I have actually encountered that method before and really liked it, but I want players to be able to enter the planet’s playable surface area from any point. This game is going to be multiplayer and if it weren’t for that, I could probably just stream in the playable area with a transform that places it where the player is going to enter, but if I implemented this in multiplayer, nobody’s position would be correct relative to other clients.
Another idea I had to possibly make it work would be to have some kind of transition effect happen between rendering levels. In a tutorial I found for accomplishing something very similar, they applied a circular mask to the more detailed surface area which blended ut the edges, making a smoother transition between that area and the larger model. That made me wonder if I could do some kind of crossfade effect starting from the center of the screen and moving out, or maybe even just a regular crossfade, as I open the ground level instead of having a stark level switch. But, I have no idea how to go about this either and my research has come up very short.
All of this is why I began considering spherical levels, but figuring out the crossfade effect, or some other way to get a system like the one they showed off with the sky and atmosphere to work from any approach and in multiplayer, would be ideal.