Copy/Pasta's from a post I made in a similar thread. What I've found so far:
The line with the main difference for shadow quality is fShadowDistance
Ultra default is =8000 but gives incredibly blocky shadows. Reducing this value to =500 gives you amazingly detailed shadows, the best I've ever seen in a game, but also significantly reduces the draw distance of shadows to about 15 feet away from the player, so also looks awful really.
I've tried playing around with the shadow map size, assuming that the game generates a shadow map, and then layers it over the size of the gameworld designated by fShadowDistance, meaning smaller sizes allow the shadow map to be concentrated and detailed, and larger sizes mean it gets stretched out over a larger area, leading to blocky edges. That was my theory, but it didn't work. Doubling the shadow map size to 8192 did nothing...
I still think it must work like this in some way, as I can't think of any other explanation as to why the shadows get so detailed when they're layered over a much smaller area. I just can't work out how to increase the shadow map size along with the draw distance.
