields good results). The basic idea is you render multiple shadow maps for a given light, with successively larger frusta (providing worse resolution the further out you get, but catching more objects); when sampling the shadow maps ("receiving" shadow) you sample the maps based on the view distance, so if you're far away, you sample the shadow map with lower resolution (and vice versa for closer objects, which sample the maps with higher resolution).

Thanks, thats what I was looking for.