There were several new innovative shadow map techniques that promised soft shadow. There are Variance shadow map, and Exponential shadow map.
They are using 32bit floating point surfaces and they assumes they work with linear hardware filter. Unfortunately PlayStation3 does not support linear nor bilinear filter for 32bit floating point surface. How am I supposed to get soft shadow?My final choice was a little bit modified version of Percentage Closer Filter, which means I fall back to the bottom line. I modified it to mimic the bilinear filter.
I am not quite happy because I cannot get any benefits from new hardware accelerations. But it seems to work fairly good.
*PS: The screenshot it from here.