Patch-based Terrain LOD:

Here is a project that utilizes my custom game engine Ludibrium. It is a patch-based terrain LOD algorithm that reads in a heightmap and chunks the terrain into 32x32 chunks. A set of index buffers is created that samples the chunk at each power of two less the original size down to 2x2, i.e. 32x32, 16x16, etc. The terrain is then stitched together using special index buffers to avoid the infamous T-junction. The terrain is frustum culled and the lowest LOD level chunks are all rendered together in one batch to maximize throughput.

Notice how the detail on the foreground peak is preserved. Here is a composite shot showing the LOD in action. This is a different view of the same terrain as the previous screenshot with the frustum locked.