Looking for some advice on shadow mapping algorithms. Currently working on this game, shadowing is a very important visual effect for the planet-based levels. I recently implemented variance shadow mapping with cascaded shadow maps. To my dismay I'm struggling with some awful visual artifacts: I believe the primary cause of this is that I'm not rendering the terrain into the shadow map. While I've found some ways to mask these effects, I have not found a silver bullet and the shadows are often detracting from the visual fidelity of the planet.
The terrain is generated from a ridiculous fractal noise equation, thus actually drawing the terrain into the shadow maps is impractically expensive. I suspect due to these issues VSM is ill-suited for my game. Are there similar soft shadow mapping approaches that do not require drawing the terrain into the shadow map that might be better choices?