MightyTerrainMesh
A Unity Plugin for Converting Terrain 2 Mesh with LOD & QaudTree infomation.
There are some introduction & result here :
https://zhuanlan.zhihu.com/p/64809281
And thanks for parahunter, I used his triangle-net-for-unity as the tessellation solution.
Update At 8th Oct. 2020
An Terrain to Mesh tool has been added into this plugin, for details, pls refer to