Which shadowing technique should I use in wide environments?

I'm programming a 3D OpenGL game with wide environments (mountains) procedurally generated (perlin noise derivates). I would like to have advices regarding the shadow techniques you would use 开发者_开发百科(shadow mapping derivates like perspective mapping? shadow volumes?).

Thanks :)

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For heightfield I recommend horizon mapping. For each heightfield point you store the azimuth→elevation to the horizon. There are several approaches to do this, but what I found to work well is storing circular harmonics parameters. With just 8 scalar values (layers in a single component 2D texture array) you get a pretty accurate model of the horizon per heightfield datapoint.