Everyone wants to make a terrain engine. We all dream about being able to create a Skyrim or Arma landscape so we can realise our crazy visions for interactive mega worlds. Not surprised you made one too!
The only system I know if is "Chunked LOD" where the map is split into loads of meshes, each with different levels of detail and the closer you get to them, the more detail they show. Is that how Blitz terrain works?
There are a bunch of things I don't like about that:
1) You have to have all these premade meshes, or you make a load of meshes on the fly from height data.
2) Large portions of the map suddenly change their geometry, resulting in noticeable detail changes.
3) There are issues with the seams between different meshes which seems tricky to resolve.
This system seems to avoid all of those issues. Only thin lines are updated as the camera moves, reducing noticeable geometry changes. Also there is just the one set of meshes in memory which are updated, and since all the meshes are connected already (have touching vertices), there are no seam issues.
Two negatives are:
1. It is really only for FPS or "Close to ground" games, because the meshes directly beneath the camera will always have full detail. This isn't much of an issue, but it isn't as efficient as a chucked lod system, which would reduce detail on that mesh as you went up.
2. It has a finite draw distance, where as chunked LOD could show the whole map. This is limited by the meshes made.
3. Also, as you said, there is definitely a performance overhead with having to update the meshes. This is really negligible though, as shown in the 1500fps frame rate.
The other positive is the landscape can be as big as the heightmap you can store, since there is no extra mesh data for larger maps.
Here's a quick wireframe example.
