My game needs a terrain, the requirements are:
- Freely Zoom in & zoom out, like GoogleEarth. Max resolution when zooming in ~100 meter, Max range when zooming out ~2000km (a whole country scale).
- Freely fly over to any direction with any height; Freely rotate camera; Framerate should not a bottleneck for all those basic camera movement.
- Support large heightmap data. I got mine real world elevation data from NASA with 7.5arc resolution, around 30k * 15k for a whole country.
- Also I need to consider the spherical earth surface curvature other than using a planar map. But this should be easy if I just map each vertex into spherical coordinates. I am not build the whole planetary LOD so it's not even a problem.
I noticed there are many different LOD algorithm out there. For example:
- ROAM: very classic algorithm, most done on CPU;
- Geomipmapping: store the whole heightmap with best resolution as vertex buffer, with different LOD in vertex index. Then determine LOD and draw range in vertex index at runtime.
- Geo Clipmapping: I am feeling excited about this one since it claims to load all 200k * 100k US heightmap into video card memory and compressed ~300M, it seems to meet all my requirements. see source paper. And this is paper in 2004 and think about the video card at that time!
That's pretty much all I know about terrain LOD. I am not familiar recently study/research in this area. Is Geo clipmapping my best option? What else algorithms are also useful to consider?