We describe an approach for rendering large terrains in real-time. A digital elevation map defines the rough shape of the terrain. During rendering, procedural geometric and texture detail is added by the graphics hardware. We show, how quad meshes can be generated quickly that have a locally varying resolution that is optimized for the inclusion of procedural detail. We obtain these distorted meshes by importance based warping of geometry images. The resulting quad mesh can then be rendered very efficiently by graphics hardware, which also adds all visible procedural detail using vertex and fragment programs. Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Picture/Image GenerationDisplay algorithms; I.3.7 [Computer Graphics]: Three-Dimensional Graphics and RealismVirtual Reality;