In this paper we present a method to achieve interactive rendering of smooth terrain based on coarse data. Therefore we use adaptive subdivision surfaces which are calculated on the fly by using information from the directed edge based mesh of the previously rendered frame and throwing away triangles not used any longer. This way we are able to gain fast, high quality meshes which are refined depending on the point of view with marginal memory consumption. Additionally, this technique is compatible to traditional data structures like progressive meshes.