Hye,
I am not programmer, so I can just share you my idea. It is about LOD for terrain/floor related to mesh crunching/reducing.
Around the character, a circular map (with a LOD definied diameter). A terrain made from two height maps. The first height map has constructed the base mesh of the terrain. The second height map works in the circular area. The seocnd height map is a more definied one. In the circular area, the terrain mesh is subdivied and the zsecond height map is apply here.
Kind of mask/alpha working and mesh definition application. It supposes the gmae engine is able to subdive the base mesh.
Do you know what I mean ?