A gameobject located in a poly which belong to the navigation mesh. I found when it move on this poly, the height(y) value is changing. However the change is small (< 0.5), but in geometry view, the y value of any point on a poly should be exactly same. My question: 1. Does game object locate on the navigation mesh surface or something else? 2. The blue surfaces which show the navigation mesh is the real mesh which unity3d use or it just a simplification. If it just a simplification, that can explain the y value changing because gameobject cross triangles which in real mesh. But those triangles not show in UI.